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ANATOMY, 


DESCRIPTIVE   AND   SURGICAL. 


BY 

HENEY  [QJRAY,  F.R.S., 

FELLOW  OF  THE  ROYAL  COLLEGE  OF  SURGEONS  AND  LECTURER  ON  ANATOMY  AT 

ST.  George's  hospital  medical  school. 


THE  DEAWINGS  BY  H.  V.  CARTER,  M.D., 

LATE  DEMONSTRATOK  OF  ANATOMY  AT  8T.  QEOKOE's  HOSPITAL. 

WITH  ADDITIONAL  DRAWINGS  IN  THE  SECOND  AND  LATER  EDITIONS 
BY  DR.  WESTMACOTT. 

THE  DISSECTIONS  JOINTLY  BY  THE  AUTHOR  AND  DR.  CARTER. 

WITH  AN  INTRODUCTION  ON  GENERAL  ANATOIY  AND  DEVELOPMENT, 


BY 

T.  HOLMES,  M.A.  Cantab. 

SURGEON  TO  ST.  GEORGE'S  HOSPITAL  ;    MEM.  COEBESP.  DE  LA  SOC.  DE   CHIR.  DE  PARIS. 

A    NEW    AMERICAN 

FROM    THE 

FIFTH   AND   ENLARGED   ENGLISH   EDITION. 


FOUR   HUNDRED   AND   SIXTY-TWO   ENGRAVINGS  ON    WOOD. 


PHILADELPHIA: 

HEITEY     O.     LEA. 

1870. 


AMERICAN  PUBLISHER'S  NOTICE. 


The  present  edition,  like  the  previous  American  reprints,  has 
been  passed  through  the  press  under  the  supervision  of  Dr. 
Richard  J.  Dunglison,  who  has  carefully  corrected  whatever 
errors  had  escaped  the  attention  of  the  author,  and  has  made  such 
changes  in  the  typographical  arrangement  as  seemed  calculated  to 
render  the  volume  more  convenient  for  consultation  and  reference. 
A  few  illustrations  have  also  been  introduced  in  the  introductory 
section.     They  will  be  found  distinguished  by  inclosure  in  brackets. 

Maech,  18T0. 


(iv  ) 


PREFACE  TO  THE  FIFTH  EDITION. 


In  this  edition  the  plan  of  the  work  has  been  so  far  altered  that  the  portion 
on  General  Anatomy,  which  was  previously  scattered  throughout  the  book, 
has  been  collected  into  an  Introductory  Chapter,  and  re-written,  so  as  to  fur- 
nish the  Student  with  a  very  succinct,  but  it  is  hoped  sufficient,  introduction 
to  the  study  of  Microscopic  Anatomy ;  and  to  this  has  been  added  a  short 
description  of  the  chief  processes  of  the  development  of  the  ovum,  and  of  the 
structures  characteristic  of  the  foetal  state :  a  subject  which,  though  undeni- 
ably an  integral  portion  of  Human  Descriptive  Anatomy,  was  passed  over  in 
previous  editions. 

This  Introduction  is  inserted  in  deference  to  the  opinions  of  persons  very 
competent  to  judge,  and  who  believe  that  some  such  addition  is  necessary  to 
the  completion  of  Gray's  "Anatomy."  It  is  not  intended,  however,  to  super- 
sede or  to  trench  upon  the  Treatises  on  Physiolog}",  nor  to  go  minutely  into 
the  more  recondite  and  more  dubious  parts  of  microscopic  research.  Nor, 
again,  is  it  intended  to  give  any  account  in  this  work  of  vital  phenomena. 
Such  phenomena  are  purely  within  the  domain  of  the  physiologist.  Conse- 
quently all  the  ingenious  and  beautiful  researches  by  which  modern  micro- 
scopists  (as  Strieker,  Von  Recklingshausen,  Beale,  and  others)  have  attempted 
to  investigate  the  living  tissues,  lie  beyond  the  scope  of  such  a  treatise  as  this. 
The  humble  aim  of  the  following  pages  is  to  provide  the  Student — in  the 
smallest  compass,  and  in  the  simplest  language — with  a  plain  account  of  things 
for  the  most  part  universally  admitted,  and  which,  with  moderate  pains,  he 
can  succeed  in  demonstratmg  for  himself.  In  order  to  make  such  verbal 
descriptions  intelligible,  figures  are  necessary :  but  it  appeared  useless  to 
manufacture  new  drawings  of  things  which  are  quite  faithfully  represented  by 
authors  who  are  in  everybody's  hands ;  and  therefore  all  the  illustrations  to 

(V) 


vi  PREFACE    TO    THE    FIFTH    EDITION. 

the  chapter  on  General  Anatomy  have  been  borrowed  from  the  English  trans- 
lation of  Kolliker's  "Manual  of  Human  Microscopic  Anatomy,"  from  the 
"  Entwicklungsgeschichte"  of  the  same  author,  Todd  and  Bowman's  "  Physi- 
ology," Harley  and  Brown's  "  Demonstrations  of  Microscopic  Anatomy,"  and 
other  well-known  works :  the  source  of  the  drawings  having  been  in  each  case 
acknowledged  in  the  Table  of  Contents. 

The  text  has  been  further  expurgated  from  errors  of  the  press;  and  the 
Editor  has  to  acknowledge  his  obligations  in  this  particular  to  his  friend  Pro- 
fessor Darling,  of  New  York,  and  to  Mr.  Matthews,  of  Kirkdale,  who  have 
been  kind  enough  to  point  out  several,  and  some  of  them  important,  clerical 
errors  which  had  escaped  notice  in  previous  revisions. 

31  Clakges  Street:  September,  1869. 


PEEFACE  TO  THE  FIEST  EDITION. 


This  work  is  intended  to  furnish  the  Student  and  Practitioner  with  an 
accurate  view  of  the  Anatomy  of  the  Human  Body,  and  more  especially  the 
application  of  this  Science  to  Practical  Surgery. 

One  of  the  chief  objects  of  the  Author  has  been,  to  induce  the  Student  to 
apply  his  anatomical  knowledge  to  the  more  practical  points  in  Surgery,  by 
introducing,  in  small  type,  under  each  subdivision  of  the  work,  such  observa- 
tions as  show  the  necessity  of  an  accurate  knowledge  of  the  part  under 
examination. 

Osteology.  Much  time  and  care  have  been  devoted  to  this  part  of  the  work, 
the  basis  of  anatomical  knowledge.  It  contains  a  concise  description  of  the 
anatomy  of  the  bones,  illustrated  by  numerous  accurately-lettered  engravings 
showing  the  various  markings  and  processes  on  each  bone.  The  attachments 
of  each  muscle  are  shown  in  dotted  lines  (after  the  plan  recently  adopted  by 
Mr.  Holden),  copied  from  recent  dissections.  The  articulations  of  each  bone 
are  shown  on  a  new  plan ;  and  a  method  has  been  adopted,  by  which  the 
hitherto  complicated  account  of  the  development  of  the  bones  is  made  more 
simple. 

The  Articulations.  In  this  section,  the  various  structures  forming  the  joint 
are  described  ;  a  classification  of  the  joints  is  given ;  and  the  anatomy  of  each 
carefully  described :  abundantly  illustrated  by  engravings,  all  of  which  are 
taken  from,  or  corrected  by,  recent  dissections. 

The  Muscles  and  Fascise.  In  this  section,  the  muscles  are  described  in  groups, 
as  in  ordinary  anatomical  works.  A  series  of  illustrations,  showing  the  lines 
of  incision  necessary  in  the  dissection  of  the  muscles  in  each  region,  are  intro- 
duced, and  the  muscles  are  shown  in  fifty-eight  engravings.  The  Surgical 
Anatomy  of  the  muscles  in  connection  with  fractures,  of  the  tendons  or  muscles 
divided  in  operations,  is  also  described  and  illustrated. 

The  Arteries.  The  course,  relations,  and  Surgical  Anatomy  of  each  artery 
are  described  in  this  section,  together  with  the  anatomy  of  the  regions  contain- 
ing the  arteries  more  especially  involved  in  surgical  operations.  This  part  of 
the  work  is  illustrated  by  twenty-eight  engravings. 

(  vii  ) 


vui  PREFACE    TO    THE    FIRST    EDITION. 

The  Veins  are  described  as  in  ordinary  anatomical  works  ;  and  illustrated  by 
a  series  of  engravings,  showing  those  in  each  region.  The  veins  of  the  spine 
are  described  and  illustrated  from  the  well-known  work  of  Breschet. 

The  Lymphatics  are  described,  and  figured  in  a  series  of  illustrations  copied 
from  the  elaborate  work  of  Mascagni. 

The  Nervous  System  and  Organs  of  Sense.  A  concise  and  accurate  description 
of  this  important  part  of  anatomy  has  been  given,  illustrated  by  sixty-six 
engravings,  showing  the  spinal  cord  and  its  membranes ;  the  anatomy  of  the 
brain,  in  a  series  of  sectional  views ;  the  origin,  course,  and  distribution  of  the 
cranial,  spinal,  and  sympatheti-o  nerves;  and  the  anatomy  of  the  organs  of 
sense. 

The  Viscera.  A  detailed  description  of  this  essential  part  of  anatomy  has 
been  given,  illustrated  by  fifty-five  large,  accurately  lettered  engravings. 

Regional  Anatomy.  The  anatomy  of  the  perineum,  of  the  ischio-rectal  region, 
and  of  femoral  and  inguinal  hernias,  is  described  at  the  end  of  the  work;  the 
region  of  the  neck,  the  axilla,  the  bend  of  the  elbow,  Scarpa's  triangle,  and 
the  popliteal  space,  in  the  section  on  the  arteries ;  the  laryngo-tracheal  region, 
with  the  anatomy  of  the  trachea  and  larynx.  The  regions  are  illustrated  by 
many  engravings. 

Microscopical  Anatomy.  A  brief  account  of  the  microscopical  anatomy  of 
some  of  the  tissues,  and  of  the  various  organs,  has  also  been  introduced. 

The  Author  gratefully  acknowledges  the  great  services  he  has  derived  in  the 
execution  of  this  work,  from  the  assistance  of  his  friend,  Dr.  H.  V.  Carter,  late 
Demonstrator  of  Anatomy  at  St.  George's  Hospital.  All  the  drawings  from 
which  the  engravings  were  made,  were  executed  by  him.  In  the  majority  of 
cases,  they  have  been  copied  from,  or  corrected  by,  recent  dissections  made 
jointly  by  the  Author  and  Dr.  Carter. 

The  Author  has  also  to  thank  his  friend,  Mr.  T.  Holmes,  for  the  able  assist- 
ance afforded  him  in  correcting  the  proof-sheets  in  their  passage  through  the 
press. 

The  engravings  have  been  executed  by  Messrs.  Butterworth  and  Heath ;  and 
the  Author  cannot  omit  thanking  these  gentlemen  for  the  great  care  and  fidelity 
displayed  in  their  execution. 


Wilton  Strkkt,  BEr.oRAVE  Square: 
August,  Iboti. 


CONTENTS. 


INTRODUCTION;  GENERAL  ANATOMY. 


The  Blood 

PAGE 
33 

Lymph  and  Chyle     .... 

37 

Cellular  and  Fibrous  Tissue    . 

38 

Adipose  Tissue         .... 

40 

Pigment 

41 

Cartilage 

41 

Fibro-cartilage 

43 

Yellow  or  Reticular  Cartilage  . 

44 

Bone 

4.T 

Development  of  Bone 

49 

Muscular  Tissue       .... 

53 

Nervous  Tissue        .... 

57 

The  Brain          .... 

60 

The  Spinal  Cord 

62 

The  Ganglia      .... 

64 

The  Nerves       .... 

65 

The  Sympathetic  Nerve    . 

66 

Terminations  of  Nerves    . 

66 

The  Vascular  System 

72 

The  Arteries     .... 

72 

The  Capillaries 

74 

The  Yeins         .... 

75 

The  Lymphatics 

77 

The  Lymphatic  Glands 

78 

The  Skin  and  its  Appendages 

78 

The  Nails          .... 

81 

The  Hairs         .... 

82 

The  Sebaceous  Glands 

83 

The  Sudoriferous  Glands  . 

84 

The  Epithelium        .... 

85 

Serous,  Mucous,  and  Synovial  Membranes 

8G 

Secreting  Glands      .... 

. 

87 

Growth  and  Development  of  the  Bo 

dy  • 

89 

Fecundation  of  the  Ovum 

89 

Formation  of  Germinal  Area 

and 

Chorda  Dorsalis     . 

, 

90 

Division  of  Blastodermic  Membrane 

90 

Parts  formed  from  each  layer  of  the 

Blastodermic  Membrane 
The  Amnion 
The  Allantois    . 
The  Umbilical  Yesicle 
The  Chorion      . 
The  Decidua 
The  Placenta    . 
The  Umbilical  Cord  . 
The  Earliest  Condition  of  the  Embryo 
Development  of  the  Yarious  Parts 
The  Spine         .... 
The  Cranium  and  Face 
The  Palate        .... 
The  Brain  .... 

The  Spinal  Marrow  and  Nerves 

The  Eye 

The  Ear 

The  Nose 

The  Skin,  Glands,  and  Soft  Parts 
The  Heart  and  Great  Yessels  . 
The  Alimentary  Canal  and  its  4-P 

pondages 

The  Respiratory  Organs   . 

The  Genito-urinary  Organs 

The  WolfiBan  Body    . 

The  Internal  Genital  Organs. 

Indifferent  type 

Female  Organs  . 

Male  Organs 

The  External  Genital  Organs 

Indifferent  type 

Female  Organs  . 

Male  Organs 

Chronological  Table  of  the  Development 

of  the  Foetus 


90 

91 

91 

93 

93 

93 

95 

96 

96 

97 

97 

97 

99 

99 

99 

101 

102 

102 

102 

103 

106 
107 
108 
108 

108 
109 
109 

109 
111 
111 

112 


ANATOMY,  DESCRIPTIVE  AND  SUEGICAL. 
The   Skeleton. 

Peculiar  Dorsal  Yertebras 
Characters  of  the  Lumbar  Yertebrae 
Structure  of  the  Yertebrte 
Development  of  the  Yertebrae 
Atlas 
Axis 

7th  Cervical 
Lumbar  Yertebrae 
Progress  of  Ossification  in  the  Spine 

Sacrum 

Coccyx     

Of  the  Spine  in  General . 

(ix 


The  Skeleton 

.    115 

Number  of  Bones     .... 

.     115 

Form  of  Bones         .... 

.     115 

The  Spine. 

General  Characters  of  a  Yertebra  . 

.    116 

Characters  of  the  Cervical  Yertebrae 

.     117 

Atlas 

.     118 

Axis 

.     119 

Vertebra  Prominens 

.    120 

Characters  of  the  Dorsal  Yertebrae 

.     121 

121 

123 
124 
124 
125 
125 
125 
125 
125 
126 
130 
131 


CONTENTS. 


The  Skull. 

Bones  of  the  Craniam 

Occipital  Bone  . 

Parietal  Bones  . 

Frontal  Bone    . 

Temporal  Bones 

Sphenoid  Bone 

Ethmoid  Bone  . 

Development  of  the  Cranium 

The  Fontanelles 

Wormian  Bones 

Congenital  Fissures  and  Gaps 
Bones  of  the  Face  : 

Nasal  Bones 

Superior  Maxillary  Bones 

Lachrymal  Bones 

Malar  Bones 

Palate  Bones    . 

Inferior  Turbinated  Bones 

Vomer       .... 

Inferior  Maxillary 

Changes  produced  in  the  Lower 
by  age    . 
Sutures  of  the  Skull 
Vertex  of  the  Skull 
Base  of  the  Skull,  Internal  Surface 
Anterior  Fossae 
Middle  Fossae 
Posterior  Fossae    . 
Base  of  Skull,  External  Surface 
Lateral  Region  of  the  Skull    . 
Temporal  Fossae 
Zygomatic  Fossaj     . 
Spheno-maxillary  Fossse  . 
Anterior  Region  of  the  Skull  . 

Orbits 

Nasal  Fossae    .... 
Os  Hyoides      .... 


Jaw 


The  TJwrax. 


The  Sternum 
The  Ribs 


PA  OB 

134 
134 
138 
140 
143 
149 
154 
156 
156 
157 
157 

158 
159 
163 
164 
166 
108 
169 
170 

174 
174 
176 
176 
176 
178 
179 
179 
183 
183 
184 
184 
184 
185 
187 
189 


190 
194 


Peculiar  Ribs   .... 

PAGB 

.     196 

Costal  Cartilages 

.     198 

The  Upper  Extremity. 

The  Clavicle     .... 

.    199 

The  Scapula     .... 

.     202 

The  Humerus  .... 

.     207 

The  Ulna          .... 

.     212 

The  Radius      .... 

.     217 

The  Hand         .... 

.     219 

The  Carpus      .... 

.     219 

Bones  of  Upper  Row 

.     219 

Bones  of  Lower  Row 

221 

The  Metacarpus 

'.     224 

Peculiar  Metacarpal  Bones 

.     225 

Phalanges        .... 

.     226 

Development  of  the  Bones  of  the  Hand  .     226 

The  Lower  Extremity. 

Os  Innorainatum 

.     227 

Ilium         .... 

.     228 

Ischium     .... 

.     230 

Pubes        .... 

.     232 

Development  of  the  Os  Innominatum    233 

The  Pelvis 

.     234 

Difference  between  the  Male  and  Fe- 

male Pelvis    . 

.    236 

The  Femur      .... 

.     237 

The  Leg 

.     242 

Patella 

.     242 

Tibia 

.     243 

Fibula       

.     247 

The  Foot 

.     249 

Tarsus 

.     249 

Os  Calcis          .... 

.     249 

Cuboid 

.     251 

Astragalus        .... 

.     253 

Scaphoid          .... 

.     254 

Cuneiform  Bone 

.     254 

Metatarsal  Bones 

.     256 

Phalanges         .... 

.     257 

Development  of  the  Foot 

.     358 

Sesamoid  Bones 

.     259 

The  Articulations. 


Structures  composing  the  Joints     .        .  260 

Articular  Lamella  of  Bone       .         .  260 

Ligaments 260 

Synovial  Membrane  ....  260 

Burs® 260 

Synovia 260 

Forms  of  Articulation 

Synarthrosis 262 

Amphiarthrosis         ....  262 

Diathrosis 262 

Movements  of  Joints       ....  265 

ArticiUations  of  the  Trunk. 

Articulations  of  the  Vertebral  Column   .  265 
Atlas  with  the  Axis  269 
Atlas  with  the  Occi- 
pital Bono    .        .  271 
Axis  with  the  Occi- 
pital Bono    .        .  272 
Tcmporo-maxillary  Artu-ulation       .        .  273 
Articulation  of  the  Ribs  with  the  Vertcbree  275 


Articulations   of  the   Cartilages  of   the 
Ribs  with  the  Sternum  and  Ensiform 

Cartilage 278 

Intercostal  Articulations          .        .         .  279 

Ligaments  of  the  Sternum       .        .        .  280 

Articulation  of  the  Pelvis  with  the  Spine  280 

Articulation  of  the  Sacrum  and  Ilium     .  281 
Ligaments  between    the  Sacrum  and 

Ischium 282 

Articulation  of  the  Sacrum  and  Coccyx  .  283 

Inter-pubic  Symphysis      ....  283 

Articulations  of  the  Upper  Extremity. 

Sterno-clavicular 285 

Scapulo-clavicular 2r^6 

Proper  Ligaments  of  the  Scapula  .        .  2^1 

Shoulder-joint 2^8 

Elbow-joint 2i^9 

Radio-ulnar  Articulations         .        .        .  291 

Wrist-joint 294 

Articulations  of  the  Carpus     .         .        .294 


CONTENTS. 


zi 


PAGK 

Carpo-metacarpal  Articulations  .  .  296 
Metacarpo-plialangeal  Articulations  .  298 
Articulation  of  the  Phalanges  .        .    298 

Articulations  of  the  Lower  Extremity. 

Hip-joint 299 

Knee-joint 301 


Articulations  between  the  Tibia  and  Fibula  305 

Ankle-joint 307 

Articulations  of  the  Tarsus     .         .        .  309 

Tarso-metatarsal  Articulations        .        .  312 

Articulations  of  the  Metatarsus       .         .  312 

Metatarso-phalano:eal  Articulations          .  313 

Articulations  of  the  Phalanges        .        .  313 


Muscles    and    Fasciae. 


General  Description  of  Muscle        .  .    314 

Tendon       .  .315 

Aponeurosis  .     315 

Fascia         .  .     315 

Muscles  and  FASCiiE  of  the  Head  and  Face. 


Subdivision  into  Groups  . 

Epicranial  Region. 

Dissection         .... 
Occipito-frontalis 


316 


317 
317 


Auricular 

Region. 

Dissection 

.    319 

AttoUens  Aurem 

.     319 

Attrahens  Aurem     . 

.    319 

Eetrahens  Aurem     . 

.     319 

Actions    . 

.     320 

Palpebral  Region. 

Dissection 

Orbicularis  Palpebrarum 

Corrugator  Supercilii 

Tensor  Tarsi    . 

Actions    .... 


Orbital  Region. 

Dissection 

Levator  Palpebrae    .        .  .        . 

Kectus  Superior,  Inferior,  Internus,  and 

Externus 

Superior  Oblique 

Inferior  Oblique       ..... 
Actions  :  Surgical  Anatomy    . 

Nasal  Region. 

Pyramid  alls  Nasi 

Levator  Labii  Superioris  Alisque  Nasi    . 
Dilatator  Naris,  Anterior  and  Posterior  . 

Compressor  Nasi 

Narium  Minor 
Depressor  Alae  Nasi        .... 
Actions 

Superior  Maxillary  Region. 

Levator  Labii  Superioris  Proprius  . 
Levator  Anguli  Oris        .... 

Zygomatici 

Actions 

Inferior  Maxillary  Region. 

Dissection 

Levator  Labii  Inferioris  .... 

Depressor  Labii  Inferioris 

Depressor  Anguli  Oris     .... 


320 
320 
320 
321 
321 


321 
321 

321 
322 
323 
323 


324 
324 
324 
324 
324 
324 
324 


325 
325 
325 
325 


325 
326 
326 
326 


Intermaxillary  Region. 
Dissection 
Orbicularis  Oris 
Buccinator 
Risorius    . 
Actions     • 

Temporo-maxillary  Region. 

Masseter 

Temporal  Fascia      .        . 
Temporal 

Ptery go-maxillary  Region. 

Dissection 

Internal  Pterygoid  .... 
External  Pterygoid  .... 
Actions 


Muscles  and  Fascia  of  the  Neck. 

Subdivision  into  Groups  .... 

Superficial  Region. 
Dissection 

Superficial  Cervical  Fascia 
Platysraa  Myoides    . 
Deep  Cervical  Fascia 
Sterno-cleido-mastoid 
Boundaries  of  the  Triangles  of  the  Neck 
Actions :   Surgical  Anatomy 

Infrahyoid  Region. 
Dissection 
Stern  o-hyoid 
Sterno-thyroid 
Thyro-hyoid 
Omo-hyoid 
Actions    . 

Suprahyoid  Region. 
Dissection 
Digastric  . 
Stylo-hyoid,  Mylo-hyoid,  Genio-hyoid 
Actions 

Lingual  Region. 

Dissection 

Genio-hyo-glossus 

Hyo-glossus 

Lingualis,  Stylo-glossus,  Palato-glossus   . 
Actions 

Pharyngeal  Region. 

Dissection 

Inferior  Constrictor,  Middle  Constrictor 
Superior  Constrictor        .... 

Stylo-pharyngeus 

Actions 


326 

326 
327 
327 
327 


327 
328 
328 


329 
329 
330 
330 


330 


331 
331 
331 
332 
332 
333 
334 


334 
334 
335 
335 
335 
336 


336 
336 
337 
337 


338 
338 
339 
339 
339 


540 
340 
341 

341 
341 


zii 


CONTENTS. 


Palatal  Region. 

FAOE 

Dissection 342 

Levator  Palati 342 

Circumflexus  or  Tensor  Palati         .        .  342 
Azygos  Uvulae,  Palato-glossus,   Palato- 

pharyngeus 343 

Actions  :  Surgical  Anatomy    .        .        .  344 

Vertebral  Region  {Anterior). 

Rectus  Capitis  Anticus  Major  and  Minor    344 

Eectus  Lateralis 344 

Longas  Colli 345 

Vertebral  Region  (Lateral). 

Scalenus  Anticus 346 

Scalenus  Medius,  Scalenus  Posticus        .    346 
Actions 346 

Muscles  and  FASciiE  of  the  Tkunk. 
Subdivision  into  Groups  ....     346 

Muscles  of  the  Back. 
Subdivision  into  Layers   ....    347 

First  Layer. 

Dissection 347 

Trapezius 347 

Ligamentum  Nuchae         ....  348 

Latissimus  Dorsi 348 

Second  Layer. 

Dissection 350 

Levator  Anguli  Scapulae  ....  350 

Rhomboideus  Minor  and  Major        .        .  350 

Actions 351 

Third  Layer. 

Dissection 351 

Serratus  Posticus  Superior  and  Inferior  .  351 

Vertebral  Aponeurosis    ....  352 

Splcnius  Capitis  and  Colli        .        .        .  352 

Actions 352 

Fourth  Layer. 

Dissection 354 

Erector  Spinas 354 

Racro-lumbalis 354 

Musculus  Accessorius  ad  Sacro-lumbalem  354 

Cervicalis  Ascendens       ....  354 

Longissimus  Dorsi 354 

Transversalis  Colli 355 

Trnchelo-inastoid 355 

Spiiialis  Dorsi 355 

Spinalis  Colli 355 

Complexus,  Biventer  Cervicis  .        .        .  355 

Fifth  Layer. 
Dissection 

Semispinalis  Dorsi  and  Colli 
Multilidus  Spinaj 
Kotatores  Spinw 
hupraspinales  . 
Interspinales    . 
Extensor  Coccygis 
Intertransversales 
Rectus  Capitis  Posticus  Major  and 
Obliquus  Inferior 
Obli(iiius  Superior 
Actions    . 


Muscles  of  the  Abdomen. 

Dissection 

Obliquus  Externus   . 

Obliquus  Internus    . 

Transversalis    . 

Lumbar  Fascia 

Rectus      .... 

Pyramidalis,  Quadratus  Lumborum 

Linea  Alba,  Lineae  Semilunares 

Lineae  Transversae     . 

Actions 


PAoa 
359 
359 
361 
362 
363 
364 
365 
365 
365 
365 


Muscles  and  Fascia  of  the  Thorax. 

Intercostal  Fasciae   .... 
Intercostales  Interni  et  Extern! 
Infra-costales,  Triangularis  Sterni    . 
Levatores  Costarum         ... 
Actions 


366 
366 
367 
367 
367 


Diaphragmatic  Region. 

Diaphragm 368 

Actions 370 

Muscles  and  Faci^  of  the  Upper  Extremity. 


Subdivision  into  Groups  . 

Dissection  of  Pectoral  Region  and  Axilla 

Fasciae  of  the  Thorax 

371 

k    372 

372 

Anterior  Thoracic  Region. 

Pectoralis  Major 
Costo-coracoid  Membrane 
Pectoralis  Minor     .... 

Subclavius 

Actions 

372 
374 
374 
375 
375 

Lateral  Thoracic  Region. 

Serratus  Magnus,  Actions        .        ^ 

376 

Acromial  Region. 
Deltoid,  Actions       .... 

377 

Anterior  Scapular  Region. 

Subscapular  Aponeurosis 
Subscapularis,  Actions     . 

377 
377 

Posterior  Scapular  Region. 

Supraspinous  Aponeurosis 
Supraspinatus  ..... 
Infraspiuous  Aponeurosis 

Infraspinatus 

Teres  Minor 

Teres  Major 

Actions 

378 
378 
378 
379 
379 
360 
380 

Anterior  Humeral  Region. 

Deep  Fascia  of  Arm 
Coraco-brachialis,  Biceps 
Brachialis  Anticus  .... 
Actions 

.    380 
381 
382 
382 

Posterior  Humeral  Region. 

Triceps 

Sub-anconeus   ..... 
Actions 

.     382 
.    383 
.    383 

Muscles  of  Forearm. 
Deep  Fascia  of  Forearm  . 


383 


CONTENTS. 


xui 


Anterior  Brachial  Region,  Superficial  Layer. 
Pronator  Radii  Teres       ....    384 


Flexor  Carpi  Radialis 
Palmaris  Longus 
Flexor  Carpi  Ulnaris 
Flexor  Digitorum  Sublimis 


384 
385 
385 
385 


Anterior  Brachial  Region,  Deep  Ijayer. 

Flexor  Profundus  Digitorura  .  .  .  386 
Flexor  Longus  Pollicis  ....  387 
Pronator  Quadratus         ....     387 


Radial  Region. 

.     d»» 

Dissection 

.    388 

Supinator  Longus     .... 

.     388 

Extensor  Carpi  Radialis  Longior    . 

.    388 

Extensor  Carpi  Radialis  Brevoir      . 

.    389 

Posterior  Brachial  Region,  Superficial  Layer. 

Extensor  Communis  Digitorura 

.     390 

Extensor  Minimi  Digiti  . 

.     390 

Extensor  Carpi  Ulnaris    . 

.     390 

Anconeus 

.     390 

Posterior  Brachial  Region,  Deep  Layer. 

Supinator  Brevis      .... 

.     391 

Extensor  Ossis  Aletacarpi  Pollicis   . 

.     391 

Extensor  Primi  Internodii  Pollicis  . 

.     391 

Extensor  Secundi  Internodii  Pollicis 

.     391 

.     392 

Actions 

.     392 

Muscles  and  Fascioe  of  the  Hand. 

Dissection 

.    393 

Anterior  Annular  Ligament    . 

.     393 

Posterior  Annular  Ligament    . 

.     393 

Palmar  Fascia         .... 

394 

Muscles  of  the  Hand. 

Radial  Group  ..... 

.     394 

Ulnar  Group 

396 

Middle  Palmar  Group 

.     397 

Actions 

.    398 

Surgical  Anatomy  of  the  Muscles  of 

the 

Upper  Extremity. 

Fractures  of  the  Clavicle 

399 

Acromion  Process 

399 

Coracoid  Process  . 

399 

Humerus 

399 

Ulna      . 

400 

Olecranon 

400 

Radius   . 

401 

Muscles  and  Fascia  of  the  Lower 
Extremity. 

Subdivision  into  Groups  .... 

Iliac  Region. 


402 


Dissection 

.     403 

Iliac  Fascia 

.     403 

Psoas  Magnus 

.     403 

Psoas  Parvus  . 

.    404 

Iliacus       .... 

.     404 

Actions    .... 

.     405 

Anterior  Femoral  Region. 


Dissection 

PAOK 

.    405 

Fasciae  of  the  Thigh,  Superficial  Fascia 

.    405 

Deep  Fascia  (Fascia  Lata) 

.     405 

Saphenous  Opening 

.    406 

Iliac  and  Pubic  Portions  of  Fas 

- 

cia  Lata 

.    407 

Tensor  Vagina?  Femoris,  Sartorius  . 

.    407 

Quadriceps  Extensor  Cruris     . 

.     408 

Rectus  Femoris,  Vastus  Externus  . 

.     408 

Vastus  Internus  and  Crurajus 

.     408 

SHb-crura8us 

.    409 

Actions 

.     409 

Internal  Femoral  Region. 

Dissection 

.     410 

Gracilis 

.     410 

Pectineus 

.    410 

Adductor  Longus,  Brevis,  and  Magnus 

.    411 

Actions 

.    412 

Gluteal  Region. 

Dissection 

.     412 

Gluteus  Maximus    .... 

.     412 

Gluteus  Medius        .... 

.    414 

Gluteus  Minimus      .... 

.     414 

Pyriformis 

.    414 

Obturator  Membrane 

.     415 

Obturator  Internus,  Gemelli    . 

.     415 

Quadratus  Femoris,  Obturator  Externus 

416 

Actions 

.     416 

Posterior  Femoral  Region. 

Dissection 

.     417 

Biceps,  Semitendinosus    . 

.     417 

Semimembranosus    .... 

.    417 

Actions 

.    417 

Surgical  Anatomy  of  Hamstring  Tendons   418 

Muscles  and  Fascice  of  the  Leg. 

Dissection  of  Front  of  Leg 

.    418 

Fascia  of  the  Leg    .... 

.    418 

Muscles  of  the  Leg  .... 

419 

Anterior  Tibio-fibular  Region. 

Tibialis  Anticus        .... 

419 

Extensor  Proprius  Pollicis 

419 

Extensor  Longus  Digitorum    . 

420 

Peroneus  Tertius      .... 

420 

Actions 

420 

Posterior  Tibio-fibtdar  Region, 

Superficial  Layer. 

Dissection 

421 

Gastrocnemius 

421 

Soleus,  Tendo  Achillis,  Plantaris    . 

422 

Actions 

422 

Posterior  Tibiofibular  Region,  Deep  Layer. 

Deep  Fascia  of  Leg         ....  423 

Popliteus 423 

Flexor  Longus  Pollicis    ....  423 
Flexor     Longus      Digitorum,     Tibialis 

Posticus 424 

Actions 425 


Fibular  Region. 

Peroneus  Longus 
Peroneus  Brevis 


425 
425 


xiv 


CONTENTS. 


PAOB 

Actions 426 

Surgical  Anatomv  of   Tendons    around 
Ankle  .        .    ' 426 

Mtiscles  and  Fascice  of  Foot. 

Anterior  Annular  Ligament  .  .  .  426 
Internal  Annular  Ligament  .  .  .427 
External  Annular  Ligament    .        .  427 

Plantar  Fascia 427 

Muscles  of  the  Foot,  Dorsal  Region. 
Extensor  Brevis  Digitorum      .        .        .428 

Plantar  Region. 

Subdivision  into  Groups  .        .        .    428 

Subdivision  into  Layers  ....    428 


First  Layer  . 
Second  Layer 
Third  Layer  . 
Fourth  Layer 


PAGE 

428 
430 
431 
432 


Surgical  Anatomy  of  the  Muscles  of  the   . 
Loiver  Extremity. 

Fracture  of  the  Neck  of  the  Femur         .    433 
the  Femur  below  Trochanter 

Minor         ....     433 
the  Femur  above   the   Con- 

dvles  ....     433 

the  Patella    .        .        .        .434 
the  Tibia       .        .        .        .434 
the    Fibula,  with    Displace- 
ment of  the  Tibia      .        .    435 


The    Arteries. 


General  Anatomy. 

Subdivision  into  Pulmonary  and  Systemic 
Distribution  of — Where  found 
Mode  of  Division — Anastomoses 

Arch  of  Aobta. 


Dissection        .... 
Ascending  Part  of  Arch 
Transverse  Part  of  Arch 
Descending  Part  of  Arch 
Peculiarities,  Surgical  Anatomy 
Branches  .... 

Peculiarities  of  Branches 

Coronary  Arteries. 

Right  Coronary  Artery    . 
Left  Coronary  Artery 

Arteria  Tnnominata. 

Relations 

Peculiarities 

Surgical  Anatomy   .... 

Common  Carotid  Arteries. 

Coarse  and  Relations 
Peculiarities,  Surgical  Anatomy 

External  Carotid  Artery. 
Oonrse  and  Relations 
Surgical  Anatomy    .... 
Branches  


Superior  Thyroid  Artery. 

Course  and  Relations 

Branches 

Surgical  Anatomy    .... 

Lingual  Artery. 
Conrsc  and  Relations 

Branches 

Sargical  Anatomy    .... 

Facial  Artery, 
Coarse  and  Relations 

Branches 

Peculiarities 

Surgical  Anatomy   .... 


436 
436 
436 


437 
438 
439 
440 
440 
441 
441 


441 
442 


442 
443 
443 


443 
446 


447 

448 
448 


448 
449 
449 


449 
449 
450 


451 
451 
452 
453 


Occipital  Artery. 
Course  and  Relations 
Branches 

Posterior  Auricular  Artery. 
Course  and  Relations 

Ascending  Pharyngeal  Artery. 
Coarse  and  Relations 

Temporal  Artery. 
Course  and  Relations 
Branches,  Surgical  Anatomy  . 

Internal  Maxillary  Artery. 

Coarse,  Relations    . 

Peculiarities     .... 

Branches  from  First  Portion  . 
Second  Portion 
Third  Portion  . 


453 
453 

454 

454 


454 
455 


455 
456 
456 
457 

458 


Surgical  Anatomy  of  the  Triangles 
OF  THE  Neck. 

Anterior  Triangular  Space. 
Inferior  Carotid  Triangle 
Superior  Carotid  Triangle 
Submaxillary  Triangle 

Posterior  Triangular  Space 
Occipital  Triangle 
Subclavian  Triangle 

Jnlcmal  Carotid  Artery 
Cervical  Portion 
Petrous  Portion 
Cavernous  Portion   . 
Cerebral  Portion 
Peculiarities,  Surgical  Anatomy 
Branches  .... 


459 
4G0 
4G0 


461 
461 


Branches 


Ophthalmic  Artery. 


463 
463 
463 
463 
464 
464 

465 


Cerebral  Branches  of  Internal  Carotid. 

Coarse  and  Relations       ....    467 

Stihclavian  Arteries. 

468 
469 


First  Part  of  Right  Subclavian  Artery 
First  Part  of  Left  Subclavian  Artery 


CONTENTS. 


XV 


Second  Part  of  Subclavian  Artery 

PAGE 

470 

'J'hird  Part  of  Subclavian  Artery 

470 

Peculiarities 

470 

Surjiical  Anatomy 

471 

Branches           

472 

Vertebral  Artery  and  its  Branches 

473 

Basilar  Artery  and  its  Branches    . 

474 

Cerebellar  Branches  of  A^ertebral 

474 

Circle  of  Willis      .... 

474 

Thyroid  Axis 

475 

Inferior  Thyroid     .... 

475 

Suprascapular  Artery    . 

475 

Transversalis  Colli 

475 

Internal  Mammary 

476 

Superior  Intercostal 

477 

Deep  Cervical  Artery    . 

477 

Surgical  Anatomy  of  the  Axilla 


478 


Axillary  Artery. 

First  Portion 

Second  Portion 

Third  Portion 

Peculiarities,  Surgical  Anatomy 

Branches 

.     479 

.  480 
.  480 
.  481 
.    481 

Brachial  Artery. 

Relations 

Bend  of  the  Elbow   . 
Peculiarities  of  Brachial  Artery 
Surgical  Anatomy    . 
Branches  

.    483 

.  484 
.  485 
.  485 
.     486 

Radial  Artery. 

Relations 

Deep  Palmar  Arch  . 

.    487 

.     488 

Peculiarities,  Surgical  Anatomy 
Branches 


489 


Ulnar  Artery. 

Relations 490 

Superficial  Palmar  Arch  ....  491 

Peculiarities  of  Ulnar  Artery  .         .         .  492 

Surgical  Anatomy 492 

Branches 492 

Descending  Aorta. 

Divisions 494 


Thoracic  Aorta. 

Course  and  Relations 
Surgical  Anatomy  . 
Branches  .... 

Abdominal  Aorta. 

Course  and  Relations 

Surgical  Anatomy    . 

branches  .... 

Coeliac  Axis,  Gastric  Artery 
Hepatic  Artery,  Branches 
Splenic  Artery 
Superior  Mesenteric  Artery 
Inferior  Mesenteric  Artery 
Supra-renal  Arteries 
Renal  Arteries 
Spermatic  Arteries   . 


494 
494 
495 


497 
497 
498 
498 
499 
500 
501 
503 
504 
504 
504 


Phrenic  Arteries 
Lumbar  Arteries 
Middle  Sacral  Arteries 

Common  Uiac  Arteries. 


PAOB 

505 
505 
506 


Course  and  Relations       ....    507 

Peculiarities 507 

Surgical  Anatomy 508 

Internal  Uiac  Artery. 

Course  and  Relations       ....     509 
Peculiarities,  Surgical  Anatomy      .        .510 

Branches ,    510 

Vesical  Arteries  ....  511 
Hsemorrhoidal  Arteries  .  .  .511 
Uterine  and  Vaginal  Arteries  .  .  511 
Obturator  Artery  ....  511 
Internal  Pudic  Artery,  Branches      .    512 

Sciatic  Artery 514 

Gluteal 515 

Ilio-lumbar  and  Lateral  Sacral  Arteries  515 

External  Iliac  Artery. 


Course  and  Relations 
Surgical  Anatomy    . 
Epigastric  Artery    . 
Circumflex  Iliac  Artery  . 

.  516 
.  516 
.  517 
.    518 

Femoral  Artery. 

Course  and  Relations 
Scarpa's  Triangle 
Surgical  Anatomy    . 
Peculiarities  of  Femoral  Artery 
Branches          .... 
Profunda  Artery  and  its  Branches 

.  518 
.  518 
.  520 
.  520 
.  521 
.    522 

Popliteal  Artery. 

Popliteal  Space 
Course  and  Relations 
Peculiarities,  Surgical  Anatomy 
Branches          .... 

.     524 

.  524 
.  525 
.    526 

Anterior  Tibial  Artery. 

Course  and  Relations 
Peculiarities,  Surgical  Anatomy 
Branches           .... 

.  527 
.  527 
.    529 

Dor  salts  Pedis  Artery. 

Course  and  Relations 
Peculiarities,  Surgical  Anatomy 
Branches          .... 

.  529 
.  530 
.    530 

Posterior  Tibial  Artery. 

Course  and  Relations 
Peculiarities,  Surgical  Anatomy 
Branches           .... 

.  530 
.  531 
.    532 

Peroneal  Artery. 

Course  and  Relations 
Peculiarities     .... 

.  532 
.    532 

Plantar  Arteries. 

Course  and  Relations 

.    534 

Pulmonary  Artery. 
Course  and  Relations 


534 


XVI 


CONTEXTS. 


The  Veins. 


General  Anatomy. 

P&OE 

Subdivision  into  Pulmonary,  Systemic, 

and  Portal 535 

Anastomoses  of  Veins      ....  535 

Superficial  Veins,  Deep  Veins,  or  Venae 

Comites 535 

Sinuses 53G 

Veins  of  the  Head  and  Neck. 

Facial  Vein 536 

Temporal  Vein 537 

Internal  Maxillary  Vein  ....  538 

Temporo-maxillary  Vein          .         .        .  538 

Posterior  Auricular  Vein,  Occipital  Vein  538 

External  Jugular  Vein    ....  538 

Posterior  External  Jugular  Vein    .        .  539 

Anterior  Jugular  Vein    ....  539 

Internal  Jugular  Vein     ....  539 

Lingual  and  Pharyngeal  ....  539 

Thyroid  Veins 539 

Vertebral  Veins 540 


Veins  of  the  DiploS 
Cerebral  Veins. 

Superficial  Cerebral  Veins 
Deep  Cerebral  Veins 
Cerebellar  Veins 


540 


541 
541 
541 


Veins  of  the  Upper  Extremity. 


Sinuses  of  the  Dura  Mater. 

Superior  Longitudinal  Sinus    .        .        .  542 
Inferior  Longitudinal,  Straight,  Lateral, 

and  Occipital  Sinuses  ....  542 

Cavernous  Sinuses 543 

Circular  Sinus 543 

Inferior  Petrosal  and  Transverse  Sinuses  544 

Superior  Petrosal  Sinus  ....  544 


Superficial  Veins     . 

PAHB 

.     544 

Deep  Veins 

.     544 

Axillary  Vein  .... 

.     546 

Subclavian  Vein      .... 

.     547 

Innominate  Veins    . 

.     547 

Internal  Mammary  Vein  . 

.    547 

Inferior  Thyroid  Veins     . 

.     548 

Superior  Intercostal  Veins 

.     548 

Superior  Vena  Cava 

.     548 

AzYQOs  Veins 

.     549 

Bronchial  Veins 

.    549 

Spinal  Veins 

.     549 

Veins  of  the  Lower  Extremity. 

Internal  Saphenous  Vein 

.     552 

External  Saphenous  Vein 

.    552 

Popliteal  Vein 

.     553 

Femoral  Vein 

.     553 

External  Iliac  Vein 

.    553 

Internal  Iliac  Vein 

.    553 

Common  Iliac  Vein 

.    554 

Inferior  Vena  Cava 

.    554 

Peculiarities      . 

.     5")4 

Lumbar  and  Spermatic  Veins 

.     555 

Ovarian,  Renal,  Supra-renal  Veins 

.    555 

Phrenic  Veins 

.     555 

Hepatic  Veins 

.    555 

Portal  System  of  Veins 

. 

Inferior  and  Superior  Mesenteric  Veins       556 

Splenic  and  Gastric  Veins 

.     556 

Portal  Vein      .... 

.     556 

Cardiac  Veins 

.    657 

Coronary  Sinus 

.     558 

Pulmonary  Veins   . 

.     558 

The  Lymphatics. 


General  AnxUomy. 

Subdivision  into  Deep  and  Superficial     .  559 

Lymphatic  or  Conglobate  Glands    .        .  559 

Thoracic  Duct 560 

Right  Lymphatic  Duct    ....  '561 

Lymphatics  of  Head,  Face,  and  Neck. 

Superficial  Lymphatic  Glands  of  Head    .  561 

Lymphatics  of  Head       .        .  561 

of  the  Face         .  562 

Deep  Lymphatics  of  the  Face         .        .  562 

of  the  Cranium    .        .  562 

Superficial  Cervical  Glands      .        .        .  563 

Deep  Cervical  Glands       ....  563 

Superficial  and  Deep  Cervical  Lymphatics  563 

Lymphatics  of  the  Upper  Extremity. 

Superficial  Lymphatic  Glands  .        .  564 

Deep  Lymphatic  Glands  ....  564 

Axillary  (Jlands 564 

Superficial  Lymphatics  of  Upper  Extremity  565 

Deep  Lymphatics  of  Upper  Extremity    .  565 


Lymphatics  of  the  Lower  Extremity. 

Superficial  Inguinal  Glands     •         .        .  565 

Deep  Lymphatic  Glands  ....  565 

Anterior 'lil)ial  Glands    ....  565 

Deep  Popliteal  Glands     ....  566 

Deep  Inguinal  Glands      ....  566 

Gluteal  and  Ischiatic  Glands    .        .        .  566 
Superficial  Lymphatics  of  Lower  Extremity  566 

Internal  Group          ....  566 

External  Group         ....  566 

Deep  Lymphatics  of  Lower  Extremity    .  567 


Lymphatics  of  Pelvis  and  Abdomen. 


Deep  Lymphatic  Glands  of  Pelvis 

External  Iliac  Glands 

Internal  Iliac  Glands 

Sacral  Glands    . 

Lumbar  Glands 

Superficial  Lymphatics  of  Wall  of  Abdomen  567 

of  (Jluteal  Region  .         .        .     567 

of  Scrotum  and  Perineum       .    567 


567 
567 
567 
567 
567 


CONTENTS. 


xvil 


PARE 

Superficial  Lymphatics  of  Penis      .        .    568 
of  Labia,  Nymphse,  and  Clitoris  568 

Deep  Lymphatics  of  Pelvis  and  Abdomen    568 

Lymphatics  of  Bladder    . 
of  Rectum     . 

.     569 
.    569 

of  Uterus 

.     569 

of  Testicle    . 

•    569 

of  Kidney 
of  Liver 

.    569 
.    569 

Lymphatic  Glands  of  Stomach 
Lymphatics  of  Stomach  . 
Lymphatic  Glands  of  Spleen    . 
Lymphatics  of  Spleen 

.     569 
.     570 
.    570 
.    570 

Lymphatic  System  of  the  Intestines. 

Lymphatic  Glands  of  Small  Intestines 

(Mesenteric  Glands)     ....     570 
Lymphatic  Glands  of  Large  Intestine     .    570 


Lymphatics  of  Small  Intestine  (Lacteals)  570 

of  Large  Intestine        .        .  570 

Lymphatics  of  Tliorax. 

Deep  Lymphatic  Glands  of  Thorax         .  570 

Intercostal  Glands  ....  570 

Internal  Mammary  Glands      .        .  570 

Anterior  Mediastinal  Glands  .        .  570 

Posterior  Mediastinal  Glands           .  570 

Superficial  Lymphatics  on  Front  of  Thorax  571 

Deep  Lymphatics  of  Thorax 

Intercostal  Lymphatics    .        .         .  571 

Internal  Mammary  Lymphatics        .  571 

Lymphatics  of  Diaphragm       .        .        .  571 

Bronchial  Glands 571 

Lymphatics  of  Lung        ....  571 
Cardiac  Lymphatics         .         .        .        .571 

Thymic  Lymphatics         ....  571 

Thyroid  Lymphatics        ....  571 

Lymphatics  of  CEsophagus      .        .        .  571 


Nervous  System. 


General  Anatomy. 

Subdivision   into   Cerebro-spinal    Axis, 
Ganglia,  and  Nerves     .        ...        .    572 


77)6  Spinal  Cord  and  its  Membranes. 

Dissection         .... 

.    572 

Membranes  of  the  Cord 

Dura  Mater 

.    572 

Arachnoid 

.     573 

Pia  Mater 

.    573 

Ligamentum  Denticulatum 

.     574 

Spinal  Cord      .... 

.     574 

Fissures  of  Cord 

.     575 

Columns  of  Cord 

.     575 

Structures  of  the  Cord 

.    575 

The  Brain  and  its  Membra 

nes. 

Membranes  of  the  Brain 

.    576 

Dura  Mater. 

Structure         .... 

.    577 

Arteries,  Veins.  Nerves  . 

.    577 

Glandulse  Pacchioni 

.    577 

Processes  of  the  Dura  Mater 

Falx  Cerebri 

.    578 

Tentorium  Cerebelli . 

.     578 

Falx  Cerebelli 

.     578 

Arachnoid  Membrane. 

Sub-arachnoid  Space 

.    578 

Cerebro-spinal  Fluid 

.    579 

Pia  Mater. 

Vessels  of        ...        . 

.    579 

The  Brain. 

Subdivision  into  Cerebrum,  Cereb 

}llum, 

Pons  Varolii,  Medulla  Oblongata 

.     579 

Weight  of  Brain 

.    580 

Medulla  Oblongata. 

Anterior  Pyramids  . 

.    580 

Lateral  Tract,  and  Olivary  Body 

.    581 

Restiform  Bodies 

.    581 

Posterior  Pyramids  .        .        .        . 

Posterior  Surface  of  Medulla  Oblongata 
Structure  of  Medulla  Oblongata 

of  Anterior  Pyramid 

of  Lateral  Tract 

of  Olivary  Body 

of  Restiform  Body  . 
Septum  of  Medulla  Oblongata 
Gray  Matter  of  Medulla  Oljlongata 

Pons  Varolii 

Structure 

Transverse  Fibres     . 
Longitudinal  Fibres 
Septum     .... 


581 

582 
582 
582 
582 
582 
582 
582 
583 


584 

584 
584 
584 


Cerebrum. 

Upper  Surface  of  Cerebrum    .        .        .    585 

Convolutions 585 

Sulci 586 

Base  of  the  Brain 587 

General  Arrangements  of  the  Parts  com- 
posing the  Cerebrum  ....  590 
Interior  of  the  Cerebrum  .  .  .  590 
Corpus  Callosum  ....  590 
Lateral  Ventricle  .  .  .  .592 
Corpus  Striatum  ....  593 
Taenia  Semicircularis  .  .  .  593 
Choroid  Plexus  .  .  .  .593 
Corpus  Fimbriatum  ....    593 

Hippocampus 594 

Transverse  Fissure  ....  595 
Septum  Lucidum  ....  595 
Fifth  Ventricle         .        .        .        .595 

Fornix 595 

Foramen  of  Monro  ....  596 
Velum  luterpositum  .  .  .  596 
Thalamus  Opticus  ....  596 
Third  Ventricle  .  .  .  .597 
Commissure  of  Third  Ventricles  597 
Gray  Matter  of  Third  Ventricles   598 

Pineal  Gland 598 

Corpora  Quadrigemina  .  .  .598 
Valve  of  Vieussens  ....    599 


CONTENTS. 


Corpora  Geniculata 
Structure  of  Cerebrum 


PAQE 

599 
599 


Cerebellum. 

Its  Position,  Size,  Weight,  &c. 

Upper  Surface  . 

Under  Surface  . 
Lobes  of  the  Cerebellum 
Structure  of  the  Cerebellum    . 

Its  Laminae 
Corpus  Dentatum     . 
Peduncles  of  Cerebellum 
Fourth  Ventricle     . 
Lining  Membrane,  Choroid  Plexus 
Gray  Matter    .... 

Cranial  Nerves. 
Subdivision  into  Groups  . 
Olfactory  Nerve 
Optic  Nerve     .... 

Tracts        .... 

Commissure 
Anditoij  Nerve 
Third  Nerve    .... 
Fourth  Nerve  .... 
Sixth  Nerve     .... 
Relations  of  the  Orbital  Nerves 

in  the  Cavernous  Sinus 

in  the  Sphenoidal  Fissure 

in  the  Orbit 
Facial  Nerve    .... 

Branches  of  Facial  Nerve 
Ninth  or  Hypoglossal  Nerve  . 
Fifth  Nerve      .... 

Casserian  Ganglion  . 

Ophthalmic  Nerve    . 

Lachrymal  and  Frontal     . 

Nasal  .... 
Ophthalmic  Ganglion 

Superior  Maxillary  Nerve 

Spbeno-palatine  Ganglion 

Inferior  Maxillary  Nerve 

Auriculo-temporal,  Gustatory,  and 
Inferior  Dental  Branches 

Otic  Ganglion    . 

Submaxillary  Ganglion  . 
Eighth  Pair      .... 

Glosso-pbaryngeal    . 

Spinal  Accessory 

Pneumogastric  (Vagus)    . 

Spinal  Nerves. 

Boots  of  the  Spinal  Nerves     . 

Origin  of  Anterior    .... 

of  Posterior  .... 

Ganglia  of  the  Spinal  Nerves 

Anterior  Branclits  of  the  Spinal  Nerves 

Posterior  Branches  of  the  Spinal  Nerves 

Cervical  Nerves. 

Roots  of  the  Cervical  Nerves  .        .        .    633 
Anterior  Branches  of  the  Cervical  Nerves  633 


600 
600 
601 
601 
602 
602 
602 
602 
603 
603 
604 


605 
605 
606 
606 
607 
607 
608 
608 
609 

610 
610 
610 
610 
611 
614 
615 
616 
616 
616 
617 
618 
618 
620 
622 

623 
624 
625 
625 
625 
627 
628 


632 
632 
632 
633 
633 
633 


Brachial  Plexus. 
Branches  above  the  Clavicle. 
Posterior  Thoracic,  Suprascapular  . 


.    639 


Cervical  Plexus. 

Superficial  Branches  of  the  Cervical 

Plexus 

Peep  Branches  of  the  Cervical  Plexus 


634 
635 


Posterior  Branches  of  the  Cervical  Nerves  636 


Branches  below  the  Clavicle. 

Anterior  Thoracic 639 

Subscapular  Nerves         ....  640 

Circumflex,  and  Musculo-cutaneous  Nerves  640 
Internal  and  Lesser  Internal  Cutaneous 

Nerves 641 

Median  Nerve G42 

Ulnar  Nerve 644 

Musculo-spiral  Nerve       ....  645 

Radial  Nerve 646 

Posterior  Interosseous  Nerve  .        .  646 

Dorsal  Nerves. 

Roots  of  the  Dorsal  Nerves     .        .        .  647 

Posterior  Branches  of  the  Dorsal  Nerves  647 

Intercostal  Nerves 647 

Upper  Intercostal  Nerves        .        .        .  647 

Intercosto-humeral  Nerve        .        .        .  648 

Lower  Intercostal  Nerves  .  .  .  648 
Peculiar  Dorsal  Nerves 

First  Dorsal  Nerve  ....  648 

Last  Dorsal  Nerve    ....  G48 

Lumbar  Nerves. 

Roots  of  Lumbar  Nerves  .  .  .  649 
Posterior  Branches  of  Lumbar  Nerves  .  649 
Anterior  Branches  of  Lumbar  Nerves    .    649 

Lumbar  Plexus. 

Branches  of  Lumbar  Plexus    .        .        .  650 

Ilio-hypogastric  Nerve     ....  650 

Ilio-inguinal  and  Genito-crural  Nerves     .  651 

External  Cutaneous,  and  Obturator  Nerves  651 

Accessory  Obturator  Nerve     .        .        .  653 

Anterior  Crural  Nerve     ....  653 

Branches  of  Anterior  Crural  .        .        .  654 

Middle  Cutaneous     ....  654 

Internal  Cutaneous,  Long  Saphenous  654 

Muscular  and  Articular  Branches     .  655 

Sacral  and  Coootgsal  Nerves. 

Roots  of 655 

Posterior  Sacral  Nerves  ....  656 

Anterior  Sacral  Nerves    ....  656 

Coccygeal  Nerve 656 

Sacral  Plexus. 

Superior  Gluteal  Nerve    .  •     . 

Pudic  and  Small  Sciatic  Nerves 

Great  Sciatic  Nerve         .... 

Internal  Popliteal  Nerve 

Short  Saphenous  Nerve   .... 

Posterior  Tibial  Nerve    .... 

Plantar  Nerves 

External  Popliteal  or  Peroneal  Nerve  . 
Anterior  Tibial  Nerve  .  .  .  , 
Musculo-cutaneous  Nerve 

Sympathetic  Nerve. 

Subdivision  of.  into  Parts 
Branches  of  the  Ganglia,  General  De- 
scription of 663 


CONTENTS. 


XIX 


fAQE 

665 
666 
666 


Cervical  Portiox  of  the  Sympathetic. 

Superior  Cervical  Ganglion 
Middle  Cervical  Ganglion 
Inferior  Cervical  Ganglion 

Carotid  and  Cavernous  Plexuses. 

Carotid  Plexus 665 

Cavernous  Plexus 665 

Cardiac  Nerves. 

Superior,  Middle,  and  Inferior  Cardiac 

Nerves 667 

Deep  Cardiac  Plexus        ....  667 

Superficial  Cardiac  Plexus       .        .        .  668 

Anterior  and  Posterior  Coronary  Plexus  668 

Thoracic  Part  of  the  Sympathetic. 

Great  Splanchnic  Nerve  ....     669 
Lesser  Splanchnic  Nerve         .        .        .     669 


Smaller  Splanchnic  Nerve        .        .        .  669 

Epigastric  or  Solar  Plexus       .        .         .  669 

Semilunar  Ganglia 669 

Phrenic  and  Suprarenal  Plexuses    .        .  669 

Renal  Plexus 670 

Spermatic,  Coeliac,  and  Gastric  Plexuses  670 
Hepatic,  Splenic,  and  Superior  Mesen- 
teric Plexuses 670 

Aortic,  and  Inferior  Mesenteric  Plexuses  670 


Lumbar  Portion  of  Sympathetic. 

Pelvic  Portion  of  Sympathetic         .        .  671 

Hypogastric  Plexus        . .         .         .        .  671 

Inferior  Hypogastric  or  Pelvic  Plexus    .  671 

Inferior  Haemorrhoidal  Plexus         .        .  673 

Vesical  Plexus 673 

Prostatic  Plexus      .         .        .        .        .  673 

Vaginal  Plexus 673 

Uterine  Nerves 673 


Organs  of  Sense. 


Tongue. 

Papillae  of 674 

Follicles,  and  Mucous  Glands  .        .        .  676 

Fibrous  Septum  of 676 

Muscular  Fibres  of 676 

Arteries  and  Nerves  of    .        .        .        .  677 

Nose. 

Cartilages  of.  Muscles      ....  678 

Skin,  Mucous  Membrane  ....  679 

Arteries,  Veins,  and  Nerves     .        .        .  679 

Nasal  Fossce. 

Mucous  Membrane  of       ...        .  679 
Peculiarities  of,  in  Superior,  Middle, 

and  Inferior  Meatuses         .         .  679 
Arteries,   Veins,  and   Nerves   of   Nasal 

FossiB 680 

Eye. 

Situation,  Form  of 680 

Sclerotic 681 

Cornea 682 

Choroid 683 

Ciliary  Processes 684 

Iris 685 

Membrana  Pupillaris,  Ciliary  Ligament  .  686 

Ciliary  Muscle 686 

Retina 686 

Structure  of  Retina 

Jacob's  Membrane         .        .        .  -687 

Granular  Layer     ....  687 

Nervous  Layer      ....  687 

Radiating  Fibres  of  the  Retina     .  688 

Arteria  Centralis  Retinae          .        .        .  688 

Structure  of  Retina,  at  Yellow  Spot        .  688 

Humors  of  the  Eye. 

Aqueous  Humor 688 

Anterior  Chamber         .        .        .  688 

Posterior  Chamber        .        .        .  689 

Vitreous  Body 689 


Crystalline  Lens  and  its  Capsule 
Changes  produced  in  the  Lens  by  Age 
Suspensory  Ligament  of  Lens  . 

Canal  of  Petit 

Vessels  of  the  Globe  of  the  Eye 
Nerves  of  Eyeball    .         .       * . 

Appendages  op  the  Eye. 

Eyebrows 
Eyelids     . 

Structure 
Tarsal  Cartilages 
Meibomian  Gland 
Eyelashes 
Conjunctiva 
Caruncula  Lachrymalis 

Lachrymal  Apparatus. 

Lachrymal  Gland 

Canals 

Sac 

Nasal  Duct 

Ear. 
External  Ear. 

Pinna,  or  Auricle 

Structure  of  Auricle  .... 
Ligaments  of  the  Pinna  .... 
Muscles  of  the  Pinna  .... 
Arteries,  Veins,  and  Nerves  of  the  Pinna 
Auditory  Canal 

Middle  Ear,  or  Tympanum. 

Cavity  of  Tympanum 
Eustachian  Tube 
Membrana  Tympani 
Structure  of  . 
Ossicles  of  the  Tympanum 
Ligaments  of  the  Ossicula 
Muscles  of  the  Tympanum 
Mucous  Membrane  of  Tympanum 
Arteries,   Veins,   and  Nerves    of    Tym-" 
panum 


689 
690 
690 
690 
690 
691 


691 
691 
691 
691 
692 
692 
692 
693 


693 
694 
694 
694 


694 
695 
695 
695 
696 
697 


698 
700 
700 
700 
700 
701 
702 
702 

702 


zx 


CONTENTS. 


Internal  Ear  or  Labyrinth. 

fAOB 

Vestibtile 703 

Semicircular  Canals         ....  704 
Cochlea 

Central  Axis  of,  or  Modiolus         .  705 

Spiral  Canal  of      .         .         .         -705 

Lamina  Spiralis  of         .        .        .  706 

Scala  Tympani,  Scala  Vestibnli       .        .  706 

Cochlearis  Muscle 706 


Perilymph         .... 
Membranous  Labyrinth    . 
Utricle  and  Saccule 
Membranous  Semiciroolar  Canals 
Endolymph-Otoliths 
Vessels  of  the  Labyrinth  . 
Auditory  Nerve,  Vestibular  Nerve,  Coch 
lear  Nerve    .... 


PAOB 

706 
706 
706 
707 
707 
708 

708 


VISCERA. 


Organs  of  Digestion  and  their  Appendages. 


Subdivisions  of  the  Alimentary  Canal 

The  Mouth 

The  Lips 

The  Cheeks 

The  Gums 

Teeth. 

General  Characters  of      ...        . 

Permanent  Teeth 

Incisors 

Canine,  Bicuspid,  Molars 

Temporary  or  Milk  Teeth 

Structure  of  the  Teeth     .        .        .        • 

Ivory  or  Dentine,  Chemical  Composition 

Enamel 

Cortical  Substance 

Development  of  the  Teeth 

of  the  Permanent  Teeth  . 
Growth  of  the  Teeth  .... 
Eruption  of  the  Teeth      .... 


Palate. 

Hard  Palate 

Soft  Palate 

Uvula,  Pillars  of  the  Soft  Palate     . 
Mucous    Membrane,    Aponeurosis, 
Muscles  of  Soft  Palate        . 

Tonsils 

Arteries,  Veins,  and  Nerves  . 


and 


Salivary  Glands. 
Parotid  Oland.  • 

Steno's  Duct 

Vessels  and  Nerves  .        .  '     . 

Submaxillary  Oland. 

Wharton's  Duct 

Vessels    and    Nerves    of   Submaxillary 
Glaud    

Sublingual  Oland. 

Vessels  and  Nerves  of     ...        . 
B I lucturc  of  Salivary  Glands  . 


Pharynx. 


Structure 


CEsOPHAOCS. 

Relations.  Surgical  Anatomy,  and  Struc- 
ture      ....... 


709 

Abdomen. 

709 

Boundaries 

723 

709 

Apertures  of 

723 

710 
710 

Regions 

724 

Peritoneum. 

Reflections  traced 

725 

711 
711 
711 
712 
713 
713 
713 

Foramen  of  Winslow        .         . 

727 

Lesser  Omentum 

727 

Great  Omentum 

728 

Gastro-splenic  Omentum  .        .        .        . 

728 

Mesentery 

728 

Mesocsecum,  Mesocolon,  Mesorectum,  Ap- 

pendices Epiploicae       .        .         .         . 

728 

714 

Stomach. 

714 

Situation  . 

728 

715 

715 

Splenic  end,  Pyloric  end  .        .        .        . 

729 

Cardiac  and  Pyloric  Orifices    . 

729 

716 

Greater  and  Lesser  Curvatures 

729 

717 

Surfaces 

729 

Ligaments  of 

730 

Alterations  in  Position    .        .        .        . 

730 

718 

Pylorus 

730 

718 

Structure  of  Stomach 

730 

718 

Serous  and  Muscular  Coats 

730 

Mucous  Membrane  .... 

731 

718 

Gastric  Follicles       .... 

731 

718 

Vessels  and  Nerves  of  Stomach 

732 

718 

Small  Intestines. 

Duodenum 

732 

Vessels  and  Nerves 

734 

719 

Jejunum 

Ileum 

734 
734 

720 

Structure  of  Small  Intestines  . 

734 

Serous,  Muscular,  and  Cellular  Coats 

.     734 

Mucous  Membrane  .... 

.     734 

720 

Epithelium  and  Valvulae  Conniventes 

734 

Villi — their  Structure 

.     735 

720 

Simple  Follicles,  Duodenal  Glands  . 

.     735 

Solitary  Glands        .... 

.     735 

Aggregate,  or  Peyer's,  Glands 

.     736 

720 
721 

Large  Intestine. 

Cfficura 

.     737 

Appendix  Vcrmiformis  . 

.    737 

Ileo-csecal  Valve   . 

.     737 

721 

Colon 

.     738 

Ascending     .... 

.     738 

Transverse     .... 

.     738 

Descending    .... 

.     738 

722 

Sigmoid  Flexure    . 

.     738 

I 


CONTENTS. 


XXI 


Rectum 739 

Structure  of  Large  Intestine    .        .        .  *739 

Serous  and  Muscular  Coats      .        .         .  739 

Cellular  and  Mucous  Coats      .        .        .  740 

Epithelium,  Simple  Follicles    .        .        .  740 

Solitary  Glands 740 

LiVKR. 

Size,  Weight,  Position  of         .        .        .  741 

Its  Surfaces  and  Borders          .        .        .  741 

Changes  of  Position 741 

Ligaments 742 

Longitudinal 742 

Lateral,  Coronary  ....  742 

Round  Ligament   ....  742 
Fissures. 

Longitudinal 743 

Fissure  of  Ductus  Venosus       .        .  743 

Portal  Fissure 743 

Fissures  for  Gall  Bladder  andVena  Cava  743 
Lobes. 

Right 744 

Left 744 

Quadratus,  Spigelii,  Caudatus  .        .  744 

Vessels  and  Nerves  of  Liver    .        .  744 

Structure  of  Liver     ....  744 

Serous  Coat,  Fibrous  Coat        .        .  745 

Lobules 745 

Hepatic  Cells 746 

Biliary  Ducts,  Portal  Vein       .        .  746 

Hepatic  Artery         ....  746 

Hepatic  Veins           ....  747 

Gall  Bladder. 

Structure 747 

Biliary  Ducts 747 

Hepatic  Duct 748 

Common  Choledoch  and  Cystic  Ducts  748 

Structure  of  Biliary  Ducts        .        .  748 

Pancreas. 

Dissection 749 

Relations 749 

Duct 750 

Structure,  Vessels,  and  Nerves        .        .  750 

Spleen. 

Relations 750 

Size  and  Weight 750 

Structure  of  Serous  and  Fibrous  Coats    .  751 

Proper  Substance 752 

Malpighian  Corpuscles     ....  753 

Splenic  Artery,  Distribution    .        .        .  754 

Capillaries  of  Spleen        ....  754 


Veins  of  Spleen 

Lymphatics  and  Nerves  .        .        .        . 

THORAX. 

Boundaries  of 

Superior  Opening,  Base   .        .        .        . 
Parts  passing  through  Upper  Opening    . 

Pericardium. 

Structure  

Fibrous  Layer,  Serous  Layer    . 

Heart. 

Position,  Size 

Subdivision  into  Four  Cavities 
Circulation  of  Blood  in  Adult 
Auriculo-ventricular,  and  Ventricular 
Grooves 

Right  Auricle. 

Openings 

Valves 

Relics  of  Foetal  Structure 

Musculi  Pectinati 

Right  Ventricle. 

Openings 

Tricuspid  Valve 

Semilunar 

Chordae  Tendinese  and  Columiisie  Carneae 


Left  Auricle. 

Sinus  and  Appendix 
Openings,  Musculi  Pectinati 

Left  Ventricle. 
Openings 
Mitral  and  Semilunar  Valves 


Endocardium. 


Characters 


754 
754 


755 
755 
755 


755 
756 


757 
757 

757 

757 


758 
759 
759 
759 


760 
760 
761 
761 


761 

762 


762 
763 


763 


Structure  of  Heart. 

Fibrous  Rings 764 

Muscular  Structure 764 

of  Auricles     ....  764 

of  Ventricles  ....  764 

Vessels  and  Nerves  of  Heart  .        .        .  765 

Peculiarities  in  Vascular  System  of  Foetus  765 

Foramen  Ovale,  Eustachian  Valve  .         .  765 

Ductus  Arteriosus 765 

Umbilical  or  Hypogastric  Arteries  .        .  767 

Foetal  Circulation 767 

Changes  in  Vascular  System  at  Birth     .  768 


Organs  of  Yoice  and  Eespiration. 


The  Larynx. 

Cartilages  of  the  Larynx 

.     769 

Thyroid  Cartilage 

.     769 

Cricoid 

.     770 

Arytenoid  Cartilages 

.    770 

Cartilages  of  Santorini,  and  Wrisberg  771 

Epiglottis 771 

Ligaments  of  the  Larynx  .        .        .     771 


Ligaments  connecting  the  Thyroid  Car- 
tilage with  the  Os  Hyoides  . 

Ligaments  connecting  the  Thyroid  Car- 
tilage with  the  Cricoid 

Ligaments  connecting  the  Arytenoid  Car- 
tilages to  the  Cricoid    .         .         .         . 

Ligaments  of  the  Epiglottis    . 

Upper  Aperture  of  the  Larynx 


772 

772 

772 
772 

772 


XXll 


CONTENTS. 


PAOB 

Cavity  of  the  Larynx       ....  773 

Glottis 773 

False  Vocal  Corda 773 

True  Vocal  Cords 774 

Ventricle  of  Larynx,  Saccnlus  Laryngis  774 

Muscles  of  Larynx 774 

Muscles  of  Vocal  Cords,  and  Rima  Glot- 

tidis 774 

Muscles  of  Epiglottis       ....  774 

Actions  of  Muscles  of  Larynx          .        .  776 

Mucous  Membrane  of  Larynx          .        .  776 

Glands,  Vessels,  and  Nerves  of  Larynx  .  776 

Trachea. 

Relations 778 

Bronchi 778 

Structure  of  Trachea       ....  778 
Surgical  Anatomy   of  Laryngo-tracheal 

Region 779 

The  Pleura. 

Reflections 780 

Vessels  and  Nerves          ....  782 

Mediastinum. 

Anterior  Mediastinum      ....  782 

Middle  Mediastinum         ....  782 

Posterior  Mediastinum    ....  782 


The  Lungs. 

PAOB 

Surfaces,  Lobes 782 

Root  of  Lung 784 

Weight,  Color,  and  Properties  of  Sub- 
stance of  Lung 785 

Structure  of  Lung 785 

Serous  Coat,  and  Subserous  Areolar  Tissue  785 

Parenchyma  and  Lobules  of  Lung  .        .  785 
Bronchi,  Arrangement  of  in  Substance  of 

Lung 785 

Structure  of  Smaller  Bronchial  Tubes    .  786 

The  Air-cells 786 

Pulmonary  Artery 786 

Pulmonary  Capillaries  and  Veins     .        .  786 

Bronchial  Arteries  and  Veins          .        .  787 

Lymphatics  and  Nerves  of  Lung     .        .  787 

Tliyroid  Gland. 

Structure 787 

Vessels  and  Nerves          ....  788 

Chemical  Composition     ....  788 

TJiymus  Gland. 

Structure         .                ....  788 

Vessels  and  Nerves          ....  789 

Chemical  Composition     ....  789 


The  Urinary  Organs. 


Kidneys. 

Relations 

Dimensions,  "Weight 
Cortical  Substance  . 
Medullary  Substance 
Minute  Structure 
Malpighian  Bodies  . 
Pelvis,  Infundibula  . 
Renal  Artery,  Renal  Veins 
Lymphatics  and  Nerves  . 

Ureters. 

Situation,  Course,  Relations 
Structure 


Relations 


Supronrenal  Capsules. 


790 
790 
790 
791 
791 
792 
792 
792 
793 


793 
793 


793 


Structure 

Vessels  and  Nerves 

The  Pelvis. 
Boundaries  and  Contents 


794 
794 


r94 


Bladder. 

Shape,  Position,  Relations 

795 

Urachus 

796 

Subdivisions      .... 

796 

Ligaments         .... 

796 

Structure          

797 

Interior  of  Bladder  . 

797 

Vessels  and  Nerves 

798 

Male  Urethra. 

Structure         

798 

Male  Generative  Organs. 


Prostate  Gland        .        .        .        . 

.    800 

Structure           .        .        .        . 

.    800 

Vessels  and  Nerves  . 

.     801 

Prostatic  Sccrctioa 

.    801 

Cowper's  Glands 

.    801 

Penis. 

Root 

.     801 

Glana  Penis      .... 

.     801 

Body 

.    801 

Corpora  Cavernosa 

.     802 

Corpus  Spongiosum 

.    802 

The  Bulb          .... 

.    802 

Structure  of  Corpus  Spongiosum 

.     803 

Erectile  Tissue 

.    803 

Arteries  of  the  Penis 
Lymphatics  of  the  Penis 
Nerves  of  the  Penis 


803 
803 
804 


The  Testes  and  their  Coverings. 

Scrotum 804 

Other  Coverings  of  the  Testis          .        .  804 
Vessels  and  Nerves  of  the  Coverings  of 

the  Testis 805 

Spermatic  Cord. 

Its  Composition 805 

Relations  of,  in  Inguinal  Canal        .        .  805 

Arteries  of  the  Cord         ....  805 

Veins  of  the  Cord    ....  805 

Lymphatics  and  Nerves  of  the  Cord        .  805 


CONTENTS. 


xxiii 


Testes. 

PAGE 

Arrangement  in  Epididymis    .  • 

PAGE 

.    807 

Form  and  Situation          ....     805 

Vasculum  Aberrans 

.     808 

Size  and  Weight 

.    806 

Vas  Deferens,  Course,  Relations 

.     808 

Coverings 

.    806 

Structure  .... 

.     808 

Tunica  Vaginalis 

.    806 

Yesiculse  Seminales 

.    809 

Tunica  Albuginea 

.    806 

Form  and  Size 

.     809 

Mediastinum  Testis 

.    807 

Relations  .... 

.     809 

Tunica  Vasculosa 

.    807 

Structure  .... 

.     809 

Structure  of  the  Testis 

.    807 

Ejaculatory  Ducts    . 

.    809 

Lobules  of  the  Testis 

.    807 

The  Semen       .... 

.    809 

Tubuli  Seminiferi     . 

.    807 

Descent  of  the  Testes 

.    810 

Arrangement  in  Lobuli    . 

.     807 

Gubernaculum  Testis 

.     810 

in  Mediasti 

lum  '' 

restis 

.    807 

Canal  of  Nuck 

.    810 

Female  Organs   of  Generatio.n. 


Mons  Veneris,  Labia  Majora   . 

Labia  Minora,  Clitoris,  Meatus  Urinarius 

Hymen,  Glands  of  Bartholine 

Bladder 

Urethra 

Rectum 


Relations 
Structure 


Vagina. 


Uterus. 


Situation,  Form,  Dimensions 

Fundus,  Body,  and  Cervix 

Ligaments 

Cavity  of  the  Uterus 

Structure 

Vessels  and  Nerves 

Its  Form,  Size,  and  Situation 


811 
812 
812 

813 

813 

814 


814 

814 


81.5 
815 
815 
815 
816 
816 
817 


in  the  Foetus 

.    817 

at  Puberty 

.    817 

during  and  after  Menstruation   .     817 

after  Parturition 

.    817 

in  Old  Age 

.    817 

Appendages  of  the  Uteru. 

'. 

Fallopian  Tubes 

.     817 

Structure 

.    818 

Ovaries     .... 

.     818 

Structure  . 

.    818 

Graafian  Vesicles 

.     818 

Discharge  of  the  Ovum    . 

.     819 

Corpus  Luteum 

.    819 

Ligament  of  the  Ovary    . 

.     820 

Round  Ligament 

.     820 

Vessels  and  Nerves  of  Appendages 

.    820 

Mammary  Glands. 

Structure  of  Mamma 

.    820 

Vessels  and  Nerves 

.    821 

Surgical  Anatomy  of  Inguinal  Hernia. 


Coverings  of  Inguinal  Hernia. 

Dissection         .... 
Superficial  Fascia     . 
Superficial  Vessels  and  Nerves 
Deep  Layer  of  Superficial  Fascia 
Aponeurosis  of  External  Oblique 
External  Abdominal  Ring 
Pillars  of  the  Ring  . 
Intercolumuar  Fibres 
Fascia 
Poupart's  Ligament 
Gimbernat's  Ligament 
Triangular  Ligament 
Internal  Oblique  Muscle 
Cremaster 

Transversalis  Muscle 
Spermatic  Canal     _ . 
Fascia  Transversalis 
Internal  Abdominal  Ring 
Subserous  Areolar  Tissue 


822 
822 
822 
823 
823 
824 
824 
824 
824 
825 
825 
825 
825 
825 
826 
826 
827 
827 
827 


Epigastric  Artery 828 

Peritoneum 828 

Inguinal  Hernia. 

Oblique  Inguinal  Hernia  ....  828 

Course  and  Coverings  of  Oblique  Hernia  828 

Seat  of  Stricture 828 

Scrotal  Hernia 828 

Bubonocele 829 

Congenital  Hernia 829 

Infantile  Hernia 829 

Direct  Inguinal  Hernia. 

Course  and  Coverings  of  the  Hernia       .  829 

Seat  of  Stricture 829 

Incomplete  Direct  Hernia        .        .        .  829 
Comparative  Frequency  of  Oblique  and 

Direct  Hernia 829 

Diagnosis  of  Oblique  and  Direct  Hernia  829 


XXIV 


CONTENTS. 


Surgical  Anatomy  of  Femoral  Hernia. 


Dissection        .... 
Superficial  Fascia    . 
Cutaneous  Vessels  . 
Internal  Saphenous  Vein 
Superficial  Inguinal  Glands 
Cutaneous  Nerves    . 
Deep  Layer  of  Superficial  Fascia 
Cribriform  Fascia    . 
Fascia  Lata 

Iliac  Portion     . 

Pubic  Portion  . 
Saphenous  Opening 


PAGE 

830 
830 
830 
830 
830 
831 
831 
831 
832 
832 
833 
833 


Crural  Arch     . 

Gimbernat's  Ligament 

Crural  Sheath  . 

Deep  Crural  Arch   . 

Crural  Canal    . 

Femoral  or  Crural  Ring 

Position  of  Parts  around  the  Ring 

Septum  Crurale 

Descent  of  Femoral  Hernia 

Coverings  of  Femoral  Hernia  . 

Varieties  of  Femoral  Hernia  . 

Seat  of  Stricture 


PAGB 

833 

834 
834 
835 
835 
836 
836 
836 
837 
837 
838 
838 


Surgical  Anatomy  of   Perineum   and  Ischio-Rectal 

Kegion. 


Ischio-Rectal  Region. 
Dissection  of    . 
Boundaries  of  . 
Superficial  Fascia    . 
External  Sphincter 
Internal  Sphincter  . 
Ischio-rectal  Fossa  . 
Position  of  Parts  contained  in 

Perineum. 
Boundaries,  and  Extent  .        .        .        . 
Superficial  Layer  of  Superficial  Fascia  . 
Deep  Layer  of  Superficial  Fascia    . 
Course  taken  by  the  Urine  in  Rupture  of 

the  Urethra 

Muscles  of  the  Perineum  (Male)     • 

Accelerator  Urinaj 

Erector  Penis 

Transversus  Perinei         .        .        .        . 
Muscles  of  th3  Perineum  (Female) 

Sphincter  Vaginae 

Erector  Clitoridis 

Transversus  Perinei        .        .        .        . 


839 
839 
839 
840 
840 
840 
840 


841 
841 
841 

841 
841 
842 
843 
843 
844 
844 
844 
844 


Deep  Perineal  Fascia 

Anterior  Layer 
Posterior  Layer 
Parts  between  the  two  Layers 
Compressor  Urethrae 
Cowper's  Glands 
Pudic  Vessels  and  Nerves 
Artery  of  the  Bulb 
Levator  Ani     . 

Relations,  Actions    . 
Coccygeus,  Relations,  Actions 
Position  of  Viscera  at  Outlet  of  Pelvis 
Prostate  Gland        .... 
Parts  concerned  in  the  Operation  of 

Lithotomy 

Parts  Divided  in  the  Operation 
Parts  to  be  avoided  in  the  Operation 
Abnormal  Course  of  Arteries  in  the 

Perineum 

Pelvic  Fascia 

Obturator  Fascia 

Becto-vesical  Fascia 


844 
845 
845 
845 
845 
845 
845 
845 
845 
846 
846 
846 
846 

847 
847 
848 

848 
849 
849 
850 


Surgical  Anatomy  of  the  Triangles  of  the  Keck 

Axilla 

Bend  of  Elbow 
Scarpa's  Triangle    . 
Popliteal  Si^ace 
Laryngo-trachcal  Region 


u 

u 

u 

u 

u 

u 

ti 

« 

ti 

u 

459 


LIST  OF  ILLUSTEATIONS. 


D^''  Tha  Illustrations,  when  copied  from  any  other  work,  have  the  author's  name  affixed;  when  no  such 
acknowledgment  is  made,  the  drawing  is  to  be  considered  original. 

Introduction. 

FIO. 

[1.  Corpuscles  of  Frog's  Blood 

2.  Humau  Blood  Globules 

3.  White  Corpuscles 

4.  Blood  Crystals 

5.  Chyle  from  the  Lacteals 
[6.  Areolar  Tissue 

7.  White  Fibrous  Tissue 

8.  Yellow  Elastic  Tissue 

9.  Formative  Cells  of  Yellow  Elastic  Tissue 
10.  Formative  Cells  of  Areolar  Tissue 
[11.  Bloodvessels  of  Fat 

12.  Adipose  Tissue     •  .  .  . 

13.  Human  Cartilage  Cells     . 

14.  Costal  Cartilage  in  Old  Age 

15.  Fibro-cartilage      .... 

16.  Yellow  Cartilage  .... 

17.  Transverse  Section  of  Bone 

18.  Longitudinal  Section  of  Bone 

19.  Section  of  Bone  after  Removal  of  Earthy  Portion 

20.  Ossification  of  Foetal  Cartilage    . 

21.  Transverse  {section  of  Muscle 

22.  Human  Muscular  Fibres  . 

23.  Elementary  Structure  of  Voluntary  Muscle 

24.  Non-striated  Muscular  Fibres 

25.  Muscular  Fibre  Cells 

26.  Nerve  Vesicles  from  Casserian  Ganglion 

27.  Nerve  Vesicles  from  Brain 

28.  Human  Nerve  Tubes 

29.  Nerve  Tubes  of  Eel 

30.  Transverse  Section  of  Spinal  Cord 

31.  Transverse  Section  of  Spinal  Cord 

32.  Longitudinal  Section  of  Spinal  Cord 

33.  Tactile  Corpuscles  of  Wagner 

34.  Pacinian  Corpuscle 

35.  Termination  of  Nerves  of  Voluntary  Muscle,  "Motorial  End 

36.  Terminations  of  Nerves  of  Voluntary  Muscle 

37.  Section  of  Small  Artery  and  Vein 

38.  Capillary  Vessels 

39.  Section  of  Small  Artery  and  Vein 

40.  Section  of  Thoracic  Duct 

41.  Sectional  View  of  the  Skin  and  its  Appendages 
[42.  Structure  of  Hair,  Hair-follicles,  &c. 

43.  Pavement  Epithelium 

44.  Columnar  Epithelium 

45.  Spheroidal  Epithelium 

46.  Ciliated  Epithelium 
[47.  Conoidal  Ciliated  Epithelium 
[48.  Plans  of  Secreting  Membranes  . 

49.  Ovum  of  Sow 

50.  Human  Ovum 

51.  Diagram  of  the  Division  of  the  Yelk 

52.  DiasTram  of  the  Division  of  the  Blastodermic  Membrane 


FROM 

Wagner] 

PAGE 

34 

Kolliker 

34 

Harley 

35 

do. 

35 

do. 

37 

.    Todd  ^  Bowman] 

38 

Harley 

38 

do. 

39 

Kolliker 

39 

do. 

39 

.    Todd  Sf  Bowman] 

40 

Harley 

41 

Kolliker 

42 

Harley 

43 

do. 

43 

do. 

44 

Kolliker 

47 

do. 

47 

Harley 

48 

Rollett 

50 

Kolliker 

54 

do. 

54 

.     Todd  and  Bowmai 

I        64 

Harley 

56 

Kolliker 

56 

.     Todd  and  Boiomai 

58 

Harley 

58 

Kolliker 

58 

.    Todd  and  Bowmai 

58 

L.  Clarke 

62 

do. 

63 

do. 

64 

Kolliker 

68 

.    Todd  and  Bowmai 

68 

'lates"  K'uhne 

70 

Beale 

71 

Kolliker 

72 

do. 

75 

do. 

75 

do. 

77 

do. 

79 

do.] 

83 

.             Harley 

85 

Kolliker 

85 

Harley 

85 

Kolliker 

86 

Carpenter] 

86 

Sharpey] 

88 

M.  Barry 

89 

Kolliker 

89 

do. 

90 

Bischoff 

91 

{   XXV 

) 

\  X 


XXVI 


LIST    OF    ILLUSTRATIONS. 


Fia, 
53. 


Diagrams  of  the  Development  of  the  Three  Layers  of  the  1 
Blastodermic  Membrane  .  .  .  .  j 

Similar  Diagrams — Antero-posterior  Sections  . 
Diagram  of  the  Membranes  of  the  Ovum 
Human  Ovum,  12  to  13  days     ..... 
Human  Ovum,  15  days  ...... 

58.  Embryo  from  the  preceding  Ovum       .... 

59.  Human  Ovum  in  the  Fourth  Week       .... 
Face  of  an  Embryo  of  25  to  28  days      .... 
Longitudinal  Section  of  Head  of  limbryo  at  Four  Weeks 
Section  of  the  Medulla  of  P^mbryo  at  Six  Weeks 
Diagram  of  Development  of  Lens  .... 

64.  Heart  of  Embryo,  Fifth  Week  ..... 

65.  Diagram  of  Formation  of  the  Aortic  Arches  and  Large  Arteries 

66.  Diagram  of  Formation  of  the  Main  Systematic  Veins  . 

67.  Development  of  External  Genital  Organs 


54 
55 
56, 
57 


60 
61 
62 
63 


FROH 

PAOR 

Beaunis  and        f 
Bouchard         \ 

92 

do. 

94 

Wagner. 

95 

A.  Thomson 

96 

do. 

96 

do. 

96 

do. 

97 

Coste 

98 

Kolliker 

99 

do. 

100 

Remak 

101 

Baer 

103 

Kolliker 

104 

do. 

106 

Ecker 

110 

Osteology. 


68.  A  Cervical  Vertebra 

69.  Atlas       .... 

70.  Axis        .... 

71.  Seventh  Cervical  Vertebra 

72.  A  Dorsal  Vertebra         .  '. 

73.  Peculiar  Dorsal  Vertebrae 

74.  A  Lumbar  Vertebra 
75  to  80.  Development  of  a  Vertebra 

81.  Sacrum,  anterior  surface 

82.  Vertical  Section  of  the  Sacrum 

83.  Sacrum,  posterior  surface 
84  to  86.  Development  of  Sacrum    . 

87.  Coccyx,  anterior  and  posterior  surfaces 

88.  Lateral  View  of  Spine  . 

89.  Occipital  Bone,  outer  surface    . 
SO.  Occipital  Bone,  inner  surface    . 

91.  Occipital  Bone,  development  of 

92.  Parietal  Bone,  external  surface 

93.  Parietal  Bone,  internal  surface 

94.  Frontal  Bone,  outer  surface 

95.  Frontal  Bone,  inner  surface 

96.  Frontal  Bone  at  Birth    . 

97.  Temporal  Bone,  outer  surface   . 

98.  Temporal  Bone,  inner  surface    . 

99.  Temporal  Bone,  petrous  portion 

100.  Temporal  Bone,  development  of 

101.  Sphenoid  Bone,  superior  surface 

102.  Sphenoid  Bone,  anterior  surface 

103.  Sphenoid  Bone,  posterior  surface 

104.  Plan  of  the  Development  of  Sphenoid 

105.  Ethmoid  Bone,  outer  surface    . 

106.  Perpendicular  Plate  of  Ethmoid,  enlarged 

107.  Ethmoid  Bone,  inner  surface  of  right  lateral  mass,  enlarged 

108.  Skull  at  birth,  showing  the  anterior  and  posterior  Fontanellea 

109.  Lateral  Fontanelles        .        •    . 

110.  Nasal  Bone,  outer  surface 

111.  Nasal  Bone,  inner  surface 

112.  Superior  Maxillary  Bone,  outer  surface 
118.  Superior  Maxillary  Bone,  inner  surface 

114.  Development  of  Superior  Maxillary  Bone 

115.  Lachrymal  Bone,  outer  surface 

116.  Malar  Bone,  outer  surface 

117.  Malar  lione,  inner  surface 

118.  Palate  Bone,  interior  view,  enlarged    . 

119.  Palate  Bone,  posterior  view,  enlarged 

120.  Inferior  Turbinated  Bone,  inner  surface 

121.  Inferior  Turbinated  Bone,  outer  surface 

122.  Vomer     ..... 

123.  liowor  Jaw,  outer  surface 

124.  Lower  Jaw,  inner  surface 


Quain 
Quain 

Quain 


Quain 


Quain 


LIST    OF    ILLUSTRATIONS. 


xxvu 


Fia. 

125.  Side-view  of  the  Lower  Jaw,  at  Birth 

126.  Side-view  of  the  Lower  Jaw,  at  Puberty 

127.  Side-view  of  the  Lower  Jaw,  in  the  Adult 

128.  Side-view  of  the  Lower  Jaw,  in  Old  Age 

129.  Base  of  Skull,  inner  surface 

130.  Base  of  Skull,  outer  surface 

131.  Side-view  of  the  Skull    .... 

132.  Anterior  Region  of  Skull 

133.  Nasal  Fosste,  outer  wall 

134.  Nasal  Fossa3,  inner  wall  or  septum 

135.  Hyoid  Bone,  anterior  surface     . 

136.  Sternum  and  Costal  Cartilages,  anterior  surface 

137.  Sternum,  posterior  surface 
138  to  141.  Development  of  Sternum 

142.  AEib 

143.  Vertebral  Extremity  of  a  Eib   . 
144  to  148.  Peculiar  Ribs       .... 

149.  Left  Clavicle,  anterior  surface  . 

150.  Left  Clavicle,  inferior  surface    . 

151.  Left  Scapula,  anterior  surface,  or  venter 

152.  Left  Scapula,  posterior  surface,  or  dorsum 

153.  Plan  of  the  Development  of  the  Scapula 

154.  Left  Humerus,  anterior  surface 

155.  Left  Humerus,  posterior  surface 

156.  Plan  of  the  Development  of  the  Humerus 

157.  Bones  of  the  Left  Forearm,  anterior  surface    . 

158.  Bones  of  the  Left  Forearm,  posterior  surface  . 

159.  Plan  of  the  Development  of  the  Ulna  . 

160.  Plan  of  the  Development  of  the  Radius 

161.  Bones  of  the  Left  Hand,  dorsal  surface 

162.  Bones  of  the  Left  Hand,  palmar  surface 

163.  Plan  of  the  Development  of  the  Hand 

164.  Os  Innorainatum,  external  surface 

165.  Os  lunominatum,  internal  surface 

166.  Plan  of  the  Development  of  the  Os  Innominatum 

167.  Male  Pelvis  (adult)         .... 

168.  Female  Pelvis  (adult)     .... 

169.  Vertical  Section  of  the  Pelvis,  with  lines  indicating  the  Axes 

170.  Right  Femur,  anterior  surface  . 

171.  Right  Femur,  posterior  surface  . 

172.  Diagram  showing  the  Structure  of  the  Neck  of  the  Femur 

173.  Plan  of  the  Development  of  the  Femur 

174.  Right  Patella,  anterior  surface  . 

175.  Right  Patella,  posterior  surface 

176.  Tibia  and  Fibula,  anterior  surface 

177.  Tibia  and  Fibula,  posterior  surface 

178.  Plan  of  the  Development  of  the  Tibia 

179.  Plan  of  the  Development  of  the  Fibula 

180.  Bones  of  the  Right  Foot,  dorsal  surface 

181.  Bones  of  the  Right  Foot,  plantar  surface 

182.  Plan  of  the  Development  of  the  Foot  . 


of  the 


Quain 


Pelvis 


Ward 


173 

173 

173 

173 

177 

180 

183 

186 

188 

189 

190 

191 

191 

193 

195 

196 

198 

200 

200 

202 

203 

206 

208 

210 

211 

213 

215 

216 

218 

220 

222 

227 

228 

230 

233 

235 

235 

236 

237 

239 

241 

242 

243 

243 

244 

246 

247 

249 

250 

252 

258 


Articulations. 

183.  Vertical  Section  of  Two  Vertebrae  and  their  Ligaments,  front  view  . 

184.  Occipito-atloid  and  Atlo-axoid  Ligament,  front  view  . 

185.  Occipito-atloid  and  Atlo-axoid  Ligaments,  posterior  view 

186.  Articulation  between  Odontoid  Process  and  Atlas 

187.  Occipito-axoid  aud  Atlo-axoid  Ligaments         .... 

188.  Temporo-maxillary  Articulation,  external  view 

189.  Temporo-maxillary  Articulation,  interual  view 

190.  Temporo-maxillary  Articulation,  vertical  section 

191.  Costo-vertebral  and  Costo-transverse  Articulations,  anterior  view 

192.  Costo-transverse  Articulations  ...... 

193.  Costo-sternal,  Costo-xiphoid,  and  Intercostal  Articulations,  anterior  view 

194.  Articulations  of  Pelvis  and  Hip,  anterior  view 

195.  Articulations  of  Pelvis  and  Hip,  posterior  view 

196.  Vertical  Section  of  the  Symphysis  Pubis  .... 

197.  Sterno-clavicular  Articulation  ...... 


Arnold 


Arnold 


260 
270 
270 
271 
272 
273 
274 
275 
276 
277 
279 
280 
281 
284 
285 


XXVIU 


LIST    OF    ILLUSTRATIONS. 


pra. 

]  98.  Shonlder-joint,  Scapulo-clavicular  Articulations,  and  proper  Ligaments  of  Scapula 

199.  Left  Elbow-joint,  showing  anterior  and  internal  Ligaments 

200.  Left  Elbow-joint,  showing  posterior  and  external  Ligaments 

201.  Ligaments  of  Wrist  and  Hand,  anterior  view  .  .  .  Arnold 

202.  Ligaments  of  Wrist  and  Hand,  posterior  view  ...  do. 

203.  Vertical  Section  of  Wrist,  showing  the  Synovial  Membranes 

204.  Articulations  of  the  Phalanges 

205.  Left  Hip-joint,  laid  open  .... 

206.  Right  Knee-joint,  anterior  view 

207.  Right  Knee-joint,  posterior  view 

208.  Right  Knee-joint,  showing  internal  Ligaments 

209.  Head  of  Tibia,  with  Semilunar  Cartilages,  seen  from  above 

210.  Ankle-joint,  Tarsal  and  Tarso-metatarsal  Articulations,  internal  view 

211.  Ankle-joint,  Tarsal  and  Tarso-metatarsal  Articulations,  external  view 

212.  Ligaments  of  Plantar  Surface  of  the  Foot        .... 

213.  Syaovial  Membranes  of  the  Tarsus  and  Metatarsus    .  .  Arnold 


Muscles  and  Fascice. 

214.  Plan  of  Dissection  of  the  Head,  Face,  and  Neck 

215.  Muscles  of  the  Head,  Face,  and  Neck 

216.  Muscles  of  the  Right  Orbit       ..... 

217.  The  relative  position  and  attachment  of  the  Muscles  of  the  Left  Eyeball 

218.  The  Temporal  Muscle    ...... 

219.  The  Pterygoid  Muscles  ..... 

220.  Muscles  of  the  Neck,  and  Boundaries  of  the  Triangles 

221.  Muscles  of  the  Neck,  anterior  view      .... 

222.  Muscles  of  the  Tongue,  left  side  .... 

223.  Muscles  of  the  Pharynx,  external  view 

224.  Muscles  of  the  Soft  Palate        ..... 

225.  The  Prevertebral  Muscles  ..... 

226.  Plan  of  Dissection  of  the  Muscles  of  the  Back 

227.  Muscles  of  the  Back — first,  second,  and  part  of  the  third  layers 

228.  Muscles  of  the  Back — deep  layers        .... 

229.  Plan  of  Dissection  of  Abdomen  .... 

230.  The  External  Oblique  Muscle  .  .  .  .  . 

231.  The  Internal  Oblique  Muscle    ..... 
2.32.  The  Transversalis,  Rectus,  and  Pyramidalis    . 

233.  Transverse  Section  of  Abdomen  in  Lumbar  Region    . 

234.  The  Diaphragm,  nnder  Surface  .  ... 

235.  Dissection  of  Upper  Extremity  .... 

236.  Muscles  of  the  Chest  and  Front  of  the  Arm,  superficial  view 

237.  Muscles  of  the  Chest  and  Front  of  the  Arm,  with  the  boundaries  of 

238.  Muscles  on  the  Dorsum  of  the  Scapula  and  the  Triceps 

239.  Front  of  the  Left  Forearm,  superficial  muscles 

240.  Front  of  the  Left  Forearm,  deep  muscles 

241.  Posterior  surface  of  Forearm,  superficial  muscles 

242.  Posterior  surface  of  Forearm,  deep  muscles    . 

243.  Transverse  Section  throu"^h  the  Wrist,  showing  the 

Canals  for  the  passage  of  the  Tendons 

244.  Muscles  of  the  Left  ifand,  palmar  surface 

245.  Dorsal  Interossei  of  Left  Hand 

246.  Palmar  Interossei  of  Left  Hand 

247.  Fracture  of  the  Middle  of  the  Clavicle 

248.  Fracture  of  the  Surgical  Neck  of  the  Humerus 

249.  Fracture  of  the  Humerus  above  the  Condyles 

250.  Fracture  of  the  Olecranon 

251.  Fracture  of  Shaft  of  the  Radius 

252.  Fracture  of  the  lower  end  of  the  Radius 

253.  Plan  of  Dissection  of  Lower  Extremity,  front  view 

254.  Muscles  of  the  Iliac  and  Anterior  Femoral  Regions 

255.  Muscles  of  the  Internal  Femoral  Region 

256.  Plan  of  Dissection  of  Lower  Extremity,  posterior  view 

257.  Muscles  of  the  Hip  and  Thigh  . 
2.58.  Muscles  of  the  Front  of  the  Leg 

259.  Muscles  of  the  Back  of  the  Leg,  superficial  layer 

260.  Muscles  of  the  Back  of  the  Leg,  deep  layer     . 
2fil.  Muscles  of  the  Solo  of  the  Foot,  first  layer 
262.  Muscles  of  the  Sole  of  the  Foot,  second  layer 


Quain 

Quain 
Quain 

Quain 


the  Axilla 


Annular  Ligaments  and  the 


Hind 
do. 
do. 
do. 
do. 
do. 


Quain 


LIST    or    ILLUSTRATIONS. 


XX12C 


263.  Muscles  of  the  Sole  of  the  Foot,  third  layer    . 

264.  Dorsal  Interossei  ...... 

265.  Plantar  Interossei  ...... 

266.  Fracture  of  the  Neck  of  the  Femur  within  the  Capsular  Ligament 

267.  Fracture  of  the  Femur  below  the  Trochanters 

268.  Fracture  of  the  Femur  above  the  Condyles 

269.  Fracture  of  the  Patella  ..... 

270.  Oblique  Fracture  of  the  Shaft  of  the  Tibia 

271.  Fracture  of  the  Fibula,  with  displacement  of  the  Tibia  (Pott's  fracture) 


PAOK 

431 

•       •       . 

432 

.        .        • 

432 

Hind 

433 

do. 

433 

do. 

434 

do. 

434 

do. 

434 

ture)   do. 

435 

Arteries. 

272.  The  Arch  of  the  Aorta  and  its  branches 

273.  Plan  of  the  branches  of  the  Arch  of  the  Aorta 

274.  Surgical  Anatomy  of  the  Arteries  of  the  Neck 

275.  Plan  of  the  branches  of  the  External  Carotid 

276.  The  Arteries  of  the  Face  and  Scalp 

277.  The  Internal  Maxillary  Artery  and  its  branches 

278.  Plan  of  the  branches  of  the  Internal  Maxillary  Artery 

279.  The  Internal  Carotid  and  Vertebral  Arteries   . 

280.  The  Ophthalmic  Artery  and  its  branches 
28L.  The  Arteries  of  the  base  of  the  Brain 

282.  Plan  of  the  branches  of  the  Eight  Subclavian  Artery 

283.  The  Scapular  and  Circumflex  Arteries 

284.  The  Axillary  Artery  and  its  branches  . 

285.  The  Surgical  Anatomy  of  the  Brachial  Artery 

286.  The  Surgical  Anatomy  of  the  Eadial  and  Ulnar  Arteries 

287.  Ulnar  and  Radial  Arteries,  deep  view  . 

288.  Arteries  of  the  Back  of  the  Forearm  and  Hand 

289.  The  Abdominal  Aorta  and  its  branches 

290.  The  Coeliac  Axis  and  its  branches,  the  Liver  having  been 

Omentum  removed       ..... 

291.  The  Coeliac  Axis  and  its  branches,  the  Stomach  having  been 

verse  Meso-colon  removed       .... 

292.  The  Superior  Mesenteric  Artery  and  its  branches 

293.  The  Inferior  Mesenteric  Artery  and  its  branches 

294.  Arteries  of  the  Pelvis    .  . 

295.  Variations  in  Origin  and  Course  of  Obturator  Artery 

296.  The  Internal  Pudic  Artery  and  its  branches     . 

297.  The  Arteries  of  the  Gluteal  and  Posterior  Femoral  Regions 

298.  Surgical  Anatomy  of  the  Femoral  Artery 

299.  The  Popliteal,  Posterior  Tibial,  and  Peroneal  Arteries 

300.  Surgical  Anatomy  of  the  Anterior  Tibial  and  Dorsalis  Pedis 

301.  The  Plantar  Arteries,  superficial  view  . 

302.  The  Plantar  Arteries,  deep  view 


raised, 
raised, 


Arteries 


and 


the 
and  the 


Lesser 
Trans 


438 
438 
445 
445 
450 
456 
456 
462 
465 
466 
472 
476 
478 
483 
487 
490 
493 
496 

499 

500 
502 
503 
508 
512 
512 
514 
519 
528 
528 
533 
533 


Veins. 

303.  Veins  of  the  Head  and  Neck    ...... 

304.  Veins  of  the  Diploe,  as  displayed  by  the  removal  of  the  outer  table  1 

of  the  Skull ) 

305.  Vertical  Section  of  the  Skull,  showing  the  Sinuses  of  the  Dura  Mater 

306.  The  Sinuses  of  the  Base  of  the  Skull    ..... 

307.  The  Superficial  Veins  of  the  Upper  Extremity 

308.  The  Vente  Cav«  and  Azygos  Veins,  with  their  Formative  Branches 

309.  Transverse  Section  of  a  Dorsal  Vertebra,  showing  the  Spinal  Veins 

310.  Vertical  Section  of  two  Dorsal  Vertebrae,  showing  the  Spinal  Veins 
31L  The  Internal,  or  Long  Saphenous  Vein  and  its  Branches 

312.  The  External,  or  Short  Saphenous  Vein  .... 

313.  The  Portal  Vein  and  its  Branches         ..... 


.      537 

Breschet       540 

.  542 
.  544 
.  545 
.  548 
550 
551 
552 
553 
557 


Breschet 
do. 


Quain 


Lymphatics. 


314.  The  Thoracic  and  Right  Lymphatic  Ducts       .  .  .  •  •  .• 

315.  The  Superficial  Lymphatics  and  Glands  of  the  Head,  Face,  and  Neck  Mascagni 

316.  The  Deep  Lymphatics  and  Glands  of  the  Neck  and  Thorax  .  .  do. 

317.  The  Superficial  Lymphatics  and  Glands  of  the  Upper  Extremity      .  do. 

318.  The  Superficial  Lymphatics  and  Glands  of  the  Lower  Extremity       .  do. 

319.  The  Deep  Lymphatic  Vessels  and  Glands  of  the  Abdomen  and  Pelvis  do. 


560 

662 
563 
564 
566 
568 


XXX 


LIST    OF    ILLUSTRATIONS. 


Nervous  System. 


FIO. 

320.  The  Spinal  Cord  and  its  Membranes     .... 

321.  Transverse  Section  of  the  Spinal  Cor(J  and  its  Membranes     . 

322 .  Spinal  Cord,  side  view.     Plan  of  the  Fissures  and  Columns   . 

323.  Transverse  Sections  of  the  Cord  .... 

324.  Medulla  Oblongata  and  Pons  "Varolii,  anterior  surface 

325.  Posterior  Surface  of  Medulla  Oblongata 

326.  Transverse  Section  of  Medulla  Oblongata 

327.  The  Columns  of  the  Medulla  Oblongata,  and  their  Connection  with  \ 

the  Cerebrum  and  Cerebellum  .  .  .  .  j 

328.  Upper  Surface  of  the.Brain,  the  Pia  Mater  having  been  removed 

329.  Base  of  the  Bfain  ...... 

330   Section  of  the  Brain,  made  on  a  level  with  the  Corpus  Callosum 

331.  The  Lateral  Ventricles  of  the  Brain     .... 

332.  The  Fornix,  Velum  Interpositum,  and  middle  or  descending  Cornu 

Ventricle  ....... 

333.  The  Third  and  Fourth  Ventricles  .... 

334.  Upper  Surface  of  the  Cerebellum  .... 

335.  Under  Surface  of  the  Cerebellum  .... 

336.  Vertical  Section  of  the  Cerebellum      .... 


Arnold 

Quain 

Arnold 


Arnold 
Altered  from 
Arnold 


of  the  Lateral 


Arnold 


PAOS 

573 

573 
575 
576 

581 
581 

582 

583 

585 

588 
591 
592 

594 
597 
600 
601 
602 


Cranial   Nerves. 

337.  The  Optic  Nerves  and  Optic  Tracts    .......  606 

338.  Course  of  the  Fibres  in  the  Optic  Commissure             .            .            .        Bowman  607 

339.  Nerves  of  the  Orbit,  seen  from  above               ....   After  Arnold  608 

340.  Nerves  of  the  Orbit  and  Ophthalmic  Ganglion,  side  view        .            .          do.  609 

341.  The  Course  and  Connections  of  the  Facial  Nerve  in  the  Temporal  Bone  After  Didder  610 

342.  The  Nerves  of  the  Scalp,  Face,  and  Side  of  the  Neck             ....  612 

343.  Hj-poglossal  Nerve,  Cervical  Plexus,  and  their  Branches        ....  614 

344.  Distribution  of  the  Second  and  Third  Divisions  of  the  Fifth  Nerve  "I     j  jNg_  Arnold  619 

and  Submaxillary  Ganglion  .  .  .  .  ]      ■^ 

345.  The  Spheno-Palatine  Ganglion  and  its  Branches         .....  620 

346.  The  Otic  Ganglion  and  its  Branches     .....  After  Arnold  624 

347.  Origin  of  the  Eighth  Pair,  their  Ganglia  and  Communications           .        Bendz       .  625 

348.  Course  and  Distribution  of  the  Eighth  Pair  of  Nerves           .           .           .           .  C26 


Spinal  Nerves. 


349.  Plan  of  the  Brachial  Plexus      ..... 

350.  Cutaneous  Nerves  of  Right  Upper  Extremity,  anterior  view 

351.  Cutaneous  Nerves  of  Right  Upper  Extremity,  posterior  view 

352.  Nerves  of  the  Left  Upper  Extremity,  front  view 

353.  The  Suprascapular,  Circumflex,  and  Musculo-spiral  Nerves 

354.  The  Lumbar  Plexus  and  its  Branches 

355.  Cutaneous  Nerves  of  the  Lower  Extremity,  front  view 

356.  Nerves  of  the  Lower  Extremity,  front  view 

357.  Cutaneous  Nerves  of  Lower  Extremity,  posterior  view 

358.  Nerves  of  the  Lower  Extremity,  posterior  view 

359.  The  Plantar  Nerves       ..... 

360.  The  Sympathetic  Nerve  .... 

361.  Ganglia  and  Nerves  of  Gravid  Uterus 


Altered  from  Quain 


After  R.  Lee 


638 
640 
641 
642 
645 
650 
652 
652 
658 
658 
660 
664 
672 


Organs 


of  Sense. 


362.  Upper  Surface  of  the  Tongue    . 

363.  The  three  kinds  of  Papillae  of  the  Tongue,  magnified 

364.  365,  Cartilages  of  the  Nose 

366.  Bones  and  Cartilages  of  Septum  of  Nose,  right  side 

367.  Nerves  of  Septum  of  Nose,  right  side 

368.  A  Vertical  Section  of  the  Eyeball,  enlarged     . 

369.  The  Choroid  and  Iris,  enlarged 

370.  The  Veins  of  the  Choroid,  enlarged     . 

371.  The  Arteries  of  the  Choroid  and  Iris,  the  Sclerotic  having  been  mostly 

removed,  enlarged  ..... 


.               .                • 

674 

Bowman 

674 

Arnold 

677 

do. 

678 

do. 

680 

.            . 

681 

Altered  from  Zinn 

683 

.     Arnold 

684 

do. 


685 


LIST    OF    ILLUSTRATIONS.  xxxi 

PAQB 

372.  The  Arteria  Centralis  Retinae,  Yellow  Spot,  etc,  the  anterior  half  of  the  Eyeball 

being  removed,  enlarged     ........  687 

373.  The  (.Crystalline  Lens,  hardened  and  divided,  enlarged            .            ,            Arnold  C90 

374.  The  Meibomian  Glands,  etc.,  seen  from  the  Inner  surface  of  the  Eyelids           do.  692 

375.  The  Lachrj'mal  Apparatus,  right  side               ......  693 

376.  The  Pinna,  or  Auricle,  outer  surface    .......  695 

377.  The  Muscles  of  the  Pinna          ......            Arnold'  696 

378.  A  Front  View  of  the  Organ  of  Hearing,  right  side      .            .            .            Scarpa  699 

379.  View  of  Inner  Wall  of  Tympanum,  enlarged                .....  699 

380.  The  Small  Bones  of  the  Ear,  seen  from  the  outside,  enlarged             .            Arnold  701 

381.  The  Osseous  Labyrinth,  laid  open,  enlarged     ....    Soemmern'ng  704 

382.  The  Cochlea  laid  open,  enlarged           .....        Arnold  705 

383.  The  Membranous  Labyrinth  detached,  enlarged          .            .            .       Breschet  707 

Organs  of  Digestion  and  their  Appendages. 

384.  Sectional  View  of  the  Nose,  Mouth,  Pharynx,  etc.     .....  710 

385.  The  Permanent  Teeth,  external  view                ......  711 

386.  The  Temporary,  or  Milk  Teeth,  external  view              .....  713 

387.  Vertical  Section  of  a  Molar  Tooth        .......  713 

388.  Vertical  Section  of  a  Bicuspid  Tooth,  magnified         .            .            .  After  Retzius  714 
389  to  394.  Development  of  Teeth     ......       Ooodsir  715 

395.  The  Salivary  Glands      .........  719 

396.  The  Regions  of  the  Abdomen  and  their  contents,  (edge  of  Costal  Cartilages  in  dotted 

outline)         ..........  724 

397.  The  Reflections  of  the  Peritoneum,  as  seen  in  a  Vertical  Section  )     Altered  from  ^^n 

of  the  Abdomen        ......)  Quain 

398.  The  Mucous  Membrane  of  the  Stomach  and  Duodenum,  with  the  Bile  Ducts           .  729 

399.  The  Muscular  Coat  of  the  Stomach      .......  731 

400.  ^linute  Anatomy  of  Mucous  Membrane  of  the  Stomach         .         Dr.  Sprott  Boyd  732 

401.  Relations  of  the  Duodenum        ........  733 

402.  Two  Villi,  magnified      .........  735 

403.  Patch  of  Peyer's  Glands,  from  the  lower  part  of  the  Ileum    ....  736 

404.  A  portion  of  Peyer's  Glands,  magnified           ....              Boehm  736 

405.  The  Cajcum  and  Colon  laid  open,  to  show  the  Ileo-c£Bcal  Valve         .            .            .  737 

406.  Minute  Structure  of  Large  Intestine    .....              Boehm  741 

407.  The  Liver,  upper  surface           ........  742 

408.  The  Liver,  under  surface           ........  743 

409.  Longitudinal  section  of  an  Hepatic  Vein        ....           Kiernan  745 

410.  Longitudinal  section  of  a  small  Portal  Vein  and  Canal           .            .                do.  745 
41L  A  transverse  section  of  a  small  Portal  Canal  and  its  vessels  .            .                do.  746 

412.  The  parts  in  the  Gastro-hepatic  Omentum       ......  748 

413.  The  Pancreas  and  its  Relations            .......  749 

414.  Transverse  Section  of  the  Spleen,  showing  the  Trabecular  Tissue,  and  the  Splenic 

Vein  and  its  branches          ........  7.51 

415.  The  Malpighian  Corpuscles,  and  their  relation  with  the  Splenic  Artery  and  its  branches  752 

416.  One  of  the  Splenic  Corpuscles,  showing  its  Relations  with  the  Bloodvessels             .  753 

417.  Transverse  section  of  the  Human  Spleen,  showing  the  distribution  of  the  Splenic 

Artery  and  its  branches      ........  754 

Organs  of  Circulation. 

418.  Front  view  of  the  Thorax,  showing  the  relation  of  the  Thoracic  Viscera  to  the  walls 

of  the  Chest             .........  756 

419.  The  Right  Auricle  and  Vefttriclc  laid  open,  the  anterior  walls  of  both  being  removed  758 

420.  The  Left  Auricle  and  Ventricle  laid  open,  the  anterior  walls  of  both  being  removed  762 

421.  Plan  of  the  FcEtal  Circulation  ........  766 

Organs  of  Voice  and  Respiration. 

422.  Side  view  of  the  Thyroid  and  Cricoid  Cartilages 

423.  The  Cartilages  of  the  Larynx,  posterior  view 

424.  The  Larynx  and  adjacent  parts,  seen  from  above 

425.  Vertical  section  of  the  Larynx  and  upper  part  of  the  Trachea 

426.  Muscles  of  Larynx,  side  view,  right  ala  of  Thyroid  Cartilage  removed 

427.  Interior  of  the  Larynx,  seen  from  above,  enlarged       .  .  . 

428.  Front  view  of  Cartilages  of  Larynx  ;  the  Trachea  and  Bronchi 


.  769 

.  770 

.  772 

.  773 

775 

Willis  775 

.  777 


xxxu  LIST    OF    ILLUSTRATIONS. 

FIO-  _  PAGE 

429.  Transverse  section  of  the  Trachea,  just  above  its  Bifurcation,  with  a  bird's-eye  view 

of  the  interior  .........  778 

430.  Surgical  Anatomy  of  the  Laryngo-tracheal  Region      .....  780 

431.  A  transverse  section  of  the  Thorax,  showing  the  relative  position  of  the  Viscera, 

and  the  reflections  of  the  Pleurae    .......  781 

432.  The  Posterior  Mediastinum       ........  783 

433.  Front  view  of  the  Heart  and  Lungs     .......  784 

The  Urinary  and  Generative  Organs. 

434.  Vertical  section  of  the  Kidney  ........  791 

435.  A  Plan  to  show  the  minute  structure  of  the  Kidney  .  .  .  Bowman  791 

436.  Vertical  section  of  Bladder,  Penis,  and  Urethra  .....  795 

437.  The  Bladder  and  Urethra  laid  open,  seen  from  above  .....  798 

438.  The  Testis,  in  situ,  the  Tunica  Vaginalis  having  been  laid  open        .  .  .  806 

439.  Plan  of  a  vertical  section  of  the  Testicle,  to  show  the  arrangement  of  the  ducts     .  807 

440.  Base  of  the  Bladder,  with  the  Vasa  Deferentia  and  Vesiculse  Seminales        Holler  808 

441.  The  Vulva,  External  Female  Organs  of  Generation    .  .  .  .  .811 

442.  Section  of  Female  Pelvis,  showing  position  of  Viscera  ....  813 

443.  The  Uterus  and  its  Appendages,  anterior  view  .  .  .  Wilson  817 

444.  Section  of  the  Ovary  of  a  Virgin  .  .  .  .  .  .  .    ,  818 

445.  Section  of  the  Graafian  Vesicle  ....  After  Von  Baer   818 

446.  Inguinal  Hernia,  Superficial  Dissection  ......  823 

447.  Inguinal  Hernia,  showing  the  Internal  Oblique,  Cremaster,  and  Spermatic  Canal     .  825 

448.  Inguinal  Hernia,  showing  the  Transversalis  Muscle,  the  Transversalis  Fascia,  and 

the  Internal  Abdominal  Ring  .......  827 

449.  Femoral  Hernia,  Superficial  Dissection  ......  831 

450.  Femoral  Hernia,  showing  Fascia  Lata  and  Saphenous  Opening  .  .  .  832 

451.  Femoral  Hernia,  Iliac  Portion  of  Fascia  Lata  removed,  and  Sheath  of  Femoral 

Vessels. and  Femoral  Canal  exposed  ......  834 

452.  Hernia ;  the  Relations  of  the  Femoral  and  Internal  Abdominal  Rings,  seen  from 

within  the  Abdomen,  right  side       .......  836 

453.  454.  Variations  in  Origin  and  Course  of  Obturator  Artery    ....  837 

455.  Plan  of  Dissection  of  Perineum  and  Ischio-rectal  Region      ....  840 

456.  The  Perineum ;    the  Integument  and  Superficial  Layer  of   Superficial  Fascia 

reflected        ..........  842 

457.  The  Superficial  Muscles  and  Vessels  of  the  Perineum  ....  643 

458.  Deep  Perineal  Fascia  ;  on  the  Left  Side  the  anterior  layer  has  been  removed  .  844 

459.  A  view  of  the  Position  of  the  Viscera  at  the  Outlet  of  the  Pelvis     .  .  .  847 

460.  A  transverse  section  of  the  Pelvis,  showing  the  Pelvic  Fascia  .  After  Wilson  848 

461.  Side  view  of  the  Pelvic  Viscera  jef  the  Male  Subject,  showing  the  Pelvic  and 

Perineal  Fascia3        .  .  '         .  .  .  .  .  .  •  849 

462.  The  Pelvic  Fascia .  .  850 


ANATOMY, 

DESCRIPTIVE    AND    SURGICAL. 


INTEODUCTION. 


GENERAL  AI^ATOMY. 

The  fluids  of  the  body,  whicli  are  intended  for  its  nutrition,  are  the  lymph, 
the  chyle,  and  the  blood.  There  are  other  fluids  also  which  partially  subserve 
the  same  purpose,  as  the  saliva,  the  gastric  juice,  the  bile,  the  intestinal  secre- 
tion; and  others  which  are  purely  excrementitious,  as  the  urine.  All  these 
fluids  form  a  part  of  the  bulk  of  the  body  under  ordinary  circumstances.  But 
there  is  no  need  to  describe  the  rest  in  this  place,  since  they  are  the  secretions 
of  special  organs,  and  are  described,  as  far  as  is  judged  necessary  for  the 
purposes  of  this  work,  in  subsequent  pages.  We  shall  here  speak  first  of  the 
blood,  and  next  of  the  lymph  and  chyle. 

THE  BLOOD. 

The  Blood  is  a  fluid  holding  a  large  number  of  minute  cells  or  corpuscles 
in  suspension.  Its  general  physical  characters  are  so  well  known  that  we 
need  merely  say  that  it  is  of  a  dark  red  or  purple  color  in  the  veins,  and  of  a 
bright  red  or  scarlet  in  the  arteries;  that  it  is  viscid,  drying  rapidly,  and  with 
a  clammy  feeling;  salt  to  the  taste,  slightly  alkaline,  and  with  a  specific 
gravity  of  about  1055. 

General  Composition  of  the  Blood. — On  standing,  blood,  under  ordinary  circum- 
stances, soon  separates  into  two  parts — a  fluid  called  the  ^^ serum"  and  a  clot  or 
"  coagulum."  The  latter  is  not  merely  the  cells  or  blood-corpuscles  spoken  of 
above  as  held  in  suspension,  and  which  have  subsided  out  of  the  fluid,  but 
consists  besides  of  fibrin  which  has  been  held  in  solution  in  the  fluid  blood, 
and  which  in  its  solidification  has  inclosed  and  implicated  the  blood-corpuscles 
as  they  subside. 

The  blood  is  thus  seen  to  consist  naturally  of  two  parts,  the  plasma,  or  liquor 
sanguinis,  a  fluid  rich  in  fibrin,  and  the  blood-cells,  or  blood-corpuscles ;  and  when 
drawn  from  the  body,  of  two  parts  composed  differently  to  the  above — viz.,  the 
clot,  which  comprises  the  blood-corpuscles  and  the  fibrin  of  the  plasma;  and 
the  serum,  which  consists  of  the  remainder  of  the  plasma. 

The  Blood-corpuscles,  Blood-disks,  or  Blood- globules,  as  they  are  more  commonly 
called,  are  of  two  kinds,  the  red  and  the  white.  The  red  globules  are  far  the 
more  numerous,  and  are  those  which  are  always  intended  when  the  expression 
blood-disks  or  blood-globules  is  used  without  any  other  qualification.  They 
are  said  to  be  in  man  about  three  or  four  hundred  times  as  numerous  as  the 
3 


34  GENERAL    ANATOMY. 

white  (Harley);  by  others  only  fifty  times  as  numerous  (Todd  and  Bowman).* 
They  differ  very  much  in  size  and  shape  in  difterent  animals  (Fig.  i).  In  man 
their  size  varies  considerably,  even  in  the  same  drop  of  blood,  between  the 
limits  of  j^*g^  and  jg'g^  of  an  inch  in  diameter,  the  average  being  about  -j^'g^ 

Fior.  2. 


Corpuscles  of  Frog's  blood  :  1,  1,  red  corpuscles  seen  on  Human  blood -globules  :  a,  seen  from  the 

their  flattened  face ;  2,  the  same  turned  nearly  edgeways  ;  surface;  A,  from  the  side;  e,  united  in  rou- 
3,  colorless  corpuscles ;  4,  red  corpuscles  altered  by  dilute  leaux ;  d,  rendered  spherical  by  water  ;  e,  de- 
acetio  acid.]  colorized   by  the  same  ;  /,    blood-globules 

shrunk  by  evaporation. 

(Todd  and  Bowman).  They  are  circular  disks,  bi-concave  in  profile,  having  a 
slight  central  depression,  with  a  raised  border  (as  seen  in  Fig.  2,  b).  Their 
color  appears  of  a  faint  yellow  when  they  are  seen  singly,  but  it  is  to  their 
aggregation  that  the  blood  owes  its  red  hue.  Human  blood-disks  present  no 
trace. of  a  nucleus.  When  the  blood  is  circulating,  under  the  microscope,  in 
one  of  the  lower  animals,  the  blood-globules  are  seen  to  be  separate  from  each 
other,  and  are  also  separated  from  the  wall  of  the  vessel  by  an  interval  or 
"  lumen."  Doubtless  the  same  is  the  case  in  the  human  body ;  but  when 
drawn  and  examined  on  a  slide  without  reagents,  the  blood-globules  often 
collect  into  heaps  like  rouleaux  of  coin  (Fig.  2,  c).  Their  shape  is  very  soon 
influenced  by  the  medium  in  which  they  are  placed,  and  by  the  specific  gravity 
of  that  medium.  In  water  they  swell  up,  lose  their  color,  and  cease  to  be 
visible,  leaving  the  white  corpuscles  in  the  field.  Solutions  of  salt  or  sugar, 
denser  than  the  serum,  give  them  a  stellate  appearance;  and  the  usual  shape 
may  be  restored  by  diluting  the  solution  to  the  proper  point.  A  solution  of 
the  proper  strength  merely  separates  the  blood-globules  mechanically,  without 
changing  their  shape.  ' 

There  can  be  no  doubt  that  the  difference  in  color  between  arterial  and 
venous  blood  must  be  due  to  some  minute  difference  in  the  red  blood-globules; 
and  it  is  also  in  the  highest  degree  probable  that  the  chemical  differences 
between  these  two  kinds  of  blood  are  due,  in  part  at  least,  to  such  differences; 
but  the  change  has  not  hitherto  been  rendered  perceptible  either  to  the  micro- 
scope or  to  chemical  analysis.  At  the  same  time,  the  researches  of  Professor 
Stokes'  show  that  the  coloring  matter  of  the  blood  produces  difterent  effects 
on  the  solar  spectrum,  according  as  it  is  in  a  more  or  less  oxidized  condition ; 
and  it  is  in  the  highest  degree  probable  that  the  same  change  in  the  oxidation 
of  the  contents  of  the  blood-globules  produces  the  difference  of  color  between 
arterial  and  venous  blood. 

The  human  white  corpuscles  are  rather  larger  than  the  red,  and  have  an 
irregular  or  granular  surface.  A  nucleus  becomes  perceptible  on  the  addition 
of  acetic  acid.  They  are  very  similar,  if  not  identical,  with  the  corpuscles  of 
the  lymph  and  chyle,  though  somewhat  more  acted  upon  by  acetic  acid  than 

"  Hirt  puts  the  proportion  as  low  as  1 :1761  during  fasting,  and  1  :  695  or  1  :429  after  food 
(Kiilliker).  Venesection,  by  withdrawing  so  much  larger  a  proportion  of  the  red  globules,  and 
also  by  favoring  the  absorption  of  lymphatic  fluid  into  the  blood,  much  increases  the  relative 
proportion  of  the  white  corpuscles,  so  that  Kolliker  asserts  that  in  the  horse,  after  enormous 
venesection  (up  to  50  lbs.)  the  colored  and  colorless  corpuscles  appear  equally  numerous. 

»  Proceedings  of  Royal  Society,  1864. 


THE    BLOOD. 


35 


tlie  latter.  Their  proportion  appears  to  vary  considerably  in  different  parts  of 
the  circulation,  being  much  larger  in  the  blood  of  the  splenic  vein  and  hepatic 
vein  than  in  other  parts  of  the  body,  while  in  the  splenic  artery  they  are  very 
scanty.  The  colorless  corpuscles  bear  a  strong  resemblance  also  to  the  cells 
found  in  pus. 

From  the  fact  that  cells  exactly  like  the  colorless  corpuscles  are  being  con- 
stantly furnished  to  the  blood  by  the 

ducts  of  the   lymphatic   glands,  the  ^'^S-  3- 

chyle-ducts  (and  even  the  liver  in  the 
foetus),  and  also  from  their  varying 
proportion  in  different  parts  of  the 
circulation,  and  in  different  pathologi- 
cal conditions,  the  colorless  corpuscles 
are  usually  regarded — with,  at  any 
rate,  considerable  probability — as  an 
earlier  stage  of  the  colored  blood- 
disks. 

Fat-granules  are  seen  in  the  blood 
of  the  lower  animals,  and  occasionally 
in  the  blood  of  pregnant  women  ;  also,  according  to  Kolliker,  in  other  persons 
after  the  abundant  use  of  milk  or  brandy,  as  well  as  in  those  who  are  fasting ; 

Fig  4. 


a.  White  corpuscles  of  human  blood  ;  d.  Red  cor- 
puscles.    (High  power.) 


^     ♦ 


Blood-crystals.  A.  Trihedral  crystals  from  blood  of  guinea-pig.  B.  Pentagonal  crystals  from  blood  of 
squirrel.  C.  Octahedr.al  crystals  from  blood  of  rat  and  mouse.  D.  Haematin  crystals  from  human  blood. 
E.  Htematoidin  crystals  from  an  old  apoplectic  clot.    F.  Haemin  crystals  from  blood  treated  with  acetic  acid. 

which  he  attributes,  in  the  latter  case,  to  the  absorption  of  the  fat  of  the  body. 
But,  under  ordinary  circumstances,  the  granular  base  of  the  chyle,  poured  into 


36  GENERAL    ANATOMY. 

the  blood,  through  the  veins  at  the  root  of  the  neck,  disappears  as  the  blood 
passes  through  the  lungs. 

The  fluid  part  of  the  blood,  the  Liquor  Sanguinis,  or  Plasma,  is  again  com- 
posed of  a  permanently  fluid  portion — the  serum — and  of  fibrin,  which  coagu- 
lates spontaneously  when  out  of  the  body,  but  which  is  held  in  solution  during 
life.  The  fibrin  can  be  separated  from  blood  after  it  has  been  drawn  by  whip- 
ping it  with  twigs,  to  which  the  fibrin  as  it  coagulates  adheres.  The  liquor 
sanguinis  may  be  obtained  free  from  the  red  corpuscles  "by  mixing  fresh-drawn 
blood  with  six  or  eight  times  its  bulk  of  serum,  allowing  the  red  particles  to 
subside,  and  then  decanting  the  supernatant  fluid  and  filtering  it  through  blot- 
ting paper"  (Professor  A.  Buchanan,  quoted  by  Dr.  Sharpey).  In  this  experi- 
ment, or  by  removing  a  portion  of  the  clear  liquor  which  is  found  above  the 
bufi'y  coat  of  inflammatory  blood  just  after  the  latter  has  formed,  the  plasma 
may  be  obtained  (but  diluted  in  the  former  method),  and  will  then  separate  by 
coagulation  into  a  colorless  clot  of  fibrin  and  a  saline  fluid.  The  former  con- 
sists of  interlacing  structureless  strings,  which  contain  in  their  meshes  some 
white  corpuscles  accidentally  inclosed  in  them.  The  office  and  uses  of  the 
fibrin,  as  well  as  its  real  nature,  whether  it  exists  as  such  in  the  living  blood, 
or  is  a  product  of  the  death  of  that  fluid,  have  been  and  are  the  subjects  of 
much  difference  of  opinion — but  such  questions  are  exclusively  within  the  do- 
main of  physiology. 

The  fluid  left  after  the  coagulation  of  the  fibrin,  which  is  the  serum  of  the 
blood  properly  so  called,  is  yellowish,  and  contains  so  much  albumen  that  it 
solidifies  almost  completely  on  being  heated.  It  is  alkaline  from  the  presence 
of  free  soda  and  carbonate  of  soda.  The  chemical  composition  of  the  blood  is 
complex,  as  might  be  anticipated  of  a  fluid  from  which  all  the  various  tissues 
of  the  body  are  to  be  formed;  and  it  must  of  course  vary  in  various  parts  of 
the  circulation.  The  following  seems  to  be  as  accurate  an  analysis  as  possible. 
It  is  quoted  in  the  last  edition  of  Carpenter's  "  Physiology"  by  Power,  from  M. 
Gorrup-Bezanez,  who  procured  two  samples  of  the  same  person's  blood,  and 
had  them  analyzed  by  himself  and  three  other  competent  chemists.  The  sepa- 
rate analyses  are  given,  but  the  variations  are  too  slight  to  be  worth  quoting. 
The  following  were  M.  Gorrup-Bezanez's  results : — 

1st  Speo.  2d  Spec. 

Water 79G.93  783.63 

Solid  matters 203.07  216.37 

Fibrin 1.95  1.56 

Corpuscles 103.23  115.12 

Albumea 70.75  62.74 

Extractive  matters  and  salts 27.14  36.95 

The  crystals  which  form  in  the  blood  under  certain  circumstances  and  when 
treated  by  certain  reagents  ought  to  be  described,  in  consequence  of  their  im- 
portance as  a  means  of  distinguishing  human  from  other  kinds  of  blood.  They 
are  of  three  kinds :  1.  Haematin  crystals,  found  in  normal  blood,  particularly 
in  the  spleen.  These  are  procured  by  the  addition  of  a  little  water,  or  by  agi-^ 
tating  the  blood  with  ether,  by  either  of  which  means  the  blood-corpuscles  aroflj 
ruptured,  and  their  contents  crystallize  on  evaporation.  2.  Ilaimatoidin  crys- 
tals, found  in  old  clots.  3.  Haemin  crystals,  formed  by  mixing  dried  blood 
with  an  equal  quantity  of  common  salt  and  boiling  it  with  a  few  drops  of  glacial 
acetic  acid  till  the  whole  has  dissolved.  A  drop  of  the  mixture  placed  on  the 
slide  will  show  the  crystals  on  cooling.  Fig.  4  shows  these  three  forms  of 
ery.stals  from  human  blood  together  with  some  from  the  lower  animals,  forj 
comparison. 

The  importance  of  being  acquainted  with  the  crystals  found  in  human  blooc 
is  obvious,  and  more  particularly  those  which  can  be  obtained  from  driec 
blood ;  since  in  this  way  old  blood-stains  can  be  recognized  as  being  human  ol 


i 


(;»00J 


LYMPH    AND    CHYLE.  3T 

otherwise,  even  long  after  their  formation.     The  spectrum  analysis,  however,  is 
said  to  be  a  more  delicate  test  of  fresh  blood. 

LYMPH  AND  CHYLE. 

The  Lymph  and  the  Chyle  are  almost  identical  in  constitution,  though  the 
proportion  of  their  constituents  varies  in  different  parts  of  the  vascular  system. 
The  lymph  is  the  secretion  of  a  system  of  vessels  and  glands,  to  be  more  fully 
described  in  the  sequel,  which  takes  up  from  the  worn-out  tissues  that  which  is 
still  available  for  purposes  of  nutrition  and  returns  it  into  the  veins  close  to  the 
heart,  there  to  be  mixed  with  the  mass  of  the  blood.  The  chyle  is  a  fluid  secreted 
by  the  villi  of  the  small  intestines  from  the  food.  It  is  intermingled  with  the 
lymph,  and  is  poured  into  the  circulation  through  the  same  channels.^  (See 
the  description  of  the  Thoracic  Duct,  Lacteals,  and  Ductus  Lymphaticus  dexter, 
in  the  body  of  the  work.) 

On  microscopical  examination,  chyle  displays  besides  the  lymph -corpuscles 
a  large  number  of  fatty  granules,  "the  granular  base  of  the  chyle"  (Fig.  5,  a), 
oil  globules,  free  nuclei  and  a  few  red  blood- 
globules.     The  white  color  of  the  chyle  is  due  Fi<r.  o. 
to  the  abundance  of  the  molecular  base.     These 
molecules    are    almost    or    entirely    absent    in        ^     fg^* 
lymph. 

In  other  respects  lymph  and  chyle  are  indis- 
tinguishable by  microscopic  examination,  but  in 
external  appearance  they  are  very  different. 

Chyle  is  a  milk-white  fluid,  which  coagulates      ^     ~  -""-    ^^'^' 
spontaneously,  and  then  on  standing  separates  _ 

more  or  less  completely  into  a  clear  part,  the        Z  ^  '•'^Sk:'0 

liguor  chyli^  which  is  identical  with  the  liquor        t/  ^ 

sanguinis,  and  a  thinnish  jelly-like  clot,  consist-         V  *^t    ^^^   ^'^^^  '^^fe^^* 
ing  of  fibrin  in  which  chyle-corpuscles  and  the  '^  - .     ^p  ,       ^  Ss^^^^ 

fatty  molecules  are  entangled.     Its  analysis,  as  Ch^ief.om  thehicteais.' 

given  by  Dr.  G.  O.  Rees,^  from  the  chyle  of  a 

criminal  examined  shortly  after  his  execution,  and  in  whom  the  thoracic  duct 
was  found  distended  with  chyle,  is  as  follows : — 

Water 90,48 

Albumen,  witli  traces  of  fibrinous  matter 7.08 

Aqueous  extractive            . .56 

Alcoholic  extractive  or  osmazome .52 

Alkaline  chloride,  carbonate  and  sulphate,  with  traces  of  alkaline  phos- 
phate and  oxide  of  iron .44 

Fatty  matters .92 

100.00 

Lymph,  as  its  name  implies,  is  a  watery  fluid.  In  the  lymph  the  molecular 
base  is  absent,  and  the  lymph-corpuscles  are  very  few  in  number,  and  indeed 
are  said  by  Kolliker  to  be  absent  in  the  smaller  vessels.  According  to  the 
same  author,  the  size  of  the  lymph-globules  increases  as  the  fluid  ascends 
higher  in  the  course  of  the  circulation.  In  this  view  the  lymph  is  at  first  a 
mere  albuminous  fluid,  and  the  chyle  at  first  a  mere  albumino-fatty  fluid,  the 
cells  in  both  being  produced  during  the  passage  of  the  fluid  through  the  glands 
(lymphatic  or  mesenteric,  as  the  case  may  be),  and  being  further  elaborated, 
and  even  new  cells  produced  by  the  division  of  the  old  ones,  in  the  course  of 
the  circulation.     The  presence  of  blood-globules  in  the  lymph  or  in  the  chyle 

■  It  may  not  be  amiss  to  remind  the  student  that  the  lacteal  or  chyliferous  vessels  only  convey 
a  portion  of  the  nutritious  matter  from  the  food,  and  this  only  during  digestion.  At  other  times 
they  seem  to  act  precisely  as  ordinary  lymphatics. 

«  Phil.  Trans.  1842,  p.  82. 


88 


GENERAL    ANATOMY 


is  regarded  by  most  authors  as  accidental,  i.  e.,  produced  by  the  manipulations 
of  the  dissector. 

The  lymph-corpuscles,  as  seen  in  the  above  figure,  are  in  all  essential  respects 
the  same  in  the  chyle,  the  lymph  and  the  blood,  where  they  have  been  described 
above  as  the  colorless  blood-corpuscles.  In  the  chyle  and  lymph,  however, 
they  vary  much  in  size.  In  some  cases  several  younger  cells  have  been  seen 
inclosed  in  the  original  corpuscles. 


CELLULAR  AND  FIBROUS  TISSUE. 

The  Cellular  or  Areolar  Tissue  is  so  called  because  its  meshes  are  easily  dis- 
tended, and  thus  separated  into  cells  or  spaces  which  all  open  freely  into  each 

other,  and  are  consequently  easily  blown  up  with 
[Fig.  6.  air  (Fig,  6),  or  permeated  by  fluid,  when  injected 

into  any  part  of  the  tissue.  Such  spaces,  however, 
do  not  exist  in  the  natural  condition  of  the  body, 
but  the  whole  tissue  forms  one  unbroken  mem- 
brane composed  of  a  number  of  interlacing  fibres, 
variously  superimposed.  Hence  the  old  term  "the 
cellular  membrane"  is  in  many  parts  of  the  body 
more  appropriate  than  its  more  modern  equivalents. 
The  chief  use  of  the  cellular  tissue  is  to  bind  parts 
together;  while  by  the  laxity  of  its  fibres  and  the 
permeability  of  its  areolae  it  allows  them  to  move 
on  each  other,  and  affords  a  ready  exit  for  inflam- 
matory and  other  effused  fluids.  It  is  consequently 
often  denominated  connective  tissue,  and  this  term  is 
still  more  appropriate  to  the  fibrous  tissue  which 
forms  the  bond  of  connection  between  the  intimate 
elements  of  solid  organs ;  in  which  more  restricted 
sense  the  term  is  often  used  in  modern  works. 
The  areolar  tissue  consists  essentially  of  two  forms 
of  fibrous  tissue,  the  white  and  yellow,  intermixed 
in  varying  proportions,  together  with  a  great  quan- 
tity of  capillary  vessels,  nerves  and  lymphatics, 
and  in  most  situations  it  contains  fat.  The  cellular 
tissue  is  continuous  over  the  whole  body;  so  that 
fluid,  and  especially  air,  when  injected  forcibly  into  it — as  from  a  wound  of  the 
lung  or  bowel — may  be  diffused  into  the  remotest  parts. 

The  White  Fibrous  Tissue  consists  of  bundles  of  wavy  fibres,  interlacing  with 
each  other,  each  composed  of  minute  filaments,  or  fihrillse,  which  appear  homo- 
geneous, and  measure  from  s^Jgu 
Fig-  7.  to  TT^f  7775  of  an  inch  in  diametei^j 

(Fig.  7.)     The  larger  fibres  havJBI 
no  definite  size,  but  are  supposed 
to  be  solid  masses  formed  by  an 
agglutination  as  it  were  of  the 
ultimate   fibrillse.     Acted   upon 
by  acetic  acid,  the  white  fibrous 
tissue    swells  up  into    an  indis- 
tinct uniform  mass,  which  gradu^- 
ally   becomes   indistinguishablejBI 
and  thus  in  the  areolar  tissue  the 
White  fibrous  tiscue.    (High  power.)  yellow    elastic    element    comes 

alone  into  view.  J|l 

The  Yellow  Elastic  Fibrous  Tissue  is  an  aggregation  of  fibres  which  are  con-fl 
siderably  larger  in  size  than  the  fibrillae  of  the  white  fibrous  element,  varying 


Portion  of  areolar  tissue,  inflated 
and  dried,  showing  the  general  cha- 
racter of  its  larger  meshes.  Each 
lamina  and  filament  here  repre- 
sented contains  numerous  smaller 
ones,  matted  together  by  the  mode 
of  preparation.  (JUagnified  twenty 
diameters.)] 


riBROrS    TISSUE. 


39 


from  5-4  Jnu  to  ^^'g^  of  an  inch  in  diameter  (Harley).  The  fibres  branch  and 
anastomose  freely  with  one  another.  They  are  homogeneous  in  appearance, 
with  dark  borders,  and  are  usually  seen  curled  up  at  their  broken  ends.  They 
remain  unaltered  by  acetic  acid. 

^Each  of  these  elements  of  the  connective  tissue  is  developed  from  cells. 
Kolliker  describes  the  yellow  elastic  fibres  as  developed  from  the  stellate 
branching  corpuscles,  which  may  sometimes  be  found  free  in  the  areolar  tissue, 
and  which  Virchow  has  denominated  "  connective-tissue-corpuscles"  (Fig.  9) ; 
while  the  white  fibrous  tissue  is  formed  from  the  coalescence  of  fusiform  cells, 
which  elongate  into  fibrillse  as  shown  by  Fig.  10. 


Fiff.  8. 


Fie:.  9. 


Fiff.  10. 


Stellate  formative 
cells  of  fine  elastic 
fibres,  from  the  ten- 
do  Achillis  of  a  new- 
born child.  (Mag- 
nified 350  times.) 


Yellow  elastic  tissue.     (High  power.) 


Formative  cells  of  areo- 
lar tissue  from  sheep's 
embryo.  (Magnified  350 
times.)  a.  Cell  without 
any  indication  of  fibril.s ; 

b,  with  commencing,  and 

c,  with  distinct  fibrils- 


The  two  tissues  just  described  are  very  widely  distributed  in  the  body,  espe- 
cially the  white  fibrous  tissue.  This  latter  forms  nearly  the  whole  of  all  the 
firm  investing  membranes,  viz.,  the  muscular  fascise,  the  periosteum,  the  invest- 
ments of  the  various  glands  (such  as  the  tunica  albuginea  testis,  the  capsule  of 
the  kidney,  &c.),  the  investing  sheath  of  the  nerves  (neurilemma),  and  of  va- 
rious organs,  as  the  penis,  and  the  eye  (sheath  of  the  corpora  cavernosa  and 
corpus  spongiosum,  sclerotic,  and  choroid).  Into  all  these  parts,  however,  the 
elastic  tissue  enters  in  greater  or  less  proportion.  The  tendons  and  most  of 
the  ligaments  are  also  formed  almost  entirely  of  the  white  fibrous  tissue,  but 
with  some  elastic  fibres  intermixed.  The  basis  of  the  serous  and  mucous  mem- 
branes is  formed  of  connective  tissue,  disposed  in  a  layer.  The  common  sub- 
cutaneous cellular  or  cellulo-adipose  tissue  has  been  taken  above  as  the  typical 
form  from  which  to  describe  connective  tissue.  Connective  tissue  also  enters 
largely  into  the  formation  of  the  bloodvessels,  glands,  and,  in  fact,  almost  every 
organ  in  the  body.  The  organs  which  are  formed  almost  exclusively  of  the 
yellow  elastic  tissue  are  the  ligamenta  subflava  of  the  vertebras,  the  elastic 


40 


GENERAL    ANATOMY. 


ligaments  of  the  larynx,  the  longitudinal  elastic  fibres  of  the  trachea,  the  elastic 
layer  of  the  middle  coat  of  the  arteries,  and  in  quadrupeds  the  ligamentum 
nuchae. 

Free  cells  are  found  in  the  areolar  tissue,  as  indicated  above.  The  chief 
forms  are  the  spindle-shaped  and  the  stellate,  but  numerous  intermediate  forms 
are  described  by  recent  observers ;  and  of  late  much  interest  has  been  excited 
by  Von  Recklingshausen's  discovery  in  the  cellular  tissue  of  cold-blooded  ani- 
mals of  "  wandering  cells,"  or  cells  endowed  with  the  power  of  automatic  mo- 
tion, and  of  changing  their  shape.  These  cells  appear  identical  with  the  white 
globules  of  the  blood ;  and  it  would  seem  from  the  researches  of  Strieker,  Cohn- 
heim,  and  others,  that  the  walls  of  the  capillary  vessels  are  permeable  to  the 
latter  bodies,  which  are  thus  allowed  to  escape  into  the  cellular  tissue,  there 
to  undergo  development,  normally  into  the  natural  cells  and  cellular  tissue,  or 
abnormally  into  the  corpuscular  forms  of  lymph  and  pus,  according  to  circum- 
stances.' 

ADIPOSE  TISSUE. 

The  common  cellular  membrane  contains  a  variable  quantity  of  Adipose 
Tissue.  The  tissue  is  found  also  in  various  parts  of  the  viscera — as  the  mesen- 
tery, the  surface  of  the  heart,  &c.,  and  fat  enters  largely  into  the  formation  of 
the  marrow  of  the  bones.  There  is,  however,  a  difference  which  should  be 
attended  to  between  mere  fat  and  adipose  tissue.  Adipose  tissue  consists  of  a 
number  of  vesicles  formed  by  an  extremely  delicate  structureless  membrane, 
round  or  spherical  where  they  have  not  been  subject  to  pressure ;  otherwise, 
variously  flattened.  They  are  supplied  and  held  together  by  capillary  blood- 
vessels (Fig.  11),  and  fine  connective  tissue,  and  each  vesicle  is  filled  with  fat. 

[Fig.  11. 


^ 


Bloodvessels  of  fat.  1.  Minute  flnttened  fat-lobule,  in  which  the  vessels  only  are  represented.  3.  Terminal 
artery.  4.  Primitive  vein.  6.  Fiit-eells  of  one  border  of  the  globule  sepiirately  represented.  (Magnified 
100  diameters.)     2.  Plun  of  arrangement  of  capillaries  on  exterior  of  fat-ceils,  mure  highly  magnified.] 


Fat  is  an  unorganized  substance,  consisting  of  liquid  oily  matter  (glycerine) 
in  combination  with  certain  fatty  acids,  stearic,  margaric,  and  elaic.  Sometimes 
the  acids  separate  spontaneously  before  the  fat  is  examined,  and  are  seen  under 
the  microscope  in  a  crystalline  form,  as  in  the  figure.    By  boiling  the  tissue  in 

'  On  this  subject  reference  may  be  made  to  Von  Recklingshausen,  in  Virchow's  Arrluy. 
Bd.  xxviii.,  and  Rollett  in  Strieker's  Lehre  von  den  Oeioeben,  chap,  ii.,  where  the  reader  will 
find  references  to  Strieker,  Cohnheim,  KUhne,  and  others. 


CARTILAGE.  41 

ether  or  strong  alcohol,  the  fat  may  be  extracted  from  the  vesicle,  which  is 
then  seen  empty  and  shrunken. 

Besides  the  fully-formed  fat-cells  above  described,  others  may  occasionally 
be  found  in  the  course  of  formation,  especially  in  cases  of  sudden  death  during 
robust  health.  They  are  described  by  Rollett  as,  in  the  first  stage,  small  round 
granular  cells,  provided  with  a  roundish  nucleus,  into  the  interior  of  which  a 


Adipose  tissue,     a.  Starlike  appearance,  from  crystallization  of  fatty  acids.     (High  power.) 

strongly  refracting  drop  of  fat  is  then  secreted,  which  is  at  first  surrounded  by 
a  ring  of  the  granular  matter,  and  gradually  increases  so  as  to  fill  the  cell.  As 
the  granular  matter  becomes  less  and  less,  the  nucleus,  which  can  at  first  be 
easily  recognized,  becomes  less  perceptible,  but  according  to  this  author  can 
always  be  brought  into  view  by  appropriate  reagents.  Fat  is  said  to  be  first 
detected  in  the  human  embryo  about  the  fourteenth  week. 

In  various  parts  of  the  body  'pigment  is  found,  viz.,  in  the  hairs,  in  the  iris 
and  choroid  coat  of  the  eye,  in  the  lungs,  in  the  nerve-cells,  in  the  rete  mucosum 
in  the  dark  races,  and  in  some  parts  of  the  body — such  as  the  areola  of  the 
nipple — which  are  of  dark  color  even  in  the  fair  races,  except  Albinoes,  in 
whom  pigment  is  absent.  Pigment-cells  are  also  found  in  the  blood,  according 
to  Virchow. 

In  many  situations  the  color  is  produced  simply  by  the  presence  of  dark 
granules  scattered  about  without  any  definite  arrangement;  in  the. choroid  coat 
the  pigment  forms  a  regular  layer  of  hexagonal  nucleated  cells  filled  with 
pigment  granules ;  in  other  parts  the  pigment  is  contained  in  branching  cells, 
probably  the  connective-tissue-corpuscles  filled  with  pigment  granules ;  and  in 
most  situations,  such  as  the  nerve-cells  and  the  epidermis,  the  pigment-granules 
form  a  greater  or  less  element  in  the  contents  of  the  nucleated  cells  of  the  part. 
In  the  dark  races  the  color  of  the  skin  is  due  to  the  accumulation  of  pigment 
in  the  deeper  layers  of  the  epidermis — the  rete  mucosum. 

CARTILAGE. 

Cartilage  is  a  non- vascular  structure  which  is  found  in  various  parts  of  the 
l3ody — in  adult  life  chiefly  in  the  joints,  in  the  parietes  of  the  thorax,  and  in 
various  tubes,  such  as  the  air-passages,  nostrils,  and  ear,  which  are  to  be  kept 
permanently  open.  In  the  foetus  at  an  early  period  the  greater  part  of  the 
skeleton  is  cartilaginous.  As  this  cartilage  is  afterwards  replaced  by  bone,  it 
is  called  temporary,  in  opposition  to  that  which  remains  unossified  during  the 
whole  of  life,  and  which  is  coXlQdi  permanent. 


88  GENERAL    ANATOMY. 

is  regarded  by  most  authors  as  accidental,  i.  e.,  produced  by  the  manipulations 
of  the  dissector. 

The  lymph-corpuscles,  as  seen  in  the  above  figure,  are  in  all  essential  respects 
the  same  in  the  chyle,  the  lymph  and  the  blood,  where  they  have  been  described 
above  as  the  colorless  blood-corpuscles.  In  the  chyle  and  lymph,  however, 
they  vary  much  in  size.  In  some  cases  several  younger  cells  have  been  seen 
inclosed  in  the  original  corpuscles. 


CELLULAR  AND  FIBROUS  TISSUE. 

The  Cellular  or  Areolar  Tissue  is  so  called  because  its  meshes  are  easily  dis- 
tended, and  thus  separated  into  cells  or  spaces  which  all  open  freely  into  each 

other,  and  are  consequently  easily  blown  up  with 
[Fig.  6.  air  (Fig.  6),  or  permeated  by  fluid,  when  injected 

into  any  part  of  the  tissue.  Such  spaces,  however, 
do  not  exist  in  the  natural  condition  of  the  body, 
but  the  whole  tissue  forms  one  unbroken  mem- 
brane composed  of  a  number  of  interlacing  fibres, 
variously  superimposed.  Hence  the  old  term  "the 
cellular  membrane"  is  in  many  parts  of  the  body 
more  appropriate  than  its  more  modern  equivalents. 
The  chief  use  of  the  cellular  tissue  is  to  bind  parts 
together ;  while  by  the  laxity  of  its  fibres  and  the 
permeability  of  its  areolsB  it  allows  them  to  move 
on  each  other,  and  affords  a  ready  exit  for  inflam- 
matory and  other  effused  fluids.  It  is  consequently 
often  denominated  connective  tissue^  and  this  term  is 
still  more  appropriate  to  the  fibrous  tissue  which 
forms  the  bond  of  connection  between  the  intimate 
elements  of  solid  organs ;  in  which  more  restricted 
sense  the  term  is  often  used  in  modern  works. 
The  areolar  tissue  consists  essentially  of  two  forms 
of  fibrous  tissue,  the  white  and  yellow^  intermixed 
in  varying  proportions,  together  with  a  great  quan- 
tity of  capillary  vessels,  nerves  and  lymphatics, 
and  in  most  situations  it  contains  fat.  The  cellular 
tissue  is  continuous  over  the  whole  body ;  so  that 
fluid,  and  especially  air,  when  injected  forcibly  into  it — as  from  a  wound  of  the 
lung  or  bowel — may  be  diffused  into  the  remotest  parts.  ^™ 

The  White  Fibrous  Tissue  consists  of  bundles  of  wavy  fibres,  interlacing  witlHj 
each  other,  each  composed  of  minute  filaments,  ov  fihrillse,  which  appear  homo- 
geneous, and  measure  from  scnnu 
Fig.  7.  to  ^^f„^  of  an  inch  in  diameter. 

(Fig.  7.)  The  larger  fibres  have 
no  definite  size,  but  are  supposed 
to  be  solid  masses  formed  by  an 
agglutination  as  it  were  of  the 
ultimate  fibrillae.  Acted  upon 
by  acetic  acid,  the  white  fibrous 
tissue  swells  up  into  an  indis- 
tinct uniform  mass,  which  gradu- 
ally becomes  indistinguishable; 
and  thus  in  the  areolar  tissue  the 
yellow    elastic    element    comes 


Portion  of  areolar  tissue,  inflated 
and  dried,  showing  the  general  cha- 
racter of  its  larger  meshes.  Each 
lamina  and  filament  here  repre- 
sented contains  numerous  smaller 
ones,  matted  together  by  the  mode 
of  preparation.  (Magnified  twenty 
diameters.}] 


White  fibrous  tissue.     (High  power.) 

alone  into  view. 
The  Yellow  Elastic  Fibrous  Tissiie  is  an  aggregation  of  fibres  which  are  con 
siderably  larger  in  size  than  the  fibrillae  of  the  white  fibrous  element,  varying 


II 


FIBROUS    TISSUE. 


39 


from  54^^15  to  4n'on  9^  ^^  i»ch  in  diameter  (Harley).  The  fibres  branch  and 
anastomose  freely  with  one  another.  They  are  homogeneous  in  appearance, 
with  dark  borders,  and  are  usually  seen  curled  up  at  their  broken  ends.  They 
remain  unaltered  by  acetic  acid. 

Each  of  these  elements  of  the  connective  tissue  is  developed  from  cells. 
Kolliker  describes  the  yellow  elastic  fibres  as  developed  from  the  stellate 
branching  corpuscles,  which  may  sometimes  be  found  free  in  the  areolar  tissue, 
and  which  Virchow  has  denominated  "connective-tissue-corpuscles"  (Fig.  9); 
while  the  white  fibrous  tissue  is  formed  from  the  coalescence  of  fusiform  cells, 
which  elongate  into  fibrillae  as  shown  by  Fig.  10. 


Fig.  9. 


Fig.  10. 


K 


Stellate  formative 
cells  of  fine  elastic 
fibres,  from  the  ten- 
do  Achillis  of  a  new- 
born child.  (Mag- 
nified 350  times.) 


Yellow  elastic  tissue.     (High  power.) 


Formative  cells  of  areo- 
lar tissue  from  sheep's 
embryo.  (Magnified  350 
times.)  a,  Cell  without 
any  indication  of  fibrils ; 

b,  with  commencing,  and 

c,  with  distinct  fibrils. 


The  two  tissues  just  described  are  very  widely  distributed  in  the  body,  espe- 
cially the  white  fibrous  tissue.  This  latter  forms  nearly  the  whole  of  all  the 
firm  investing  membranes,  viz.,  the  muscular  fascije,  the  periosteum,  the  invest- 
ments of  the  various  glands  (such  as  the  tunica  albuginea  testis,  the  capsule  of 
the  kidney,  &c.),  the  investing  sheath  of  the  nerves  (neurilemma),  and  of  va- 
rious organs,  as  the  penis,  and  the  eye  (sheath  of  the  corpora  cavernosa  and 
corpus  spongiosum,  sclerotic,  and  choroid).  Into  all  these  parts,  however,  the 
elastic  tissue  enters  in  greater  or  less  proportion.  The  tendons  and  most  of 
the  ligaments  are  also  formed  almost  entirely  of  the  white  fibrous  tissue,  but 
with  some  elastic  fibres  intermixed.  The  basis  of  the  serous  and  mucous  mem- 
branes is  formed  of  connective  tissue,  disposed  in  a  layer.  The  common  sub- 
cutaneous cellular  or  cellulo-adipose  tissue  has  been  taken  above  as  the  typical 
form  from  which  to  describe  connective  tissue.  Connective  tissue  also  enters 
largely  into  the  formation  of  the  bloodvessels,  glands,  and,  in  fact,  almost  every 
organ  in  the  body.  The  organs  which  are  formed  almost  exclusively  of  the 
yellow  elastic  tissue  are  the  ligamenta  subflava  of  the  vertebrae,  the  elastic 


40 


GENERAL    ANATOMY. 


ligaments  of  the  larynx,  the  longitudinal  elastic  fibres  of  the  trachea,  the  elastic 
laver  of  the  middle  coat  of  the  arteries,  and  in  quadrupeds  the  ligamentum 
nuchas. 

Free  cells  are  found  in  the  areolar  tissue,  as  indicated  above.  The  chief 
forms  are  the  spindle-shaped  and  the  stellate,  but  numerous  intermediate  forms 
are  described  by  recent  observers ;  and  of  late  much  interest  has  been  excited 
by  Yon  Eecklingshausen's  discovery  in  the  cellular  tissue  of  cold-blooded  ani- 
mals of  "  wandering  cells,"  or  cells  endowed  with  the  power  of  automatic  mo- 
tion, and  of  changing  their  shape.  These  cells  appear  identical  with  the  white 
globules  of  the  blood ;  and  it  would  seem  from  the  researches  of  Strieker,  Cohn- 
heim,  and  others,  that  the  walls  of  the  capillary  vessels  are  permeable  to  the 
latter  bodies,  which  are  thus  allowed  to  escape  into  the  cellular  tissue,  there 
to  undergo  development,  normally  into  the  natural  cells  and  cellular  tissue,  or 
abnormally  into  the  corpuscular  forms  of  lymph  and  pus,  according  to  circum- 
stances.' 

ADIPOSE  TISSUE. 

The  common  cellular  membrane  contains  a  variable  quantity  of  Adipose 
Tissue.  The  tissue  is  found  also  in  various  parts  of  the  viscera — as  the  mesen- 
tery, the  surface  of  the  heart,  &c.,  and  fat  enters  largely  into  the  formation  of 
the  marrow  of  the  bones.  There  is,  however,  a  difference  which  should  be 
attended  to  between  mere  fat  and  adipose  tissue.  Adipose  tissue  consists  of  a 
number  of  vesicles  formed  by  an  extremely  delicate  structureless  membrane, 
round  or  spherical  where  they  have  not  been  subject  to  pressure;  otherwise, 
variously  flattened.  They  are  supplied  and  held  together  by  capillary  blood- 
vessels (Fig.  11),  and  fine  connective  tissue,  and  each  vesicle  is  filled  with  fat. 

[Fig.  11. 


Bloodvessels  of  fat.  1.  Minute  flattened  fat-lobule,  in  which  the  vey^els  only  nre  represented.  3.  Terminal 
artery.  4.  Primitive  vein.  5.  Fiit-cells  of  one  border  of  the  globule  sepjirately  represented.  (M.-ignified 
100  diameters.)     2.  Plan  of  arrangement  of  capillaries  on  exterior  of  fat-ceils,  more  highly  magnified.] 


Fat  is  an  unorganized  substance,  consisting  of  liquid  oily  matter  (glycerine) 
in  combination  with  certain  fatty  acids,  stearic,  margaric,  and  elaic.  Sometimes 
the  acids  separate  spontaneously  before  the  fat  is  examined,  and  are  seen  under 
the  microscope  in  a  crystalline  form,  as  in  the  figure.    By  boiling  the  tissue  in 

'  On  this  subject  reference  may  be  made  to  Von  Recklingshansen,  in  Virchow's  Archiy. 
B(l.  x.wiii.,  and'Rollett  in  Strieker's  //fi/jre  von  den  Gf'^jwefcen,  chap,  ii.,  where  the  reader  will 
find  references  to  Strieker,  Cohnheim,  Kuhne,  and  others. 


CARTILAGE.  41 

ether  or  strong  alcohol,  the  fat  may  be  extracted  from  the  vesicle,  which  is 
then  seen  empty  and  shrunken. 

Besides  the  fully-formed  fat-cells  above  described,  others  may  occasionally 
be  found  in  the  course  of  formation,  especially  in  cases  of  sudden  death  during 
robust  health.  They  are  described  hy  Rollett  as,  in  the  first  stage,  small  round 
granular  cells,  provided  with  a  roundish  nucleus,  into  the  interior  of  which  a 

Fig.  12. 


Adipose  tissue,     a.  Starlike  appearance,  from  crystallization  of  fatty  acids.     (High  power.) 

strongly  refracting  drop  of  fat  is  then  secreted,  which  is  at  first  surrounded  by 
a  ring  of  the  granular  matter,  and  gradually  increases  so  as  to  fill  the  cell.  As 
the  granular  matter  becomes  less  and  less,  the  nucleus,  which  can  at  first  be 
easily  recognized,  becomes  less  perceptible,  but  according  to  this  author  can 
always  be  brought  into  view  by  appropriate  reagents.  Fat  is  said  to  be  first 
detected  in  the  human  embryo  about  the  fourteenth  week. 

In  various  parts  of  the  body  pigment  is  found,  viz.,  in  the  hairs,  in  the  iris 
and  choroid  coat  of  the  eye,  in  the  lungs,  in  the  nerve-cells,  in  the  rete  mucosum 
in  the  dark  races,  and  in  some  parts  of  the  body — such  as  the  areola  of  the 
nipple — which  are  of  dark  color  even  in  the  fair  races,  except  Albinoes,  in 
whom  pigment  is  absent.  Pigment-cells  are  also  found  in  the  blood,  according 
to  Yirchow. 

In  many  situations  the  color  is  produced  simply  by  the  presence  of  dark 
granules  scattered  about  without  any  definite  arrangement;  in  the -choroid  coat 
the  pigment  forms  a  regular  layer  of  hexagonal  nucleated  cells  filled  with 
pigment  granules ;  in  other  parts  the  pigment  is  contained  in  branching  cells, 
probably  the  connective-tissue-corpuscles  filled  with  pigment  granules ;  and  in 
most  situations,  such  as  the  nerve-cells  and  the  epidermis,  the  pigment-granules 
form  a  greater  or  less  element  in  the  contents  of  the  nucleated  cells  of  the  part. 
In  the  dark  races  the  color  of  the  skin  is  due  to  the  accumulation  of  pigment 
in  the  deeper  layers  of  the  epidermis — the  rete  mucosum. 

CAETILAGE. 

Cartilage  is  a  non- vascular  structure  which  is  found  in  various  parts  of  the 
body — in  adult  life  chiefly  in  the  joints,  in  the  parietes  of  the  thorax,  and  in 
various  tubes,  such  as  the  air-passages,  nostrils,  and  ear,  which  are  to  be  kept 
permanently  open.  In  the  foetus  at  an  early  period  the  greater  part  of  the 
skeleton  is  cartilaginous.  As  this  cartilage  is  afterwards  replaced  by  bone,  it 
is  called  temporary,  in  opposition  to  that  which  remains  unossified  during  the 
whole  of  life,  and  which  is  oaWed  permanent. 


42  GENERAL    ANATOMY. 

Cartilage  is  divided  according  to  its  minute  anatomy  into  true  or  hyaline 
cartilage,  fibrous,  or  fibro- cartilage,  and  yellow,  or  elastic,  or  reticular  cartilage. 
The  various  cartilages  in  the  body  are  also  classified  according  to  their  function 
and  position,  into  articular,  interarticular,  costal,  and  membraniform. 

True  Cartilage,  which  rnay  be  taken  as  the  type  of  this  tissue,  consists  of  a 
gristly  mass,  of  a  pearly  bluish,  color,  enveloped  in  a  fibrous  membrane,  the 

perichondrium,  from  the  vessels  of 

^^'  which  it  imbibes  its  nutritive  fluids, 

b   ^  being  itself  destitute  of  bloodvessels ; 

E  v. -:j     nor  have  nerves  been  traced  into  it. 

U..r_'   r  "'/oT*^  -  "ii^     Its  intimate  structure  is  very  simple. 

|-:-> _      "n^-^  ■0'^^&     ^^  ^  *^^^  slice  be  examined  under 

Li^^=^^j-fe_^-    ^  ,.^  .  \,_.^^^     the  microscope,  it  will  be  found  to 

^^^J^^/^^i^^^Sr^'^^--*  "^  '    ^     consist  of  cells  of  a  rounded  or  an- 

F^^^^^~^kv'^//f   Q,\qj^  g^l^r  shape,  with  nucleus  and  nucleo- 

f .  ~^^^::^^^jL^^4i  lus,  lying  in  groups,  surrounded  by 

*~~rj  .T     ~  11    .<•      *!,      •    A      *-i  a  granular  or  almost  homogeneous 

Hntnan  cartilage  cells,  from  the  cricoid  cartilage.  «=    ,  °     . 

(Magnified  350  times.)  matrix.      By  boilmg  the  cartilage 

for  some  hours,  and  treating  it  with 
acetic  acid,  the  cell  membrane  which  lines  the  cavity  in  the  matrix  may  be 
made  visible.     The  matrix  is  often  arranged  in  the  form  of  a  concentric  ring 
around  the  cartilage-cell,  forming  what  is  described  by  some  authors  as  the . 
cartilage-capsule. 

The  articular  cartilages,  the  temporary  cartilages,  and  the  costal  cartilages, 
are  all  of  the  hyaline  variety.  They  present  minute  differences  in  the  size  and 
shape  of  their  cells,  and  in  the  arrangement  of  the  matrix.  In  the  articular 
cartilages,  which  show  no  tendency  to  ossification,  the  matrix  is  finely  granular 
under  a  high  power;  the  cells  and  nuclei  are  small,  and  are  disposed  parallel 
to  the  surface  in  the  superficial  part,  while  nearer  to  the  bone  they  become 
vertical.  Articular  cartilages  have  a  tendency  to  split  in  a  vertical  direction, 
probably  from  some  peculiarity  in  the  intimate  structure,  or  arrangement  of  the 
component  parts,  of  the  matrix.  In  disease  this  tendency  to  a  fibrous  splitting 
becomes  very  manifest.  Articular  cartilage  in  the  adult  is  not  covered  by  peri- 
chondrium, at  least  on  its  free  surface,  where  it  is  exposed  to  friction,  though  an 
epithelial  layer  can  be  traced  in  the  foetus  over  the  whole  surface  of  the  car- 
tilage, and  in  the  adult  over  a  small  part  of  its  circumference,  continuous  with 
the  epithelium  of  the  synovial  membrane.  This  is  probably  the  remains  of  an 
investing  membrane  which  is  worn  away  in  after-life  by  the  action  of  the  joint. 
Articular  cartilage  forms  a  thin  incrustation  upon  the  joint-surfaces  of  the 
bones,  and  its  elasticity  enables  it  to  break  the  force  of  any  concussion,  whilst 
its  smoothness  affords  ease  and  freedom  of  movement.  It  varies  in  thickness 
according  to  the  shape  of  the  bone  on  which  it  lies ;  where  this  is  convex,  the 
cartilage  is  thickest  over  the  convexity  where  the  greatest  pressure  is  received, 
and  the  reverse  is  the  case  in  the  concavities  of  the  joints.  Articular  cartilage 
appears  to  imbibe  its  nutriment  partly  from  the  vessels  of  the  neighboring 
synovial  membrane,  partly  from  those  of  the  bone  upon  which  it  is  implanted. 
Mr.  Toynbee  has  shown  that  the  minute  vessels  of  the  cancellous  tissue,  as 
they  approach  the  articular  lamella,  dilate,  and,  forming  arches,  return  into  the 
substances  of  the  bone. 

Temporary  cartilage,  and  the  process  of  its  ossification,  will  be  described 
with  bone.  _■ 

In  the  costal  cartilages  the  cells  and  nuclei  are  large,  and  the  matrix  has  dfl 
tendency  to  fibrous  striation,  especially  in  old  age.     These  cartilages  also  are 
very  prone  to  ossify.     In  the  thickest  parts  of  the  costal  cartilages  a  few  large 
vascuhir  channels  may  be  detected.     This  appears  at  first  sight  an  exception  t(J|| 
the  statement  that  cartilage  is  a  non-vascular  tissue,  but  it  is  not  so  really,  foi«i 
the  vessels  give  no  branches  to  the  cartilage-substance  itself,  and  the  channels 


CARTILAGE. 


43 


Fig.  14. 


may  rather  be  looked  upon  as  involutions  of  the  perichondrium.  The  ensiform 
cartilage  may  be  regarded  as  one  of  the  costal  cartilages,  and  the  cartilage  of 
the  nose  and  of  the  larynx  and  trachea 
resemble  them  in  microscopical  charac- 
ters, except  the  epiglottis  and  cornicula 
laryngis,  which  are  of  the  reticular 
variety. 

The  hyaline  cartilages,  especially  in 
adult  and  advanced  life,  are  prone  to 
calcify — that  is  to  say,  to  have  their 
matrix  permeated  by  the  salts  of  lime, 
without  any  appearance  of  true  bone. 
This  process  of  calcification  occurs  also, 
and  still  more  frequently  according  to 
Eollett,  in  such  cartilages  as  those  of  the 
trachea,  which  are  prone  afterwards  to 
conversion  into  true  bone.  It  is  on  the 
confines  of  true  ossification  that  this  cal- 
cerous  change  or  degeneration  is  most 
liable  to  occur,  so  that  it  is  rare  to  find 
true  bone  and  true  cartilage  in  juxtapo- 
sition at  the  confines  of  the  normal  ossi- 
fication, as  for  instance  at  the  joint  ends, 
at  the  ends  of  the  ribs,  in  the  symphysis 
pubis  and  intervertebral  cartilages. 

Fih'o-cariilage  consists  of  a  mixture  of  white  fibrous  and  cartilaginous  tissues 
in  various  proportions ;  it  is  to  the  first  of  these  two  constituents  that  its  flexi- 


Coital  caitilage  from  a  man  seventy  ^ix  years 
of  age,  showing  the  development  of  fibrous  struc. 
ture  in  the  matrix.  In  several  portions  of  the 
specimen,  two  or  three  generations  of  cells  are  seen 
inclosed  in  a  parent  cell-wall.     (High  power.) 


Fiff.  15. 


White  fibrous  cartilages  from  the  semilunar  disk  of  the  patella  joint  of  an  ox,     (Magnified  100  times.) 

bility  and  toughness  is  chiefly  owing,  and  to  the  latter  its  elasticity.  The 
fibro-cartilages  admit  of  arrangement  into  four  groups — interarticular,  connect- 
ing, circumferential,  and  stratiform. 

The  interarticular  fihro-cartilages  {menisci)  are  flattened  fibro-cartilaginous 
plates,  of  a  round,  oval,  or  sickle-like  form,  interposed  between  the  articular 
cartilages  of  certain  joints.  They  are  free  on  both  surfaces,  thinner  toward 
their  centre  than  at  their  circumference,  and  held  in  position  by  their  extremi- 
ties being  connected  to  the  surrounding  ligaments.  The  synovial  membrane 
of  the  joint  is  prolonged  over  them  a  short  distance  from  their  attached  margin. 
They  are  found  in  the  temporo-maxillary,  sterno-clavicular,  acromio-clavicular, 
wri.st  and  knee-joints.  These  cartilages  are  usually  found  in  those  joints  most 
exposed  to  violent  concussions,  and  subject  to  frequent  movement.     Their  use 


44 


GENERAL    ANATOMY. 


is — to  maintain  the  apposition  of  the  opposed  surfaces  in  their  various  motions*, 
to  increase  the  depth  of  the  articular  surface,  and  give  ease  to  the  gliding 
movement;  to  moderate  the  effects  of  great  pressure,  and  deaden  the  intensity 
of  the  shocks  to  which  the  parts  may  be  submitted.  Virchow  describes  in  the 
semilunar  cartilages  of  the  knee  a  system  of  anastomosing  tubes,  formed  by 
cells  which  communicate  with  each  other,  and  by  means  of  which  the  nutritious 
fluids  are  conveyed  into  the  interior  of  the  mass.  The  semilunar  disks,  accord- 
ing to  this  author,  are  wrongly  denominated  cartilages,  since  they  yield  no 
chondrine  on  boiling ;  and  he  appears  to  regard  them  as  a  modification  of  ten- 
dinous structure,  which,  however,  agrees  with  the  cartilages  in  the  important 
particular  of  being  non- vascular.  (See  Virchow's  "Cellular  Pathology,"  by 
Chance,  pp.  87-89.) 

The  connecting fihro-cartilages  are  interposed  between  the  bony  surfaces  of  those 
joints  which  admit  of  only  slight  mobility,  as  between  the  bodies  of  the  verte- 
brae and  the  pubic  symphyses ;  they  form  disks,  which  adhere  closely  to  both 
of  the  opposed  bones,  and  are  composed  of  concentric  rings  of  fibrous  tissue, 
with  cartilaginous  laminae  interposed,  the  former  tissue  predominating  towards 
the  circumference,  the  latter  towards  the  centre. 

The  circumferential  fihro-cartilages  consist  of  a  rim  of  fibro-cartilage,  which 
surrounds  the  margin  of  some  of  the  articular  cavities,  as  the  cotyloid  cavity 
of  the  hip,  and  the  glenoid  cavity  of  the  shoulder;  they  serve  to  deepen  the 
articular  surface  and  to  protect  the  edges  of  the  bone. 

The  stratiform  fihro-cartilages  are  those  which  form  a  thin  layer  in  the  osseous 
grooves,  through  which  the  tendons  of  certain  muscles  glide. 


Fisr.  16. 


Yellow  cartilage,  ear  of  horse.     (High  power.) 

The  Yelloic  or  Reticular  Cartilages  found  in  the  human  body  are  the  epiglot- 
tis, cornicula  laryngis,  and  the  cartilaginous  parts  of  the  ear  (auricle  and 
Eustachian  tube).  In  this  variety  the  cartilage  cells  lie  in  the  meshes  of  a 
network  of  yellow  elastic  fibres,  with  a  double  outline,  branching  and  anasto- 
mosing in  all  directions.  The  fibres  resemble  those  of  the  yellow  elastic 
fibrous  tissue,  both  in  appearance  and  in  being  unaffected  by  acetic  acid,  and 
according  to  Rollett  their  continuity  with  the  elastic  fibres  of  the  neighboring 
cellular  tissue  admits  of  being  demonstrated. 

The  distinguishing  feature  of  cartilage  as  to  its  chemical  composition  is  that 
it  yields  on  boiling  a  sub.stance  called  chondrine,  very  similar  to  gelatine,  but 
differing  from  it  in  not  being  precipitated  by  tannin. 


BOXE.  45 


BONE. 


Structure  and  Physical  Properties  of  Bone.  Bone  is  one  of  the  hardest  struc- 
tures of  the  animal  body ;  it  possesses  also  a  certain  degree  of  toughness  and 
elasticity.  Its  color,  in  a  fresh  state,  is  of  a  pinkish  white  externally,  and  deep 
red  within.  On  examining  a  section  of  any  bone,  it  is  seen  to  be  composed  of 
two  kinds  of  tissue,  one  of  which  is  dense  and  compact  in  texture,  like  ivory ; 
the  other  consisting  of  slender  fibres  and  lamellae,  which  join  to  form  a  reticu- 
lar structure ;  this,  from  its  resemblance  to  lattice- work,  is  called  cancellous. 
The  compact  tissue  is  always  placed  on  the  exterior  of  a  bone  ;  the  cancellous 
tissue  is  always  internal.  The  relative  quantity  of  these  two  kinds  of  tissue 
varies  in  different  bones,  and  in  different  parts  of  the  same  bone,  as  strength  or 
lightness  is  requisite.  Close  examination  of  the  compact  tissue  shows  it  to  be 
extremely  porous,  so  that  the  difference  in  structure  between  it  and  the  cancel- 
lous tissue  depends  merely  upon  the  different  amount  of  solid  matter,  and  the 
size  and  number  of  the  spaces  in  each ;  the  cavities  being  small  in  the  compact 
tissue,  and  the  solid  matter  between  them  being  abundant;  whilst  in  the  can- 
cellous tissue  the  spaces  are  large,  and  the  solid  matter  in  smaller  quantity. 

Bone  during  life  is  permeated  by  vessels,  and  is  inclosed  in  a  fibrous  mem- 
brane, the  periosteum,  by  means  of  which  most  of  these  vessels  reach  the  hard 
tissue.  If  the  periosteum  be  stripped  from  the  surface  of  the  living  bone, 
small  bleeding  points  are  seen,  which  mark  the  entrance  of  the  periosteal  ves- 
sels ;  and  on  section  during  life  every  part  of  the  bone  will  be  seen  to  exude 
blood,  from  the  minute  vessels  which  ramify  in  the  Haversian  canals.  The 
interior  of  the  bones  of  the  limbs  presents  a  cylindrical  cavity  filled  with  mar- 
row, and  lined  by  a  highly  vascular  areolar  membrane,  the  medullary  mem- 
brane or  internal  periosteum.  The  larger  Haversian  canals  are  also  filled  with 
marrow. 

The  p)eriosteum  adheres  to  the  surface  of  the  bones  in  nearly  every  part,  ex- 
cepting at  their  cartilaginous  extremities.  Where  strong  tendons  or  ligaments 
are  attached  to  the  bone,  the  periosteum  is  incorporated  with  them.  It  consists 
of  two  layers  closely  united  together;  the  outer  one  formed  chiefly  of  con- 
nective tissue,  containing  occasionally  a  few  fat-cells;  the  inner  one,  of  elastic 
fibres  of  the  finer  kind,  forming  dense  membranous  networks,  which  can  be 
again  separated  into  several  layers  (Kcilliker).  In  young  bones  the  periosteum 
is  thick,  and  very  vascular,  and  is  intimately  connected  at  either  end  of  the  bone 
with  the  epiphysial  cartilage,  but  less  closely  with  the  shaft,  from  which  it  is 
separated  by  a  layer  of  soft  blastema,  in  which  ossification  proceeds  on  the  ex- 
terior of  the  young  bone.  Later  in  life  the  periosteum  is  thinner,  less  vascular, 
and  more  closely  connected  with  the  adjacent  bone,  this  adhesion  growing 
stronger  as  age  advances.  The  periosteum  serves  as  a  nidus  for  the  ramifica- 
tion of  the  vessels  previous  to  their  distribution  in  the  bone ;  hence  the  liability 
of  bone  to  exfoliation  or  necrosis,  when,  from  injury,  it  is  denuded  of  this 
membrane. 

The  marrow  differs  in  composition  at  different  periods  of  life,  and  in  different 
bones.  In  young  bones,  it  is  a  transparent  reddish  fluid,  of  tenacious  consist- 
ence, free  from  fat ;  and  contains  numerous  minute  roundish  cells  with  many 
nuclei.  In  the  shafts  of  adult  long  bones,  the  marrow  is  of  a  yellow  color,  and 
contains,  in  100  parts,  96  fat,  1  areolar  tissue  and  vessels,  and  three  of  fluid 
with  extractive  matters ;  whilst,  in  the  flat  and  short  bones,  in  the  articular 
ends  of  the  long  bones,  in  the  bodies  of  the  vertebrae,  in  the  base  of  the  cranium, 
and  in  the  sternum  and  ribs,  it  is  of  a  red  color,  and  contains,  in  100  parts,  75 
water  and  25  solid  matter,  consisting  of  albumen,  fibrin,  extractive  matter,  salts, 
and  a  mere  trace  of  fat.  The  red  marrow  is  said  by  Kolliker  to  consist  of  a 
small  quantity  of  areolar  tissue  and  numerous  medullary  cells,  and  fat-cells 
with  a  large  quantity  of  fluid. 


46  GENERAL    ANATOMY. 

Vessels  of  Bone.  The  bloodvessels  of  bone  are  very  numerous.  Those  of  the 
compact  tissue  are  derived  from  a  close  and  dense  network  of  vessels,  ramifying 
in  the  periosteum.  From  this  membrane,  vessels  pass  into  the  minute  orifices 
in  the  compact  tissUe,  running  through  the  canals  which  traverse  its  substance. 
The  cancellous  tissue  is  supplied  in  a  similar  way,  but  by  a  less  numerous  set 
of  larger  vessels,  which,  perforating  the  outer  compact  tissue,  are  distributed 
to  the  cavities  of  the  spongy  portion  of  the  bone.  In  the  long  bones,  numerous 
apertures  may  be  seen  at  the  ends  near  the  articular  surfaces,  some  of  which 
give  passage  to  the  arteries  referred  to ;  but  the  most  numerous  and  largest 
apertures  are  for  the  veins  of  the  cancellous  tissue  which  run  separately  from 
the  arteries.  The  medullary  canal  in  the  shafts  of  the  long  bones  is  supplied 
by  one  large  artery  (or  sometimes  more),  which  enters  the  bone  at  the  nutrient 
foramen  (situated  in  most  cases,  near  the  centre  of  the  shaft),  and  perforates 
obliquely  the  compact  substanca.  This  medullary  or  nutrient  artery,  usually 
accompanied  by  one  or  two  veins,  sends  branches  upwards  and  downwards,  to 
supply  the  medullary  membrane,  which  lines  the  central  cavity  and  the  adjoin- 
ing canals.  The  ramifications  of  this  vessel  anastomose  with  the  arteries  both 
of  the  cancellous  and  compact  tissues.  In  most  of  the  flat,  and  in  many  of  the 
short  spongy  bones,  one  or  more  large  apertures  are  observed,  which  transmit, 
to  the  central  parts  of  the  bone,  vessels  corresponding  to  the  medullary  arteries 
and  veins. 

The  veins  emerge  from  the  long  bones  in  three  places  (Kolliker).  1.  By  a 
large  vein  which  accompanies  the  nutrient  artery ;  2.  By  numerous  large  and 
small  veins  at  the  articular  extremities ;  3.  By  many  small  veins  which  arise 
in  the  compact  substance.  In  the  flat  cranial  bones,  the  veins  are  large,  very 
numerous,  and  run  in  tortuous  canals  in  the  diploic  tissue,  the  sides  of  the 
canals  being  formed  of  a  thin  lamella  of  bone,  perforated  here  and  there  for  the 
passage  of  branches  from  the  adjacent  cancelli.  The  veins  thus  inclosed  and 
supported  by  the  osseous  structure,  have  exceedingly  thin  coats ;  and  when 
the  bony  structure  is  divided,  they  remain  patulous,  and  do  not  contract  in  the 
canals  in  which  they  are  contained.  Hence  the  constant  occurrence  of  purulent 
absorption  after  amputation,  in  those  cases  where  the  stump  becomes  inflamed, 
and  the  cancellous  tissue  is  infiltrated  and  bathed  in  pus. 

Lymphatic  vessels  have  been  traced,  by  Cruikshank,  into  the  substance  of 
bone,  but  Kolliker  doubts  their  existence.  Nerves  are  distributed  freely  to 
the  periosteum,  and  accompany  the  nutrient  arteries  into  the  interior  of  the 
bone.  They  are  said,  by  Kolliker,  to  be  most  numerous  in  the  articular  ex- 
tremities of  the  long  bones,  in  the  vertebrae,  and  the  larger  flat  bones. 

Minute  Anatomy.  The  intimate  structure  of  bone  which  in  all  essential  par- 
ticulars is  identical  in  the  compact  and  cancellous  tissue,  is  most  easily  studied 
in  a  transverse  section  from  the  compact  wall  of  one  of  the  long  bones  after 
maceration,  such  as  is  shown  in  Fig.  17.  The  large  round  spaces  seen  in 
the  figure  are  the  Haversian  canals,  and  in  these  canals  the  larger  vessels  of  the 
bone  ramify.  The  fine  lines  leading  out  of  (or  into)  these  canals  are  called 
canaliculi,  and  the  irregular  dark  spaces,  which  may  be  noticed  to  have  a  gene- 
ral circular  arrangement  round  the  Haversian  canals,  are  called  the  lacunve. 
The  canaliculi  which  originate  in  one  lacuna  most  frequently  run  into  a  neigh- 
boring lacuna,  or  else  into  a  neighboring  Haversian  canal ;  some  of  them,  how- 
ever, anastomose  with  others  in  their  neighborhood,  and  a  few  appear  to  termi- 
nate in  blind  extremities  or  to  bend  backwards.  The  concentric  rings  of  lacunaa 
round  each  Haversian  canal  are  called  lamellse.  The  irregular  intervals  which 
would  be  left  by  the  juxtaposition  of  these  lamellae,  are  seen  in  the  figure  to 
be  filled  up  by  lacunar  and  canaliculi  which  communicate  with  the  systems 
composing  the  adjacent  lamellae.  The  interspaces  between  the  lacunae  and 
canaliculi  are  filled  with  a  granular  homogeneous  solid  material,  the  ultimate 
mineral  base  of  the  bone. 

If  a   longitudinal    section   be  taken,  as  in   Fig.  18,  the  appearances    are 


BOXE. 


47 


identical.     The  lamellated  or  concentric  arrangement  is  indeed  lost,  and  the 
Haversian  canals  appear  like  half-tubea  instead  of  circular  spaces,  and  these 


Fig.  17. 


Fig.  18. 


A  transverse  section  of  the  diapbysis  of  the  hnme^ 
rus.  (Magnified  350  times.)  a,  Haversian  canals  ; 
i,  lacunae  with  their  canaliouli  in  the  lamellae  of 
these  canals;  c,  lacunse  of  the  interstitial  lamellse; 
d,  others  at  the  surface  of  the  Haversian  systems, 
with  oanalioali  going  off  from  one  side. 


Section  parallel  to  the  surface  from  the  shaft 
of  the  femur.  (Magnified  100  times.)  a,  Ha- 
versian  canals  ;  b,  lacunae  seen  from  the  side; 
c,  others  seen  from  the  surface  in  lamellae  which 
are  cut  horizontally. 


tubes  are  seen  to  branch,  and  communicate  (so  that  each  separate  Haversian 
canal  runs  only  a  short  distance),  but  in  other  respects  the  structure  has  much 
the  same  appearance  as  in  transverse  sections. 

In  sections  of  thin  plates  of  bone  (as  in  the  walls  of  the  cells  which  form 
the  cancellous  tissue),  the  Haversian  canals  are  absent,  whenever  the  thickness 
of  bone  is  not  too  great  to  allow  of  its  nutritious  juices  being  absorbed  from 
the  fibrous  membrane  coating  either  side  by  means  of  the  lacunae  and  canaliculi 
only;  but  when  the  thickness  becomes  at  all  considerable,  Haversian  systems 
begin  to  appear.  Thus  the  spaces  of  the  cancellous  tissue  {medullary  spaces) 
have  the  same  function  there  that  the  Haversian  canals  have  in  the  more 
compact  tissue. 

In  the  long  bones,  by  maceration  in  dilute  mineral  acid,  it  may  easily  be 
shown  that  besides  these  microscopic  lamellae  surrounding  each  Haversian 
canal,  the  whole  bone  is  composed  of  distinct  laminae,  concentrically  disposed 
around  the  medullary  tube.  These  laminae  are  crossed  and  pinned  together,  as 
it  were,  by  the  fibres  of  bone  running  obliquely  through  them,  which  were 
first  described  by  Dr.  Sharpey,  and  named  by  him  perforating  fibres.  In  the 
flat  bones  parallel  or  superimposed  plates  can  be  demonstrated  similarly  held 
together  by  perforating  fibres,  which  are  more  numerous  than  in  the  long  bones.^ 

Besides  the  Haversian  canals  larger  and  irregularly  shaped  spaces  are  found — 
Haver'iian  spaces — which  are  as  it  were  a  transition  from  the  Haversian  canals 
to  the  medullary  spaces  of  the  cancellous  tissue.  It  seems  as  if  both  the 
medullary  spaces  and  the  Haversian  spaces  are  formed  by  absorption,  as  we 


'  Sharpey,  in  Quain's  Anatomy,  7th  edit.,  p.  xcviL 


48 


GENERAL    ANATOMY. 


shall  try  to  explain  in  speaking  of  the  development  and  growth  of  bone.  These 
Haversian  spaces  are  found  chiefly  in  growing  bones;  but  they  occur  also, 
though  in  less  number,  in  the  adult  bones.  They  have  irregular  jagged  out- 
lines, and  the  adjoining  systems  of  lacunaa  and  canaliculi  are  seen  to  be  eaten 
away  by  them. 

When  the  microscopic  structure  of  bone  was  first  demonstrated,  it  was 
believed  that  the  lacunas  were  solid  cells,  and  their  canaliculi  solid  processes 
from  those  cells.  Subsequently,  when  it  was  seen  that  the  Haversian  canals 
are  channels,  which  lodge  the  vessels  of  the  part,  and  the  canaliculi  and  lacunas 
spaces  by  which  the  plasma  of  the  blood,  or  the  blood  itself,  circulates  through 
the  tissue,  it  was  taught  that  the  lacunae  were  hollow  spaces  filled  during  life 
with  that  fluid,  and  only  lined  (if  lined  at  all)  by  a  delicate  membrane.  But 
this  view  appears  also  to  be  delusive.  Examination  of  the  structure  of  the 
bone,  when  recent,  has  led  Virchow  to  believe  that  the  so-called  lacunae  are 
really  filled  up  during  life  with  a  nucleated  cell,  the  processes  from  which  pass 
down  the  canaliculi.  It  is  by  means  of  these  cells  that  the  fluids  necessary  for 
nutrition  are  brought  into  contact  with  the  ultimate  tissue  of  the  bone. 

The  animal  part  of  a  bone  may  be  obtained  by  immersing  the  bone  for  a 
considerable  time  in  dilute  mineral  acid,  after  which  process  the  bone  comes 
out  exactly  the  same  size  and  shape  as  before,  but  perfectly  flexible — so  that  a 
long  bone  (one  of  the  ribs  is  the  usual  example)  can  easily  be  tied  in  a  knot. 
If  now  a  transverse  section  be  made,  the  same  general  arrangement  of  the 
Haversian  canals,  lamellae,  lacunae,  and  canaliculi  is  seen,  though  not  so  plainly 
as  in  the  macerated  specimen.     If  the  individual  lamellae  are  examined,  they 

are  found  to  be  composed  of  fibres,  most 
of  which  are  nearly  parallel ;  but  which 
interlace  together,  and  anastomose  or 
communicate  with  the  fibres  of  the  neigh- 
boring lamellae.  The  organic  or  animal 
constituents  of  a  bone  is  only  incompletely 
removed  by  maceration,  leaving  the  bone 
for  an  indefinite  period  perfectly  tough 
and  coherent;  but  after  being  long  kept 
in  a  warm  dry  atmosphere,  or  by  incine- 
ration in  a  furnace,  the  animal  part  may 
be  entirely  removed,  and  then  the  earthy 
constituent  will  retain  the  form  of  the 
original  bone,  but  on  the  slightest  force  it 
will  crumble  down.  The  animal  base  is  often  called  cartilage,  but  differs  from 
it  in  the  following  respects,  viz.,  that  it  is  softer  and  more  flexible,  and  when 
boiled  under  a  high  pressure  is  almost  entirely  resolved  into  gelatine.  Carti- 
lage does,  however,  form  the  animal  basis  of  bone  in  certain  parts  of  the  skeleton. 
Thus,  according  to  Tomes  and  De  Morgan,  it  occurs  in  the  petrous  part  of  the 
temporal  bone,  and,  according  to  Dr.  Sharpey,  on  the  articular  ends  of  aduli 
bones,  lying  underneath  the  natural  cartilage  of  the  joint. 

Chemical  Analysis.     The  organic  constituent  of  bone  forms  about  one-thin 
or  83.3  per  cent.;  the  inorganic  matter,  two-thirds^  or  GG.7  per  cent.:  as  is  seen 
in  the  subjoined  analysis  by  Berzelius : — 


Section  of  bone  after  the  removal  of  the  earthy 
matter  by  the  action  of  acids. 


> 


Organic  matter,     Gelatine  and  bloodvessels 33.30 

'Phosphate  of  lime 51.04 

Carbonate  of  lime 11.30 

Fluoride  of  calcium 2.00 

Phosphate  of  magnesia 1.16 

Soda  and  chloride  of  sodium 1.20 


Inorganic, 

or 

Earthy  Matter, 


100.00 


Some  chemists  add  to  this  about  one  per  cent,  of  fat. 

The  relative  proportions  of  the  two  constituents  of  bone  are  found  to  differ 


BONE.  49 

in  different  hones  of  the  skeleton,  as  shown  by  Dr.  Owen  Eees.  Thus,  the  bones 
of  the  head,  and  the  long  bones  of  the  extremities,  contain  more  earthy  matter 
than  those  of  the  trunk ;  and  those  of  the  upper  extremity  somewhat  more  than 
the  corresponding  bones  of  the  lower  extremity.  The  humerus  contains  more 
earthy  matter  than  the  bones  of  the  forearm ;  and  the  femur  more  than  the 
tibia  and  fibula.  The  vertebrae,  ribs,  and  clavicle,  contain  nearly  the  same 
proportion  of  earthy  matter.  The  metacarpal  and  metatarsal  bones  contain 
about  the  same  proportion  as  those  of  the  trunk. 

Much  difference  exists  in  the  analyses  given  by  chemists  as  to  the  proportion 
between  the  two  constituents  of  bone  at  different  periods  of  life.  According  to 
Schreger  and  others,  there  is  a  considerable  increase  in  the  earthy  constituents 
of  the  bones  with  advancing  years.  Dr.  Eees  states,  that  this  is  especially 
marked  in  the  long  bones,  and  the  bones  of  the  head,  which,  in  the  foetus,  do 
not  contain  the  excess  of  earthy  matter  found  in  those  of  the  adult.  But  the 
bones  of  the  trunk  in  the  foetus,  according  to  this  analyst,  contain  as  much 
earthy  matter  as  those  of  the  adult.  On  the  other  hand,  the  analyses  of  Stark 
and  Von  Bibra  show,  that  the  proportions  of  animal  and  earthy  matter  are 
almost  precisely  the  same  at  different  periods  of  life.  According  to  the  analyses 
of  Von  Bibra,  Valentin,  and  Dr.  Eees,  the  compact  substance  contains  more 
earthy  matter  than  the  cancellous.  The  comparative  analysis  of  the  same  bones 
in  both  sexes  shows  no  essential  difference  between  them. 

There  are  facts  of  some  practical  interest,  bearing  upon  the  difference  which 
seems  to  exist  in  the  amount  of  the  two  constituents  of  bone  at  different  periods 
of  life.  Thus,  in  the  child,  where  the  animal  matter  predominates,  it  is  not 
uncommon  to  find,  after  an  injury  to  the  bones,  that  they  become  bent,  or  only 
partially  broken,  from  the  large  amount  of  flexible  animal  matter  which  they 
contain.  Again,  in  aged  people,  where  the  bones  contain  a  large  proportion  of 
earthy  matter,  the  animal  matter  at  the  same  time  being  deficient  in  quantity 
and  quality,  the  bones  are  more  brittle,  their  elasticity  is  destroyed ;  and,  hence^ 
fracture  taices  place  more  readily.  Some  of  the  diseases,  also,  to  which  bones 
are  liable,  mainly  depend  on  the  disproportion  between  the  two  constituents 
of  bone.  Thus,  in  the  disease  called  rickets,  so  common  in  the  children  of 
scrofulous  parents,  the  bones  become  bent  and  curved,  either  from  the  super- 
incumbent weight  of  the  body,  or  under  the  action  of  certain  muscles.  This 
depends  upon  some  defect  of  nutrition,  by  which  bone  becomes  deprived  of  its 
normal  proportion  of  earthy  matter,  whilst  the  animal  matter  is  of  unhealthy 
quality.  In  the  vertebra  of  a  rickety  subject.  Dr.  Bostock  found  in  100  parts. 
79.75  animal  and  20.25  earthy  matter. 

Develojmient  of  Bone.  In  the  foetal  skeleton  some  bones,  such  as  the  long 
bones  of  the  limbs,  are  cartilaginous,  others,  as  the  cranial  bones,  are  mem- 
branous.^ Hence  two  kinds  of  ossification  are  described — the  intra-cartilaginous 
and  the  intra-membranous ;  and  to  these  a  third  is  sometimes  added,  the  sub- 
periosteal,  which  is  a  variety  of  the  second. 

In  the  intra-cartilaginous  ossification  the  first  step  is  that  the  cartilage  cells 
increase  rapidly  in  number,  and  arrange  themselves  in  rows,  with  the  long  axis 
of  the  cell  transverse  to  that  of  the  future  bone.  The  cells  are  closely  packed, 
and  in  some  places  are  even  wedged  together,  an  appearance  which  is  supposed 
to  be  due  to  their  cleavage  horizontally.  The  accompanying  illustration,  taken 
from  EoUett's  article  in  Strieker's  "Handbuch  der  Lehre  von  den  Geweben." 
p.  95,  will  save  much  of  minute  detail,  and  make  the  accompanying  descrif)tion 
intelligible. 

The  intra-cellular  matrix  of  the  cartilage  a  is  still  semi-transparent,  though: 

'  The  bones  which  are  developed  entirely  in  membrane  are  the  occipital,  as  far  as  it  enters: 
into  the  formation  of  the  vault  of  the  skull,  the  parietal  and  frontal  bones,  the  squamous  portion 
of  the  temporal  with  the  tympanitic  ring,  the  Wormian  bones,  the  nasal,  lachrymal,  malar,  palate, 
upper  and  lower  maxillary,  and  vomer ;  also,  apparently,  the  internal  pterygoid  plate  and  the 
sphenoidal  turbinated  bones. 

4 


50 


GENERAL    ANATOMY. 


somewhat  granular.     Lying  below  this  cartilaginous  layer  {{.  e.,  nearer  to  tLe 
centre  of  ossification),  is  a  layer,  b,  consisting  of  large  round  clear  cells  (the 

Fig.  20. 


Longitndinal  section  through  the  ossifying  portion  of  a  long  bone  in  the  human  embryo,    a.  Cartilaginous 
region,     b.  Region  of  the  round  clear  cells,    g.  Region  of  the  dark  granular  cells. 

"osteoblasts"  of  some  anatomists),  with  granular  contents,  also  arranged  in 
somewhat  parallel  rows,  each  row  and  each  pair  of  superimposed  cells  being 
separated  by  a  transparent  cartilaginous  matrix — the  arrangement  being  com- 
pared by  Rollett  to  a  ladder.  In  the  lower  part  of  this  region  the  matrix  is 
encroached  upon  by  calcareous  matter,  so  that  if  a  transverse  section  be  made 
here,  rings  of  dark  granular  calcareous  deposit  are  seen  inclosing  the  large 
round  clear  cells.  As  the  section  is  taken  deeper  and  deeper  into  the  ossifying 
part,  the  calcified  rings  or  areoloB  are  seen  to  inclose  numerous  smaller  granular 
masses  ("primitive  marrow"  of  some  authors)  which  have  replaced  the  single 
clear  cells,  and  may  be  formed  by  the  proliferation  of  those  cells.  This,  how- 
ever, is  doubted  by  Rollett  and  others,  who  believe  that  these  masses  are  fur- 
nished by  the  underlying  periosteal  vessels.  In  the  longitudinal  section  (Fig. 
20)  these  masses  are  seen  at  g  to  succeed  very  suddenly  to  the  separate  clear 
cells.  If  they  are  detached  from  the  surface,  they  are  found  to  have  one  or 
more  processes.  Deeper  down  in  the  ossifying  or  ossified  portion,  bloodvessektai 
arc  met  with,  which  proceed  from  the  periosteum.  f  | 

The  next  step  in  the  process  is  that  the  above-described  areolas  ("primary 
areola?")  break  into  each  other,  so  as  to  give  rise  to  the  "secondary  areola?,"  or 
medullary  spaces  of  H.  Miiller.  These  spaces  are  filled  with  the  red  or  foetal 
marrow  above  described.  The  cells  of  this  marrow  appeared  to  be  furnished 
directly  from  the  bloodvessels  which  are  abundantly  supplied  to  these  spaces 


BONE.  51 

from  the  underlying  vessels  proceeding  from  the  periosteal  tissue.  It  is  to 
these  vessels,  and  to  the  cavities  or  tubes  which  they  form  for  themselves  as 
they  proceed  inwards,  that  the  origin  of  the  Haversian  canals  is  due. 

The  origin  of  the  lacunae  and  of  the  bone-cells  which  fill  them  is  still  a 
matter  of  dispute.  Kolliker,  Virchow,  and  many  other  anatomists,  maintain 
that  in  the  intra-cartilaginous  ossification  they  are  developed  directly  from  the 
cartilage-cells,  the  investing  membrane  of  which  ossifies  and  forms  the  bony 
lacuna,  while  its  nucleus  is  developed  into  the  bone-cell.  Others,  as  Dr. 
Sharpey,  H.  Miiller,  and  Eollett,  believe  that  the  cartilage-cells,  after  becoming 
developed  into  the  "  osteoblasts,"  above  described,  and  shown  at  b,  Fig.  2U, 
become  dissolved,  and  shed  their  granular  contents  to  form  the  bony  matrix, 
while  the  lacunae  and  bone  corpuscles  are  developed  from  the  granular  masses, 
which  are  seen  below  g  in  the  figure,  and  which  are  furnished,  according  to 
these  authors,  from  the  vessels  of  the  periosteum  or  perichondrium.  If  this 
view  be  correct,  the  intimate  process  is  the  same  in  all  forms  of  ossification. 

Thus  far,  then,  we  have  followed  the  steps  of  a  process  by  which  a  solid 
bony  mass  is  produced,  having  vessels  running  into  it  from  the  periosteum. 
Haversian  canals  in  which  those  vessels  run,  medullary  spaces  filled  with  foetal 
marrow,  lacunte  with  their  contained  bone-cells,  and  canaliculi  growing  out  of 
those  lacunas. 

This  process  of  ossification,  however,  is  not  the  origin  of  the  whole  of  the 
skeleton,  for  even  in  those  bones  in  which  the  ossification  proceeds  in  a  great 
measure  from  a  single  centre,  situated  in  the  cartilaginous  diaphysis,  a  con- 
siderable part  of  the  original  bone  is  formed  by  inlra-inemhranous  ossification 
beneath  the  perichondrium  or  periosteum.  Kolliker  (following  H.  Miiller,  and 
referring  to  an  observation  of  Howship  to  the  same  effect,  made  so  long  ago 
as  1819),  describes  the  first  rudiment  of  a  long  bone  as  having  the  form  of  a 
tube,  surrounding  the  primordial  cartilage ;  thus  showing  that  the  intra- 
merabranous  ossification  of  the  outer  part  of  the  bone  from  the  periosteum 
even  precedes  the  intra-cartilaginous  development  of  its  interior  from  the 
"ossific  centre."  Also,  a  great  part  of  the  increase  in  girth  of  the  bone  takes 
place  by  bony  deposit  from  the  deeper  layer  of  the  periosteum.  This  process 
is  now  acknowledged  to  belonsr  to  the  intra-membranous  form  of  ossification. 
1  hus  even  m  long  bones  only  a  portion  of  their  tissue  is  formed  by  intra-carti- 
laginous ossification. 

The  shaft  of  the  bone  is  at  first  solid,  but  a  tube  is  gradually  hollowed  out 
in  it  by  absorption  around  the  vessels  passing  into  it,  which  becomes  the 
medullary  canal;  and  as  more  and  more  bone  is  deposited  from  the  periosteum, 
so  more  and  more  is  removed  from  around  the  medullary  membrane,  until  at 
length  the  bone  has  attained  the  shape  and  size  which  it  is  destined  to  retain 
during  adult  life.  As  the  ossification  of  the  cartilaginous  diaphysis  extends 
towards  the  articular  ends  it  carries  with  it,  as  it  were,  a  layer  of  cartilage,  or 
the  cartilage  grows  as  it  ossifies.  During  this  period  of  growth  the  articular 
end,  or  epiphysis,  remains  for  some  time  entirely  cartilaginous,  then  a  bony 
centre  appears  in  it,  and  it  commences  the  same  process  of  intra-cartilaginous 
ossification,  but  this  process  never  extends  to  any  very  great  distance.  The 
epiphyses  remain  separated  from  the  shaft  by  a  narrow  cartilaginous  layer  for 
a  definite  time.  This  layer  ultimately  ossifies,  the  distinction  between  shaft 
and  epiphysis  is  obliterated,  and  the  bone  has  assumed  its  completed  form  and 
shape.  The  same  remarks  also  apply  to  the  processes  of  bone  which  are  sepa- 
rately ossified,  and  called  apophyses. 

The  intra-cartilaginous  ossification,  and  the  growth  by  means  of  epiphyses, 
are  usually  described  from  the  long  bones;  but  almost  all  the  bones  of  the 
body  are  primarily  laid  down  in  cartilage  (see  note,  p.  49);  and  a  great  many  of 
the  flat  and  short  bones  grow  by  means  of  epiphyses,  as  will  be  seen  in  the  de- 
tailed description  of  each,  given  in  the  body  of  the  work. 

The  medullary  spaces  which  characterize  the  cancellous  tissue  are  produced 


52  GENERAL    ANATOMY. 

by  the  absorption  of  the  original  foetal  bone  in  the  same  way  as  the  medullary 
tube  is  formed,  and  the  same  is  the  case  with  the  Haversian  spaces  above  re- 
ferred to  as  a  sort  of  intermediate  step  between  the  Haversian  canals  and  the 
medullary  spaces.  Thus  the  distinction  between  the  cancellous  and  compact 
tissue  appears  to  depend  essentially  upon  the  extent  to  which  this  process  of 
absorption  has  been  carried,  and  we  may  perhaps  remind  the  reader  that  in 
morbid  states  of  the  bone  inflammatory  absorption  effects  exactly  the  same 
change,  and  converts  portions  of  bone  naturally  compact,  into  cancellous 
tissue. 

The  intra-membranous  ossification  is  that  by  which  the  bones  of  the  vertex 
of  the  skull  are  entirely  formed.  In  the  bones  which  are  so  developed  no 
cartilaginous  mould  precedes  the  appearance  of  the  bony  tissue.  The  process, 
though  pointed  out  originally  by  Dr.  Nesbitt,  in  the  year  1786,  was  first  accu- 
rately described  by  Dr.  Sharpey;  .and  it  does  not  appear  that  subsequent  ob- 
servers have  been  able  to  add  anything  essential  to  his  description.  This  is, 
substantially,  as  follows:  In  the  membrane  which  occupies  the  place  of  the 
future  bone  a  little  network  of  bony  spiculae  is  first  noticed,  radiating  from  the 
point  of  ossification.  When  these  rays  of  growing  bone  are  examined  by  the 
microscope,  there  is  found  a  network  of  fine  clear  fibres  (osteogenic  fibres), 
which  become  dark  and  granular  from  calcification,  and  as  they  calcify  they 
are  found  to  inclose  in  their  interior  large  granular  corpuscles  (the  so-called 
"osteoblasts"  described  above  in  the  account  of  the  intra-cartilaginous  ossifi- 
cation). These  corpuscles  at  first  lie  upon  the  osteogenic  fibres,  so  that  the 
corpuscles  must  be  removed  by  brushing  the  specimen  with  a  hair  pencil  in 
order  to  render  the  fibres  clear;  but  they  gradually  sink  into  areolae  developed 
among  the  fibres.  The  areolae  appear  to  be  the  rudiments  of  the  lacunae, 
the  passages  between  the  fibres  form  the  canaliculi,  and  the  osteoblasts  are  the 
rudiments  of  the  bone  cells.  As  the  tissue  increases  in  thickness  vessels  shoot 
into  it,  grooving  for  themselves  spaces  or  channels,  which  become  the  Haver- 
sian canals. 

The  subperiosteal  is  in  all  essential  respects  identical  with  the  intra-membran- 
ous process  of  ossification. 

The  Period  of  Ossification  is  different  in  different  bones.  The  order  of  succes- 
sion may  be  thus  arranged  (Kcilliker): — 

In  the  second  month,  first,  in  the  clavicle,  and  lower  jaw  (fifth  to  seventh 
week);  then,  in  the  vertebrae,  humerus,  femur,  the  ribs,  and  the  cartilaginous 
portion  of  the  occipital  bone. 

At  the  end  of  the  second,  and  commencement  of  the  third  month,  the  frontal 
bone,  the  scapula,  the  bones  of  the  forearm  and  leg,  and  upper  jaw,  make  their 
appearance. 

In  the  third  month,  the  remaining  cranial  bones,  with  few  exceptions,  the 
metatarsus,  the  metacarpus,  and  the  phalanges,  begin  to  ossify. 

In  the  fourth  month,  the  iliac  bones,  and  the  ossicula  auditus. 

In  the  fourth  or  fifth  month,  the  ethmoid,  sternum,  os  pubis,  and  ischium. 

From  the  sixth  to  the  seventh  month,  the  calcaneum,  and  astragalus. 

In  the  eighth  month,  the  hyoid  bone. 

At  birth,  the  epiphyses  of  all  the  cylindrical  bones,  with  the  exception  of  th 
lower  epiphysis  of  the  femur,  and  occasionally  the  upper  epiphysis  of  the  tibia; 
all  the  bones  of  the  carpus;  the  five  smaller  ones  of  the  tarsus;  the  patella;  the 
sesamoid  bones;  and  the  coccyx,'  are  still  ossified. 

From  the  time  of  birth  to  the  fourth  year,  osseous  nuclei  make  their  appear 
ance  also  in  these  parts. 

At  twelve  years,  in  the  pisiform  bone. 

The  number  of  ossifio  centres  is  different  in  different  bones.  In  most  of  th 
short  bones,  ossification  commences  by  a  single  point  in  the  centre,  and  pro 

'  Oq  the  development  of  the  coccyx,  vide  Coccyx. 


I 


MUSCULAR    TISSUE.  53 

ceeds  towards  the  circumference.  In  the  long  bones,  there  is  a  central  point 
of  ossification  for  the  shaft  or  diaphysis;  and  one  or  more  for  each  extremity, 
the  epiphyses.  That  for  the  shaft  is  the  first  to  appear;  those  for  the  extremi- 
ties appear  later.  The  union  of  the  epiphyses  with  the  shaft  takes  place  in  the 
inverse  order  to  that  in  which  their  ossification  began;  for,  although  ossification 
commences  latest  in  those  epiphyses  towards  which  the  nutrient  artery  in  the 
several  bones  is  directed,  they  become  joined  to  the  diaphyses  sooner  than  the 
epiphyses  at  the  opposite  extremity,  with  the  exception  of  the  fibula,  the  lower 
end  of  which  commences  to  ossify  at  an  earlier  period  than  the  upper  end,  but, 
nevertheless,  is  joined  to  the  shaft  earliest. 

The  order  in  which  the  epiphyses  become  united  to  the  shaft,  appears  to  be 
regulated  by  the  direction  of  the  nutrient  artery  of  the  bone.  Thus  the  arteries 
of  the  bones  of  the  arm  and  forearm  are  directed  towards  the  elbow,  and  the 
epiphyses  of  the  bones  forming  this  joint  become  united  to  the  shaft  before 
those  at  the  opposite  extremity.  In  the  lower  extremities,  on  the  contrary,  the 
nutrient  arteries  pass  in  a  direction  from  the  knee;  that  is,  upwards  in  the 
femur,  downwards  in  the  tibia  and  fibula;  and  in  them  it  is  observed,  that  the 
upper  epiphysis  of  the  femur,  and  the  lower  epiphyses  of  the  tibia  and  fibula, 
become  first  united  to  the  shaft. 

Where  there  is  only  one  epiphysis,  the  medullary  artery  is  directed  towards 
that  end  of  the  bone  where  there  is  no  additional  centre:  as,  towards  the  acro- 
mial end  in  the  clavicle;  towards  the  distal  end  of  the  metacarpal  bone  of  the 
thumb  and  great  toe;  and  towards  the  proximal  end  of  the  other  metacarpal 
and  metatarsal  bones. 

Besides  these  epiphyses  for  the  articular  ends,  there  are  others  (more  com- 
monly called  apojohyses)  for  projecting  parts,  or  processes,  which  are  formed 
separately  from  the  bulk  of  the  bone.  For  an  account  of  these  the  reader  must 
be  referred  to  the  descriptions  of  the  individual  bones  in  the  sequel. 

A  knowledge  of  the  exact  periods  when  the  epiphyses  become  joined  to  the 
shaft,  is  often  of  great  importance  in  medico-legal  inquiries.  It  also  aids  the 
surgeon  in  the  diagnosis  of  many  of  the  injuries  to  which  the  joints  are  liable; 
for  it  not  unfrequently  happens,  that  on  the  application  of  severe  force  to  a 
joint,  the  epiphyses  become  separated  from  the  shaft,  and  such  injuries  may  be 
mistaken  for  fracture  or  dislocation. 

MUSCULAR  TISSUE. 

The  Muscles  are  formed  of  bundles  of  reddish  fibres,  endowed  with  the  pro- 
perty of  contractilit3^  Two  kinds  of  muscular  tissue  are  found  in  the  animal 
body,  viz.,  that  of  voluntary  or  animal  life,  and  that  of  involuntary  or  organic 
life. 

The  Muscles  of  Animal  Life  (striped  muscles)  are  capable  of  being  put  in 
action  and  controlled  by  the  will.  They  are  composed  of  bundles  of  fibres 
inclosed  in  a  delicate  web  of  areolar  tissue,  called  in  the  figure  the  "perimy- 
sium." Bach  bundle  consists  of  numerous  smaller  bundles,  inclosed  in  a 
similar  fibro-areolar  covering,  and  these  again  of  primitive  fasciculi. 

The  fibres  are  of  no  great  length — not  extending,  it  is  said,  further  than  an 
inch  and  a  half.  They  end  either  by  blending  with  the  tendon  or  aponeurosis, 
or  else  by  becoming  drawn  out  into  a  tapering  extremity  which  is  connected 
to  the  neighboring  fibre  by  means  of  the  sarcolemma.  The  precise  mode  in 
which  the  muscular  fibre  joins  the  tendon  has  been  variously  described  by 
different  observers.  It  may,  perhaps,  be  sufficient  here  to  say  that  the  sarco- 
lemma, or  membranous  investment  of  the  muscular  fibre,  appears  to  become 
blended  with  the  tissue  of  the  tendon,  and  that  the  muscular  fibre  appears  to 
be  prolonged  more  or  less  into  the  tendon,  so  that  the  latter  forms  a  kind 
of  sheath  around  the  fibre  for  a  longer  or  shorter  distance.     When  muscular 


54 


GENERAL    ANATOxMY. 


Fig.  21. 


fibres  are  attached  to  the  skin  or  mucous  membranes,  the  fibres  are  described 
by  Salter  as  becoming  continuous  with  those  of  the  areolar  tissue. 

The  primitive  fasciculi  consist  of  a  number  of  filaments,  inclosed  in  a  tubular 

sheath  of  transparent,  elastic,  and  apparently  homo- 
geneous membrane,  named  by  Bowman  the  "sar- 
colemma."  The  primitive  fasciculi  are  cylindriform 
or  prismatic.  Their  breadth  varies  in  man  from 
unn  to  jl^g  of  an  inch,  the  average  of  the  majority 
"^eing  about  ^J^;  their  length  is  not  always  in 
proportion  to  the  length  of  the  muscle,  but  depends 
on  the  arrangement  of  the  tendons.  This  form  of 
muscular  fibre  is  especially  characterized  by  being 
apparently  marked  with  very  fine,  dark  lines  or 
strise^  which  pass  transversely  round  the  fibre,  in 
curved  or  wavy  parallel  directions,  from  Tu^TfTT  to 
ynrjon  of  an  inch  apart.  Other  striae  pass  longitu- 
dinally over  the  fibres,  indicating  the  direction  of 
the  primitive  fibrils  of  which  the  primitive  fasci- 
culus is  composed.  They  are  less  distinct  than  the 
former. 

The  primitive  fihrils  constitute  the  proper  con- 
tractile tissue  of  the  muscle.  Each  fibril  is  cylin- 
driform, somewhat  flattened,  about  jgonTj  ^^  '\ri(i\i 
in  thickness,  and  marked  by  transverse  stria3  placed  at  the  same  distance  from 
each  other  as  the  striae  on  the  surface  of  the  fasciculus.  Each  fibril  apparently 
consists  of  a  single  row  of  minute  particles  (named  "  sarcous  elements"  by 


Transverse  section  from  the  ster- 
ro-inastcid  in  man  (50  times  mag- 
nified), a.  ExternnI  perimysium. 
b.  Internal  perimysium,  e.  Primi- 
tive and  secondary  fasciculi. 


Fig.  22. 


Fig.  23. 


Two  human  nnifciilnr  fibres 
(mngnifled  ?>bi)  limes).  In  the 
one,  the  bundle  of  fibrillaa 
(h)  is  torn,  and  the  cnrco- 
lemraa  (a)  is  seen  as  an  empty 
tube. 


m0 

Fragments  of  striped  elementary  fibres,  showing  a  cleavnge  in  op- 
posite  directions  (magnified  300  diameters).  A.  Longitudinal  cleavuge. 
The  longitadinal  .nndtransverse  lines  are  both  seen.  Some  longitudinnl 
lines  are  darker  and  wider  than  the  rest,  and  are  not  continuous  from 
end  to  end.  This  results  from  partial  separation  of  the  fibrilla;. 
c.  FibrillsB  sepnrated  from  one  another  by  violence  at  the  broken  end 
of  the  fibre,  and  marked  by  transverse  lines  equal  in  width  to  those 
on  the  fibre,  c'  c"  represent  two  appearances  commonly  presented 
by  the  separated  single  flbrillse  (more  highly  magnified).  At  r'  the 
borders  and  transverse  lines  are  all  perfectly  rectilinear,  and  the  in- 
cluded spaces  perfectly  rectangular.  At  c"  the  borders  are  scalloped, 
and  the  spaces  bead-like.  When  most  distinct  and  definite,  the  fibrilla 
presents  the  former  of  these  appearances.  B.  Transverse  cleavage. 
The  longitudinal  lines  are  scarcely  visible,  a.  Incomplete  fracture 
following  the  opposite  surfaces  of  a  disk,  which  stretches  across  the  in- 
terval, and  retains  the  two  fragments  in  connection.  Tiio  edge  and 
surfaces  of  this  disk  are  seen  to  be  minutely  granular,  the  granules 
corresponding  in  size  to  the  thickness  of  the  disk,  and  to  the  distance 
between  the  faint  longitudinal  lines,  b.  Another  di.<k  nearly  detached. 
bf.  Detached  disk,  more  highly  magnified,  showing  the  sarcous  elements. 


MUSCULAR    TISSUE.  65 

Bowman),  connected  together  like  a  string  of  beads.  Closer  examination, 
however,  shows  that  the  elementary  particles  are  little  masses  of  pellucid 
substance,  having  a  rectangular  outline,  and  appearing  dark  in  the  centre. 
Tliese  appearances  would  favor  the  suggestion  that  the  elementary  particles 
of  which  the  fibrils  are  composed  are  possibly  nucleated  cells,  cohering  in  a 
linear  series,  the  transverse  marks  between  them  corresponding  to  their  line 
of  junction.  Kolliker,  however,  considers  "the  sarcous  elements  as  artificial 
products,  occasioned  by  the  breaking  up  of  the  fibril  at  the  parts  where  they 
are  thinner." 

This  form  of  muscular  fibre  composes  the  whole  of  the  voluntary  muscles, 
all  the  muscles  of  the  ear,  those  of  the  larynx,  pharynx,  tongue,  the  upper 
half  of  the  oesophagus,  the  heart,  and  the  walls  of  the  large  veins  at  the  point 
where  they  open  into  it. 

The  fibres  of  the  heart,  however,  differ  in  several  particulars  from  those  of 
other  striped  muscles.  They  are  smaller  by  about  one  third,  and  their  trans- 
verse striae  are  by  no  means  so  distinct.  Fat-cells  are  also  often  found  in  them 
to  a  large  extent,  even  apart  from  any  obvious  disease  of  the  organ.  They 
break  up  much  more  readily  into  their  smallest  elements.  There  is  also  much 
less  (if  any)  connective  tissue  separating  the  bundles  of  fibres ;  and  Kolliker 
has  described  and  figured  the  ultimate  fibres  as  anastomosing  with  each  other. 

The  UnsLriped  Muscle^  or  Iluscle  of  Liorganic  Life^  is  found  in  the  walls  of 
the  hollow  viscera,  viz.,  the  lower  half  of  the  oesophagus  and  the  whole  of  the 
remainder  of  the  gastro-intestinal  tube ;  in  the  trachea  and  bronchi ;  in  the 
gall-bladder  and  ductus  communis  choledochus;  in  the  pelvis  and  calices  of 
the  kidney,  the  ureters,  bladder,  and  urethra;  in  the  female  sexual  organs,  viz., 
the  Fallopian  tubes,  the  uterus  (enormously  developed  in  pregnancy),  the 
vagina,  the  broad  ligaments,  and  the  erectile  tissue  of  the  clitoris ;  in  the  naale 
sexual  organs,  viz.,  the  dartos  scroti,  the  vas  deferens,  and  epididymis,  the 
vesiculae  seminales,  the  prostate  gland  and  the  corpora  cavernosa;'  in  the 
ducts  of  certain  glands,  as  in  Wharton's  duct;  in  the  capsule  and  trabeculae 
of  the  spleen ;  in  the  arteries,  veins,  and  lymphatics ;  in  the  iris ;  and  in  the 
skin. 

The  fibres  of  inorganic  muscle  form  flattened  bands,  interlacing  in  various 
directions,  and  which  when  viewed  without  reagents  appear  nearly  homo- 
geneous, though  if  the  organ  from  which  the  fibres  are  taken  has  been  mace- 
rated previously  for  some  time  in  dilute  acid,  the  nuclei  can  be  perceived. 
Even  in  fresh  fibres  the  nuclei  are  occasionally  visible. 

In  many  situations  these  fibres,  by  prolonged  immersion  in  chromic  or  nitric 
acid,  can  be  resolved  into  the  elementary  contractile  fibre-cells,  of  which 
Kolliker  has  shown  that  they  really  consist;  and  in  some  parts,  as  in  the 
arteries  and  in  the  skin,  such  fibre-cells  are  found  single.  They  are  elongated, 
their  length  about  ten  to  fifteen  times  their  breadth  (.02'"  to  0,4'"  in  length, 
.002'"  to  .003'"  in  breadth,  according  to  Kolliker),  consisting  of  a  spindle- 
shaped,  homogeneous-looking,  fibre-cell,  in  which  a  rod  shaped  nucleus  is 
faintly  visible.  Acetic  acid  dissolves  out  the  granular  contents  of  the  cell,  and 
brings  the  nucleus  clearly  into  view. 

The  unstriped  muscle,  as  a  rule,  is  not  under  the  influence  of  the  will,  nor 
is  the  contraction  rapid  and  involving  the  whole  muscle,  as  is  the  case  with 
the  muscles  of  animal  life.  The  membranes  which  are  composed  of  the  un- 
striped muscle  slowly  contract  in  a  part  of  their  extent,  generally  under  the 
influence  of  mechanical  stimulus,  as  that  of  distension  or  of  cold,  and  then  the 
contracted  part  slowly  relaxes,  while  another  portion  of  the  membrane  takes 
up  the  contraction.  This  peculiarity  of  action  is  most  strongly  marked  in  the 
intestines,  constituting  their  vermicular  nwiion. 

In  chemical  composition^  the  muscular  fibres  of  both  forms  consist  mainly  of 

'  Kolliker  describes  muscular  fibres  also  in  the  tunica  vaginalis  testis. 


56 


GENERAL    ANATOMY. 


a  substance  called  syntonin,  nearly  identical  with  the  librine  of  the  blood ;  but, 
unlike  the  latter,  not  dissolved  by  nitrate  of  potash.  Muscle  after  death  ex- 
hibits an  acid  reaction ;  but  this  appears  to  be  due  to  post-mortem  changes. 


Fig.  25. 


Non-striated  elementary  fibres  from  the  human 
colon,  a.  Treated  with  acetic  acid,  showing  the 
corpuscles,  b.  Fragment  of  a  detached  fibre, 
not  touched  with  acid. 


Muscular  fibre  cells  from  human  arteries.  1.  From 
the  popliteal  artery :  a,  without ;  i,  with  acetic  acid. 
2.  From  a  branch  of  the  anterior  tibial  :  a,  nuclei  of 
the  fibres.     (Magnified  350  times.) 


The  capillaries  of  muscle  are  very  abundant,  and  form  a  series  of  rectancrular 
areolae,  the  branches,  which  run  longitudinally  between  the  muscular  fibres, 
being  united  at  short  intervals  by  transverse  anastomosing  branches. 

Nerves  are  profusely  distributed  to  the  muscular  tissue,  more  especially  to 
the  voluntary  muscles.  The  mode  of  their  termination  will  be  described  on  a 
subsequent  page. 

The  distribution  and  the  mode  of  origin  of  the  lymphatic  vessels  of  muscle 
has  not  yet  been  ascertained. 

The  muscles  during  life,  and  for  some  time  after  death,  respond  to  the  appro- 
priate stimulus  by  contracting  in  the  manner  peculiar  to  the  class  to  which  they 
belong.  Thus,  for  some  time  after  a  limb  has  been  amputated,  its  muscles  can 
be  set  m  motion  by  scratching,  pinching,  or  galvanizing  them;  and  even  after 
the  irritability  of  the  muscular  tissue  has  been  exhausted  by  the  prolonged 
suspension  of  the  circulation,  it  can  be  at  first  temporarily  restored  by  injecting 
fresh  arterial  blood  through  it  (Brown-Sequard).  The  time  at  which  muscular 
irritability  ceases  after  death  depends  on  the  vitality  of  the  subject;  thus  it 
ceases  in  birds,  whose  circulation  and  vital  heat  are  of  a  very  high  degree, 
sooner  than  in  man  and  quadrupeds ;  in  these  sooner  than  in  fishes,  &c.  Dr. 
Sharpey  says  that  it  lasts  long  in  hybernating  animals  killed  during  their 
winter  sleep.  It  is  also  affected  by  the  mode  of  dying,  being  extinguished  in- 
stantaneously (as  is  asserted)  in  some  cases  of  liglitning-stroke,  and  much  di- 
minished by  certain  gaseous  poisons,  particularly  sulphuretted  hydrogen. 

As  the  muscles  die  they  become  stiff,  and  it  is  to  this  cause  that  the  rigidity 
so  characteristic  of  recent  death  f "  rigor  mortis")  is  due.  The  ultimate  cause 
of  the  phenomenon  is  not  well  understood,  beyond  the  obvious  fact  that  it  must 
be  duo  to  the  change  from  partial  fluidity  to  a  solid  condition  of  the  contents 
of  the  sarcolemma.  The  periods  of  its  occurrence  and  of  its  disappearance  are 
very  variable,  and  the  causes  of  those  variations  are  of  extreme  interest  and 
importance,  especially  in  medico-legal  inquiries,  but  the  subject  is  too  compli- 


I 

II 
II 


NERVOUS    TISSUE.  57 

cated  to  be  adequately  treated  here.  All  that  need  be  said  in  this  place  is  that, 
as  might  be  expected,  the  rigor  is  stronger  the  more  powerful  and  more  healthy 
the  muscles  are,  and,  consequently,  is  both  more  powerful  and  more  lasting  in 
cases  of  sudden  or  violent  death.  It  also  sets  in  later  in  such  cases,  while  in 
emaciated  and  exhausted  subjects  it  is  more  rapid  and  transient:  as  is  also  the 
case,  according  to  Hunter,  in  animals  which  have  been  hunted  to  death.  In 
some  instances  of  violent  death  in  persons  of  robust  frame,  the  rigor  mortis  has 
not  entirely  disappeared  till  the  end  of  the  first  week  after  death.  In  rare 
cases,  as  in  some  instances  of  death  from  lightning,  the  muscles  are  found  rigid 
immediately,  and  in  other  cases  rigor  commences  in  a  few  minutes,  but  usually 
not  till  six  or  seven  hours  after  death.  The  cessation  of  rigidity  in  the  muscles 
must  be  regarded  as  the  commencement  of  putrefactive  changes. 

NERVOUS  TISSUE. 

The  Nervous  Tissue  is  composed  chiefly  of  two  different  structures,  the  gray 
or  vesicular,  and  the  white  or  fibrous.  It  is  in  the  former,  as  is  generally  sup- 
posed, that  nervous  impressions  and  impulses  originate,  and  by  the  latter  that 
they  are  conducted.  Hence  the  gray  matter  forms  the  essential  constituent  of 
all  the  ganglionic  centres,  both  those  separated  in  the  ganglia,  and  those  aggre- 
gated in  the  cerebro-spinal  axis ;  while  the  white  matter  is  found  in  all  the 
commissural  portions  of  the  nerve  centres,  and  in  all  the  cerebro-spinal  nerves. 
Besides  these  two  principal  kinds  of  nervous  matter,  there  is  found  a  third 
structure — chiefly  in  the  sympathetic  system — called  the  gelatinous  nerve-tissue. 

The  nervous  substance  is  again  divided  into  two  different  systems.  The  first 
is  connected  directly  with  the  great  central  mass  inclosed  in  the  skull  and 
spine.  This  is  called  the  cerebrospinal  system,  and  is  divided  into  the  brain  (in- 
cluding the  medulla  oblongata),  the  spinal  cord,  the  cranial  nerves,  the  spinal 
nerves,  and  the  ganglia  connected  with  both  those  classes  of  nerves.  The 
second,  called  the  sympathetic  system,  is  not  directly  connected  with  the  brain 
or  spinal  cord,  though  it  is  so  indirectly  by  means  of  its  numerous  communi- 
cations with  the  cranial  and  spinal  nerves.  It  consists  of  a  double  chain  of 
ganglia,  with  the  branches  which  go  to  and  come  from  them. 

A  third  method  of  division  of  the  nervous  system  is  based  upon  the  functions 
which  it  performs.  On  this  principle  it  is  divided  into  the  nervous  system  of 
animal  life  and  the  nervous  system  of  organic  life — the  former  subserving  the 
higher  functions  of  volition,  sensation,  &c.,  the  latter  those  of  growth  and  nu- 
trition. It  is  clear  that  the  former  qualities  reside  mainly  in  the  cerebro-spinal 
system,  while  the  intimate  connection  between  the  sympathetic  nerve  and  the 
great  viscera  renders  it  highly  probable  that  the  sympathetic  system  has  mainly 
to  do  with  the  organic  functions.  Consequently  the  cerebro-spinal  system  was 
designated  the  system  of  animal  life,  and  the  sympathetic  the  system  of  organic 
life.  But  the  distinction,  though  true  to  a  certain  extent,  is  by  no  means  com- 
plete, as  the  student  may  easily  see  by  consulting  the  works  of  modern  phy- 
siologists. 

The  gray  or  vesicular  nervous  substance  is  distinguished  by  its  dark  reddish- 
gray  color  and  soft  consistence.  It  is  found  in  the  brain,  spinal  cord,  and 
various  ganglia,  intermingled  with  the  fibrous  nervous  substance,  but  is  never 
found  in  the  nerves.  It  is  composed,  as  its  name  implies,  of  vesicles,  or  cor- 
puscles, commonly  called  nerve-corpuscles  or  ganglion-corpuscles,  containing 
nuclei  and  nucleoli;  the  vesicles  being  imbedded  either  in  a  fine  granular  sub- 
stance, as  in  the  brain,  or  in  a  capsule  of  nucleated  cells,  as  in  the  ganglia. 
Each  vesicle  consists  of  an  exceedingly  delicate  membranous  wall,  inclosing  a 
finely  granular  material,  part  of  which  is  occasionally  of  a  coarser  kind,  and  of 
a  reddish  or  yellowish-brown  color.  The  nucleus  is  vesicular,  much  smaller 
than  the  vesicle,  and  adherent  to  some  part  of  its  interior.  The  nucleolus, 
which  is  inclosed  within  the  nucleus,  is  vesicular  in  form,  of  minute  size,  and 


58 


GENERAL    ANATOMY. 


peculiarly  clear  and  brilliant.     The  nerve-corpuscles  vary  in  shape  and  size; 
some  are  small,  spherical,  or  ovoidal,  with  an  uninterrupted  outline.     These 


Fig.  26. 


Fijj.  27. 


Nerve-vesiole8  from  the  Casseri.in  gan- 
glion of  the  human  subject,  a.  A  globa* 
lar  one  with  defined  border ;  b,  its  nucleus ; 
c,  its  nucleolus,  d.  Cnudate  vesicle ;  e. 
Elongated  vesicle,  with  two  groups  of  pig- 
ment particles;/.  Vesicle  surrounded  by 
its  sheath  or  capsule  of  nucleated  parti- 
cles ;  g.  The  same,  the  sheath  only  being 
in  focus.  (Magnified  300  diameters.) 


Nerve-vesicles  from  the  inner  parts  of  the  gray  matter 
of  the  convolutions  of  the  human  brain  (magnified  .S50 
times).  Nerve  cells:  a,  larger;  d,  smaller,  c.  Nerve 
fibre,  wrth  axis-cylinder. 


forms  are  most  numerous  in  the  ganglia  of  the  sympathetic.     Others,  called 
caudate  or  stellate  nerve-corpuscles,  are  characterized  by  their  larger  size,  and 

Fig.  29. 


Human  nerve-tubes  (magnified  350  times). 
Three  of  them  are  fine,  one  of  which  is  varicose, 
one  of  middling  thickness,  and  with  a  simple 
contour ;  and  three  thick,  two  of  which  are 
double  oontoured,  and  one  with  grumous  con- 
tents. 


Nerve-tube  of  the  common  eel  in  water.  The 
delicnte  line  on  its  exterior  indicates  the  tubu- 
lar membrane.  The  dark  double-edged  inner 
one  is  the  white  substance  of  Schwann,  slightly 
wrinkled,  b.  The  siime  in  ether.  Several  oil 
globules  have  coalesced  in  the  interior,  and 
others  have  accumulated  around  the  exterior  of 
the  tube.  The  white  substance  has  in  part 
disappeared.     (Magnified  800  diameters.) 


from  having  one  or  more  tail-like  processes  issuing  from  them,  which  occasion- 
ally divide  and  subdivide  into  numerous  branches.     These  processes  are  very 


NERVOUS    TISSUE.  59 

delicate,  apparently  tubular,  and  contain  a  similar  granular  material  to  that 
found  within  the  corpuscle.  Some  of  the  processes  terminate  in  fine  transparent 
fibres,  which  become  lost  among  the  other  elements  of  the  nervous  tissue ; 
others  may  be  traced  until,  after  losing  their  granular  appearance,  they  become 
continuous  with  an  ordinary  nerve-fibre. 

The  white,  otherwise  called  tubular  or  fibrous  nervous  substance,  is  found  con- 
stituting a  great  part  of  the  brain  and  spinal  cord,  almost  the  whole  of  the 
cerebro-spinal  nerves,  and  a  great  part  of  the  sympathetic. 

The  tubes,  when  perfectly  fresh,  appear  to  be  homogeneous,  but  they  soon 
separate  into  two  parts,  the  white  substance  of  Schwann  and  the  axis-cylinder  of 
Purkinje,  the  whole  being  inclosed  in  a  structureless  membrane — the  ttibular 
membrane}  The  white  substance  is  regarded  as  being  a  fatty  matter  in  a  fluid 
state,  which  isolates  and  protects  the  essential  part  of  the  nerve — ih.e  axis-cijlin- 
der.  The  partial  coagulation  of  this  white  substance  which  follows  on  cooling 
gives  the  nerve-tube,  when  examined  after  death,  a  double  contour — the  darker 
part  seen  on  the  outside  of  the  axis-cylinder  being  the  white  substance  of 
Schwann.  In  consequence  of  the  extreme  delicacy  of  the  tubular  membrane, 
even  slight  pressure  will  often  give  nerve-tubes  a  varicose  outline,  and  drops  of 
oil,  from  the  transudation  of  the  fatty  matter,  often  form  outside  the  tubular 
membrane.     This  is,  of  course,  promoted  by  the  action  of  ether. 

The  axis-cylinder  constitutes  about  one-half  or  one-third  of  the  nerve  tube, 
the  white  substance  being  greater  in  proportion  in  the  nerves  than  in  the  cen- 
tral organs.  The  axis-cylinder  is  perfectly  transparent,  and  is  therefore  indis- 
tinguishable in  a  perfectly  fresh  and  natural  state  of  the  nerve.  It  is  described 
by  Kolliker  as  being  distinguished  from  the  white  substance  by  the  fact  that 
though  soft  and  flexible  it  is  not  fluid  and  viscid,  but  firm  and  elastic,  some- 
what like  coagulated  albumen,  with  which  it  appears  for  the  most  part  also  to 
agree  in  its  chemical  characters.  In  appearance  it  is  pale  and  homogeneous,  or 
more  rarely  finely  granular  or  striated. 

Besides  these  nerve-fibres  which  consist  of  two  distinct  parts,  others  are 
found  in  which  only  the  axis-cylinder  can  be  recognized,  surrounded  by  its 
medullary  membrane,  whilst  there  are  again  mere  primitive  fibrils  found  in 
various  parts,  which  are  perfectly  destitute  of  any  visible  structure,  and  only 
recognized  as  nerves  by  their  connection  with  ganglionic  cells,  or  with  obvious 
nerve-tubes.^  They  display  a  great  tendency  to  become  varicose  on  manipula- 
tion. The  finely-striated  appearance  of  those  nerves,  which  consist  only  of 
the  axis-cylinder  and  its  membranous  investtnent,  renders  it  probable  that  these 
also  are  formed  of  an  aggregation  of  the  primitive  fibrillse. 

Thus  three  different  kinds  of  white  nerve-fibres  are  described  by  recent 
aulhorities — -viz.,  1.  Those  which  consist  of  the  axis-C3dinder,  ensheathed  in 
the  white  substance  of  Schwann,  the  whole  being  invested  by  the  tubular  mem- 
brane; 2.  Those  which  consist  of  the  axis-cylinder  and  medullary  membrane 
only;  and  3.  The  primitive  fibrils,  of  which  it  is  believed  that  the  axis-cylinder 
of  the  more  composite  nerves  is  made  up.^ 

Most  of  the  nerves  of  the  sympathetic  system,  and  some  of  the  cerebro-spinal 
(see  especially  the  description  of  the  olfactory  nerve),  consist  of  a  fourth  de- 
scription of  nervous  fibres,^  which  are  called  the  gray  or  gelatinous  nerve-fibres 

•  Dr.  Beale  describes  and  figures  cases  in  which  several  fibres,  some  with,  others  without  the 
white  substance,  are  inclosed  in  a  common  tubular  membrane.     See  Phil.  Trans.,  1862. 

2  Schultze  (Strieker's  Handbuch,  fio^.  17,  p.  109}  represents  these  primitive  fibrils,  both  ia 
their  connection  M'ith  ganglion-cells  and  with  large  nerves.     See  also  below,  Fig.  36. 

'  Schultze  believes  that  the  primitive  fibrils  are  the  essential  elements  of  all  nerves;  thus, 
according  to  him,  the  essential  difference  between  the  gelatinous  and  the  ordinary  nerve  fibrils 
consists  in  the  absence  from  the  former  of  the  white  substance  (medulla)  of  Schwann,  while  the 
tubular  membrane  is  present.  The  small  nerve-fibres,  on  the  other  hand,  described  as  primitive 
fibrils  or  naked  axis-cylinders,  are  either  destitute  of  any  investment,  or  surrounded  merely  by  a 
structureless  basement  membrane. 

*  The  real  nature  of  these  fibres  has  been  doubted  by  several  authors.  It  seems  better,  how- 
ever, and  more  consonant  with  the  prevalent  opinion,  to  describe  them  as  truly  nervous. 


60  GENERAL    ANATOMY. 

(fibres  of  Remak).  These  consist  of  a  bundle  of  finely  granular  fibrillae,  in- 
closed in  a  sheath.  Nuclei  may  be  detected  at  intervals  in  each  fibre,  which 
Schultze  believes  to  be  situated  in  the  sheath  of  the  nerve.  In  external  ap- 
pearance the  gelatinous  nerves  are  semi- transparent,  and  gray  or  yellowish- 
gray.  The  individual  fibres  va.ry  in  size — most  of  them  being  of  smaller  size 
than  in  the  cerebro-spinal  nerves,  so  that  the  average  size  of  the  latter  is  given 
at  nTT^Tr  to  ■575'i575  of  au  inch,  and  of  the  former  at  only  half  that  size;  but  on  the 
one  hand  the  smallest  fibrils  of  the  cerebro-spinal  system  are,  as  we  have  seen, 
of  hardly  appreciable  thickness;  while  on  the  other  some  of  the  gelatinous 
fibres  (especially  those  in  the  olfactory  bulb),  are  said  to  be  three  or  four  times 
as  thick  as  those  of  the  cerebro-spinal  nerves. 

Chemical  composition.  The  following  analysis,  by  Lassaigne,  represents  the 
relative  proportion  of  the  different  constituents  composing  the  gray  and  white 
matter  of  the  brain. 

Gray.  White. 

Water 85.2  73.0 

Albuminous  matter 7. .5  9.9 

Colorless  fat 1.0  13.9 

Ked  fat 3.7  0.9 

Osmazome  and  lactates 1.4  1.0 

Phosphates        .        .        .        ." 1.2  1.3 

100.0  100.0 

It  appears  from  this  analysis,  that  the  cerebral  substance  consists  of  albumetf' 
dissolved  in  water,  combined  with  fatty  matters  and  salts.  The  fatty  matters, 
according  to  Fremy,  consist  of  cerebric  acid,  which  is  most  abundant,  choleste- 
rin,  oleophosphoric  acid,  and  olein,  margarin,  and  traces  of  their  acids.  The 
same  analyst  states,  that  the  fat  contained  in  the  brain  is  confined  almost  ex- 
clusively to  the  white  substance,  and  that  its  color  becomes  lost  when  the  fatty 
matters  are  removed.  According  to  Vauquelin,  the  cord  contains  a  larger  pro- 
portion of  fat  than  the  brain;  and,  according  to  L'Hdritier,  the  nerves  contain 
more  albumen  and  more  soft  fat  than  the  brain. 

With  regard  to  the  constitution  of  the  different  portions  of  the  nervous  sys- 
tem, the  cerebro-spinal  axis  is  composed  of  the  two  above-described  kinds  of 
nervous  structure,  intermingled  in  various  proportions,  and  having  in  the  brain 
a  very  intricate  arrangement,  which  can  only  be  fully  understood  by  a  careful 
study  of  the  details  of  its  descriptive  anatomy  in  the  sequel.  The  gray  or 
vesicular  nervous  matter  is  found  partly  on  the  surface  of  the  brain,  forming 
the  convolutions  of  the  cerebrum,  which  are  in  the  most  direct  relation  to  the 
mental  faculties,  and  the  laminae  of  the  cerebellum,  the  functions  of  which  are 
still  a  matter  of  dispute.  Again,  gray  matter  is  found  in  the  interior  of  the 
brain,  collected  into  large  and  distinct  masses  or  ganglionic  bodies,  such  as  the 
corpus  striatum,  optic  thalamus,  and  corpora  quadrigemina;  the  functions  of 
which  bodies,  so  far  as  they  have  been  ascertained,  have  been  found  to  be  con- 
nected with  some  of  the  main  organic  endowments  of  the  body,  such  as  volun- 
tary motion,  sensation,  sight.  Finally,  gray  matter  is  found  intermingled  inti- 
mately with  the  white,  and  without  definite  arrangement,  as  in  the  corpora 
dentata  of  the  medulla  and  cerebellum,  or  the  gray  matter  in  the  pons  and  the 
floor  of  the  fourth  ventricle.  Such  scattered  masses  of  gray  matter  are,  in 
many  instances  at  any  rate,  connected  to  all  appearance  with  the  origin  of  par- 
ticular nerve.s.     In  other  situations  their  use  is  as  yet  unknown. 

The  proper  nervous  matter,  both  in  the  brain  and  spinal  cord,  is  traversed 
and  supported  by  a  network  of  fine  connective  tissue.  This  has  been  termed 
by  Virchow  the  neuroglia^  and  is  supposed  to  be  the  source  of  one  of  the  forms 
of  tumor  recently  described  by  that  author  under  the  name  of  glioma. 

The  white  matter  of  the  brain  is  divisible  into  four  distinct  classes  of  fibres. 
There  are,  in  the  first  place,  the  nerves  which  arise  in  the  gray  matter,  and  ])ass 
out  through  the  cranial  foramina.    Next  the  fibres  which  connect  the  brain 


BRAIN.  61 

witli  the  spinal  cord;  that  is  to  say,  those  which  are  usually  traced  upwards 
from  the  columns  of  the  spinal  cord,  through  the  medulla  oblongata  into  the 
cerebrum,  chiefly  by  means  of  the  anterior  pyramids,  fasciculi  teretes,  and 
restiform  bodies,  passing  through  the  pons  and  crura  cerebri,  to  expand  into 
the  corpora  striata,  optic  thalami  and  convolutions  (corona  radiata),  and  by 
means  of  the  restiform  bodies,  into  the  cerebellum. 

The  other  two  classes  of  white  fibres  in  the  brain  are  commissural ;  some  of 
the  commissures  serving  to  connect  different  parts  of  the  same  hemisphere 
together  (as  the  fornix,  the  processus  e  cerebello  ad  testes,  &c.),  or  even  different 
parts  of  the  same  section  or  organ,  as  the  arciform  fibres  of  the  medulla.  Most 
of  these  commissures  are  longitudinal ;  while  others — as  the  corpus  callosura 
and  the  transverse  fibres  of  the  pons  Varolii — are  transverse,  serving  to  con- 
nect opposite  hemispheres  together,  and  thus  probably  securing  the  single 
action  of  a  double  organ. 

The  following  is  Mr.  Lockhart  Clarke's  account  of  the  intimate  structure  of 
the  cerebral  convolutions : — • 

"  Most  of  the  convolutions,  when  properly  examined,  may  be  seen  to  consist 
of  at  least  seven  distinct  and  concentric  layers  of  nervous  substance,  which  are 
alternately  paler  and  darker  from  the  circumference  to  the  centre.  The  lami- 
nated structure  is  most  strongly  marked  at  the  extremity  of  the  posterior  lobe. 
In  this  situation  all  the  nerve-cells  are  small,  but  differ  considerably  in  shape, 
and  are  much  more  abundant  in  some  layers  than  in  others.  In  the  superficial 
layer,  which  is  pale,  they  are  round,  oval,  fusiform,  and  angular,  but  not  nume- 
rous. The  second  and  darker  layer  is  densely  crowded  with  cells  of  a  similar 
kind,  in  company  with  others  that  are  pyriform  and  pyramidal,  and  lie  with 
their  tapering  ends  either  towards  the  surface  or  parallel  with  it,  in  connection 
with  fibres  which  run  in  corresponding  directions.  The  broader  ends  of  the 
pyramidal  cells  give  off  two,  three,  four,  or  more  processes,  which  run  partly 
through  the  white  axis  of  the  convolution,  and  in  part  horizontally  along  the 
plane  of  the  layer,  to  be  continuous  like  those  at  the  opposite  ends  of  the  cells, 
with  nerve  fibres  running  in  different  directions.  The  ihii'd  layer  is  of  a  much 
paler  color.  It  is  crossed,  however,  at  right  angles  by  narrow  and  elongated 
groups  of  small  cells  and  nuclei  of  the  same  general  appearance  as  those  of  the 
preceding  layer.  These  groups  are  separated  from  each  other  by  bundles  of 
fibres,  radiating  towards  the  surface  from  the  central  white  axis  of  the  convolu- 
tions, and  together  with  them  form  a  beautiful  fanlike  structure.  The  fourth 
layer  also  contains  elongated  groups  of  small  cells  and  nuclei,  radiating  at  right 
angles  to  its  plane ;  but  the  groups  are  broader,  more  regular,  and,  together 
with  the  bundles  of  fibres  between  them,  present  a  more  distinctly  fanlike 
structure.  The  fifth  layer  is  again  paler  and  somewhat  white.  It  contains, 
however,  cells  and  nuclei  which  have  a  general  resemblance  to  those  of  the 
preceding  layers,  but  they  exhibit  only  a  faintly  radiating  arrangement.  The 
sixth  and  most  internal  layer  is  reddish-gray.  It  not  only  abounds  in  cells  like 
those  already  described  but  contains  others  that  are  rather  larger.  It  is  only 
here  and  there  that  the  cells  are  collected  into  elongated  groups,  which  give 
the  appearance  of  radiations.  On  its  under  side  it  gradually  blends  with  the 
central  white  axis  of  the  convolution,  into  which  its  cells  are  scattered  for  some 
distance. 

"  The  seventh  layer  is  this  central  white  stem  or  axis  of  the  convolution.  On 
every  side  it  gives  off  bundles  of  fibres,  which  diverge  in  all  directions,  and  in 
a  fanlike  manner  towards  the  surface,  through  the  several  gray  layers.  As  they 
pass  between  the  elongated  and  radiating  groups  of  cells  in  the  i'nner  gray 
layers,  some  of  them  become  continuous  with  the  processes  of  the  cells  in  the 
same  section  or  plane,  but  others  bend  round  and  run  horizontally,  both  in  a 
transverse  and  longitudinal  direction  (in  reference  to  the  course  of  the  entire 
convolution),  and  with  various  degrees  of  obliquity.  While  the  bundles  them- 
selves are  by  this  means  reduced  in  size,  their  component  fibres  become  finer 


62 


GENERAL    ANATOMY. 


in  proportion  as  they  traverse  the  layers  towards  the  surface,  in  consequence, 
apparently,  of  branches  which  they  give  oft"  to  be  connected  with  cells  in  their 
course.  Those  which  reach  the  outer  gray  layer  are  reduced  to  the  finest 
dimensions,  and  form  a  close  network,  with  which  the  nuclei  and  cells  are  in 
connection. 

"  Besides  these  fibres  which  diverge  from  the  central  white  axis  of  the  con- 
volution, another  set,  springing  from  the  same  source,  converge  or  rather  curve 
inwards  from  opposite  sides,  to  form  arches  along  some  of  the  gray  layers. 
These  arciform  fibres  run  in  different  planes — transversely,  obliquely,  and 
longitudinally — and  appear  to  be  partly  continuous  with  those  of  the  divergent 
set  which  bend  round,  as  already  stated,  to  follow  a  similar  course.  All  these 
fibres  establish  an  infinite  number  of  communications  in  every  direction,  be- 
tween different  parts  of  each  convolution,  between  different  convolutions,  and 
between  these  and  the  central  white  substance." 

Mr.  Clarke  then  goes  on  to  describe  in  detail  the  minuter  differences  which 
exist  between  the  structure  of  the  convolutions  in  different  parts  of  the  brain.' 

Spinal  Cord.  In  the  spinal  cord,  on  the  other  hand,  the  gray  matter  is  entirely 
in  the  interior  of  the  organ,  and  is  collected  together  into  one  central  mass, 
while  the  whole  of  the  white  matter  is  external,  and  is  arranged  into  various 
columns  and  commissures.  {See  Spinal  Cord.)  We  shall  here  merely  give  an 
account  of  the  intimate  structure  of  the  cord,  which  is  condensed  from  the 
researches  of  Mr.  Lockhart  Clarke.* 

The  white  suhstance  of  the  cord  consists  of  transverse,  oblique,  and  longitudinal 
fibres,  with  bloodvessels  and  connective  tissue. 

The  transverse  fibres  proceed  from  the  gray  substance,  and  form  with  each 
other  a  kind  of  plexus  between  the  bundles  of  longitudinal  fibres,  with  whicli 
many  are  continuous;  while  others  reach  the  surface  of  the  cord  through 
fissures  containing  connective  tissue.  "Within  the  gray  substance  they  are 
continuous  with  the  roots  of  the  nerveSj  with  the  processes  of  the  nerve-cells, 

and  with  the  anterior  and  posterior 
Fig-  30.  commissures.    The  oi/iVywe^^6?-e5  pro- 

ceed from  the  gray  substance  both 
upwards  and  downwards :  they  form 
the  deep  strata  of  the  white  columns, 
and,  after  running  a  variable  length, 
become  superficial.  The  longitudinal 
fibres  are  more  superficial,  rufi  nearly 
parallel  with  each  other,  and  form 
the  greater  portion  of  the  white 
columns. 

The  gray  snhstaiice  of  the  cord 
consists  of,  1.  Nerve  fibres  of  varia- 
ble, but  smaller  average  diameter 
than  those  of  the!columns.  2.  Nerve- 
cells  of  various  shapes  and  sizes,  with 
from  two  to  eight  processes.  3, 
Bloodvessels  and  connective  tissue 
Each  lateral  half  of  the  gray  sub- 
stance is  divided  into  an  anterior 
and  posterior  horn,  and  the  tractus 
intermedio-lateralis,  or  lateral  part  of  the  gray  substance  between  the  anterior 
and  posterior  cornua. 

'  See  Mr.  Clarke's  summary  of  his  researches  on  this  subject  in  Maudsley  on  the  Pathologic 
aiul  Physiology  of  Mind,  pp.  60-63. 
»  Phil.  Trans.,  1851-1853,  part  ill. ;  1858  part  i. ;  1859  part  i. ;  1862  part  ii. 


/^v?-$ 


Trati 

/ntrrntdia       , 


Transverse  section  of  the  gray  substance  of  the  spinal 
cord,  near  the  middle  of  the  dorsal  region.  (Magnified 
13  diameters.) 


SPINAL    CORD. 


68 


The  posterior  horn  consists  of  two  parts,  the  caput  cornu,  or  expanded  ex- 
tremity of  the  horn  (Fig.  30),  round  which  is  the  lighter  space  or  lamina,  the 
gelatinous  substance;  and  the  cervix  cornu^  or  remaining  narrow  portion  of  the 
horn,  as  far  forwards  as  the  central  canal. 

The  gelatinous  substance  contains  along  its  border  a  series  of  large  nerve- 
cells;  but  more  internally  consists  of  a  stratum  of  small  cells  traversed  by 
transverse,  oblique,  and  longitudinal  fibres  (Figs.  31,  32). 

Fig.  31. 


Ksru 


Trnnsverse  section  of  the  gray  substance  of  the  spinal  cord  through  the  middle  of  the  lumber  enlargement. 
On  the  left  side  the  groups  of  large  cells  are  seen  ;  on  the  right  side  the  course  of  the  fibres  without  the  cells. 
(Magnified  13  diameters.) 

Nearly  the  whole  inner  half  of  the  cervix  is  occupied  by  a  remarkable  and 
important  column  of  nerve-cells,  called  the  posterior  vesicular  column  (Fig.  30), 
which  varies  in  size  and  appearance  in  different  regions  of  the  cord,  and  is 
intimately  connected  with  the  posterior  roots  of  the  nerves. 

Within,  and  along  the  outer  border  of  the  cervix,  are  several  thick  bundles 
of  longitudinal  fibres,  represented  in  Fig.  30  by  the  dark  spots ;  other  bundles 
of  the  same  kind  may  be  seen  in  the  gray  substance  along  the  line  of  junction 
of  the  caput  with  the  cervix  cornu  (Fig.  31). 

The  anterior  horn  of  the  gray  substance  in  the  cervical  and  lumbar  swellings, 
where  it  gives  origin  to  the  nerves  of  the  extremities,  is  much  larger  tiian  in 
any  other  region,  and  contains  several  distinct  groups  of  large  and  variously 
shaped  cells.     This  is  well  shown  on  comparing  the  above  figures. 

The  iractus  intermedio -lateralis  (Fig.  30)  extends  from  the  upper  part  of  the 
lumbar  to  the  lower  part  of  the  cervical  enlargement,  and  consists  of  variously 
shaped  cells,  which  are  smaller  than  those  of  the  anterior  cornu.  In  the  neck 
above  the  cervical  enlargement,  a  similar  tract  reappears,  and  is  traversed  by 
the  lower  part  of  the  spinal  accessory  nerve. 

Origin  of  the  Spinal  Nerves  in  the  Cord.  The  posterior  roots  are  larger  than  the 
anterior ;  but  their  component  filaments  are  finer  and  more  delicate.  They  are 
all  attached  immediately  to  the  posterior  columns  only,  and  decussate  each 
other  in  all  directions  through  the  columns ;  but  some  of  them  pass  through 


64 


GENERAL    ANATOMY. 


Fig.  32. 


Tott^  Jtfotn 


Subulante 


Substanee 


the  gray  substance  into  both  the  lateral  and  anterior  columns.     Within  the 
gray  substance,  they  run  longitudinally  upwards  and  downwards ;  transversely 

through  the  posterior  commissure  to  the  oppo- 
site side ;  and  into  the  anterior  cornu  of  their 
own  side  (Figs.  31,  32). 

The  arderior  roots  are  attached  exclusively  to 
the  anterior  column,  or  rather  to  the  anterior 
part  of  the  antero-lateral  columns ;  for  there  is 
no  antero-lateral  fissure  dividing  the  anterior 
from  the  lateral  column.  Within  the  gray 
substance,  the  fibrils  cross  each  other,  and  di- 
verge in  all  directions,  like  the  expanded  hairs 
of  a  brush  (Figs.  31,  32),  some  of  them  run- 
ning more  or  less  longitudinally  upwards  and 
downwards;  and  others  decussating  those  of 
the  opposite  side  through  the  anterior  com- 
missure in  front  of  the  central  canal. 

All  the  fibres  of  both  roots  of  the  nerves 
proceed  through  the  white  columns  into  the 
gray  substance,  with,  perhaps,  the  exception 
of  some  which  appear  to  run  longitudinally 
in  the  posterior  columns;  but  whether  these 
latter  fibres  of  the  posterior  roots  ultimately 
enter  the  gray  substance  of  the  cord  after  a 
very  oblique  course,  or  whether  they  proceed 
upwards  to  the  brain,  is  uncertain. 

The  Central  Canal  of  the  Spinal  Cord.  In 
the  foetus,  until  after  the  sixth  month,  a  canal, 
continuous  with  the  general  ventricular  cavity 
of  the  brain,  extends  throughout  the  entire 
length  of  the  spinal  cord,  formed  by  the  clos- 
ing-in  of  a  previously  open  groove. 

In  the  adult,  this  canal  can  only  be  seen  at 
the  upper  part  of  the  cord,  extending  from  the  point  of  the  calamus  scriptorius, 
in  the  floor  of  the  fourth  ventricle,  for  about  half  an  inch  down  the  centre  of 
the  cord,  where  it  terminates  in  a  cul-de-sac;  the  remnant  of  the  canal  being 
just  visible  in  a  section  of  the  cord,  as  a  small,  pale  spot,  corresponding  to  the 
centre  of  the  gray  commissure;  its  cavity  is  lined  with  a  layer  of  cylindrical 
ciliated  epithelium.  In  some  cases,  this  canal  remains  pervious  throughout 
the  whole  length  of  the  cord. 

The  Ganglia  may  be  regarded  as  separate  and  independent  nervous  centres, 
of  smaller  size  and  less  complex  structure  than  the  brain,  connected  with  each 
other,  with  the  cerebro-spinal  axis,  and  with  the  nerves  in  various  situations. 
They  are  found  on  the  posterior  root  of  each  of  the  spinal  nerves ;  on  the  pos- 
terior or  sensory  root  of  the  fifth  cranial  nerve ;  on  the  facial  nerve ;  on  the 
glosso-pharyngeal  and  pneumogastric  nerves;  in  a  connected  series  along  each 
side  of  the  vertebral  column,  forming  the  trunk  of  the  sympathetic ;  on  the 
branches  of  that  nerve,  and  at  the  point  of  junction  of  those  branches  with  the 
cerebro-spinal  nerves.  On  section,  they  are  seen  to  consist  of  a  reddish-gray 
substance,  traversed  by  numerous  white  nerve-fibres :  they  vary  considerably 
in  form  and  size ;  the  largest  are  found  in  the  cavity  of  the  abdomen ;  the 
smallest,  not  visible  with  the  naked  eye,  exist  in  considerable  numbers  upon 
the  nerves  distributed  to  the  different  viscera.  The  ganglia  are  invested  by  a 
smooth  and  firm  closely-adhering  membranous  envelope,  consisting  of  dense 
areolar  tissue ;  this  sheath  is  continuous  with  the  neurilemma  of  the  nerves, 


Longitudinal  section  of  the  white  and 
gray  substance  of  the  spinal  cord,  through 
the  middle  of  the  lumbar  enlargement. 
(Magnified  14  diameters.) 


THE    NERVES.  65 

and  sends  numerous  processes  into  the  interior  of  the  ganglia,  which  support 
the  bloodvessels  supplying  its  substance. 

In  structure,  all  ganglia  are  essentially  similar  ;  consisting  of  the  same  struc- 
tural elements  as  the  other  nervous  centres,  viz.,  a  collection  of  vesicular  nervous 
matter^  traversed  by  tubular  and  gelatinous  nerve-fihres.  The  vesicular  nervous 
matter  consists  of  nerve-cells  or  ganglion  globules,  most  of  which  appear  free, 
and  of  a  round  or  oval  form:  these  are  more  especially  seated  near  the  surface 
of  the  ganglion ;  others  have  caudate  processes,  and  give  origin  to  nerve-fibres. 
In  the  ganglia,  the  nerve-cells  are  usually  inclosed  in  a  capsule  of  granular 
corpuscles  and  fibres.  The  tubular  nerve-fibres  run  through  the  ganglion, 
some  being  collected  into  bundles,  while  others,  separating  from  each  other, 
take  a  circuitous  course  among  the  nerve-cells  before  leaving  the  ganglia. 

The  Nerves  are  round  or  flattened  cords,  which  are  connected  at  one  end  with 
the  cerebro-spinal  centre  or  the  ganglia,  and  are  distributed,  at  the  other,  to 
the  various  textures  of  the  body :  they  are  subdivided  into  two  great  classes, 
the  Cerebro-spinal,  which  proceed  from  the  cerebro-spinal  axis,  and  the  Sym- 
pathetic or  Ganglionic  nerves,  which  proceed  from  the  ganglia  of  the  sympa- 
thetic. 

The  cerebro-spinal  nerves  consist  of  numerous  nerve-fibres,  collected  together 
and  inclosed  in  a  membranous  sheath.  A  small  bundle  of  primitive  fibres, 
inclosed  in  a  tubular  sheath,  is  called  o.  funiculus:  if  the  nerve  is  of  small  size, 
it  may  consist  only  of  a  single  funiculus,  but  if  large,  the  funiculi  are  collected 
together  into  larger  bundles  or  fasciculi ;  and  are  bound  together  in  a  common 
membranous  investment,  termed  the  sheath.  In  structure,  the  common  sheath 
investing  the  whole  nerve,  as  well  as  the  septa  given  off  from  the  sheath,  and 
which  separate  the  fasciculi,  consist  of  areolar  tissue,  composed  of  white  and 
yellow  elastic  fibres,  the  latter  existing  in  greatest  abundance.  The  tubular 
sheath  of  the  funiculi,  or  neurilemma^  consists  of  a  fine,  smooth,  transparent 
membrane,  which  may  be  easily  separated,  in  the  form  of  a  tube,  from  the 
fibres  it  incloses ;  in  structure,  it  is,  for  the  most  part,  a  simple  and  homo- 
geneous transparent  film,  occasionally  composed  of  numerous  minute  reticular 
fibres. 

The  cerebro-spinal  nerves  consist  almost  exclusively  of  the  tubular  nerve- 
fibres,  the  gelatinous  fibres  existing  in  very  small  proportion. 

The  bloodvessels  supplying  a  nerve  terminate  in  a  minute  capillary  plexus, 
the  vessels  composing  which  run,  for  the  most  part,  parallel  with  the  funiculi; 
they  are  connected  together  by  short  transverse  vessels,  forming  narrow  oblong 
meshes,  similar  to  the  capillary  system  of  muscle. 

The  nerve-fibres,  as  far  as  is  at  present  known,  do  not  coalesce,  but  pursue 
an  uninterrupted  course  from  the  centre  to  the  periphery.  In  separating  a 
nerve,  however,  into  its  component  funiculi,  it  may  be  seen  that  they  do  not 
pursue  a  perfectly  insulated  course,  but  occasionally  join  at  a  very  acute  angle 
with  other  funiculi  proceeding  in  the  same  direction ;  from  which,  again, 
branches  are  given  off,  to  join  again  in  like  manner  with  other  funiculi.  It 
must  be  remembered,  however,  that  in  these  communications  the  nerve-fibres 
do  not  coalesce,  but  merely  pass  into  the  sheath  of  the  adjacent  nerve,  become 
intermixed  with  its  nerve-fibres,  and  again  pass  on  to  become  blended  with  the 
nerve-fibres  in  some  adjoining  fasciculus. 

Nerves,  in  their  course,  subdivide  into  branches,  and  these  frequently  com- 
municate with  branches  of  a  neighboring  nerve.  In  the  subdivision  of  a  nerve, 
the  filaments  of  which  it  is  composed  are  continued  from  the  trunk  into  the 
branches,  and  at  their  junction  with  the  branches  or  neighboring  nerves,  the 
filaments  pass  to  become  intermixed  with  those  of  the  other  nerve  in  their  fur- 
ther progress;  in  no  instance,  however,  have  the  separate  nerve-fibres  been 
shown  to  inosculate. 

The  communications  which  take  place  between  two  or  more  nerves,  form 
6 


6G  GENERAL    ANATOMY. 

what  is  called  a  plexus.  Sometimes  a  plexus  is  formed  by  the  primary  branches 
of  the  trunks  of  the  nerves,  as  the  cervical,  brachial,  lumbar,  and  sacral  plex- 
uses,  and  occasionally  by  the  terminal  fasciculi,  as  in  the  plexuses  formed  at 
the  periphery  of  the  body.  In  the  formation  of  a  plexus,  the  component  nerves 
divide,  then  join,  and  again  subdivide  in  such  a  complex  manner  that  the  indi- 
vidual fasciculi  become  interlaced  most  intricately ;  so  that  each  branch  leav- 
ing a  plexus  may  contain  filaments  from  each  of  the  primary  nervous  trunks 
•which  form  it.  In  the  formation  also  of  the  smaller  plexuses  at  the  periphery 
of  the  body,  there  is  a  free  interchange  of  the  fasciculi  and  primitive  fibrils. 
In  each  case,  however,  the  individual  filaments  remain  separate  and  distinct, 
and  do  not  inosculate  with  each  other. 

It  is  probable  that,  through  this  interchange  of  fibres,  the  different  branches 
passing  off"  from  a  plexus  have  a  more  extensive  connection  with  the  spinal 
cord  than  if  they  each  had  proceeded  to  be  distributed  without  such  connection 
with  other  nerves.  Consequently,  the  parts  supplied  by  these  nerves  have 
more  extended  relations  with  the  nervous  centres;  by  this  means,  also,  groups 
of  muscles  may  be  associated  for  combined  action. 

The  sympathetic  nerve  consists  of  tubular  and  gelatinous  fibres,  intermixed 
with  a  varying  proportion  of  filamentous  areolar  tissue,  and  inclosed  in  a 
sheath  formed  of  fibro-areolar  tissue.  The  tubular  fibres  are,  for  the  most 
part,  smaller  than  those  composing  the  cerebro-spinal  nerves;  their  double 
contour  is  less  distinct,  and,  according  to  Remak,  they  present  nuclei  similar 
to  those  found  in  the  gelatinous  nerve-fibres.  Those  branches  of  the  sym- 
pathetic which  present  a  well-marked  gray  color,  are  composed  more  especially 
of  gelatinous  nerve-fibres,  intermixed  with  a  few  tubular  fibres;  whilst  those 
of  a  white  color  contain  more  of  the  tubular  fibres,  and  few  gelatinous. 
Occasionally  the  gray  and  white  cords  run  together  in  a  single  nerve,  without 
any  intermixture,  as  in  the  branches  of  communication  between  the  sym- 
pathetic ganglia  and  the  spinal  nerves,  or  in  the  communicating  cords  between 
the  ganglia. 

The  nerve-fibres,  both  of  the  cerebro-spinal  and  sympathetic  system,  convey 
impressions  of  a  twofold  kind.  The  sensory  nerves,  called  also  centripetal  or 
afferent  nerves,  transmit  to  the  nervous  centres  impressions  made  upon  the 
peripheral  extremities  of  the  nerves,  and  in  this  way  the  mind,  through  the 
medium  of  the  brain,  becomes  conscious  of  external  objects.  The  motor 
nerves,  called  also  centrifugal  or  efferent  nerves,  transmit  impressions  from  the 
nervous  centres  to  the  parts  to  wliich  the  nerves  are  distributed,  these  impres- 
sions either  exciting  muscular  contractions,  or  influencing  the  processes  of 
nutrition,  growth,  and  secretion. 

Terminations  of  Nerves.  By  the  expression  "the  termination  of  nerve-fibres" 
is  signified  their  connections  with  the  nerve  centres,  and  with  the  parts  which 
they  supply.  The  former  are  called  their  central^  the  latter  their  perijjheral 
terminations.  With  regard  to  the  central  terminations  of  the  nerves,  little  is 
as  yet  certainly  known.'  The  nerve-cells,  or  nerve-corpuscles,  above  figured, 
have  been  regarded  as  the  central  origin  of  the  fibres  with  which  they  are 
connected;  and  it  is  very  probable  that  in  many  cases  they  are  so.  There  are 
instances,  however,  in  which  such  cells  occur  as  mere  nucleated  swellings  in 
the  course  of  a  nerve,  and  in  these  cases  they  obviously  cannot  be  regarded  as 
being  in  any  sense  the  origins  of  the  nerves.  In  other  cases,  as  in  the  nerve- 
cells  in  the  anterior  horn  of  the  gray  matter  of  the  cord,  there  are  numerous 
processes  springing  out  of  the  cell ;  one  of  thes^^  (and  according  to  Deiters  one 
only)  is  recognized  as  an  axis-cylinder;  the  others  are  fibrillae,  which  are  con- 

'  The  most  recent  author,  nnd  one  of  the  moat  distinfruished  observers  on  this  subject,  Max 
Schultze,  speaks  thus  :  "  In  the  present  state  of  our  knowledge,  we  are  not  in  a  position  to 
assign  its  central  origin  to  nny  pinirlo  primitive  fibril  of  the  nervous  system,  however  certainly 
we  may  have  discovered  the  peripheral  terminations  of  a  great  part  of  them."  (Schultze.  in 
StrickeV's  Handbuch,  1868,  p.  134.) 


THE    NERVES.  et 

tinuous  with  similar  fibrillas,  of  which,  under  high  powers,  the  apparently 
granular  contents  of  the  cell  are  found  to  be  composed,  and  which  appear 
therefore  simply  to  run  through  the  cell.  The  fibrillae  may  be,  and  probably 
are,  primitive  nervous  fibrils,  but  they  are  so  delicate,  that  it  has  not  as  yet 
been  found  possible  to  ascertain  their  destination.  With  regard  also  to  the 
axis-cylinder  which  is  seen  proceeding  out  of  the  ganglionic  corpuscle,  although 
it  is  highly  probable  that  it  originates  in  that  corpuscle,  the  fact  has  not  been 
proved — nor  has  its  relation  to  the  nucleus  of  the  corpuscle  been  demonstrated. 
In  fine,  all  that  is  known  on  the  subject  is,  that  many  of  the  fibrillas  and  axis- 
cylinders  can  be  shown  either  to  originate  in  or  to  pass  through  ganglionic 
corpuscles  (or  nerve-cells),  and  other  nerves  can  be  shown  to  contain  such 
nerve-cells  in  their  anterior  at  certain  parts  of  their  course.  But  whether  in 
the  case  of  such  connection  in  one  of  the  central  organs  the  cell*  is  to  be 
regarded  as  the  origin  of  the  nervous  fibril,  or  whether  the  fibril  merely  passes 
througli  the  cell  (as  some  observers  believe),  just  in  the  same  manner  as  nerves 
pass  through  ganglia,  has  not  been  determined.  If  the  latter  view  be  correct, 
it  may  be  that  nerves  have  really  no  central  termination,  but  that  their  fibrils 
start  from  their  peripheral  distribution,  travel  to  the  nervous  centre,  are  there 
brought  into  connection  with  the  nerve-cells,  and  thence  return  to  their  distri- 
bution. However,  in  the  present  state  of  anatomical  knowledge,  the  more 
probable  opinion  seems  to  be  that  which  is  usually  entertained,  viz.,  that  each 
nerve-fibre  is  connected  somewhere  with  a  ganglionic  corpuscle,  which  is  to  be 
regarded  as  its  central  termination  or  origin.  Dr.  Beale  asserts,  that  even  in 
those  ganglion-cells,  which  appear  either  altogether  destitute  of  processes,  or 
unipolar,  numerous  fibres  can  be  seen  proceeding  out  of  them  if  the  proper 
reagents  be  used  and  very  high  powers  employed. 

The  peripheral  connections,  or  terminations  of  the  nerve-fibres,  are  some- 
what more  easy  to  ascertain,  though  even  as  to  these  a  great  difference  exists 
with  respect  to  minute  details.  They  are  usually  and  naturally  studied  in  the 
sensory  and  motor  nerves  separately. 

Sensory  nerves  sometimes  terminate  in  minute  plexuses  in  the  subcutaneous 
or  submucous  areolar  tissue.  Dr.  Sharpey  says  that  he  has  seen  the  ultirnate 
fibres  of  these  minute  plexuses  come  into  close  contact  with  the  connective- 
tissue  corpuscles,  but  has  not  been  able  to  trace  any  distinct  connection  between 
them. 

The  white  substance  of  Schwann  and  the  tubular  sheath  usually  disappear 
as  the  nerve  approaches  its  termination,  leaving  only  the  axis-cylinder  invested 
by  its  proper  basement-merabrane,  on  which  nuclei  can  be  seen  at  intervals, 
and  in  many  cases  the  axis-cylinder  itself  breaks  up  into  the  primitive  fibrils. 
In  some  parts,  however,  the  fibres  appear  to  be  inclosed  up  to  their  termination 
in  a  sheath,  which  is  either  a  prolongation  of  the  neurilemma,  or  a  continuation 
of  the  tubular  membrane.  The  differences  of  opinion  prevailing  on  the  ques- 
tion of  the  ultimate  distribution  of  the  nerve-fibres  depend  on  their  extreme 
delicacy  and  the  consequent  great  difficulty  of  following  individual  fibres  in 
continuity.  Hence  what  some  observers  describe  as  a  free  end,  in  which  the 
nerve  terminates,  others  regard  as  merely  a  bending  of  the  fibre  where  it  be- 
comes lost  to  sight,  or  a  spot  where  it  is  lost  sight  of  in  consequence  of  the 
power  used  being  too  low,  or  from  difficulty  in  focussing.  These  ultimate 
fibres,  it  should  be  remembered,  are  structureless,  and  can  therefore  only  be 
recognized  positively  as  nervous  by  their  continuity  with  a  nerve  of  more 
complex  structure. 

In  the  papillee  of  the  skin,  or  mucous  membrane,  and  on  the  surface  of  various 
membranes  (conjunctiva,  mesentery,  &c.),  three  different  kinds  of  terminal 
organs  have  been  found  connected  with  the  nerves,  viz.,  the  end-bulbs  of  Krause, 
the  tactile  corpuscles  of  Rudolph  Wagner,  and  the  Pacinian  corpuscles. 

The  end-bulbs  of  Krause  are  small  capsules  of  connective  tissue,  in  which 
nuclei  can  be  detected  by  reagents,  and  in  which  one  or  more  nerve-fibrils 


68 


GENERAL    ANATOMY. 


terminate  either  in  a  coiled  plexiform  mass  or  in  a  bulbous  extremity.  Thev 
have  been  described  as  occurring  in  the  conjunctiva,  the  mucous  membrane  of 
the  mouth,  and  the  surface  of  the  glans  penis  and  glans  clitoridis.^ 

The  tactile  corpuscles  of  Wagner  (Fig.  33)  are  described  by  him  as  oval- 
shaped  bodies,  made  up  of  superimposed  saccular  lamina,  presenting  some 
resemblance  to  a  miniature  fir-cone,  and  he  regarded  them  as  directly  concerned 
in  the  sense  of  touch.  Kcilliker  considers  that  the  central  part  of  the  papillae 
generally  consists  of  a  connective  tissue  more  homogeneous  than  that  of  the 
outer  part,  surrounded  by  a  sort  of  sheath  of  elastic  fibres,  and  he  believes  that 
these  corpuscles  are  merely  a  variety   of  this  structure.     The  nerve-fibres, 


Fig.  33. 


Fiix.  34. 


A.  Side  view  of  a  pnpilla  of  the  hand.  a.  Cortical 
layer;  ^,  tactile  corpuscle,  with  transverse  nuclei;  c, 
small  nerve  of  the  papilla,  with  neurileinina;  d,  its  two 
nervous  fibres  running  with  spiral  coils  around  the  tactile 
corpuscle;  e,  apparent  termination  of  one  of  these  fibres. 
B.  A  tactile  papilla  seen  from  above,  so  as  to  show  its 
transverse  section,  a.  Cortical  layer;  b,  nerve  fibre ; 
c,  outer  layer  of  the  tactile  body,  with  nuclei ;  d,  clear 
interior  substance.  From  the  human  subject,  treated 
with  acetic  acid.     (Magnified  350  times.) 


Pacinian  corpuscle  with  its  system  of  capsules 
and  central  cavity,  a.  Arterial  twig,  ending  in 
capillaries,  which  form  loops  in  foine  of  the 
intercapsular  spaces,  and  one  penetrates  to  the 
central  capsule  ;  b,  the  fibrous  tissue  of  the  stalk 
prolonged  from  the  neurilemma;  n,  nerve-tube 
advancing  to  the  central  capsule,  there  losing 
its  white  substance,  and  stretching  along  the 
axis  to  the  opposite  end,  where  it  is  fixed  by  a 


tubercular  enlargement.  ^^ 

1 

according  to  this  observer,  run  up  in  a  waving  course  to  the  corpuscle,  not 
penetrating  it,  but  forming  two  or  three  coils  round  it,  and  finally  join  together 
in  loops.  These  bodies  are  not  found  in  all  the  papillae;  but  from  their  exist- 
ence in  those  parts  in  which  the  skin  is  highly  sensitive,  it  is  probable  that 
they  are  especially  concerned  in  the  sense  of  touch,  though  their  absence  from 
the  papillae  of  other  tactile  parts  shows  that  they  are  not  essential  to  this  sense. 
The  Pacinian  corpuscles'  (Fig.  3-1)  are  found  in  the  human  subject  chiefly  on 
the  nerves  of  the  fingers  and  toes,  lying  in  the  subcutaneous  cellular  tissue;  but 


'  Krausc,  Die  (rrmi'nalen  Korperrhm,  1860.     Anntnmische  Untersuchungen,  1861. 
'  Often  called  in  German  anatomical  works  "  corpuscles  of  Vater." 


THE    NERVES.  69 

they  have  also  been  described  by  Rauber  as  connected  with  the  nerves  of  the 
joints,  and  with  the  nerves  lying  between  many  of  the  muscles  of  the  trunk 
and  limbs.  Each  of  these  corpuscles  is  attached  to  and  incloses  the  termination 
of  a  single  nerve.  The  corpuscle,  which  is  perfectly  visible  to  the  naked  eye 
(and  which  can  be  most  easily  demonstrated  in  the  mesentery  of  a  cat),  consists 
of  a  number  of  concentric  layers  of  cellulur  tissue,  between  which  Todd  and 
Bowman  have  figured  capillary  vessels  as  running.  The  nerve,  at  its  entrance 
into  this  body,  parts  with  its  white  substance,  and  the  axis-cylinder  runs 
forwards  in  a  kind  of  cavity  in  the  centre  of  the  corpuscle  to  terminate  in  a 
rounded  end  or  knob,  sometimes  bifurcating  previously,  in  which  case  each 
branch  has  a  similar  termination.  Grandry,  who  has  examined  these  corpus- 
cles with  very  high  magnifying  powers,  describes  the  axis-cylinder  as  exhibit- 
ing a  very  well  marked  fibrillar  structure,  and  the  bulbous  end  as  consisting 
of  a  mass  of  granules  into  which  the  fibrils  run,  diverging  as  they  approach  it. 
The  investing  capsules  are  from  thirty  to  sixty  in  number,  the  outer  being 
more  separated  from  each  other,  as  if  by  a  clear  fluid,  while  the  inner  are 
closely  applied  together.  Schultz  calls  attention  to  the  striking  resemblance  in 
all  essential  particulars  between  these  corpuscles  and  Krause's  end-bulbs  above 
described.^ 

In  the  special  organs  the  nerves  end  in  various  ways,  which  hitherto  are  not 
perfectly  known. 

Hoyer  and  Cohnheim  have  described  the  nerves  of  the  cornea  as  terminating 
in  primitive  fibrillae,  which  run  between  the  cells  forming  the  pavement-epithe- 
lium of  that  membrane,  and  end  on  its  free  surface.  This,  however,  is  doubted 
by  Hulke,^  who  has  only  succeeded  in  tracing  them  as  far  as  the  middle  tier 
of  the  epithelial  cells.  Schultze  discovers  in  the  olfactory  mucous  membrane, 
lying  between  the  cells  of  its  epithelium,  spindle-shaped  cells,  each  possessing  a 
central  and  a  peripheral  process — the  central  process  being,  according  to  him, 
continuous  with  a  primitive  fibril  of  the  olfactory  nerve,  and  the  peripheral 
process  either  ending  on  the  free  surface  of  the  epithelium,  as  is  the  case  in  men, 
mammals,  and  fishes,  or  in  some  other  animals  prolonged  into  a  long  stiff  hair. 
These  cells  he  has  denominated  "olfactory  cells;"  and  similar  cells  have  been 
described  by  Axel  Key,  Schwalbe,  and  Loven,  in  the  papillae  circumvallatse  of 
men,  and  the  fungiform  papillae  of  the  frog  ("taste-cells").  The  fibres  also  of 
the  optic  nerve  have,  according  to  Schultze,  a  similar  connection  with  the  cells 
("sight-cells")  of  the  retina;  and  cells  somewhat  similar,  and  connected  with 
processes  that  pass  through  the  epithelium,  are  to  be  found  on  the  nerve  fibrils 
of  the  auditory  nerve,  in  the  membranous  labyrinth  ("hearing-cells"). 

The  terminations  of  the  nerves  in  the  hair-bulbs  are  probably  to  be  found  in 
the  papillae  at  their  root,  as  is  also  the  case  in  the  teeth.  In  glands  the  nerves, 
according  to  Pfliiger,  are  connected  with  the  caecal  commencements  of  the 
gland  tubes — at  least  he  has  described  this  arrangement  in  the  salivary  glands, 
and  thus  he  is  led  to  regard  the  nuclei  of  these  caecal  pouches  as  the  termina- 
tions of  the  nerves. 

Motor  nerves  are  to  be  traced  either  into  unstriped  or  striped  fibres. 
In  the  unstriped  fibres  it  appears  from  the  researches  of  Beale,  Franken^ 
haiiser,  and  Julius  Arnold,  that  the  ultimate  fibrils  of  the  nerves  form  plexuses 
at  the  junctions  of  the  branches  of  which  small  nuclear  bodies  are  situated. 
These  nuclei  are  regarded  by  Arnold  as  the  real  terminations  of  the  nerves, 
for  although  he  agrees  with  Frankenhaiiser  in  stating  that  the  nervous  filaments 
penetrate  the  muscular  fibres,  and  enter  into  relation  with  the  granular  con- 
tents of  their  nuclei,  he  traces  the  filaments  buck  again  from  that  point  to  the 
nuclei  situated  at  the  junctions  of  the  nervous  plexuses,  in  the  connective 
tissue  of  the  muscular  fibres. 

'  Strieker's  HaiuJhnrh,  p.  123. 

*  Lectures  on  the  Histology  of  the  Eye,  at  the  Royal  College  of  Surgeons,  June,  1869. 


TO 


GENERAL    ANATOMY. 


In  the  voluntary  muscles  Beale  and  Kolliker  have  described  the  nerve-fibres 
as  terminating  either  in  a  plexiform  arrangement,  or  (according  to  the  latter 
author),  sometimes  in  free  ends  between  the  muscular  fibres  external  to  the 
sarcolemma.  Lately  another  method  of  termination,  which  had  been  formerly 
described,  has  received  the  support  of  numerous  eminent  authorities — viz.,  the 
^^ motorial  end-plates'^  of  Kiihne,  or  "nerve-hillocks"  (nerve-tufts)  of  Doyere. 

The  latter  author  had  described,  nearly  thirty  years  ago,  a  connection  between 
the  nervous  and  muscular  fibres  in  some  of  the  lower  animals,  consisting  in  an 
elevation  at  the  point  of  junction  of  the  two,  where  the  sarcolemma  of  the 
muscular  fibre  became  blended  with  the  tubular  membrane  of  the  nerve.  This 
has  been  since  so  far  confirmed  by  subsequent  researches,  that  it  seems  well  to 
figure,  from  the  most  recent  author,  Kiihne,  what  he  supposes  to  be  the  termi- 
nation of  all  motor  nerves  of  voluntary  muscles.  The  following  is  Kiihne's 
description  of  the  method  of  connection. 

"In  all  striped  muscles  the  nerve  terminates  below  the  sarcolemma — the 
tubular  membrane  being  blended  with  the  sarcolemma.  The  white  substance 
accompanies  the  axis-cylinder  as  far  as  this  point.  The  ending  of  the  axis- 
cylinder  always  represents  an  expansion  with  a  considerably  increased  surface, 
and  this  is  constantly  formed  by  its  branching  out  on  a  flat  plate.  This  nerve- 
end-plate  is  sometimes  more  like  a  membrane,  at  others  like  a  system  of  fibres. 
In  most  cases  the  plate  rests  upon  a  base  of  granules  and  finely-granular  proto- 
plasm; in  other  cases  there  is  no  such  support,  and  the  nerve-plates  then  possess 
the  so-called  nerve-end-bulbs.  The  ends  of  the  nerves  never  penetrate  the  in- 
terior of  the  contractile  cylinder,  nor  does  the  plate  ever  embrace  the  whole 

Fisr.  35. 


a.  Ik* 

Husoalar  fibres  of  Locerta  Viridis  with  the  terminalinns  of  nerves,  a.  Seen  in  profile  ;  p  r,  the  nerro 
end-plates ;  s  s,  the  bnse  of  the  plate,  consisting  of  a  griinular  mass  with  nuclei,  b  The  same  a.s  seen  in 
looking  at  a  perfectly  fresh  fibre,  the  nervous  ends  being  probably  still  e.xeitable.  (The  forms  of  the  variously- 
divided  pinte  can  hardly  be  represented  in  a  wood-cut  by  sufficiently  delicate  and  pale  contours  to  reproduce 
correctly  what  is  seen  in  nature.)     e.  The  same  as  seen  two  hoars  after  death  from  poisoning  by  curare. 

circumference  of  the  cylinder.     Short  muscular  fibres  generally  have  only  one 
nerve-end,  while  longer  fibres  have  several."  S] 

It  is  right,  however,  to  state  that  the  most  eminent  English  authority  on  thnPi 
subject  entirely  denies  the  description  above  given,  and  explains  the  appear- 
ances, figured  by  Kiihne  and  others,  in  a  different  manner.  h\  a  very  interest- 
ing paper  by  Ur.  Beale,  published  in  1807,'  he  endeavors  to  show  that  the 
nerve-hillocks  of  Doyere  are  merely  accidental  elevations  produced  by  the  sarco- 
lemma being  drawn  up  in  a  cone,  as  the  nerve  which  is  attached  to  it  is  stretched 
by. the  manipulation  of  the  observer;  and  with  reference  to  the  end-plates  of 

'  On  Anatomical  Controversy.    Beal's  Archives,  iv.  161. 


THE    NERVES. 


n 


Klihne,  he  asserts  that  by  his  own  method  of  examination  he  is  able  to  follow 
the  nerve-fibrils  much  beyond  the  point  at  which  that  author  describes  them 
as  terminating.  The  appearance  of  their  penetrating  the  sarcolemma  he  regards 
as  an  optical  illusion,  and  the  nuclei  shown  in  the  above  figures  are,  accordmg 
to  him,  situated  outside  of  the  muscular  fibres  on  the  points  of  junction  of 
the  fibrils  which  form  the  intricate  and  extensive  plexus  in  which  the  nerves 
terminate,  so  that  the  nerves  nowhere  terminate  in  free  ends,  not  at  any  definite 
part  of  the  fibre;  but,  on  the  contrary,  surround  every  point  of  the  latter  with 
a  very  close  interlacement. 

Fiff.  36. 


Terminations  of  motor  nerves,  according  to  Beale.  1.  Nerve-tuft  on  the  sarcolemma  of  a  muscular  fibre; 
chameleon.  Nerve-fibres  are  seen  passing  oiU  of  as  well  as  into  the  tuft.  2.  Nerve-fibrea  distributed  to 
elementary  muscular  fibre;  chameleon,  x  3000,  and  reduced  half.  This  ia  a  very  simple  form  of  "nerve 
tuft,"  clearly  external  to  the  sarcolemma.  3.  The  intimate  structure  of  a  very  simple  "nerve  tuft"  on  a 
muscular  fibre  of  the  chameleon.  It  will  be  observed  that  the  nerve  fibres  are  continuous  throughout,  and 
that  the  whole  is  on  the  surface  of  the  sarcolemma,  x  3000.  This  "  nerve  tuft"  is,  as  it  were,  but  a  com- 
pound network. 

By  the  kindness  of  Dr.  Beale  we  are  enabled  to  reproduce  some  of  the  figures 
representing  preparations  which  he  exhibited  to  the  British  Medical  Associa- 
tion at  Oxford,  in  1868,  in  illustration  of  this  view. 


TS 


GENERAL    ANATOMY. 


THE  VASCULAR  SYSTEM. 

The  Vascular  System,  exclusive  of  its  central  organ,  the  Heart,  is  divided 
into  four  classes  of  vessels — the  Arteries,  Capillaries,  Veins,  and  Lymphatics — 
the  minute  structure  of  which  we  will  now  proceed  briefly  to  describe,  referrinfr 
the  reader  to  the  body  of  the  work  for  all  that  is  necessary  in  the  details  of 
their  ordinary  anatomy. 

The  Arteries.  The  arteries  are  composed  of  three  coats — internal  serous,  or 
epithelial  coat  {tunica  intima  of  Kcilliker),  middle  fibrous  or  circular  coat,  and 
external  cellular  coat  or  tunica  adventitia. 

The  two  inner  coats  together  are  very  easily  separated  from  the  external,  as 
by  the  ordinary  operation  of  tying  a  ligature  on  the  artery.  If  a  fine  string 
be  tied  forcibly  upon  an  artery,  either  before  or  after  death,  and  then  taken  oft', 
the  external  coat  will  be  found  uninjured,  but  the  internal  coats  are  divided  in 
the  track  of  the  ligature,  and  can  easily  be  further  dissected  from  the  outer  coat. 
The  inner  coat  can  be  separated  from  the  middle  by  a  little  maceration. 

The  inner  coat  consists  of:  1.  A  layer  of  pavement  epithelium,  the  cells  of 
which  are  oval  or  fusiform,  and  have  very  distinct  nuclei.  2.  This  epithelium 
rests  upon  a  layer  of  longitudinal  elastic  fibres,  in  which,  under  the  microscope, 
small  elongated  apertures  are  seen,  and  which  was  therefore  called  by  Henle 
the  fenestrated  membrane.  This  layer  is  marked  with  numerous  reticulations; 
it  is  perfectly  smooth  when  the  artery  is  distended ;  but  when  empty,  presents 
longitudinal  and  transverse  folds.  The  fenestrated  membrane  can  often  be 
separated  into  more  than  one  layer. 


An  artery  from  the  rnejentery  of  a  child,  .062'",  nnd  b,  vein  .067'",  in  diameter  (treated  with  aoetto  aol 
and  mngniSed  350  times),     a.  Tunica  ndventitia,  with  elonsjated  nuclei.     /?.  Nuclei  of  the  contractile  fibre- 
cells  of  the  tunica  media,  seen  partly  from  the  purfiice,  partly  apparent  in  transverse  section,     y.  Nuclei  of 
the  epithelial  cells.     cT.  Elastic  longitudinal  fibrous  cont. 


In  arteries  of  less  than  a  line  in  diameter,  the  internal  coat  consists  of  two 
layers,  as  above  de.<!cribed;  but  in  middle-sized  arteries,  several  lamellae, 
composed  of  elastic  fibres  and  connective  tissue,  are  interposed  between  the 
epithelial  and  elastic  coats.  In  the  largest  arteries,  the  inner  coat  is  usually 
much  thickened,  especially  in  the  aorta ;  and  consists  of  a  homogeneous  sub- 
stance, occasionally  striated  or  fibrillated,  transversed  by  longitudinal  elastic 
networks,  which  are  very  fine  in  the  lamellaa  immediately  beneath  the  epithe- 


fl 


THE    ARTERIES.  7« 

liam,  but  increase  in  thickness  from  within  outwards.  The  internal  and  middle 
coats  are  separated,  by  either  a  dense  elastic  reticulated  coat,  or  a  true  fenes- 
trated membrane. 

The  middle  coat  is  distinguished  from  the  inner  by  its  color,  and  by  the  trans- 
verse arrangement  of  its  fibres,  in  contradistinction  to  the  longitudinal  direction 
of  those  of  the  inner  coat.  In  the  largest  arteries,  this  coat  is  of  great  thick- 
ness, of  a  yellow  color,  and  highly  elastic;  it  diminishes  in  thickness,  and 
becomes  redder  in  color  as  the  arteries  become  smaller;  becomes  very  thin,  and 
finally  disappears.  In  small  arteries,  this  coat  is  purely  muscular,  consisting 
of  muscular  fibre-cells  united  to  form  lamellae  which  vary  in  number  according 
to  the  size  of  the  artery,  the  very  small  arteries  having  only  a  single  layer,  and 
those  not  larger  than  the  -f^^th  of  a  line  in  diameter,  three  or  four  layers.  In 
arteries  of  medium  size,  this  coat  becomes  thicker  in  proportion  to  the  size  of 
the  vessel ;  its  layers  of  muscular  tissue  are  more  numerous,  and  intermixed 
with  numerous  fine  elastic  fibres  which  unite  to  form  broad-meshed  networks. 
In  the  larger  vessels,  as  the  femoral,  superior  mesenteric,  cocliac,  external  iliac, 
brachial,  and  popliteal  arteries,  the  elastic  fibres  unite  to  form  lamellae,  Avhich 
alternate  with  the  layers  of  muscular  fibre.  In  the  largest  arteries,  the  muscular 
tissue  is  only  slightly  developed,  and  forms  about  one-third  or  one-fourth  of  the 
whole  substance  of  the  middle  coat ;  this  is  especially  the  case  in  the  aorta,  and 
trunk  of  the  pulmonary  artery,  in  which  the  individual  cells  of  the  muscular 
layer  are  imperfectly  formed ;  while,  in  the  carotid,  axillary,  iliac,  and  subclavian 
arteries,  the  muscular  tissue  of  the  middle  coat  is  more  developed.  The  elastic 
lamellae  are  well  marked,  may  amount  to  fifty  or  sixty  in  number,  and  alternate 
regularly  with  the  layers  of  muscular  fibre.  They  are  most  distinct,  and 
arranged  with  most  regularity  in  the  abdominal  aorta,  innominate  artery,  and 
common  carotid. 

The  external  coat  consists  mainly  of  connective  tissue,  and  contains  elastic 
fibres  in  all  but  the  smallest  arteries.  In  the  largest  vessels,  the  external  coat 
is  relatively  thin;  but  in  small  arteries,  it  is  as  thick,  or  thicker,  than  the  mid- 
dle coat.  In  arteries  of  the  medium  size,  and  above  it,  the  external  coat  is 
formed  of  two  layers,  the  outer  of  which  consists  of  connective  tissue,  con- 
taining an  irregular  elastic  network,  while  the  inner  is  composed  of  elastic  tissue 
onlv.  The  inner  elastic  layer  is  very  distinct  in  the  carotid,  femoral,  brachial, 
profunda,  mesenteric  and  coeliac  arteries,  the  elastic  fibres  being  often  arranged 
in  lamellae.  In  the  smaller  arteries,  the  former  layer  of  mixed  connective  tis- 
sue and  elastic  fibres  composes  the  whole  of  the  external  tunic;  while  in  the 
smallest  arteries  just  above  the  capillaries,  the  elastic  fibres  are  wanting,  and 
the  connective  tiss,ue  of  which  the  coat  is  composed  becomes  more  homoge- 
neous the  nearer  it  approaches  the  capillaries,  and  is  gradually  reduced  to  a 
thin  membranous  envelope,  which  finally  disappears. 

Some  arteries  have  extremely  thin  coats  in  proportion  to  their  size;  this  is 
especially  the  case  in  those  situated  in  the  cavity  of  the  cranium  and  spinal 
canal,  the  difference  depending  upon  the  greater  thinness  of  the  external  and 
middle  coats. 

The  arteries,  in  their  distribution  throughout  the  body,  are  included  in  a  thin 
areolo-fibrous  investment,  which  forms  what  is  called  their  sheath.  In  the  limbs, 
this  is  usually  formed  by  a  prolongation  of  the  deep  fascia;  in  the  upper  part 
of  the  thigh,  it  consists  of  a  continuation  downwards  of  the  transversalis  and 
iliac  fasciae  of  the  abdomen;  in  the  neck,  of  a  ))rolongation  of  the  deep  cervical 
fascia.  The  included  vessel  is  loosely  connected  with  its  sheath  by  a  delicate 
areolar  tissue  ;  and  the  sheath  usually  incloses  the  accompanying  veins,  and 
sometimes  a  nerve.  Some  arteries,  as  those  in  the  cranium,  are  not  included 
in  sheaths. 

AH  the  larger  arteries  are  supplied  with  bloodvessels  like  the  other  organs 
of  the  body ;  they  are  called  vasa  vasorum.  These  nutrient  vessels  arise  from 
a  branch  of  the  artery  or  from  a  neighboring  vessel,  at  some  considerable  dis- 


74  GENERAL    ANATOMY. 

tance  from  the  point  at  which  they  are  distributed;  they  ramify  in  the  loose 
areolar  tissue  connecting  the  artery  with  its  sheath,  and  are  distributed  to  the 
external  and  middle  coats,  and,  according  to  Arnold  and  others,  supply  the  in- 
ternal coat.  Minute  veins  serve  to  return  the  blood  from  these  vessels  ;  they 
empty  themselves  into  the  venae  comites  in  connection  with  the  artery. 

Arteries  are  also  provided  with  nerves,  which  are  derived  chiefly  from  the 
sympathetic,  but  partly  from  the  cerebro-spinal  system.  They  form  intricate 
plexuses  upon  the  surface  of  the  largest  trunks,  the  smaller  branches  being 
usually  accompanied  by  single  filaments ;  their  exact  mode  of  distribution  is 
unknown.  According  to  Kcilliker,  the  majority  of  the  arteries  of  the  brain 
and  spinal  cord,  those  of  the  choroid  and  of  the  placenta,  as  well  as  many  arte- 
ries of  muscles,  glands,  and  membranes,  are  unprovided  with  nerves. 

TJte  Capillaries.  The  smaller  arterial  branches  (excepting  those  of  the  caver- 
nous structures  of  the  sexual  organs,  and  in  the  uterine  placenta)  terminate  in 
a  network  of  vessels  which  pervade  nearly  every  tissue  of  the  body.  These 
vessels,  from  their  minute  size,  are  termed  capillaries  {capillus^  "a  hair").  They 
are  interposed  between  the  smallest  branches  of  the  arteries  and  the  commencing 
veins,  constituting  a  network,  the  branches  of  which  maintain  the  same  diame- 
ter throughout,  the  meshes  of  the  network  being  more  uniform  in  shape  and 
size  than  those  formed  by  the  anastomoses  of  the  small  arteries  and  veins. 

The  diameter  of  the  capillaries  varies  in  the  different  tissues  of  the  body, 
their  usual  size  being  about  -5555  of  an  inch.  The  smallest  are  those  of  the 
brain,  and  the  mucous  membrane  of  the  intestines ;  the  largest,  those  of  the 
skin,  and  the  marrow  of  bones. 

The  form  of  the  capillary  net  varies  in  the  different  tissues,  being  modifica- 
tions chiefly  of  rounded  or  elongated  meshes.  The  rounded  form  of  mesh  is  most 
common,  and  prevails  where  there  is  a  dense  network,  as  in  the  lungs,  in  most 
glands  and  mucous  membranes,  and  in  the  cutis ;  the  meshes  being  more  or  less 
angular,  sometimes  nearly  quadrangular,  or  polygonal ;  more  frequently,  ir- 
regular. Elongated  meshes  are  observed  in  the  bundles  of  fibres  and  tubes  com- 
posing muscles  and  nerves,  the  meshes  being  usually  of  a  parallelogram  form, 
the  long  axis  of  the  mesh  running  parallel  with  the  long  axis  of  the  nerve  or 
fibre.     Sometimes,  the  capillaries  have  a  looped  arrangement,  a  single  vessel 

f)rojecting  from  the  common  network,  and  returning  after  forming  one  or  more 
oops,  as  in  the  papillae  of  the  tongue  and  skin. 

The  number  of  the  capillaries,  and  the  size  of  the  meshes,  determines  the 
degree  of  vascularity  of  a  part.  The  closest  network,  and  the  smallest  inter- 
spaces are  found  in  the  lungs  and  in  the  choroid  coat  of  the  eye.  In  the  liver 
and  lung,  the  interspaces  are  smaller  than  the  capillary  vessels  themselves.  In 
the  kidney,  in  the  conjunctiva,  and  in  the  cutis,  the  interspaces  are  from  three 
to  four  times  as  large  as  the  capillaries  which  form  them ;  and  in  the  brain  from 
eight  to  ten  times  as  large  as  the  capillaries,  in  their  long  diameter,  and  from 
four  to  six  times  as  large  in  their  transverse  diameter.  In  the  cellular  coat  of 
the  arteries,  the  width  of  the  meshes  is  ten  times  that  of  the  capillary  vessels. 
As  a  general  rule,  the  more  active  the  function  of  an  organ  is,  the  closer  is  its 
capillary  net,  and  the  larger  its  supply  of  blood,  the  network  being  very  nar- 
row in  all  growing  parts,  in  the  glands,  and  in  the  mucous  membranes;  wider 
in  bones  and  ligaments,  which  are  comparatively  inactive;  and  nearly  alto- 
gether absent  in  tendons  and  cartilages,  in  which  very  little  organic  change 
occurs  after  their  formation. 

Structure.  The  walls  of  the  capillaries  consist  of  a  fine,  transparent,  homo- 
geneous membrane,  in  which  are  imbedded,  at  intervals,  minute  oval  corpuscles, 
probably  the  remains  of  the  nuclei  of  the  cells  from  which  the  vessel  was 
originally  formed. 

In  the  largest  capillaries  (which  ought  perhaps  to  be  described  rather  as  the 


THE    YEINS. 


76 


smallest  arteries)  traces  of  an  epithelial  lining,  and  of  circular  transverse  fibres, 
are  to  be  seen. 

The  Veins  are  composed  of  three  coats,  internal,  middle,  and  external,  as  the 
arteries  are;  and  these  coats  are,  with  the  necessary  modifications,  analogous 


Fiff.  38. 


Fis:.  39. 


Finest  vessels  (in  the  nrterial  side.  1.  Smnllest  artery.  2. 
Transition  vessel.  3.  Coarser  capillaries.  4.  Finer  capillaries. 
a.  Structureless  membriine  still  with  some  nuclei,  representative 
of  the  tunica  adventitia  ;  b,  nuclei  of  the  muscular  fibre-cells  ; 
c,  nuclei  within  the  small  artery,  perhaps  appertaining  to  an 
epithelium ;  d,  nuclei  in  the  transition  vessels.  From  the 
human  brain.     (Magnified  300  times.) 


An  artery,  .01'",  and  b,  a  vein,  .015", 
from  the  mesentery  of  a  child  (mag- 
nified 350  times  and  treated  with 
acetic  acid).  The  letters  as  in  Fig. 
37.  e.  The  tunica  media  of  the  vein, 
consisting  of  nucleated  connective 
tissue. 


to  the  coats  of  the  arteries — the  internal  being  the  epithelial,  the  middle  the 
fibrous,  and  the  external  the  connective  or  areolar.  The  main  difference  be- 
tween the  veins  and  the  arteries  is  in  the  comparative  weakness  of  the  middle 
coat  of  the  former;  and  to  this  it  is  due  that  the  veins  do  not  stand  open  when 
divided,  as  the  arteries  do ;  and  that  they  are  passive  rather  than  active  organs 
of  the  circulation. 

In  the  veins  immediately  above  the  capillaries,  the  three  coats  are  hardly  to 
be  distinguished.  The  epithelium  is  supported  on  an  outer  membrane  of  nu- 
cleated connective  tissue,  separable  into  two  layers,  the  outer  of  which  is  the 
thicker,  the  fibres  of  both  being  longitudinal.  The  interior  thinner  layer  of 
nucleated  tissue  is  regarded  by  Kcilliker  as  the  analogue  of  the  middle  coat. 
In  the  veins  next  above  these  in  size  (one  fifth  of  a  line,  according  to  Kolliker) 
a  muscular  layer  and  a  layer  of  circular  fibres  can  be  traced,  forming  the  middle 
coat,  while  the  ela.stic  and  connective  elements  of  the  outer  coat  become  more 
distinctly  perceptible. 

In  the  middle-sized  veins,  the  typical  structure  of  these  vessels  becomes 
clear.  The  epithelium  is  of  the  same  character  as  in  the  arteries,  but  its  cells 
are  more  oval,  less  fusiform.  It  is  supported  by  one  or  more  layers  of  nucle- 
ated fibrous  tissue,  arranged  longitudinally,  and  external  to  this  is  a  layer  of 
elastic  fibrous  tissue.     This  constitutes  the  internal  coat.     The  middle  coat  is 


76  GENERAL    ANATOMY. 

composed  of  a  thick  inner  layer  of  connective  tissue  with  elastic  fibres,  having 
iHtermixed  in  some  veins  a  transverse  layer  of  muscular  fibres;  and  an  outer 
layer  consisting  of  longitudinal  elastic  lamella,  varying  from  five  to  ten  in 
number,  alternating  with  layers  of  transverse  muscular  fibres  and  connective 
tissue,  which  resembles  somewhat  in  structure  the  middle  coat  of  large  arteries. 
The  outer  coat  is  similar  in  all  essential  respects  to  that  of  the  arteries.  In  the 
large  veins,  as  in  the  commencement  of  the  vena  portae,  in  the  upper  part  of 
the  abdominal  portion  of  the  inferior  vena  cava,  and  in  the  large  hepatic 
trunks  within  the  liver,  the  middle  coat  is  thick,  and  its  structure  similar  to 
that  of  the  middle  coat  in  medium-sized  veins;  but  its  muscular  tissue  is  scanty, 
and  the  longitudinal  elastic  networks  less  distinctly  lamellated.  The  muscular 
tissue  of  this  coat  is  best  marked  in  the  splenic  and  portal  veins;  it  is  absent 
in  certain  parts  of  the  vena  cava  below  the  liver,  and  wanting  in  the  subcla- 
vian vein  and  terminal  parts  of  the  two  cavae. 

In  the  largest  veins,  the  outer  coat  is  from  two  to  five  times  thicker  than  the 
middle  coat,  and  contains  a  larger  number  of  longitudinal  muscular  fibres. 
This  is  most  distinct  in  the  hepatic  part  of  the  inferior  vena  cava,  and  at  the 
termination  of  this  vein  in  the  heart;  in  the  trunks  of  the  hepatic  veins;  in  all 
the  large  trunks  of  the  vena  portae;  in  the  splenic,  superior  mesenteric,  external 
iliac,  renal,  and  azygos  veins.  Where  the  middle  coat  is  absent,  this  muscular 
layer  extends  as  far  as  the  inner  coat.  In  the  renal  and  portal  veins,  it 
extends  through  the  whole  thickness  of  the  outer  coat:  but  in  the  other  veins 
mentioned,  a  layer  of  connective  and  elastic  tissues  is  found  external  to  the 
muscular  fibres.  All  the  large  veins  which  open  into  the  heart  are  covered  for 
a  short  distance  by  a  layer  of  muscular  tissue  continued  on  to  them  from  the 
heart. 

Muscular  tissue  is  wanting  in  the  veins :  1.  Of  the  maternal  part  of  tho 
placenta.  2.  In  most  of  the  cerebral  veins  and  sinuses  of  the  dura  mater.  3. 
In  the  veins  of  the  retina.  4.  In  the  veins  of  the  cancellous  tissue  of  bones. 
6.  In  the  venous  spaces  of  the  corpora  cavernosa.  The  veins  of  the  above- 
mentioned  parts  consist  of  an  internal  epithelial  lining,  supported  on  one  or 
more  layers  of  areolar  tissue. 

Most  veins  are  provided  with  valves,  which  serve  to  prevent  the  reflux  of ' 
the  blood.  They  are  formed  by  a  reduplication  of  the  middle  and  inner  coats, 
and  consist  of  connective  tissue  and  elastic  fibres,  covered  on  both  surfaces  by 
epithelium;  their  form  is  semilunar.  They  are  attached  by  their  convex  edge 
to  the  wall  of  the  vein;  the  concave  margin  is  free,  directed  in  the  course  of 
the  venous  current,  and  lies  in  close  apposition  with  the  wall  of  the  vein  as 
long  as  the  current  of  blood  takes  its  natural  course ;  if,  however,  any  regurgi- 
tation takes  place,  the  valves  become  distended,  their  opposed  edges  are 
brought  into  contact,  and  the  current  is  intercepted.  Most  commonly  two  such 
valves  are  found,  placed  opposite  one  another,  more  especially  in  the  smaller 
veins,  or  in  the  larger  trunks  at  the  point  where  they  are  joined  by  small 
branches;  occasionally  there  are  three,  and  sometimes  only  one.  The  wall  of 
the  vein  immediately  above  the  point  of  attachment  of  each  segment  of  the 
valve,  is  expanded  into  a  pouch  or  sinus,  which  gives  to  the  vessel,  when  in- 
jected or  distended  with  blood,  a  knotted  appearance.  The  valves  are  very 
numerous  in  the  veins  of  the  extremities,  especially  of  the  lower  extremities, 
these  vessels  having  to  conduct  the  blood  against  the  force  of  gravity.  They 
are  absent  in  the  very  small  veins,  also  in  the  venae  cavae,  the  hepatic  vein, 
portal  vein  and  its  branches,  the  renal,  uterine,  and  ovarian  veins.  A  few 
valves  are  found  in  the  spermatic  veins,  and  one  also  at  their  point  of  junction 
with  the  renal  vein  and  inferior  cava  in  both  sexes.  The  cerebral  and  spinal 
veins,  the  veins  of  the  cancellated  tissue  of  bone,  the  pulmonary  veins,  and 
the  umbilical  vein  and  its  branches,  are  also  destitute  of  valves.  They  are 
occasionally  found,  few  in  number,  in  the  venae  azygos  and  intercostal  veins. 

The  veins  are  supplied  with  nutrient  vessels,  vasa  vasorum,  like  the  arteries; 


THE    LYMPHATICS.  T7 

but  nerves  are  not  generally  found  distributed  upon  them.  The  only  vessels 
upon  which  they  have  at  present  been  traced,  are  the  sinuses  of  the  dura 
mater;  on  the  spinal  veins;  on  the  venae  cavas;  on  the  common  jugular,  iliac, 
and  crural  veins ;  and  on  the  hepatic  veins  (Kolliker). 

The  Lymjihatic  Vessels,  like  arteries. and  veins,  are  composed  of  three  coats. 
The  internal  is  an  epithelial  and  elastic  coat.  It  is  thin,  transparent,  slightly 
elastic,  and  ruptures  sooner  than  the  other  coats.  It  is  composed  of  a  layer 
of  elongated  epithelial  cells,  supported  on  a  simple  network  of  elastic  fibres. 
The  middle  coat  is  composed  of  smooth  muscular  and  fine  elastic  fibres,  dis- 
posed in  a  transverse  direction.  The  external,  or  areolar-fibrous  coat,  consists 
of  filaments  of  the  areolar  tissue,  intermixed  with  smooth  muscular  fibres, 
longitudinally  or  obliquely  disposed.  It  forms  a  protective  covering  to  the 
other  coats,  and  serves  to  connect  the  vessel  with  the  neighboring  structures. 

The  lymphatics  are  supplied  by  nutrient  vessels,  which  are  distributed  to 
their  outer  and  middle  coats ;  but  no  nerves  have  at  present  been  traced  into 
them. 

The  lymphatics  are  very  generally  provided  with  valves,  which  assist  ma- 
terially in  effecting  the  circulation  of  the  fluid  they  contain.     These  valves 
are  formed  of  a  thin  layer  of  fibrous  tissue,  lined  on  both  surfaces  with  scaly 
epithelium.     Tlieir  form  is  semilunar ;  they  are 
attached  by  their  convex  edge  to  the  sides  of  Fig-  40. 

the  vessel,  the  concave  edge  being  free,  and 
directed  along  the  course  of  the  contained  cur- 
rent. Usually,  two  such  valves,  of  equal  size, 
are  found  opposite  one  another  ;  but  occasionally 
exceptions  occur,  especially  at  or  near  the 
anastomoses  of  lymphatic  vessels.  Thus,  one 
valve  may  be  of  very  rudimentary  size,  and  the 

other  increased  in  proportion.  In  other  cases,  Tmnsverse  section  through  thecoats 
the  semilunar  flaps  have   been  found  directed     of  the  thoracic  duct  of  man.    (Mngni- 

,  ^       ,,  ,       .  T        f>       1  fied 30  tinie.^) .    «•  Lpitheluim,  stnated 

transversely  across  the  vessel,  instead  of  ob-  j^^^,,^  ^^^  j„„^^  ^,.,,,5^  ^^.^^.  ^^ 
liquely,  so  as  to  impede  the  circulation  in  both     longitudinal  connective  tissue  of  the 

directions,    but    not    to     completely    arrest    it     in       middle  coat;    c,  transverse  musdeg  of 

either;  or  the  semilunar  flaps,  taking  the  same     the smne ;  tf, tunica ndventitia,  with c, 
direction,  have  been  found  united  on  one  side,     the  longitudinal  muscular  fibres, 
so  as  to  form,  by  their  union,  a  transverse  sep- 
tum, having  a  partial  transverse  slit;  and  sometimes  the  flap  is  constituted  of 
a  circular  fold,  attached  to  the  entire  circumference  of  the  vessel,  and  having 
in  its  centre  a  circular  or  elliptical  aperture,  like  the  ileo-caecal  valve. 

The  valves  in  the  lymphatic  vessels  are  placed  at  much  shorter  intervals 
than  in  the  veins.  They  are  most  numerous  near  the  lymphatic  glands,  and 
they  are  found  more  frequently  in  the  lymphatics  of  the  neck  and  upper  ex- 
tremity, than  in  the  lower.  The  wall  of  the  lymphatics,  immediately  above 
the  point  of  attachment  of  each  segment  of  a  valve,  is  expanded  into  a  pouch 
or  sinus,  which  gives  to  these  vessels,  when  distended,  the  knotted  or  beaded 
appearance  which  they  present.  Valves  are  wanting  in  the  vessels  composing^ 
the  plexiform  network,  in  which  the  lymphatics  usually  originate  on  the  sur- 
face of  the  body.  Besides  this  plexiform  commencement,  however,  there  are 
other  modes  of  origin  of  the  lymphatics,  for  those  of  the  intestinal  villi  arise 
sometimes  by  closed  extremities ;  and  the  lymphatics  which  arise  in  the  in- 
terior of  the' organs  (as  in  the  glands  to  be  presently  described)  originate  in 
irregular  spaces,  lymph-sinuses,  or  lacunae. 

There  is  no  satisfactory  evidence  to  prove  that  any  natural  communication 
exists  between  the  lymphatics  of  glandular  organs  and  their  ducts,  or  between 
the  lymphatics  and  the  capillary  vessels. 


78  GENERAL    ANATOMY. 

With  respect  to  the  structure  of  the  Lymphatic  Glands,  there  are  some  points 
which  are  certain,  while  others  must  be  allowed  to  be  doubtful.  It  is  certain 
that  a  number  of  vessels  enter  them  at  various  points  of  their  circumference 
{afferent  vessels),  and  that  one  or  two  vessels  leave  them  {eff^erent  vessels),  usually 
at  a  definite  spot,  the  hilnm.  Further,  that  the  external  coats  of  these  vessels 
are  continuous  with  an  envelope  of  fibrous  tissue,  which  constitutes  the  capsule 
of  the  gland,  and  that  all  parts  of  the  gland  are  freely  supplied  with  capillary 
bloodvessels.  The  intimate  structure,  however,  of  the  gland,  is  a  matter  of 
some  doubt.  In  former  editions  of  this  work,  the  description  of  Hewson  was 
adopted,  according  to  which  the  afferent  vessels  break  up  into  a  plexus  of 
smaller  vessels,  and  these  reunite  to  form  the  efferent  vessels,  so  that  the 
afferent  and  efjerent  lymphatics  are  directly  continuous.  Some  observers 
added  to  this  description,  that  there  were  a  number  of  minute  dotted  cor- 
puscles lying  between  the  meshes  of  the  network  of  vessels  in  the  interior  of 
the  gland,  and  grouped  in  cells  like  the  acini  of  secreting  glands. 

But  the  description  given  by  His  and  Kcilliker,  and  which  has  been  adopted 
by  Dr.  Sharpey,  makes  the  structure  more  complex  than  this.  It  is,  in  brief,  as 
follows:  Passing  inwards  from  the  capsule  of  the  gland  are  a  number  of  septa 
or  trabeculae,  fibrous  in  man,  muscular  in  some  of  the  lower  animals,  which 
separate  the  outer  or  cortical  portion  of  the  gland  into  alveoli.  The  afferent 
vessels  break  up  and  open  into  these  alveoli,  much  in  the  same  way  that  the 
splenic  capillaries  open  into  the  pulp  of  that  organ.  The  alveoli  contain  a 
grayish-white  pulp,  consisting,  according  to  Kcilliker,  of  the  minutest  ramifica- 
tions of  fibrous  tissue,  and  of  a  juice,  containing  round  cells  identical  with  those 
of  the  chyle  or  lymph.  ^ 

The  interior  of  the  gland  {medullary  portion)  is  formed  of  a  number  of  vascular  I 
channels  (together  with  capillaries  and  connective  tissue),  which  are  the  radi- 
cles of  the  efferent  vessels,  and  converge  to  the  hilum.     The  cortical  portion  is 
usually  deficient  at  the  hilum,  where  the  medullary  tissue  of  the  gland  passes 
directly  into  the  efferent  channels.  •  > 

The  afferent  lymphatics,  after  passing  at  various  points  through-  the  capsule^' 
break  up  in  the  septa  between  the  alveoli  into  their  terminal  ramifications;  and 
here,  as  Kcilliker  supposes,  they  open  into  those  spaces  just  as  the  arteries  of 
erectile  tissue  do  into  the  cavernous  spaces  of  which  that  tissue  is  composed 
From  the  walls  of  the  alveoli  lymphatic  channels  can  again  be  traced,  which  are 
the  radicles  of  the  efferent  vessels,  and  accompany  the  arterial  branches. 

The  gland-pulp  does  not  completely  fill  the  alveoli  of  the  cortical,  nor  th 
vascular  channels  of  the  medullary  portion,  but  leaves  a  space,  visible  in  seO' 
tions  from  which  the  lymph-corpuscles  have  been  washed  away.  This  space  is 
called  the  lymph-sinus ;  but  it  seems  to  be  distinguished  from  the  rest  of  the 
alveolus  merely  by  a  less  close  arrangement  of  the  connective  tissue,  through 
which  the  lymph  circuktes.  Dr.  Sharpey  describes  the  lymph-sinus  as  lined 
throughout  by  a  layer  of  pavement-epithelium  similar  to  that  of  the  lymphatic 
vessels  with  which  it  is  continuous. 

The  arteries  and  veins  pass  into  and  out  of  the  gland  at  the  hilum,  and 
liker  has  described  some  fine  nervous  filaments,  as  accompanying  them. 

THE  SKIN  AND  ITS  APPENDAGES. 

The  Skin  is  the  principal  seat  of  the  sense  of  touch,  and  may  be  regarded  aa 
R  covering  for  the  protection  of  the  deeper  tissues;  it  is  also  an  important 
excretory  and  absorbing  organ.  It  consists  of  two  layers,  the  derma  or  cutis 
vera,  and  the  epidermis  or  cuticle.  On  the  surface  of  the  former  layer  are  the 
sensitive  papillaB;  and  within,  or  imbedded  beneath  it,  are  the  sweat-glands, 
hair-follicles,  and  sebaceous  glands. 

The  derma,  or  true  skin,  is  tough,  flexible,  and  highly  elastic,  in  order  to  de- 
fend the  internal  parts  from  violence.     It  consists  of  fibro-areolar  tissue,  inter- 


I 


e 

i 


THE    SKIN. 


19 


mixed  with  numerous  bloodvessels,  lymphatics,  and  nerves.  The  fibro-areolar 
tissue  forms  the  framework  of  the  cutis;  it  is  composed  of  firm  interlacing 
bundles  of  white  fibrous  tissue,  intermixed  with  a  much  smaller  proportion  of 
yellow  elastic  fibres,  the  amount  of  which  varies  iri  different  parts.  The  fibro- 
areolar  tissue  is  more  abundant  in  the  deeper  layers  of  the  cutis,  where  it  is 


Fiff.  41. 


A  sectional  view  of  the  skin  (magnified). 

dense  and  firm,  the  meshes  being  large,  and  gradually  becoming  blended  with 
the  subcutaneous  areolar  tissue;  towards  the  surface,  the  fibres  become  finer 
and  more  closely  interlaced,  the  most  superficial  layer  being  covered  with 
numerous  small  conical  vascular  eminences,  the  papillae.  From  these  differ- 
ences in  the  structure  of  the  cutis  at  different  parts,  it  is  usual  to  describe  it  as 
consisting  of  two  layers ;  the  deeper  layer  or  corium,  and  the  superficial  or 
papillary  layer. 

The  corium  consists  of  strong  interlacing  fibrous  bands,  composed  chiefly  of 
the  white  variety  of  fibrous  tissue;  but  containinof,  also,  some  fibres  of  the 
yellow  elastic  tissue,  which  vary  in  amount  in  different  parts.  Towards  the 
attached  surface,  the  fasciculi  are  large  and  coarse;  and  the  areolre  which  are 
left  by  their  interlacement  are  large,  and  occupied  by  adipose  tissue  and  the 
sweat-glands.  This  element  of  the  skin  becomes  gradually  blended  with  the 
subcutaneous  areolar  tissue.  Towards  the  free  surface,  the  fasciculi  are  much 
finer,  and  they  have  a  closer  interlacing,  the  most  superficial  layers  consisting 
of  a  transparent,  homogeneous  matrix,  with  imbedded  nuclei. 

The  corium  varies  in  thickness,  from  a  quarter  of  a  line  to  a  line  and  a  half, 
in  different  parts  of  the  body.  Thus,  it  is  thicker  in  the  more  exposed  regions, 
as  the  palm  of  the  hand  and  sole  of  the  foot;  on  the  posterior  aspect  of  the 
body,  than  the  front;  and  on  the  outer,  than  the  inner  side  of  the  limbs.     In 


80  GENERAL    ANATOMY. 

the  eyelids,  scrotum,  and  penis,  it  is  exceedingly  thin  and  delicate.     The  skin 
generally  is  thicker  in  the  male  than  in  the  female. 

The  areolse  are  occupied  by  adipose  tissue,  hair-follicles,  and  the  sudoriferous 
and  sebaceous  glands  ;  they  are  the  channels  by  which  the  vessels  and  nerves 
are  distributed  to  the  more  superficial  strata  of  the  coriura,  and  to  the  papillary 
layer. 

Uhstriped  muscular  fibres  are  found  in  the  superficial  layers  of  ihe  corium, 
wherever  hairs  are  found ;  and  in  the  subcutaneous  areolar  tissue  of  the  scro- 
tum, penis,  perineum,  and  areolae  of  the  nipple.  In  the  latter  situations  the 
fibres  are  arranged  in  bands,  closely  reticulated,  and  disposed  in  superimposed 
laminae. 

The  papillary  layer  is  situated  upon  the  free  surface  of  the  corium  :  it  con- 
sists of  numerous  small,  highly  sensitive,  and  vascular  eminences,  the  papillae, 
which  rise  perpendicularly  from  its  surface,  and  form  the  essential  element  of 
the  organ  of  touch.  The  papillae  are  conical-shaped  eminences,  having  a  round 
or  blunted  extremity,  occasionally  divided  into  two  or  more  parts,  and  con- 
nected by  their  base  with  the  free  surface  of  the  corium.  Their  average  length 
is  about  T^Tjth  of  an  inch,  and  they  measure  at  their  base  about  j^fith  of  an 
inch  in  diameter.  On  the  general  surface  of  the  body,  more  especially  in  those 
parts  which  are  endowed  with  slight  sensibility,  they  are  few  in  number,  short, 
exceedingly  minute,  and  irregularly  scattered  over  the  surface;  but  in  other 
situations,  as  upon  the  palmar  surface  of  the  hands  and  fingers,  upon  the  plan- 
tar surface  of  the  feet  and  toes,  and  around  the  nipple,  they  are  long,  of  large 
size,  closely  aggregated  together,  and  arranged  in  parallel  curved  lines,  forming 
the  elevated  ridges  seen  on  the  free  surface  of  the  epidermis.  In  these  ridges, 
the  larger  papillae  are  arranged  in  a  double  row,  with  smaller  papillae  between 
them ;  and  these  rows  are  subdivided  into  small  square-shaped  masses  by  short 
transverse  furrows,  regularly  disposed,  in  the  centre  of  each  of  which  is  the 
minute  orifice  of  the  duct  of  a  sweat-gland.  No  papillae  exist  in  the  grooves 
between  the  ridges.  In  structure,  the  papillae  resemble  the  superficial  layer  of 
the  cutis;  consisting  of  a  homogeneous  tissue,  faintly  fibrillated,  and  contain- 
ing a  few  fine  elastic  fibres.  The  smaller  papillae  contain  a  single  capillary 
loop:  but  in  the  larger  the  vessels  are  convoluted  to  a  greater  or  less  degree; 
each  papilla  also  contains  one  or  more  nerve-fibres,  but  the  mode  in  which 
these  terminate  is  uncertain.  In  those  parts  in  which  the  sense  of  touch  is 
highly  developed,  as  in  the  lips  and  palm  of  the  hand,  the  nerve-fibres  are  con- 
nected with  the  "tactile  corpuscles."  Kcilliker  considers  that  the  central  part 
of  the  papillae  generally  consists  of  a  connective  tissue  more  homogeneous  than 
that  of  the  outer  part,  surrounded  by  a  sort  of  sheath  of  elastic  fibres,  and  he 
believes  that  these  corpuscles  are  merely  a  variety  of  this  structure.  The  cor- 
puscles, and  their  connection  with  the  nerves,  have  been  described  above. 

The  epidermis,  or  cuticle  (scarfskin),  is  an  epithelial  structure,  accurate!] 
moulded  on  the  papillary  layer  of  the  derma.  It  forms  a  defensive  coverinj^ 
to  the  surface  of  the  true  skin,  and  limits  the  evaporation  of  watery  vapor  from 
its  free  surface.  It  varies  in  thickness  in  different  parts.  Where  it  is  exposed 
to  pressure  and  the  influence  of  the  atmosphere,  as  upon  the  palms  of  the  hands 
and  soles  of  the  feet,  it  is  thick,  hard,  and  horny  in  texture;  whilst  that  which 
lies  in  contact  with  the  rest  of  the  body,  is  soft  and  cellular  in  structure.  The 
deeper  and  softer  layers  have  been  called  the  rete  mvcosnm,  the  term  rete  being 
used  from  the  deepest  lavers  presenting,  when  isolated,  numerous  depressions, 
or  complete  apertures,  which  have  been  occupied  by  the  projecting  papillae. 

The  free  surface  of  the  epidermis  is  marked  by  a  network  of  linear  furrows 
of  variable  size,  marking  out  the  surface  into  a  number  of  spaces  of  polygonal 
or  lozenge-shaped  form.  Some  of  these  furrows  are  large,  as  opposite  the  flex- 
ures of  the  joints,  and  correspond  to  the  folds  in  the  derma  produced  by  their 
movements.  In  other  situations,  as  upon  the  back  of  the  hand,  they  are  ex- 
ceedingly fine,  and  intersect  one  another  at  various  angles:  upon  the  palmar 


APPENDAGES    OF    THE    SKIN.  81 

surface  of  the  hand  and  fingers,  and  upon  the  sole,  these  lines  are  very  distinct, 
and  are  disposed  in  curves.  They  depend  upon  the  large  size  and  peculiar 
arrangement  of  the  papillae  upon  which  the  epidermis  is  placed.  The  deep 
surface  of  the  epidermis  is  accurately  moulded  upon  the  papillary  layer  of  the 
derma,  each  papilla  being  invested  by  its  epidermic  sheath  ;  so  that  when  this 
layer  is  removed  by  maceration,  it  presents  a  number  of  pits  or  depressions 
corresponding  to  the  elevations  of  the  papillae,  as  well  as  the  furrows  left  in 
the  intervals  between  them.  Fine  tubular  prolongations  from  this  layer  are 
continued  into  the  ducts  of  the  sudoriferous  and  sebaceous  glands.  In  struc- 
ture, the  epidermis  consists  of  flattened  cells,  agglutinated  together,  and  having 
a  laminated  arrangement.  In  the  deeper  layers  the  cells  are  large,  rounded, 
or  columnar,  and  filled  with  soft  opaque  contents.  In  the  superficial  layers 
the  cells  are  flattened,  transparent,  dry,  and  firm,  and  their  contents  converted 
into  a  kind  of  horny  matter.  The  difference  in  the  structure  of  these  layers  is 
dependent  upon  the  mode  of  growth  of  the  epidermis.  As  the  external  layers 
desquamate,  from  their  being  constantly  subjected  to  attrition,  they  are  repro- 
duced from  beneath,  successive  layers  gradually  approaching  towards  the  free 
surface,  which,  in  their  turn,  die  and  are  cast  off. 

These  cells  are  developed  in  the  liquor  sanguinis,  which  is  poured  out  on 
the  free  surface  of  the  derma ;  they  contain  nuclei,  and  form  a  thin  stratum  of 
closely-aggregated  nucleated  cells,  which  cover  the  entire  extent  of  the  papil- 
lary layer.  The  deepest  layer  of  cells,  according  to  Kcilliker,  are  of  a  columnar 
form,  and  are  arranged  perpendicularly  to  the  free  surface  of  the  derma,  form- 
ing either  a  single  or  a  double,  or  even  triple,  layer;  the  laminae  succeeding 
these  are  composed  of  cells  of  a  more  rounded  form,  the  contents  of  which  are 
soft,  opaque,  granular,  and  soluble  in  acetic  acid.  As  these  cells  successively 
approach  the  surface  by  the  development  of  fresh  layers  from  beneath,  they 
assume  a  flattened  form  from  the  evaporation  of  their  fluid  contents,  and  finally 
form  a  transparent,  dry,  membranous  scale,  lose  their  nuclei,  and  apparently 
become  changed  in  their  chemical  composition,  as  they  are  unaffected  now  by 
acetic  acid. 

The  black  color  of  the  skin  in  the  negro,  and  the  tawny  color  among  some 
of  the  white  races,  is  due  to  the  presence  of  pigment  in  the  cells  of  the  cuticle. 
This  pigment  is  more  especially  distinct  in  the  cells  of  the  deeper  layer,  or  rete 
mucosum,  and  is  similar  to  that  found  in  the  choroid.  As  the  cells  approach 
the  surface  and  desiccate,  the  color  becomes  partially  lost. 

The  arteries  which  supply  the  skin  divide  into  numerous  branches  in  the 
subcutaneous  tissue;  they  then  pass  through  the  areolae  of  the  corium,  and 
divide  into  a  dense  capillary  plexus,  which  supplies  the  sudoriferous  and  seba- 
ceous glands  and  the  hair-follicles,  terminating  in  the  superficial  layers  of  the 
corium,  by  forming  a  capillary  network,  from  which  numerous  fine  branches 
ascend  to  the  papillae. 

The  lymphatic  vessels  are  arranged  in  a  minute  plexiform  network  in  the 
superficial  layers  of  the  corium,  where  they  become  interwoven  with  the  capil- 
lary and  nervous  plexuses;  they  are  especially  abundant  in  the  scrotum  and 
round  the  nipple. 

The  nerves  which  supply  the  skin  ascend  with  the  vessels  through  the  areolae 
of  the  deep  layers  of  the  corium  to  the  more  superficial  layers,  where  they 
form  a  minute  plexiform  mesh.  From  this  plexus  the  primitive  nerve-fibres 
pass  to  be  distributed  to  the  papillae.  The  nerves  are  most  numerous  in  those 
parts  which  are  provided  with  the  greatest  sensibility. 

The  appendages  of  the  skin  are,  the  Nails,  the  Hairs,  the  Sudoriferous  and 
Sebaceous  Glands,  and  their  ducts. 

The  nails  and  hairs  are  peculiar  modifications  of  the  epidermis,  consisting 
essentially  of  the  same  cellular  structure  as  that  membrane. 

The  Nails  are  flattened,  elastic  structures,  of  a  horny  texture,  placed  upon 
6 


82  GENERAL    ANATOMY. 

the  dorsal  surface  of  the  terminal  phalanges  of  the  fingers  and  toes.  Each  nail 
is  convex  on  its  outer  surface,  concave  within,  and  is  implanted  by  a  portion 
called  the  root  into  a  groove  of  the  skin;  the  exposed  portion  is  called  the  body, 
and  the  anterior  extremity  the  free  edge.  The  nail  has  a  very  firm  adhesion  to 
the  cutis,  being  accurately  moulded  upon  its  surface,  as  the  epidermis  is  in  other 
parts.  The  part  of  the  cutis  beneath  the  body  and  root  of  the  nail  is  called 
the  matrix,  because  it  is  the  part  from  which  the  nail  is  produced.  Correspond- 
ing to  the  body  of  the  nail,  the  matrix  is  thick,  and  covered  with  large,  highly 
vascular  papillae,  arranged  in  longitudinal  rows,  the  color  of  which  is  seen 
through  the  transparent  tissue.  Behind  this,  near  the  root  of  the  nail,  the 
papillae  are  small,  less  vascular,  and  have  no  regular  arrangement;  hence,  the 
portion  of  the  nail  corresponding  to  this  part  is  of  a  whiter  color,  and  called 
lunula,  from  its  form. 

The  cuticle,  as  it  passes  forwards  on  the  dorsal  surface  of  the  finger,  is  at- 
tached to  the  surface  of  the  nail,  a  little  in  advance  of  its  root.  At  the  ex- 
tremity of  the  finger  it  is  connected  with  the  under  surface  of  the  nail,  a  little 
behind  its  free  edge.  The  cuticle  and  horny  structure  of  the  nail  (both  epi- 
dermic structures),  are  thus  directly  continuous  with  each  other.  The  nails,  in 
structure,  consist  of  cells  having  a  laminated  arrangement,  and  these  are  essen- 
tially similar  to  those  composing  the  epidermis.  The  deepest  layer  of  cells 
which  lie  in  contact  with  the  papillae  at  the  root  and  under  surface  of  the  nail, 
are  of  elongated  form,  arranged  perpendicularly  to  the  surface,  and  provided 
with  nuclei;  those  which  succeed  these  are  of  a  rounded  or  polygonal  form,  the 
more  superficial  ones  becoming  broad,  thin,  and  flattened,  and  so  closely  com- 
pacted together  as  to  make  the  limits  of  each  cell  very  indistinct.  n 

It  is  by  the  successive  growth  of  new  cells  at  the  root  and  under  surface  of  | 
the  body  of  the  nail,  that  it  advances  forwards,  and  maintains  a  due  thickness, 
whilst,  at  the  same  time,  the  growth  of  the  nail  in  the  proper  direction  is 
secured.  As  these  cells  in  their  turn  become  displaced  by  the  growth  of  new 
cells,  they  assume  a  flattened  form,  lose  their  nuclei,  and  finally  become  closely 
compacted  together  into  a  firm,  dense,  horny  texture.  In  chemical  composition, 
the  nails  resemble  the  epidermis.  According  to  Mulder,  they  contain  a  some- 
what larger  proportion  of  carbon  and  sulphur. 

The  Hairs  are  peculiar  modifications  of  the  epidermis,  and  consist  essentially 
of  the  same  structure  as  that  membrane.  They  are  found  on  nearly  every  part 
of  the  surface  of  the.  body,  excepting  the  palms  of  the  hands  and  soles  of  the 
feet,  and  vary  much  in  length,  thickness,  and  color,  in  different  parts  of  the 
body,  and  in  different  races  of  mankind.  In  some  parts  they  are  so  short  as 
not  to  project  beyond  the  follicles  containing  them;  in  other  parts,  as  upon  the 
scalp,  they  are  of  considerable  length;  along  the  margin  of  the  eyelids  and 
upon  the  face,  they  are  remarkable  for  their  thickness.  A  hair  consists  of  a 
root,  the  part  implanted  in  the  skin;  the  shaft,  the  portion  projecting  from  ita, 
surface,  and  the  point.  They  generally  present  a  cylindrical  or  more  or  lee' 
flattened  form,  and  a  reniform  outline  upon  a  transverse  section  (Fig.  42). 

The  root  of  the  hair  presents  at  its  extremity  a  bulbous  enlargement,  which  U 
whiter  in  color,  and  softer  in  texture  than  the  stem,  and  is  lodged  in  a  follicular 
involution  of  the  epidermis,  called  the  hair-follicle.  When  the  hair  is  of  con- 
siderable length,  the  follicle  extends  into  the  subcutaneous  cellular  tissue.  Tho 
hair-follicle  is  bulbous  at  its  deep  extremity,  like  the  hair  which  it  contains, 
and  has  opening  into  it,  near  its  free  extremity,  the  orifices  of  the  ducts  of  one 
or  more  sebaceous  glands.  In  structure,  the  hair-follicle  consists  of  two  coats 
— an  outer  or  dermic,  and  an  inner  or  cuticular.  The  outer  coat  is  formed 
mainly  of  areolar  tissue;  it  is  continuous  with  the  corium,  is  highly  vascular, 
and  supplied  by  numerous  minute  nervous  filaments.  The  inner  or  cuticular 
lining  is  continuous  with  the  epidermis,  and,  at  the  bottom  of  the  hair-follicle, 
with  the  root  of  the  hair;  this  cuticular  lining  resembles  the  epidermis  in  the 
peculiar  rounded  form  and  soft  character  of  those  cells  which  lie  in  contact 


it». 

i 


SEBACEOUS    GLANDS. 


83 


[Fig.  42. 


Diagram  of  structure   of  hnir,    hair 


with  the  outer  coat  of  the  hair-follicle,  and  the  thin,  drj,  and  scaly  character 
of  those  which  lie  near  the  surface  of  the  hair,  to  which  they  are  closely  adhe- 
rent. When  the  hair  is  plucked  from  its  follicle,  this  cuticular  lining  most 
commonly  adheres  to  it,  and  forms  what  is  called 
the  root-sheath.  At  the  bottom  of  each  hair- 
follicle  is  a  small  conical  vascular  eminence  or 
papilla,  similar  in  every  respect  to  those  found 
upon  the  surface  of  the  skin;  it  is  continuous 
with  the  dermic  layer  of  the  follicle,  is  highly 
vascular,  and  probably  supplied  with  nervous 
fibrils.  This  is  the  part  through  which  material 
is  supplied  for  the  production  and  constant 
growth  of  the  hair.  The  root  of  the  hair  rests 
upon  this  conical-shaped  eminence,  and  is  con- 
tinuous with  the  cuticular  lining  of  the  follicle 
at  this  part.  It  consists  of  nucleated  cells,  simi- 
lar in  every  respect  to  those  which  in  other 
situations  form  the  epidermis.  These  cells 
gradually  enlarge  as  they  are  pushed  upwards 
into  the  soft  bulb,  and  some  of  them  contain 
pigment  granules,  which  either  exist  in  separate 

cells,  or  are  separate,  or  aggregated  round  the  foiiicir.  and  sebaceous  ginnds(Koiiiker). 
nucleus;  it  is  these  granules  which  give  rise  to  a.  Root  of  hair,  in  its  follicle,  i.  Outer 
the  color  of  the  hair.  It  occasionally  happens  •^'■y  layer  of  cuticle.  2.  Maipighian  or 
that  these  pigment-granules  completely  fill  the  mucous  layer,  both  dipping  into  hair  sac. 
cells  in  the  centre  of  the  bulb,  which  gives  rise    ^-  ^"'■'''  ""'  *"■""  ^'^'"-    ^-  S«i'-'^««°"« 

,  T         ^      1      J.        1         c       •  J.       tj.         r         J        /?     glands,  opening  into  hair  sac.     5.  Root 

to  the  dark  track  ot  pigment  oiten  lound,  or      „,   •    «  w  n    <-i,  •         t  -o    -n 

,      ,r  o  r>     1       1      •  of  hair.  6.  Walls  of  hair  sac.   7.  Papilla, 

greater  or  less  length,  in  the  axis  of  the  hair.         ^^  .^^ich  hair  grows,    b.  Larger  view 

The  shaft  of  the  hair  consists  of  a  central  part      of  lower  end  of  root  of  hair,  and  bottom 

or  medulla,  the  fibrous  part  of  the  hair,  and  the    of  hair  sac.   6.  Hair  sac,  showing  outer 

cortex    externally.        The    medulla    occupies    the      and  inner  root-sheath,  latter  adhering 

centre  of  the  shaft,  and  ceases  toward  the  point  ^o  hair.  7.  Vascular  papilla  on  which 
of  the  hair.     It  is  usually  wanting  in  the  fine    ^"''"  S"""^'-    ^^^  ^'^''^  itself  shows  its 

T      •  •         ,1  x>  f  ii       1,    J  J  fibrous  structure,  its  dark  medulla,  and 

hairs  covering  the  suriace  or  the  body,  and  com-     ^  ,.        , .. 

,.        if.li  1         T-  transverse   lines  of  its  scaly   covering. 

monly  in  those  or  the  head.     It  is  more  opaque    ^  rn,.  „„„„„.„.„+;„„„?„  i,^;.  .i,.™;,,^ 

J  1/11  1        •   -Iraiisverse  section  or  a  hair,  snowing 

and  deeper  colored  than  the  fibrous  part,  and    ijg  outer  covering,  its  fibrous  part,  and 
consists  of  cells  containing  pigment  or  fat-gran-     central  softer  medulla  or  pith.] 
ules.    The  fibrous  portion  of  the  hair  constitutes 

the  chief  part  of  the  stem ;  its  cells  are  elongated,  and  unite  to  form  flattened 
fusiform  fibres.  These  also  contain  pigment  granules,  which  assume  a  linear 
arrangement.  The  cells  which  form  the  cortex  of  the  hair  consist  of  a  single 
layer  which  surrounds  those  of  the  fibrous  layer;  they  are  converted  into  thin 
flat  scales,  having  an  imbricated  arrangement. 

The  Sebaceous  Glands  are  small,  sacculated,  glandular  organs,  lodged  in  the 
substance  of  the  corium,  or  subdermoid  tissue.  They  are  found  in  most  parts 
of  the  skin,  but  are  most  abundant  in  the  scalp  and  face;  they  are  also  very 
numerous  around  the  apertures  of  the  anus,  nose,  mouth,  and  external  ear;  but 
are  wanting  in  the  palms  of  the  hands  and  soles  of  the  feet.  Each  gland  con- 
sists of  a  single  duct,  more  or  less  capacious,  which  terminates  in  a  lobulated 
pouch-like  extremity.  The  basement  membrane  forming  the  wall  of  the  sac, 
as  well  as  the  duct,  is  lined  by  epithelium,  which  is  filled  with  particles  of  se- 
baceous matter;  and  this  becoming  detached  into  the  cavity  of  the  sac,  as  its 
growth  is  renewed,  constitutes  the  secretion.  The  sacculi  connected  with  each 
duct  vary  in  number  from  two  to  five,  or  even  twenty.  The  orifices  of  the 
ducts  open  most  frequently  into  the  hair-follicles,  but  occasionally  upon  the 
general  surface.  On  the  nose  and'  face,  the  glands  are  of  large  size,  distinctly 
lobulated,  and  often  become  much  enlarged  from  the  accumulation  of  pent-up 


84  GENERAL    ANATOMY. 

secretion.     The   largest   sebaceous   glands  are  those  found  in  the  eyelids,  the 
Meibomian  glands. 

The  Sudoriferous  or  Sweat-  Glands  are  the  organs  by  which  a  large  portion  of 
the  aqueous  and  gaseous  materials  are  excreted  by  the  skin.  They  are  found 
in  almost  every  part  of  the  skin,  and  are  situated  in  small  pits  in  the  deep  parts 
of  the  corium,  or  in  the  subcutaneous  areolar  tissue,  surrounded  by  a  quantity 
of  adipose  tissue.  They  are  small,  lobular,  reddish  bodies,  consisting  of  one 
or  more  convoluted  tubuli,  from  which  the  efferent  duct  proceeds  upwards 
through  the  corium  and  cuticle,  and  opens  upon  the  surface  by  a  slightly  en- 
larged orifice.  The  efferent  duct,  as  it  passes  through  the  corium,  pursues,  for 
a  short  distance,  a  spiral  course,  becoming  straight  in  the  more  superficial  part 
of  this  layer,  and  opens  on  the  surface  of  the  cuticle  by  an  oblique  valve-like 
aperture.  In  the  parts  where  the  epidermis  is  thin,  the  ducts  are  finer  and  al- 
most straight  in  their  course;  but  where  the  epidermis  is  thicker,  they  assume 
again  a  spiral  arrangement,  the  separate  windings  of  the  tube  being  as  close  and 
as  regular  as  those  of  a  common  screw.  The  spiral  course  of  these  ducts  is 
especially  distinct  in  the  thick  cuticle  of  the  palm  of  the  hand  and  sole  of 
the  foot.  The  size  of  these  glands  varies.  They  are  especially  large  in  those 
regions  where  the  amount  of  perspiration  is  great,  as  in  the  axillae,  where  they 
form  a  thin  mammillated  layer  of  a  reddish  color,  which  corresponds  exactly 
to  the  situation  of  the  hair  in  this  region ;  they  are  large,  also,  in  the  groin. 
Their  number  varies.  They  are  most  numerous  on  the  palm  of  the  hand,  pre- 
senting, according  to  Krause,  2800  orifices  on  a  square  inch  of  the  integument, 
and  are  rather  less  numerous  on  the  sole  of  the  foot.  In  both  of  these  situa- 
tions, the  orifices  of  the  ducts  are  exceedingly  regular,  and  correspond  to  the  ^ 
small  transverse  grooves  which  intersect  the  ridges  of  papillae.  In  other  situations  ■ 
they  are  more  irregularly  scattered,  but  in  nearly  equal  numbers  over  parts  in- 
cluding the  same  extent  of  surface.  In  the  neck  and  back  they  are  least  nume- 
rous, their  number  amounting  to  417  on  the  square  inch  (Krause).  Their  total 
number  is  estimated  by  the  same  writer  at  2,381,248 ;  and  supposing  the  aperture 
of  each  gland  to  represent  a  surface  of  j'g  of  a  line  in  diameter,  he  calculates 
that  the  whole  of  these  glands  would  present  an  evaporating  surface  of  about 
eight  square  inches.  Each  gland  consists  of  a  single  tube  intricately  convoluted, 
terminating  at  one  end  by  a  blind  extremity,  and  opening  at  the  other  end  upon 
the  surface  of  the  skin.  In  the  larger  glands  this  single  duct  usually  divides 
and  subdivides  dichotomously ;  the  smaller  ducts  ultimately  terminating  in 
short  caecal  pouches,  rarely  anastomosing.  The  wall  of  the  duct  is  thick  :  the^ 
width  of  the  canal  rarely  exceeding  one-third  of  its  diameter.  The  tube,  bothiH 
in  the  gland  and  where  it  forms  the  excretory  duct,  consists  of  two  layers ;  an 
outer,  formed  by  fine  areolar  tissue;  and  an  inner  layer  of  epithelium.  The 
external,  or  fibro-cellular  coat,  is  thin,  continuous  with  the  superficial  layer  of 
the  corium,  and  extends  only  as  high  as  the  surface  of  the  true  skin.  The 
epithelial  lining  is  much  thicker,  continuous  with  the  epidermis,  and  alone  formsH 
the  spiral  portion  of  the  tube.  When  the  cuticle  is  carefully  removed  from  the 
surface  of  the  cutis,  these  convoluted  tubes  of  epidermis  may  be  drawn  out,  and 
form  nipple-shaped  projections  on  its  under  surface.  According  to  Kolliker,  a 
layer  of  non-striated  muscular  fibres,  arranged  longitudinally,  is  found  between 
the  areolar  and  epithelial  coats  of  the  ducts  of  the  larger  sweat-glands,  as  in  the 
axilla,  root  of  the  penis,  on  the  labia  majora,  and  round  the  anus. 

The  contents  of  the  smaller  sweat-glands  are  quite  fluid;  but  in  the  larger 
jrlands,  the  contents  are  semi-fluid  and  opaque,  and  contain  a  number  of  col- 
ored granules,  and  cells  which  appear  analogous  to  epithelial  cells. 


EPITHELIUM. 


85 


THE  EPITHELIUM. 

All  the  surfaces  of  the  body,  the  external  surface  of  the  skin,  the  internal 
surface  of  the  digestive  and  respiratory  tracts,  the  closed  serous  cavities,  and 
the  ducts  of  all  glands,  are  covered  by  one  or  more  layers  of  simple  cells,  called 
Epithelium  or  Epithelial  Cells,  which  serve  various  purposes,  both  as  a  protec- 
tive layer,  and  as  an  agent  in  secretion.  Thus,  in  the  skin,  the  main  purpose 
served  by  the  epithelium  (here  called  the  epidermis)  is  that  of  protection.  As 
the  surface  is  worn  away  by  the  agency  of  friction  or  change  of  temperature, 
new  cells  are  supplied,  and  thus  the  surface  of  the  true  skin,  and  the  vessels 
and  nerves  which  it  contains,  are  defended  from  damage.  In  the  gastro-intestinal 
mucous  membrane  and  in  the  glands,  the  epithelial  cells  appear  to  be  the  prin- 
cipal agents  in  separating  the  secretion  from  the  blood  or  from  the  alimentary 
fluids.  In  other  situations  (as  the  nose,  fauces,  and  respiratory  passages)  the 
chief  office  of  the  epithelial  cells  appears  to  be  to  maintain  an  equable  tempera- 
ture by  the  moisture  with  which  they  keep  the  surface  always  slightly  lubri- 
cated. In  the  serous  cavities  they  also  keep  the  opposed  layers- moist,  and  thus 
facilitate  their  movements  on  each  other.  Finally,  in  all  internal  parts  they 
insure  a  perfectly  smooth  surface. 

The  epithelium  is  usually  spoken  of  as  tessellated  or  pavement,  columnar, 
spheroidal  or  glandular,  and  ciliated. 

Fig.  43. 


Epithelial  cells  in  the  oral  cavity  of  man.     a.  Large,     h.  Middle-sized,     e.  The  same  with  two  nuclei, 
(Magnified  350  times.) 

The  pavement  epithelium  is  composed  of  flat  nucleated  scales  of  various  shapes, 
usually  polygonal,  and  varying  in  size.    These  scales  often  contain  granules,  as 


Fig.  44. 


Fig.  45. 


Epithelium  of  the  intestinal  villi  of  the  rabhit.    a.  Base- 
ment-membrane.    (Magnified  300  times.) 


Spheroidal  epithelium  from  the  human 
bladder.     (Magnified  350  times.) 


in  Fig.  43.     This  kind  of  epithelium  is  found  on  the  surface  of  the  skin  (the 
epidermis),  on  all  the  serous  surfaces  (unless  the  ventricles  of  the  brain  be  an 


86 


GENERAL    ANATOMY. 


exception),  on  the  lining  membranes  of  the  bloodvessels,  on  many  of  the  mucous 
membranes,  and  in  the  ducts.  The  nails,  hairs,  and  in  animals  the  horns,  are 
a  variety  of  this  kind  of  epithelium. 

The  columnar  epithelinm  (Fig.  44)  is  formed  of  cylindrical  or  rod-shaped  cells, 
each  containing  a  nucleus,  and  set  together,  so  as  to  form  a  complete  membrane. 

This  form  of  epithelium  covers  the  mucous  membrane  of  the  whole  gastro- 
intestinal tract  and  the  glands  of  that  part,  the  greater  part  of  the  urethra,  the 
vas  deferens,  'the  prostate,  Cowper's  glands,  Bartholine's  glands,  and  a  poi-tion 
of  the  uterine  mucous  membrane. 

The  spheroidal  or  glandular  epithelium  (Fig.  45)  is  composed  of  circular  cells, 
with  granular  contents  and  a  small  nucleus. 

This  form  is  found  in  the  kidney,  ureters,  and  bladder,  and  in  the  secreting 
glands. 

Ciliated  epithelium  (Fig.  46)  may  be  of  any  of  the  preceding  forms,  but  usually 
inclines  to  the  columnar  shape.     It  is  distinguished  by  the  presence  of  minute 


Fig.  46. 


[Fig.  47. 


Simple  conoidal  ciliated  epithelium. 
Cilia  and  their  free  extremities.] 


a.  Nucleated  cells. 


processes,  like  hairs  or  eyelashes  (cilia), 
standing  up  from  the  free  surface  (Fig.  47). 
If  the  cells  be  examined  during  life,  or  imme- 
diately on  removal  from  the  living  body  (for 
which  in  the  human  subject  the  removal  of  a 
nasal  polypus  offers  a  frequent  opportunity), 
in  tepid  water,  the  cilia  will  be  seen  in  active 
lashing  motion,  and  if  the  cells  be  separate, 
they  will  often  be  moved  about  in  the  field 
by  that  motion.  ■ 

The  situations  in  which  ciliated  epithelium  is  found  in  the  human  body  are:  fl 
the  respiratory  tract  from  the  nose  downwards,  the  tympanum  and  Eustachian  ™ 
tube,  the  Fallopian  tube  and  upper  portion  of  the  uterus,  and  the  ventricles  of 
the  brain. 


Ciliated  epithelium,  from  the  hamau  tra- 
chea. (Mngnified  350  times.)  a.  Innermost 
layers  of  the  elastic  longitudinal  fibres,  b. 
Homogeneous  innermo.st  layers  of  the  mu- 
cous membrane,  c.  Deepest  round  cells,  d. 
Middle,  elongated,  e.  Superfisial,  bearing 
cilia. 


SEROUS,  SYNOVIAL,  AND  MUCOUS  MEMBRANES. 

These  membranes  consist  of  a  layer  of  epithelium  supported  on  a  structure- 
less membrane,  called  the  basement  membrane,  beneath  which  lies  a  tract  of 
connective  or  areolar  tissue,  which  in  tlie  mucous  membranes  lodges  glands  of 
various  kinds,  and  contains  unstriped  muscle,  or  contractile  muscular  fibre- 
cells,  and  in  both  serous  and  mucous  membranes  conveys  the  bloodvessels  out 
of  which  the  secretion  is  to  be  eliminated. 

The  Serous  Membranes  are  the  simplest  of  the  three,  and  will  therefore  be 
first  described. 

They  form  shut  sacs,  sometimes  arranged  quite  simply,  as  the  tunica  vaginalis 
testis,  at  others  with  numerous  involutions  and  reces.ses,  as  the  peritoneum,  but 
which  can  always  be  traced  continuously  around  the  whole  circumference.  The 
sac  is  completely  closed,  so  that  no  communication  exists  between  the  serous 
cavity  and  the  parts  in  its  neighborhood.  An  apparent  exception  exists  in  the 
peritianenm  of  the  female;  for  the  Fallopian  tube  opens  freely  into  the  perito- 
neal cavity  in  the  dead  subject,  so  that  a  bristle  can  be  passed  from  the  one  into 


SECRETING    GLANDS.  87 

the  other.  But  this  communication  is  closed  during  life,  except  at  the  moment 
of  the  passage  of  the  ovum  out  of  the  ovary  into  the  tube,  as  is  proved  by  the 
fact  that  no  interchange  of  fluids  ever  takes  pLace  between  the  two  cavities  in 
dropsy  of  the  peritoneum,  or  in  accumulation  of  fluid  in  the  Fallopian  tubes. 
The  serous  membrane  is  often  supported  by  a  firm  fibrous  layer,  as  is  the  case 
with  the  pericardium,  and  such  membranes  are  sometimes  spoken  of  as  "fibro- 
serous."  In  the  parietal  portion  of  the  arachnoid  there  is,  according  to  many 
anatomists,  no  serous  membrane  in  the  proper  sense  of  the  term;  but  the  dura 
mater  is  merely  lined  with  a  layer  of  epithelium,  the  basement-membrane  being 
here  indistinguishable.  In  other  situations,  the  following  parts  may  be  recog- 
nized as  constituting  a  serous  membrane.  1.  The  epithelium,  a  single  layer  of 
polygonal  or  pavement-epithelial  cells.  2.  A  structureless  basement-membrane. 
3.  The  connective  tissue  and  vessels  which  support  the  latter,  connect  it  with 
the  parts  below,  and  supply  blood  to  its  deep  surface.  Some  of  the  serous 
portion  of  the  blood  is  secreted,  or  transudes,  through  the  basement-membrane 
to  furnish  the  special  secretion.  This  latter  is,  in  most  cases,  only  in  sufficient 
quantity  to  moisten  the  membrane,  but  not  to  furnish  any  appreciable  quantity 
of  fluid.  When  a  small  quantity  can  be  collected,  it  appears  to  resemble  in 
many  respects  the  lymph,  and  like  that  fluid  coagulates  spontaneously,  but 
when  secreted  in  large  quantities,  as  in  dropsy,  it  is  a  watery  fluid  containing 
usually  sufficient  albumen  to  gelatinize  with  heat.^ 

The  Mticous  Membranes  are  more  complex  in  their  structure  than  the  serous. 
Their  epithelium  is  of  various  forms,  including  the  spheroidal,  columnar,  and 
ciliated,  and  is  often  arranged  in  several  layers  (see  Fig.  46).  This  epithelial 
layer  is  supported  by  the  cormm,  which  is  analogous  to  the  derma  of  the  skin; 
and  is  in  fact  continuous  with  it  at  the  orifices  of  the  body.  The  corium  con- 
sists, as  it  is  usually  described,  of  a  transparent  structureless  basement-mem- 
brane next  to  the  epithelium,  supported  by  a  fibro-vascular  layer  of  variable 
thickness  below  it,  and  this  merging  into  the  submucous  areolar  tissue.  It  is 
only  in  some  situations  that  the  basement-membrane  can  be  demonstrated. 

The  fibro-vascular  layer  of  the  corium  contains,  beside  the  white  and  yellow 
fibrous  tissue  and  the  vessels,  muscular  fibre-cells,  nerves,  and  lymphatics,  in 
various  proportions.  Imbedded  in  it  are  found  numerous  glands,  and  project- 
ing out  of  it  are  processes  (villi  and  papillae)  analogous  to  the  papillae  of  the 
skin.  These  glands  and  processes,  however,  exist  only  at  certain  parts,  and  it 
will  be  more  convenient  to  refer  for  their  description  to  the  sequel,  where  the 
parts  are  described  in  which  they  occur.  Thus  the  mucous  glands  are  described 
in  the  account  of  the  mouth,  the  stomach,  the  intestines,  &c.,  the  papillae  and 
villi  with  that  of  the  tongue  and  the  small  intestine. 

The  Synovial  Meonhranes  are  analogous  in  structure  to  the  serous,  but  differ 
from  them  in  the  nature  of  their  secretion,  which  rather  resembles  mucus. 
They  are  described  in  connection  with  the  Articulations. 

SECRETING  GLANDS. 

The  Secreting  Glands  are  organs  in  which  the  blood  circulating  in  capillary 
vessels  is  brought  into  contact  with  the  epithelial  cells  of  a  mucous  membrane, 
whereby  certain  elements  are  separated  ("secreted")  out  of  the  blood,  and  are 
poured  into  the  mucous  cavity.  This  cavity  is  arranged  in  the  form  of  a  rami- 
lying  duct,  the  secreting  cells  lying  in,  or  touching,  the  terminal  ramifications 
(or  more  correctly  the  commencing  radicles)  of  the  duct. 

In  size  these  glands  vary  extremely:  thus  the  liver  weighs  nearly  four 
pounds,  while  many  of  the  mucous  glands  are  only  visible  to  the  naked  eye 
when  distended  with  secretion ;  and  they  vary  not  less  in  structure.     Thus  the 

'  The  resemblance  between  lymph  and  serum  led  Ilewson  to  the  belief  that  the  serous  cavities 
are  sacs  into  which  the  lymphatics  open. 


88 


GENERAL    ANATOMY. 


[Fig.  48. 


structure  of  the  liver  is  so  complex  that  it  can  hardly  yet  be  regarded  as  known 
with  absolute  certainty,  while  there  are  a  great  many  glands  which  consist 

either  of  a  single  tube  lined  with  epithelium,  on 
the  outer  side  of  which  the  blood  circulates,  or 
even  a  simple  closed  sac  which  opens  when  it 
becomes  charged  with  secretion. 

The  great  majority  of  glands,  however,  can  be 
reduced  ideally  to  a  very  simple  form,  viz.,  to  an 
involution  more  or  less  complex  of  the  basement- 
membrane,  carrying  of  course  its  epithelium  with 
it,  and  having  the  capillary  vessels  distributed  on 
its  attached  surface  (Fig.  48).     If  this  involution 
be  perfectly  simple,  an  open  tube  results,  as  in  the 
stomach  (see  Fig.  400),  or  the  common  mucous 
crypts  of  the  urethra  (Figs.  404,  406) ;  and  should 
/^  IV IR'     7/JS^^WK^\         ^^®  mouth  of  such  a  tube  become  closed,  a  simple 
^(i\  mVV  /p^^^^^H^i       follicle  is  formed,  as  in  the  intestine.     Branches 
"  "^^  **'     "  projecting  out  from  the  bottom  of  this  tube  con- 

stitute the  simplest  form  of  racemose  gland.  The 
most  rudimentary  condition  of  such  a  gland  is 
shown  in  the  branched  tubes  of  the  gastric  mu- 
cous membrane  in  Figure  400.  If  such  a  tube  be 
conceived  of  as  divided  into  branches  as  well  as 
branching  out  at  its  extremity,  we  have  a  com- 
pound racemose  gland  consisting  of  a  single 
lobule  terminating  in  its  duct  (such  as  Brunner's 
glands),  and  an  aggregation  of  such  lobules  may 
all  open  into  a  common  duct,  or  may  have  a  great 
number  of  separate  ducts.  Instances  of  such 
glands  will  be  found  in  the  salivary  glands,  the 
pancreas,  &c.  Or  the  necessary  extent  of  epithe- 
lial surface  may  be  obtained  by  the  duct  being 
coiled  on  itself,  as  in  the  sweat-glands  (Fig.  41, 
page  79),  or  the  extremity  of  the  duct  only  may 
be  thus  arranged  (Fig.  370).  In  other  glands, 
as  in  the  kidney,  the  mucous  duct  is  undivided 
from  the  beginning,  and  the  capillaries  from 
which  the  secretion  is  to  be  eliminated  are  dis- 
tributed upon  its  walls  or  project  into  its  ampul- 
lated  commencement  (Fig.  385). 


Three  plans,  a,  b,  c,  of  supposed  sec- 
tions of  secreting  membranes,  to  show 
general  arrangement  of  their  compo- 
nent structures,  and  the  wny  in  which 
their  surfaces  are  increafed.  In  all 
three  plans,  the  broad  shaded  line  re- 
presents the  areolo-vascular  layer,  the 
thin  solid  line  is  the  basement  or  limit- 
ing membrane,  and  the  dotted  line  the 
epithelial  or  covering  layer,  a,  shows 
an  increase  by  simple  plaited  or  fringed 
projections;  b,  five  modes  of  increase 
by  recesses,  forming  five  kinds  of  sim- 
ple glands,  viz.,  1,  a  tubular  follicle  or 
crypt;  2,  a  saccular  follicle  or  sac;  3, 
a  coiled  tube  ;  4,  a  multilonilar  tube, 
that  is,  a  tube  with  depressions  in  it  ; 
5,  a  m.nltilocular  sac.  c,  shows  two 
forms  of  compound  glands  ;  6,  branch- 
ed tubes  forming  a  compound  tubular 
gland;  7,  branched  tubes  ending  in 
little  recesses  or  vesicles,  forming  a 
compound  racemose  or  conglomerate 
gland.     (After  Sharpey.)] 


For  the  description  of  the  Ductless  or  Blood 
Glands,  we  must  refer  to  the  sections  in  the  text 
relating  to  the  Anatomy  of  the  Spleen,  Suprarenal  Capsules,  Thyroid,  and 
Thymus. 


Growth  and  Development  of  the  Body. 


Fig.  49. 


-Discuipli^ 


Ovum  of  the  sow. 


The  whole  body  grows  out  of  tlie  fecundated  ovum,  and  it  is  accordingly 
necessary  to  follow,  in  as  few  words  as  possible,  the  various  stages  in  which 
the  ovum  is  found  in  the  uterus,  from  the  earliest  moment  at  which  conception 
can  be  recognized  as  having  taken  place,  down  to  the  birth  of  the  complete 
foetus.  The  ovum  is  a  small  spherical  body,  situated  in  immature  Graafian 
vesicles  near  their  centre,  but  in  the  mature  ones  in  contact  with  the  raembrana 
granulosa  (see  Ovum  in  body  of  the  work),  at  that  part  of  the  vesicle  which 
projects  from  the  surface  of  the  ovary.  The  cells  of  the  membrana  granulosa 
are  accumulated  round  the  ovum  in  greater  number  than  at  any  other  part  of 
the  vesicle,  forming  a  kind  of  granular  zone,  the  discus  proligerus  (Fig.  49). 

The  human  ovum  (Fig.  50)  is  extremely  minute, 
measuring  from  j^^jth  to  -j-iTjth  of  an  inch  in 
diameter.  It  is  a  cell,  consisting  externally  of  a 
transparent  envelope,  the  zona  pellucida  or  vitel- 
line membrane.  Within  this,  and  in  close  contact 
with  it,  is  the  yelk  or  viielhis ;  imbedded  in  the 
substance  of  the  yelk  is  a  small  vesicular  body, 
the  germinal  vesicle  (vesicle  of  Purkinje) — the 
nucleus  of  the  cell ;  and  this  contains  as  its  nucle- 
olus a  small  spot — the  macula  germinativa,  or  the 
spot  of  Wagner. 

The  zona  pellucida^  or  vitelline  membrane,  is  a  thick,  colorless,  transparent 
membrane,  which  appears  under  the  microscope  as  a  bright  ring,  bounded 
externally  and  internally  by  a  dark  outline.  It  corresponds  to  the  chorion  of 
the  impregnated  ovum. 

The  yellc  consists  of  granules  and  globules 
of  various  sizes,  imbedded  in  a  more  or  less 
viscid  fluid.  The  smaller  granules  resemble 
pigment ;  the  larger  granules,  which  are  in 
greatest  number  at  the  periphery  of  the  yelk, 
resemble  fat-globules.  In  the  human  ovum, 
the  number  of  granules  is  comparatively 
small. 

The  germinal  vesicle  consists  of  a  fine,  trans- 
parent, structureless  membrane,  containing  a 
watery  fluid,  in  which  are  occasionally  found 
a  few  granules.  It  is  about  ^\-^  of  an  inch  in 
diameter,  and  in  immature  ova  lies  nearly  in 
the  centre  of  the  yelk ;  but,  as  the  ovum  be- 
comes developed,  it  approaches  the  surface,  and  enlarges  much  less  rapidly 
than  the  yelk. 

The  germinal  spot  occupies  that  part  of  the  periphery  of  the  germinal 
vesicle  which  is  nearest  to  the  periphery  of  the  yelk.  It  is  opaque,  of  a 
yellow  color,  and  finely-granular  in  structure,  measuring  from  ^^'^^  to  2^50  of 
an  inch. 

The  phenomena  attending  the  discharge  of  the  ova  from  the  Graafian 
vesicles,  since  they  belong  as  much  or  more  to  the  ordinary  functions  of  the 
ovary  than  to  the  general  subject  of  the  growth  of  the  body,  are  described 
with  the  anatomy  of  the  ovaries  in  the  body  of  the  work. 


Fiff.  50. 


Human  ovum,  from  a  middle-sized  foi- 
licle  (magnified  250  tirae.«).  a.  Vitelline 
membrane.  Zo)ia  pellucida.  h.  External 
border  of  th*?  yelk  and  internal  border  of 
the  vitelline  membrane,  c.  Germinal  vesi- 
cle and  germinal  spot. 


90 


GENERAL    ANATOMY. 


The  first  changes  in  the  ovum  which  take  place  upon  conception,  appear  to 
be  as  follows:  The  spermatozoon  penetrates  the  ovum/  the  effect  of  which  is 
to  bring  it  into  contact  with  the  yelk,  and  with  the  germinal  vesicle  contained 
in  the  yelk.  It  seems  as  if  this  normally  occurs  in  the  Fallopian  tube,^  and 
abnormally  it  may  even  take  place  in  the  peritoneal  cavity.  The  first  effect  is 
to  produce  a  cleavage  and  multiplication  of  the  yelk,  which  becomes  first  cleft 

Fig.  51. 


Pour  diagrams  to  show  the  division  of  the  3elk.     The  ovum  is  surrounded  by  spermatozoa, 
oorpuscles  (polar  globules  of  Robin)  are  seen  in  the  first  two. 


The  clear 


into  two  masses,  then  into  four,  and  so  on,  until  at  length  a  mulberry-like 
agglomeration  of  nucleated  cells  results  (Fig.  51).  It  appears  probable  that 
this  proliferation  is  due  to  some  change  in  the  germinal  vesicle  and  its 
nucleolus,  but  the  nature  of  such  change  has  not  been  made  out.  Some 
observers  describe  it  as  consisting  simply  in  the  cleavage  of  the  vesicle  and 
nucleolus,  others  in  their  disappearance  and  replacement  by  a  fresh  cell,  or 
nucleus,  the  emhryo-cell,  around  which  the  yelk  gathers.  In  this  view  the  fer- 
tilization of  the  yelk  is  due  to  the  solution  of  the  germinal  vesicle  under  the 
action  of  the  spermatozoon. 

There  are  also  found  within  the  vitelline  membrane  one  or  more  clear 
globules,  called  "polar  globules,"  by  Robin,  because  they  lie  near  one  of  the 
poles  of  segmentation.  The  nature,  origin,  and  uses  of  these  bodies  are  not 
known.  They  seem  to  be  usually  regarded  as  produced  by  the  liquefaction 
of  the  yelk,  and  as  not  being  essential  to  the  process  of  fructification. 

The  globules  of  which  the  yelk  is  now  composed  soon  arrange  themselves 
into  the  form  of  a  membrane  lined  with  pavement-epithelium.  As  the  yelk- 
mass  softens,  fluid  accumulates  in  the  interior  of  this  membrane,  spreading 
it  out  on  the  internal  surface  of  the  vitelline  membrane.  The  latter  (external) 
membrane  (Fig.  53)  soon  becomes  covered  with  granulations  or  vegetations, 
giving  it  a  shaggy  appearance,  and  then  takes  the  name  of  the  "primitive 
chorion,"  whilst  the  internal  membrane  is  called  the  "  blastodermic  vesicle." 

The  blastodermic  membrane  soon  afterwards  splits  into  two  layers,  the 
division  proceeding  from  the  point  where  the  thickening  or  aggregation  next 
to  be  described  as  the  germinal  area  occurs,  and  extending  gradually  over  the 
whole  circumference  of  the  ovum,  which  now  consists  of  three  concentric 
layers  of  membrane — the  external,  the  primitive  chorion,  the  middle,  the 
external  layer  of  the  blastodermic  vesicle,  and  the  inner,  its  internal  layer. 
The  annexed  figure  shows  this  division  commencing.  It  is  said  that  the  ovum 
is  in  this  condition  at  about  eight  days,  but  no  observations  of  the  human 
ovum  at  so  early  a  period  exist.  The  internal  layer  of  the  blastodermic  mem- 
brane next  separates  into  two  at  the  situation  of  the  area  germinativa.  The 
membrane  which  results  from  this  separation  is  called  the  middle  layer  of  the 
germinal  or  blastodermic  membrane,  and  is  distinguished  from  the  others  in 
not  being  coextensive  with  the  embryo,  but  existing  only  at  the  germinal  area. 

'  See  Newport  Phil.  Tram.  18.'i3,  vol.  ii.  p.  2.^.3.  This  has  been  since  confirmed  by  other 
observers  on  various  lower  animals,  and  may  be  assumed  to  be  jrencrally  true. 

»  Many  physiologists,  as  Rischoff  and  Dr.  M.  Barry,  believe  that  the  ovum  is  fecundated  in 
the  ovary,  hut  the  reasoning  of  Dr.  Allen  Thomson"  appears  very  cogent  in  proving  that  the 
usual  spot  at  which  the  spermatozoon  meets  with  the  ovum  is  in  the  tube. 


THE    AMNION.  91 

Germinal  area. — In  the  mass  of  nucleated  cells  into  which  the  jelk  becomes 
converted  during  the  formation  of  the  blastodermic  vesicle,  a  small  agglome- 
ration is  formed,  which  then  spreads  out  into 
an  area  of  nucleated  cells,  from  which  the  em-  ^ig-  52. 

bryo  is  to  be  formed,  and  which  has  accord- 
ingly received  the  name  of  germinal  disk  or 
area  germi-nativa.  In  this  portion  of  the  ovum 
the  first  trace  of  the  embryo  appears  as  a  faint 
streak,  which  is  called  the  ^nimitive  trace  or 
iwimitive  groove.  This  groove  first  deepens  into 
a  furrow,  bounded  by  two  plates — the  laminse 
dorsales^  beneath  which  a  delicate  fibril  appeals 
— the  chorda  dorsah's  or  notochord — in  which 
cartilage  can  very  early  be  recognized,  and 
which  forms  the  future  spinal  column. 

The  germinal  disk  is  found  to  consist  on  a 
transverse  section  of  three  layers;    an  upper       O-'^^'tli the gc^ai  area  seen  in 

f       .  -Is,  1  /•  IX   ^  profile  to  show  the  division  of  the  bias- 

(external),    or     serous;     a     lower     (internal),    or  todermic  memhrane.     l.  Vitelline  mem- 

mucous  ;    and    a    middle  layer,  which  is  formed  brane.     2.  Blastoderm.     Germinal  nrea. 

from  the  mucous  lamina,  as  above  shown.  4.  Place  where  the  blastoderm  is  just  di- 

The  chorda  dorsalis  and  the  laminae  dorsales     vided  into  its  two  layers, 
are  the  rudiments  of  the  vertebral  column  and 

canal.  The  upper  or  serous  layer  of  the  embryo  gives  origin  to  the  cere- 
bro-spinal  nervous  centres,  and  to  the  organs  of  the  senses,  including  the 
cuticle  and  its  appendages,  as  also  to  the  mammary  glands.  From  the  middle 
layer  are  developed  the  locomotive  organs,  the  spinal  and  sympathetic  nerves, 
the  vascular  system,  the  ductless  glands,  the  sexual  organs,  the  cutis,  where 
the  middle  layer  touches  on  the  external,  and  the  muscular  and  submucous 
coats  of  the  intestines,  where  it  touches  on  the  internal  layer.  The  latter  fur- 
nishes the  lining  of  the  alimentary  canal  and  its  various  appendages,  liver, 
pancreas,  &c.,  the  respiratory  organs,  and  the  urinary  organs.  Besides  this, 
however,  there  are  three  appendages  to  the  ovum,  which  must  now  be  described 
as  the  amnion^  the  umbilical  vesicle^  and  the  allanlois. 

Formation  of  the  Amiiion. — The  amnion  is  formed  from  the  external  germinal 
layer,  which  is  drawn  in  on  all  sides  by  the  changes  of  shape  of  the  embryo. 
The  embryo  as  it  grows  becomes  curved  at  its  anterior  and  posterior  end,  so 
as  to  form  the  cephalic  and  caudal  flexures  (Fig.  54,  B);  it  also  curves  on  itself 
laterally  towards  the  umbilicus  (Fig.  53,  7),  and  as  it  does  so,  it  draws  the  ex- 
ternal germinal  layer  with  it,  forming  double  folds  which  meet  at  the  umbili- 
cus, and  at  a  point  opposite  to  the  umbilicus  on  the  dorsal  aspect  of  the  embryo, 
sometimes  called  "the  posterior  umbilicus"  (Fig.  54,  8'),  and  finally  communi- 
cate so  as  to  form  a  delicate  closed  sac,  into  which  a  serous  fluid — the  liquor 
o.mnii — is  secreted.  This  fluid  increases  in  quantity  up  to  about  the  end  of 
the  fifth  or  the  sixth  month,  when  it  reaches  the  amount  of  about  two  pints. 
Thence  it  diminishes,  and  at  the  end  of  pregnancy  is  about  half  its  maximum 
quantity.  The  outer  layer  of  the  amnion  incloses  all  the  parts  of  which  the 
embryo  consists,  and  is  in  contact  externally  with  the  chorion. 

The  portion  of  the  external  germinal  layer  which  does  not  take  part  in  the 
formation  of  the  amnion  is  called  the  vesicula  serosa  (Fig.  54,  2').  When  the 
sac  of  the  amnion  is  completely  closed,  the  vesicula  serosa  becomes  detached 
from  it,  and  then  forms  an  envelope  to  the  ovum,  lining  the  primitive  chorion. 
Its  future  destination  appears  to  be  to  form  the  epithelial  layer  of  the  secondary 
or  permanent  chorion. 

The  allantois  (Fig.  54,  aT)  is  a  projection  from  near  the  hinder  part  of  the 
embryo,  formed  by  the  middle  and  internal  germinal  layers,  and  therefore  con- 
tinuous with  the  intestinal  cavity.     The  lower  part  of  this  cavity  becomes  the 


92 


GENERAL    ANATOMY. 


Fig.  53.» 


Dingrnms  to  show  the  development  of  the  three  layers  of  the  blnstodermio  membrnne  on  trnnsveriJe  sec- 
tions. A.  Portion  of  the  ovum  with  the  zona  pellucida  and  the  germinal  area.  B  C  D  E  F  Q.  Different 
stages  of  development,  o.  Umbilical  vesicle,  a.  Amnion.  ».  Intestine,  p.  Peritoneal  ciivity.  1.  Vitelline 
membrane.  2.  External  blastodermic  layer.  3.  Middle  layer.  4.  Internal  layer.  5.  Medullary  laminse 
and  groove.  5'.  Medullary  canal.  6.  Epiilermio  laminiB.  7.  Lateral  flexures  of  the  amnion.  T.  The 
same  almost  in  contact.  8.  Internal  epithelial  layer  of  the  amnion.  9.  Eiiidermis  of  the  embryo.  10. 
Chorda  dorsalis.  11.  Vertebral  laminae.  12.  ProtovertebrBe  proper.  13.  Muscular  laminse.  14.  Lateral 
laminSB.  15.  Fibro-intestinal  laminae.  16.  Cutaneous  lamina.  17.  Internal  fibrous  layer  of  the  umbilical 
vesicle.  18.  Muscular  laminae  extending  to  meet  the  cutaneous.  19.  External  layer  f>{  the  cutaneous 
laminae.     20.  Internal  layer  of  the  same.     21.  Mesentery.     22.  Fibrous  layer  of  the  intestine. 


'  The  dotted  lines  indicate  the  parts  belonging  to  the  internal  blastodermic  layer ;  the  plain 
lines  those  belonging  to  the  middle ;  the  interrupted  lines  those  belonging  to  the  external. 


THE    CHORION— THE    DECIDUA.  93 

uro-genital  sinus,  and  it  is  to  the  urinary  tract  that  the  allantois  mainly  belongs. 
It  projects  out  from  the  embryo  through  the  same  opening  as  the  vitelline  or 
umbilical  duct.  The  lower  part  of  the  allantois  which  is  contained  wuthin  the 
embryo  becomes  the  bladder;  the  upper  part  of  its  intra-embryonic  portion  is 
denominated  the  urachus;  the  extra-embryonic  portion  is  divided  into  two 
parts,  called  the  allantoic  vesicle,  or  the  epithelial  portion  of  the  allantois,  and 
the  fibrous  or  vascular  portion.  The  allantois,  which  is  at  first  a  simple  serous 
membrane,  becomes  vascular  over  its  whole  extent  about  the  fifth  week,  and 
its  vessels  communicate,  as  will  be  described  presently,  with  those  of  the  cho- 
rion, forming  the  vascular  connection  between  the  mother  and  foetus.  In  the 
human  foetus  the  allantoic  vesicle  is  small,  soon  withers  and  disappears,  and  its 
vessels  are  soon  limited  to  the  two  umbilical  arteries  and  one  vein. 

The  allantoic  fluid  is  alkaline,  and  contains  from  one  to  four  per  cent,  of 
solid  matters — uric  acid,  urea,  allantoin,  sugar,  and  saline  matters. 

^  Umbilical  Vesicle  (Figs.  53,  54,  o). — The  embryo  itself  in  the  earliest  recog- 
nizable condition  is,  above  stated,  a  mere  streak,  but  it  soon  becomes  curved  at 
either  end,  corresponding  to  the  head  and  lower  extremity  of  the  future  animal 
(the  tail  of  animals,  the  buttocks  and  lower  limbs  in  man);  the  lower  part  is, 
however,  open,  and  from  this  a  body  projects  which  at  first  consists  of  the 
matter  into  which  the  yelk  has  been  developed  (yelk-sac),  and  later  on  is  con- 
verted into  a  vesicular  body  filled  with  clear  fluid  (the  umbilical  vesicle),  and 
communicating  with  the  body  of  the  embryo  by  a  constriction,  the  umbilical 
duct,  opening  at  first  into  the  intestinal  cavity.  As  the  development  of  the 
intestine  proceeds,  this  canal  is  closed,  and  the  umbilical  vesicle  is  then  a  closed 
sac,  lying  external  to  the  amnion.  It  is  formed  mainly  by  the  internal  germi- 
nal layer,  but  has  a  lining  derived  from  the  middle  layer.  As  the  arteries 
developed  in  the  middle  layer  grow  they  cover  the  umbilical  vesicle,  forming 
the  vascular  area,  the  chief  vessels  of  which  are  the  omphalo -mesenteric,  two  in 
number.  The  vessels  of  this  area  appear  to  absorb  the  fluid  of  the  umbilical 
vesicle,  which  dries  up  into  a  disk-like  body  attached  to  the  amnion,  and  hav- 
ing no  further  function.  The  activity  of  the  umbilical  vesicle  ceases  about  the 
same  time  (fifth  or  sixth  week)  as  the  allantois  is  formed.  In  fact,  the  umbilical 
vesicle  provides  nutrition  to  the  foetus  from  the  ovum  itself,  while  the  allantois 
is  the  channel  whereby  nutrition  is  conveyed  to  it  from  the  uterine  tissues. 
The  umbilical  vesicle,  however,  is  visible,  containing  fluid  up  to  the  fourth  or 
fifth  month,  between  the  amnion  and  the  chorion,  with  its  pedicle  and  the 
omphalo-mesenteric  vessels.  The  latter  vessels  then  become  atrophied,  as  the 
functional  activity  of  the  body  with  whicb  they  are  connected  ceases. 

The  Ghorion  (Figs.  55,  k,  and  56). — The  jmiyiitive  chorion  has  already  been 
described.  It  is  formed  by  the  vitelline  membrane,  which  becomes  covered 
with  shaggy  villous  processes,  and  disappears  about  the  fifteenth  day,  to  give 
place  to  the  secondary  or  permanent  chorion.  The  latter  is  composed  of  two 
lamellae,  the  external  one  of  which  is  furnished  by  the  vesicula  serosa  (or 
false  amnion),  and  the  internal  by  the  fibrous  layer  of  the  allantois.  This 
latter  furnishes  a  vascular  membrane,  which  is  applied  to  the  epithelial  layer 
of  the  chorion  (vesicula  serosa)  (Fig.  54,  13,  14,  15).  As  the  latter  becomes^ 
villous  by  the  development  of  tufts  upon  it  {shaggy  chorion),  the  bloodvessels  of" 
the  internal  layer  pass  into  those  tufts,  forming  the  foetal  portion  of  the  placenta, 
and  dipping  through  the  decidua  into  the  uterine  sinuses  of  the  maternal 
placenta. 

The  Decidua  (Figs.  54,  65)  is  formed  from  the  mucous  membrane  of  the 
uterus.  Even  before  the  arrival  of  the  fecundated  ovum  in  the  uterus,  the 
mucous  membrane  of  the  latter  becomes  vascular  and  tumid,  and  when  the  ovum 
has  reached  the  uterus,  it  is  imbedded  in  the  folds  of  the  mucous  membrane, 
which  overlap,  and  finally  completely  encircle  the  ovum.  Thus  two  portions 
of  the  uterine  mucous  membrane  (decidua)  are  formed — viz.,  that  which  coats 


94 


GENERAL    ANATOMY. 
Fig.  54.' 


Pingrams  to  show  the  development  of  the  three  binstoderraic  layers  on  nntero-pnsterior  sections.  A 
tioii  of  ovum  with  the  vitelline  membrane  and  germinal  area.  B  C  D  E  F.  Various  stages  of  development. 
Q.  Ovum  in  the  uterus  and  formation  of  decidua.  1.  Vitelline  membrane.  2.  E.Tternal  blastodermic  layer. 
2'.  Vesicula  serosa.  3.  Middle  blastodermic  layer.  4.  Internal  layer.  6.  Vestige  of  the  future  embryo. 
6.  Cephalic  flexure  of  the  amnion.  7.  Caudal  fle.xure.  8.  Spot  where  the  amnion  and  vesicula  serosa  are 
continuous.  8'.  Posturior  umbilicus.  9.  Cardiac  cavity.  10.  External  fibrous  layer  of  the  umbilical  vesicle. 
11.  External  fibrous  layer  of  the  amnion.  12.  Internal  layer  of  the  bl.astoderm  forming  the  intestine.  13. 
14.  External  layer  of  the  allantois,  extending  to  the  inner  surface  of  the  vesicula  serosa.  15.  The  same  now 
completely  applied  to  the  inner  surfivce  of  the  vesicula  serosa.  16.  Umbilical  cord.  17.  Umbilical  vessels. 
18.  Amnion.  19.  Chorion.  20.  Foetal  placenta.  21.  Mucous  membrane  of  uterus.  22.  Maternal  pla- 
centa.    2'°t.   Deoidua  reflexa.     24.  Muscular  wall  of  uterus. 


'  The  same  note  applies  to  this  as  to  the  preceding  diagram. 


J 


THE    PLACENTA. 


95 


the  muscular  wall  of  the  uterus,  decidua  vera^  and  that  which  is  in  contact  with 
the  ovum,  decidua  rejlexa.  The  decidua  does  not  extend  into  the  neck  of  the 
uterus,  which  after  conception  is  closed 
by  a  plug  of  mucus.  The  decidua  vera 
is  perforated  by  the  openings  formed 
by  the  enlarged  uterine  glands,  which 
become  much  hypertrophied  and  de- 
_veloped  into  tortuous  tubes.  It  con- 
tains at  a  later  period  n  umerous  arteries 
and  venous  channels,  continuous  with 
the  uterine  sinuses,  and  it  is  from  it 
that  the  uterine  part  of  the  placenta  is 
developed.  The  portion  of  the  de- 
cidua vera  which  takes  part  in  the  for- 
mation of  the  placenta  is  called  "de- 
cidua serotina." 

The  decidua  reflexa  is  shaggy  on  its 
outer  aspect,  but  smooth  within.  The 
vessels  which  it  contains  at  first  dis- 
appear after  about  the  third  month; 
about  the  fifth  or  sixth  month  the 
space  between  the  two  layers  of  the 
decidua  disappears,  and  towards  the 
end  of  pregnancy  the  decidua  is  trans- 
formed into  a  thin  yellowish  mem- 
brane, which  constitutes  the  external 
envelope  of  the  ovum. 

The  Placenta  is  the  organ  by  which 
the  connection  between  the  foetus  and 
mother  is  maintained,  and  through 
which  blood  reaches  the  foetus  and  is 
returned  to  the  uterus.  It  therefore 
subserves  the  purposes  both  of  circu- 
lation and  respiration.  It  is  formed 
of  two  parts,  as  already  shown,  viz., 
the  maternal  portion  which  is  devel- 
oped out  of  the  decidua  vera  (sero- 
tina), and  the  foetal  placenta  formed  by 
the  villous  chorion.  Its  shape  in  the 
human  subject  is  that  of  a  disk,  one 
side  of  which  adheres  to  the  uterine 
walls,  while  the  other  is  covered  by 
the  amnion.  The  villi  of  the  chorion 
(or  foetal  placenta)  gradually  enlarge,  forming  large  projections — "  cotyledons''' — 
which  each  contain  the  ramifications  of  vessels  communicating  with  the  umbi- 
lical arteries  and  veins  of  the  foetus.  These  vascular  tufts  are  covered  with 
epithelium,  and  project  into  corresponding  depressions  in  the  mucous  mem- 
brane of  the  uterine  walls.  The  maternal  portion  of  the  placenta  consists  of  a 
large  number  of  cells  formed  by  an  enlargement  of  the  vessels  of  the  uterine 
wall,  and  conveying  the  uterine  blood  into  close  proximity  to  the  villi  of  the 
toetal  placenta,  which  dip  into  these  cells.  The  interchange  of  fluids,  necessary 
for  the  growth  of  the  foetus,  and  the  depuration  of  the  blood,  take  place  through 
the  wails  of  these  villi,  but  there  is  no  direct  continuity  between  the  maternal 
and  foetal  vessels.  The  arteries  open  into  the  placental  cells  somewhat  after  the 
manner  of  the  erectile  tissue.  The  veins  anastomose  freely  with  one  another, 
and  give  rise  at  the  edge  of  the  placenta  to  a  venous  channel  which  runs  aroun'J 
its  whole  circumference — the  placental  sinus. 


Sectional  plan  of  the  gravid  uteru?,  from  Wagner, 
in  the  third  and  fourth  month,  a.  Plug  of  mucus  in 
neck  of  uterus,  b.  Fallopian  tube.  c.  The  decidua 
Vera ;  c\  The  decidua  vera  passing  into  the  right 
Fallopian  tube.  The  cavity  of  the  uterus  i.i  almost 
completely  occupied  by  the  ovum,  e  e.  Points  of  the 
reflection  of  the  decidua  reflexa  (in  nature  the  united 
deciduaa  do  not  stop  here,  but  pass  over  the  whole 
uterine  surface  of  the  placenta),  g.  Supposed  allan- 
tois.  h.  Umbilical  vesicle,  t.  Amnion,  k.  Chorion, 
covered  with  the  decidua  reflexa.  d.  Cavity  of  tho 
decidua,    f.  Decidua  serotina,  or  placentol  decidua. 


96 


GENERAL    ANATOMY. 


The  umbilical  cord  appears  about  the  end  of  the  fifth  month  after  pregnancy. 
It  consists  of  the  coils  of  two  arteries  (umbilical)  and  a  single  vein,  united  to- 
gether by  a  gelatinous  mass  (gelatin  of  Wharton)  contained  in  the  cells  of  an 
areolar  structure.  There  are  originally  two  umbilical  veins,  but  one  of  these 
vessels  becomes  obliterated,  as  do  also  the  two  omphalo-mesenteric  arteries  and 
veins,  and  the  duct  of  the  umbilical  vesicle,  all  of  which  are  originally  con- 
tained in  the  rudimentary  cord.  The  permanent  structures  of  the  cord  are 
therefore  those  furnished  by  the  allantois. 

Orowih  of  the  Embryo. — The  youngest  human  embryos  which  have  been  met 
with  are  two  described  by  Dr.  A.  Thomson,  in  the  "Edinb.  Med.  and  Surgical 
Journal,  1839,"  and  in  his  paper  references  to  the  other  extant  descriptions  of 
early  ova  will  be  found.  The  ova  in  question  were  believed  to  be  of  the  ages  re- 
spectively of  twelve  to  fourteen  days,  and  about  fifteen  days.'  The  figures  are  here 
reproduced.  The  earliest  ovum  (Fig.  56)  was  /^  of  an  inch  in  diameter,  when 
freed  from  some  adherent  decidua.    The  chorion  presented  a  slightly  villous  ap- 


Fiff.  56. 


Fig.  57. 


Fiff.  58. 


I 


Human  ovum,  12  to  14  dnys. 
1.  Natural  size.     2    Enlarged. 


Human  ovum, 
15  days. 


Embryo  from  the  preceding  ovura.  1.  Umbilical 
vesicle.  2.  Medullary  groove.  3.  Cephalic  por 
tion  of  the  embryo.  4,  Cnudal  portion.  5.  Frag 
ment  of  membrane  (amnion?). 


pearance,  and  consisted  only  of  one  layer  of  membrane.  On  opening  it  the  um- 
bilical vesicle  and  embryo  were  found  not  to  fill  its  cavity  completely.  The 
embryo  was  a  line  in  length,  and  nearly  ^V  of  an  inch  in  thickness.  The  chorion 
was  united  to  the  embryo  and  umbilical  vesicle  by  a  thin  tenacious  web  of  albu- 
minous filaments,  formed  probably  by  coagulation  in  the  spirit  in  which  it  had 
been  kept.  There  were  no  vessels  on  the  umbilical  vesicle.  The  abdomen  of  the 
embryo  presented  no  appearance  of  intestine,  but  merely  a  long  shallow  groove, 
forming  a  common  cavity  with  the  yelk-sac.  Around  this  intestinal  groove  the 
germinal  membrane  was  continuous  with  that  on  the  surface  of  the  yelk-sac. 
One  extremity  of  the  embryo,  probably  the  cephalic,  was  enlarged,  but  this  the 
author  believed  to  be  accidental.  A  more  opaque  and  expanded  portion  be- 
tween the  cephalic  extremity  and  the  surface  of  the  yelk-sac  appeared  to  him 
to  indicate  the  rudimentary  heart. 

The  second  embryo  (Figs.  67,  58)  was  in  a  slightly  more  advanced  condition. 
In  it,  as  in  the  former,  the  amnion  and  allantois  were  not  found,  though  the 
adhesion  of  the  embryo  by  its  dorsal  aspect  to  the  inner  side  of  the  chorion 
renders  it  probable  that  the  amnion  was  formed.  The  cephalic  and  caudal 
extremities  could  be  easily  distinguished ;  the  vertebral  groove  appeared  to  be 
open  in  its  whole  extent;  there  was  a  more  perfect  intestinal  groove  than  in 
the  former  case,  and  there  was  an  irregular  shaped  mass  between  the  yelk  and 
the  cephalic  extremity  of  the  embryo,  which  Professor  Thompson  believed  to 


1 


'  For  the  data  on  which  these  calculations  are  founded,  the  reader  is  referred  to  the  original 
paper. 


GROWTH    OF    THE    EMBRYO. 


9T 


Fia-.  69. 


be  the  rudiment  of  the  heart.     No  distinct  trace  of  the  omphalo- mesenteric 
vessels  could  be  observed,^ 

In  an  embryo  of  fifteen  to  eighteen  days,  described  by  Coste,  the  villi  of  the 
chorion  were  well  formed,  the  umbilical  vesicle  communicated  largely  with  the 
intestine,  and  the  allantois  was  present,  united  to 
the  inner  surface  of  the  chorion,  and  communicat- 
ing by  a  large  pedicle  with  the  intestine.  Both 
the  allantois  and  umbilical  vesicle  were  vascular. 
The  amnion  was  not  yet  closed. 

In  ova  of  the  third  and  fourth  week  the  amnion 
has  been  found  closed,  the  rudiments  of  the  eye, 
ear,  maxillary  projections,  pharyngeal  arches,  cere- 
bral vesicles,  anterior  and  posterior  extremities, 
liver  and  umbilical  cord  are  observed  (Fig.  59). 

The  further  development  of  the  embryo  will 
perhaps  be  better  understood  if  we  follow  as  briefly 
as  possible  the  principal  facts  relating  to  the  chief 
the  cranium,  the  pharyngeahcavity,  mouth,  &c.,  the 
nervous  centres,  the  organs  of  the  senses,  the  circu- 
latory system,  the  alimentary  canal  and  its  append- 
ages, the  organs  of  respiration,  and  the  genito- 
parts  of  which  the  body  consists,  viz.,  the  spine, 
urinary  organs.^  The  reader  is  also  referred  to  the 
table  of  the  development  of  the  foetus  on  page  112. 


Human  embryo  in  the  fourth  week. 
1.  Amnion  removed  in  part  of  the 
dorsal  region.  2.  Umbilical  vesicle, 
3.  Omphalo-mesenteric  duct.  4.  In- 
ferior maxillary  tubercle  of  first  phn- 
ryngeal  arch.  5.  Superior  ma.xillary 
tubercle  from  the  same  arch.  6. 
Second  pharyngeal  arch.  7.  Third. 
8.  Fourth.  9.  Eye.  10.  Primitive 
auditory  vesicle.  11.  Anterior  ex 
tremity.  12.  Posterior  extremity. 
13.  Umbilical  cord.  14.  Heart.  15- 
Liver. 


Development  of  the  Spine. — The  first  trace  of  the 
future  spinal  column  is  found  at  a  very  early  period 
of  foetal  life,  constituting  the  chorda  dorsalis  or 
notochord  (Fig.  53).  This  is  a  cylindrical  tube, 
composed  of  a  transparent  sheath,  containing  em- 
bryonic cells,  and  extending  from  the  cephalic  to 
the  caudal  extremity  of  the  foetus  below  the  spinal  canal,  ^he proto-vertehrse  or 
primitive  vertehrse  appear  early,  as  dark  spots,  which  soon  enlarge  and  form 
quadrangular  laminae,  one  on  either  side  of  the  chorda  dorsalis,  commencing  in 
the  cervical  region.  These  spread  out  and  bend  towards  each  other,  so  as  to 
come  into  contact  around  the  spinal  canal  and  inclose  it,  forming  the  rudiment 
of  the  future  bodies  and  arches  of  the  vertebrae,  as  well  as  of  the  vertebral  and 
other  muscles.  This  primitive  vertebral  column  is,  however,  entirely  mem- 
branous until  about  the  sixth  or  seventh  week,  when  cartilage  begins  to  be 
deposited  in  it.  The  proto-vertebree  do  not  coincide  with  the  permanent  verte- 
brae. On  the  contrary,  each  primitive  vertebra  separates  into  two  parts,  the 
upper  part  belonging  to  the  permanent  vertebra,  which  lies  above  the  point  of 
separation,  and  the  lower  one  to  that  below.  The  chorda  dorsalis  becomes 
gradually  atrophied,  except  at  the  part  corresponding  to  the  intervals  between 
the  permanent  vertebrae,  where  it  forms  the  intervertebral  disks,  (The  particular 
facts  relating  to  the  ossification  of  the  spinal  column  will  be  found  under  the 
description  of  the  Vertebrse.) 

Development  of  the  Cranium  in  general,  and  of  the  Face. — The  foetal  cranium 
is  developed  from  the  primitive  vertebral  disks  surrounding  the  upper  extremity 

'  A  third  early  embryo  is  figured  and  described  in  this  paper,  but  the  author  is  more  uncertain 
as  to  its  date. 

^  The  scope  of  this  work  only  permits  the  briefest  possible  reference  to  these  subjects.  Those 
who  wish  to  study  the  subject  of  embryology  in  more  detail  are  referred  to  Kiilliker's  Entwicke- 
lunijsgeschichte,  to  the  chapters  on  the  development  of  the  various  organs  iu  the  7th  edition  of 
(iuain's  Anatomy,  or  to  Beaunis  et  Bouchard,  Nouvc.aux  Elements  d'Anatomie  descn'pttye  et 
u'Einbryoloyie;  to  the  latter  of  which  works  espeoially  the  editor  must  express  his  obligations. 


98 


GENERAL    ANATOMY. 


Fig.  60. 


of  the  chorda  dorsalis.  These  advance  in  the  form  of  a  membranous  capsule, 
which  covers  the  end  of  the  chorda  dorsalis,  forming  the  rudiment  of  the  base 
of  the  skull,  and  moulds  itself  on  the  cerebral  vesicles,  so  as  to  constitute  the 
membrane  in  which  the  vault  of  the  skull  is  developed.  The  membranous 
capsule  presents  at  the  base  of  the  skull  two  thickenings  (lateral  trabeculae  of 
Eathke)  directed  forwards,  and  inclosing  an  opening  (pituitary  opening)  which 
is  partly  closed  by  a  thinner  membrane — the  middle  trabecula.  The  upper  end 
of  the  chorda  dorsalis  terminates  in  a  pointed  extremity,  which  extends  about 
as  far  forwards  as  the  body  of  the  sphenoid  bone,  where  it  becomes  lost  about 
the  situation  of  the  pituitary  body.  The  membrane  becomes  replaced  by  carti- 
lage in  the  part  corresponding  to  the  base  of  the  skull  and  the  trabeculae.  A 
portion  of  this  primitive  cartilaginous  cranium  becomes  atrophied  and  disap- 
pears, a  portion  persists — forming  the  cartilages  of  the  nose  and  those  of  the 
articulations;  the  rest  forms  the  cartilaginous  nidus  of  the  basilar  part  of  the 
occipital,  the  greater  part  of  the  sphenoid,  the  petrous  and  mastoid  portions  of 
the  temporal,  the  ethmoid  bone,  and  the  septum  nasi.  / 

As  the  cerebral  extremity  of  the  foetus  grows  it  becomes  twice  bent  forwards 
on  its  own  axis  (Fig.  61).  The  upper  or  posterior  curvature  is  called  the  cere- 
bral ;  the  lower  or  anterior,  the  frontal  pro- 
tuberance. From  the  anterior  end  of  the 
chorda  dorsalis  four  prolongations  proceed 
on  either  side,  and  meet  in  the  middle  line 
(Fig.  60,  4,  7,  8,  9).  These  are  the  pharyn- 
geal arches,  and  in  them,  and  in  the  frontal 
protuberance,  certain  bones  are  developed, 
which  are  called  secondary  bones,  to  distin- 
guish them  from  those  above  enumerated, 
which  are  formed  from  the  primitive  cra- 
nium itself.  Between  the  first  pharyngeal 
arch  and  the  frontal  protuberance  is  situated 
the  buccal  depression,  which  afterwards  be- 
comes the  cavity  of  the  mouth.  The  frontal 
protuberance  next  gives  off  two  lateral  parts 
(lateral  frontal  protuberances),  on  each  of 
which  a  depression  is  formed,  the  olfactory 
fossa,  bounded  on  either  side  by  the  internal 
and  external  nasal  processes.  There  is  a 
groove  external  to  the  external  nasal  pro- 
cess, which  afterwards  is  transformed  into 
the  lachrymal  canal,  and  another  groove 
leading  from  the  olfactory  fossa  to  the  buc- 
cal cavity — the  nasal  groove. 

The  first  pharyngeal  arch  divides  at  its 
anterior  extremity  into  two  parts — a  superior 
and  inferior  maxillary  protuberance.  The 
latter  unites  very  early  to  its  fellow  of  the 
opposite  side  to  form  the  lower  jaw.  The 
superior  maxillary  protuberances  are  displaced  outwards  and  unite  to  the  ex- 
ternal nasal  process;  from  this  part  are  developed  the  internal  plate  of  the 
pterygoid  process,  the  palate  bone,  the  superior  maxillary,  and  the  malar.  The 
lateral  masses  of  the  ethmoid,  the  os  unguis,  and  nasal  bones  are  furnished  by 
the  internal  nasal  process.  The  rest  of  these  processes  on  either  side  are  united 
into  a  single  protuberance,  the  incisive  tubercle,  from  which  the  intermaxillary 
bone  and  the  middle  of  the  upper  lip  are  formed,  and,  according  to  some,  the 
vomer. 

Besides  the  lower  jaw,  the  inferior  maxillary  protuberance  furnishes  a  transi- 
tory cartilaginous  mass — the  cartilage  of  Meckel — from  which  the  malleus  and 

I 


I 


Ftifie  of  an  embryo  of  25  to  28  dayn.  (Mag- 
nifieil  15  times  )  1.  Frontal  prominence.  2, 
3.  Right  nnd  left  olfactory  fossae.  4.  Infe- 
rior maxillory  tubercles,  united  in  the  middle 
line.  6.  Superior  maxillary  tubercles.  6. 
Mouth.  7.  Second  pharyngeal  arch.  8. 
Third.  9.  Fourth.  10.  Primitive  ocular 
vesicle.     11.  Primitive  auditory  vesicle. 


DEVELOPMENT  OF  THE  NERVOUS  CENTRES. 


9i) 


incus  are  formed.  The  remains  of  Meckel's  cartilage  persist  as  long  as  till  the 
end  of  the  seventh  or  the  eighth  month  of  foetal  life,  in  the  form  of  a  rod  of 
cartilage  lying  inside  the  lower  jaw.  From  the  second  pharyngeal  arch  are 
formed  the  stapes  and  stapedius  muscle,  the  pyramid,  the  styloid  process,  the 
stylohyoid  ligament,  and  tlie  small  cornu  of  the  hyoid  bone.  The  great  cornu 
and  body  of  the  hyoid  bone  are  developed  from  the  third  arch,  wdnle  the  fourth 
pharyngeal  arch  enters  merely  into  the  formation  of  the  soft  parts  of  the  neck, 
and  does  not  give  origin  to  any  special  organ.  The  pharyngeal  or  branchial 
fissures  are  four  in  number,  tlie  fourth  being  situated  behind  or  below  the 
fourth  arch ;  the  first  persists,  though  only  in  a  portion  of  its  extent,  forming 
the  Eustachian  tube,  the  meatus  auditorius,  and  the  tympanic  cavity.  The 
other  fissures  are  wholly  closed  by  the  sixth  week. 

Development  of  the  Palate. — The  buccal  cavity  is  at  first  common  to  the  mouth 
and  nose.  Then  a  lamella  is  given  off  from  the  superior  maxillary  tuberosity 
on  either  side,  which  is  directed  horizontally  inwards.  These  two  palatine 
lamellas  meet  in  the  median  line,  in  front,  about  the  eighth  week,  and  by  the 
ninth  week  the  septum  should  be  complete.  The  superior  maxillary  bones 
proper,  and  the  soft  parts  covering  them,  unite  at  an  early  period  with  the  in- 
cisive bone,  and  the  median  portion  of  the  lower  lip.  The  olfactory  fossae  open 
into  the  upper  (respiratory)  portion  of  the  cavity,  forming  the  nostrils.  The 
student  will  notice  that  the  various  forms  of  harelip  correspond  to  various 
interruptions  of  the  process  of  union ;  thus  the  ordinary  single  harelip  on  one 
side  of  the  median  line  results  from  the  mere  absence  of  union  on  that  side, 
between  the  soft  parts  which  cover  the  incisive  bone  and  those  connected  with 
the  proper  superior  maxillary;  if  this  occurs  on  both  sides,  we  have  the  sim- 
plest form  of  double  harelip ;  if  besides  this  the  intermaxillary  bone  remains 
ununited,  it  usually  is  carried  forward  at  the  end  of  the  vomer,  forming  the 
double  harelip,  complicated  with  projection  of  the  intermaxillary  bone;  if, 
added  to  this,  the  palatine  lamellae  also  remain  unu- 
nited, we  have  the  complete  degree  of  fissured  palate  Fig.  61. 
and  harelip.  Fissure  of  the  soft  palate  only,  or  of  -^t^  7  6 
the  soft  and  a  portion  of  the  hard,  represent  various 
degrees  of  non-union  of  the  palatine  lamellae. 

Development  of  the  Nervous  Centres. — The  medullary 
groove  above  described  (page  91  )  presents  about 
the  third  week  three  dilatations  at  its  upper  part, 
separated  by  two  constrictions,  and  at  its  posterior 

Eart  another  dilatation  called  the  rhomboidal  sinus, 
oon  afterwards  the  groove  becomes  a  closed  canal 
(medullary  canal),  and  a  soft  blastema  is  deposited 
in  it  which  lines  it,  corresponding  to  its  dilatations, 
and,  like  it,  assuming  a  tubular  form.  This  is  the 
rudiment  of  the  cerebro-spinal  axis.  As  the  embryo 
grows,  its  cephalic  part  becomes  more  curved,  and 
the  three  dilatations  in  the  anterior  end  of  the  primi- 
tive cerebro-spinal  axis  become  vesicles  distinctly 
separated  from  each  other  (Fig.  61).  These  are  the 
cerebral  vesicles — anterior,  middle,  and  posterior. 
The  anterior  cerebral  vesicle  (situated  at  this  period 
quite  below  the  middle  vesicle)  is  the  rudiment  of 
the  lateral  and  third  ventricles,  and  of  the  parts  sur- 
rounding them — viz.,  the  cerebral  hemispheres,  optic  thalami,  corpora  striata, 
corpus  callosum,  fornix,  and  all  the  parts  which  form  the  floor  of  the  third 
ventricle.  The  middle  vesicle  represents  the  aqueduct  of^  Sylvius,  with  the 
corpora  quadrigemina,  and  the  crura  cerebri.     The  posterior  vesicle  is  deve- 


Longitudinal  section  of  the  head 
of  an  embryo  four  weeks  old  seen 
from  the  inside.  1.  Oculnr  vesi- 
cle. 2.  Optic  nerve  flattened  out. 
3.  Pore  brain.  4.  Intermediary 
brain.  6.  Middle  brain.  6.  Hind- 
er brain.  7.  After-brain.  8.  An- 
terior portion  of  the  tentorium 
cerebelli.  9.  Its  lateral  portion 
interveninf^  between  Nos.  4  and 
5.  10.  The  pharyngeal  curve, 
bent  into  a  cul-de-sao.  11.  The 
auditory  vesicle. 


100 


GENERAL    ANATOMY. 


loped  into  the  fourth  ventricle,  and  its  walls  form  the  cerebellum,  pons  Varolii, 
medulla  oblongata,  and  parts  in  the  floor  of  the  fourth  ventricle.  The  antero- 
posterior fissure  which  indicates  the  division  of  the  brain  into  two  halves 
appears  early,  and  the  primary  anterior  and  posterior  cerebral  vesicles  are 
also  soon  divided  by  a  transverse  fissure  into  two  parts,  so  as  to  constitute  five 
permanent  rudiments  of  the  brain  and  medulla  oblongata.  The  middle  pri- 
mary vesicle  remains  undivided. 

The  anterior  part  of  the  anterior  cerebral  vesicle  (Yorderhirn,  fore  brain) 
constitutes  the  cerebral  hemispheres,  corpus  callosum,  corpora  striata,  fornix, 
lateral  ventricles,  and  olfactory  nerves.  These  parts  lie  at  first  quite  covered 
and  concealed  by  those  formed  from  the  middle  vesicle,  and  by  the  optic 
thalami,  which,  with  the  optic  nerves,  the  third  ventricle,  and  the  parts  in 
its  floor,^  are  furnished  by  the  posterior  portion  of  the  anterior  vesicle  (Zwis- 
chenhirn,  intermediary  brain).  By  the  third  month,  however,  the  hemis- 
pheres have  risen  above  the  optic  thalami,  and  by  the  sixth  month  above  the 
cerebellum.  Fissures  are  seen  on  the  surface  of  the  hemispheres  at  the  third 
month,  but  all  except  one  disappear.  This  one  persists,  and  forms  the  fissure  of 
Sylvius.  The  permanent  fissures  for  the  convolutions  do  not  form  till  about 
the  seventh  or  eighth  month.  The  middle  cerebral  vesicle  (Mittelhirn,  middle 
brain)  is  at  first  situated  at  the  summit  of  the  angle  shown  on  Fig.  61.  Its  sur- 
face, at  first  smooth,  is  soon  divided  by  a  median  and  transverse  groove  into 
four  tubercles  (tubercula  quadrigemina),  which  are  gradually  covered  in  by  the 
growth  of  the  cerebral  hemispheres.  The  cavity  diminishes  as  its  walls  thick- 
en, and  contracts  to  form  the  aqueduct  of  Sylvius.  The  crura  cerebri  are  also 
formed  from  this  vesicle.  The  third  primary  cerebral  vesicle  is  divided  at  an 
early  period  (between  the  ninth  and  twelfth  week)  into  two,  the  anterior  part 

(Hinterhirn,  hinder  brain),  forming  the  cerebellum,  and 
a  membrane  (membrana  obturatrix),  which  closes  the 
upper  part  of  the  fourth  ventricle,  and  which  disap- 
pears as  development  progresses;  its  posterior  part 
(Nachhirn,  after-brain)  forms  the  medulla  oblongata, 
with  the  restiform  bodies  and  auditory  nerves. 

When  the  medullary  groove  is  closed,  the  foetal 
spinal  marrow  at  first  occupies  the  whole  of  the  canal 
so  formed.  It  presents  at  first  a  large  central  canal, 
which  gradually  contracts,  and  in  after  life  is  no 
longer  perceptible  to  the  eye,  though  it  is  still  visi- 
ble on  microscopic  sections  (p.  64).  After  the  fourth 
month  the  spinal  column  begins  to  grow  in  length 
more  rapidly  than  the  medulla,  so  that  the  latter  no 
longer  occupies  the  whole  canal.  The  ganglia  and 
anterior  roots  of  the  nerves  are  perceptible  at  the 
fourth  week,  the  posterior  roots  at  the  sixth.  The 
cord  is  composed  at  first  entirely  of  uniform- looking 
cells,  which  soon  separate  into  two  layers,  the  inner 
of  which  forms  the  epithelium  of  the  central  canal, 
while  the  outer  forms  the  central  gray  substance  of 
the  cord.  The  white  columns  are  formed  later;  their 
rudiments  can  be  detected  about  the  fourth  week. 
The  central  canal  of  the  spinal  cord  is  at  first  unclosed 
behind,  except  by  the  epithelial  layer,  but  at  the  ago 
of  nine  weeks  the  medullary  substance  is  united  hero 
also.  The  ganglia  appear  to  be  developed  from  the 
protovertebral  disks,  and  it  is  possible  that  the  posterior  roots  also  are ;  the 
anterior  roots  ])roceed  from  the  medulla  itself.     The  development  of  the  nerves 


7  S 

Section  of  the  medulla  in  ibe 
cervical  region,  at  six  weeks 
(magnified  60  dinmelers).  1. 
Central  canal.  2.  Its  epithe- 
lium. .3.  Anterior  gray  m;itter 
4.  Posterior  gray  matter.  5. 
Anterior  commissure.  6.  Pos- 
terior portiiin  of  the  canal, 
closed  by  the  epithelium  only. 
7.  Ant?rior  column.  8.  Late- 
ral column.  9.  Posterior  col- 
umn. 10.  Anterior  roots.  11. 
Posterior  roots. 


'  The  development  of  the  pituitary  body  is  still  a  matter  of  question. 


DEYELOPMENT    OF    THE    ORGANS    OF    SENSE.  101 

has  not  yet  been  followed.     The  sympathetic  can  be  seen  as  a  knotted  cord  at 
the  end  of  the  second  month. 

The  cerebral  and  spinal  membranes  are  also,  according  to  Kiilliker,  a  pro- 
duction from  the  protovertebral  disks,  and  are  recognizable  about  the  sixth 
week.  As  the  fissures  separating  the  parts  of  the  cerebro-spinal  axis  appear, 
the  membranes  extend  down  them,  and  the  pia  mater  passes  into  the  cerebral 
ventricles.  Bischoff,  however,  describes  the  pia  mater  and  arachnoid  as  deve- 
loped from  the  cerebral  vesicles,  and  formed  in  the  position  which  they  perma- 
nently occupy. 

Development  of  the  Eye. — The  first  rudiment  of  the  eye  is  seen  about  the  third 
week,  in  a  vesicle  (primitive  ocular  vesicle),  which  communicates  with  the  first 
cerebral  vesicle,  and  after  the  latter  is  divided  into  two,  communicates  with  its 
posterior  division — the  Zwischenhirn  or  intermediary  brain — by  a  hollow 
stalk,  which  afterwards  becomes  the  optic  nerve.  This  primitive  ocular  vesi- 
cle, derived  from  the  cerebral  mass,  is  invested  by  a  layer  from  the  epidermic 
lamina  of  the  blastoderm ;  from  the  latter  layer  are  derived  the  conjunctiva, 
the  epithelium  of  the  cornea,  and  the  crystalline  lens ;  while  the  cephalic  layer 
gives  origin  to  the  vitreous  body,  the  fibrous  coat  of  the  eye  (sclerotic  and 
cornea),  the  choroid  and  iris,  and  the  retina. 

The  lens  is  formed  by  a  thickening  of  the  epidemic  layer,  opposite  to  the 
primitive  ocular  vesicle,  by  which  that  vesicle  is  at  first  depressed,  and  then 
reversed  in  the  manner  indicated  by  the  annexed  figures;  so  that  the  cavity  of 
the  primitive  ocular  vesicle  is  finally  obliterated.  As  this  process  takes  place, 
a  secondary  cavity  (secondary  ocular  vesicle)  is  formed  between  the  rudi- 
mentary lens  and  the  coats  of  the  reversed  primitive  vesicle,  and  in  this  space 
the  vitreous  humor  is  secreted. 


Diagram  of  development  of  the  lens.  ABC.  Different  stages  of  development.  1.  Epidermic  layer.  2. 
Thickening  of  this  layer.  3.  Crystalline  depression.  4.  Primitive  ocular  vesicle,  its  anterior  part  pushed 
back  by  the  crystalline  depression.  6.  Posterior  part  of  the  primitive  ocular  vesicle,  forming  the  external 
Inyer  of  the  secondary  ocular  vesicle.  6.  Point  of  separation  between  the  lens  and  the  epidermic  layer.  7. 
Cavity  of  the  secondary  ocular  vesicle,  occupied  by  the  vitreous. 

The  lens  is  at  first  a  mere  depression  in  the  epidermic  layer.  When  this  is 
closed  the  lens  becomes  a  vesicle,  formed  of  epithelial  cells,  which  grow  and 
fill  its  cavity,  becoming  gradually  transformed  into  fibres.  It  is  at  first  sur- 
rounded by  a  vascular  membrane — the  vascular  capsule  of  the  lens — which  is 
connected  with  the  termination  of  the  temporary  artery  (hj'-aloid)  that  forms  the 
continuation  of  the  central  artery  of  the  retina  through  the  vitreous  chamber. 
This  vascular  capsule  of  the  crystalline  lens  forms  the  membrane  papillaris 
(described  under  the  Anatomy  of  the  Eye),  and  attaches  the  borders  of  the  iris 
to  the  capsule  of  the  lens.     It  disappears  about  the  seventh  month. 

The  sclerotic  and  cornea,  except  the  epithelial  layer  of  the  latter,  are  formed 
from  the  outer  layer  of  the  reversed  primitive  ocular  vesicle,  the  retina  from 
the  inner  layer;  the  pigment  of  the  choroid  is  also  derived  from  the  inner  layer, 
its  proper  tissue  from  one  of  these  layers,  but  which  has  not  yet  been  deter- 
mined. The  cavity  of  the  primitive  ocular  vesicle  disappears  as  that  of  the 
optic  nerve  does. 


102  GENERAL    ANATOMY. 

The  eyelids  are  formed  at  the  end  of  third  month,  as  small  cutaneous  folds, 
which  come  together  in  front  of  the  globe  and  cohere.  This  union  is  broken 
up,  and  the  eyelids  separate  before  the  end  of  foetal  life. 

The  lachrymal  canal  appears  to  result  from  the  non-closure  of  a  fissure  which 
exists  between  the  external  nasal  process  and  the  maxillary  process  (p.  98). 

Development  of  the  Ear. — The  first  rudiment  of  the  ear  appears  about  the  same 
time  as  that  of  the  eye,  in  the  form  of  a  vesicle  (primitive  auditory  vesicle.  Fig. 
60,  11)  situated  close  on  the  outside  of  the  third  cerebral  vesicle,  though  not 
communicating  with  it.  It  is  formed  by  a  depression  of  the  epithelium  over 
the  second  pharyngeal  arch,  which  becomes  converted  into  a  closed  sac.  From 
this  vesicle  the  internal  ear  is  developed.  The  auditory  nerve  is  described  either 
as  a  projection  from  the  third  cerebral  vesicle,  or  as  an  independent  formation 
which  unites  with  both,  and  thus  establishes  a  communication  between  the 
cerebral  and  the  auditory  vesicles.  The  middle  ear  and  Eustachian  tube  con- 
stitute the  remains  of  the  first  pharyngeal  or  branchial  cleft.  The  formation 
of  the  ossicles  of  the  tympanum  has  been  already  pointed  out,  viz.,  the  yicus 
and  malleus  from  Meckel's  cartilage,  and  the  stapes,  with  its  muscle,  from  the 
second  pharyngeal  arch.  These  parts  project  into  the  first  pharyngeal  cleft, 
which  remains  occupied  by  connective  tissue  during  the  whole  of  foetal  life, 
according  to  Kolliker.  The  membrana  tympani  forms  across  the  cleft,  dividing 
it  into  an  outer  and  inner  portion.  The  pinna,  or  external  ear,  is  developed 
from  the  soft  parts  covering  the  first  pharyngeal  arch. 

Development  of  the  Nose. — Two  fossae  (olfactory  fossae)  have  been  already 
spoken  of,  which  are  found  below  and  in  front  of  the  ocular  vesicles  and  the 
upper  maxillary  projection  (Fig.  60,  2,  3).  They  appear  about  the  fourth  week. 
Their  borders  become  prominent,  and  the  fossae  deepen,  except  at  the  lower 
part,  where  they  lead  by  a  groove  (olfactory  groove)  into  the  buccal  cavity. 
This  groove  is  bounded  by  the  internal  and  external  nasal  process.  As  the 
superior  maxillary  projection  increases,  the  olfactory  groove  is  transformed 
into  a  deep  canal,  the  rudiment  of  the  two  superior  meatus  of  the  nose.  As  the 
palatine  septum  is  formed,  the  buccal  cavity  is  divided  into  two  parts,  the  upper 
of  which  represents  the  inferior  meatus  of  the  nose,  while  the  lower  forms  the 
mouth.  The  soft  parts  of  the  nose  are  formed  from  the  coverings  of  the  frontal 
projection,  and  of  the  olfactory  fossae.  The  nose  is  perceptible  about  the  end 
of  the  second  month.  The  nostrils  are  at  first  closed  by  epithelium,  but  this 
disappears  about  the  fifth  month. 

The  olfactory  nerve,  as  above  pointed  out,  is  a  prolongation,  at  first  in  the 
form  of  a  hollow  stalk,  from  the  anterior  cerebral  vesicle. 


The  Development  of  the  Teeth  is  spoken  of  in  the  body  of  the  work. 


Development  of  the  Skin,  Glands,  and  Soft  Parts. — The  epidermis  is  produce 
from  the  external,  the  true  skin  from  the  middle  blastodermic  layer  (Fig.  53, 
19,  20).  About  the  fifth  week  the  epidermis  presents  two  layers,  the  deeper 
one  corresponding  to  the  rete  mucosum.  The  subcutaneous  fat  forms  about  the 
fourth  month,  and  the  papillae  of  the  true  skin  about  the  sixth.  A  considerable 
desquamation  of  epidermis  takes  place  during  foetal  life,  and  this  desquamated 
epidermis  mixed  with  a  sebaceous  secretion  constitutes  the  vernix  caseosa,  with 
which  the  skin  is  smeared  during  the  last  three  months  of  foetal  life.  The  nails 
are  formed  at  the  third  month,  and  begin  to  project  from  the  epidermis  about 
the  sixth.  The  hairs  appear  between  the  third  and  fourth  month  in  the  form 
of  a  depression  of  the  deeper  layer  of  the  epithelium,  which  then  becomes 
inverted  by  a  projection  from  the  papillary  layer  of  the  skin.  The  papilla 
grows  into  the  interior  of  the  epithelial  layer,  and  finally,  about  the  fifth  month, 
the  foetal  hairs  (lanugo)  appear  first  on  the  head  and  then  on  the  other  parts. 


cea 


DEVELOPMENT    OF    THE    HEART    AND    VESSELS.       103 

These  hairs  drop  off  after  birth,  and  give  place  to  the  permanent  hairs.  The 
sudoriferous  and  sebaceous  glands  are  also  formed  from  the  epithelial  layer 
about  the  fifth  and  sixth  month  respectively.  The  mammary  gland  is  also 
formed  from  the  deeper  layer  of  the  epithelium.  Its  first  rudiment  is  seen 
about  the  third  month,  in  the  form  of  a  small  projection,  from  which  others 
radiate,  and  which  then  give  rise  to  the  glandular  follicles  and  ducts.  The 
development  of  the  former,  however,  remains  imperfect,  except  in  the  adult 
female,  and  especially  after  pregnancy. 

The  muscles  become  visible  about  the  seventh  or  eighth  week.  The  source 
of  their  development  is  not  completely  determined,  for  the  muscles  of  the 
limbs.  The  vertebral  muscles  appear  to  be  developed  from  the  "  muscular 
laminae"  of  the  primitive  vertebral  disks  (Fig.  53,  13),  and  the  muscles  of  the 
neck  and  jaws,  as  well  as  those  which  inclose  the  cavities  of  the  thorax  and 
abdomen,  are  also  formed  from  the  same  source.  They  do  not  meet  in  the 
middle  line  of  the  body  till  about  the  fourth  month.  The  cutaneous  muscles 
are  developed  from  the  cutaneous  portion  of  the  middle  blastodermic  layer. 

Development  of  the  Heart  and  Great  Vessels. — The  first  trace  of  the  heart  is 
found  about  the  tenth  or  twelfth  day,  in  the  form  of  a  mass  of  cells  proceeding 
from  the  middle  layer  of  the  blastodermic  vesicle,  and  the  anterior  wall  of  the 
intestinal  cavity.  It  soon  forms  a  bent  tube  lying  in  front  of  the  embryo,  and 
only  connected  to  it  by  its  vessels  (Fig,  59,  14).  The  heart  is  situated  at  first 
at  the  anterior  end  of  the  embryo,  lying  opposite  the  last  two  cerebral  vesicles. 
As  the  head  is  developed,  the  heart  falls  as  it  were  backwards  to  the  lower  part 
of  the  neck,  and  then  to  the  thorax.  It  fills  the  whole  thoracic  cavity  about 
the  second  month.  As  the  lungs  and  thoracic  parietes  form,  the  heart  assumes 
its  permanent  position.  The  tube  is  soon  curved  into  the  shape  of  the  letter 
S,  the  arterial  part  being  situated  above,  in  front,  and  to  the  right,  the  venous 
below,  behind,  and  to  the  left.  Traces  of  the  auricular  appendages  are  early 
perceptible  on  the  venous  part.  Then  the  walls  of  the  ventricular  portion  begin 
to  thicken  in  regard  to  the  auricular  part.  The  ventricle  is  separated  by  a  con- 
striction from  the  dilated  part  above,  which  corresponds  to  the  aortic  sinus  or 
bulb  (Fig.  64,  1),  and  from  the  posterior  or  auricular  dilatation.     Then  each  of 

Fiff.  64. 


i 

Heart  at  the  fifth  week.  A.  Opened  from  the  abdominal  aspect.  1.  Arterial  sinus.  2.  Aortic  arches 
uniting  behind  to  form  the  descending  aorta.  3.  Auricle.  4.  Auriculo-ventricular  orifice.  5.  Commencing 
septum  ventriculorum.  6.  Ventricle.  7.  Inferior  vena  cava.  B.  Posterior  view  of  the  snme.  1.  Trachea. 
2.  Lungs.  3.  Ventricles.  4,  5.  Auricles.  6.  Diaphragm.  7.  Descending  aorta.  8,  9,  10.  Pneumogostrio 
nerves  and  their  branches. 

these  three  parts  becomes  subdivided  by  a  septum.  After  the  completion  of 
the  ventricular  septum  the  auricular  is  commenced.  The  septum  ventriculorum 
is  at  first  almost  transverse,  and  divides  ofi:*  a  smaller  portion  (the  right  ven- 
tricle) from  the  common  cavity.  This  septum  is  complete  about  the  eighth 
week,  and  then  the  interauricular  begins  to  grow,  commencing  from  above  and 
behind,  and  coalescing  with  the  edge  of  the  interventricular  septum,  so  as  to 
leave  an  orifice  (auriculo-ventricular)  on  either  side.     The  auricular  septum, 


104 


GENERAL    ANATOMY. 


however,  is  not  complete  during  foetal  life,  but  leaves  an  aperture  (foramen 
ovale)  by  which  the  two  auricles  communicate. 

The  heart  is  at  first  composed  of  a  mass  of  foetal  cells,  but  its  rhythmic  con- 
tractions can  be  observed  even  in  this  condition  before  the  development  of  any 
muscular  fibres,  and  even,  according  to  some  authors,  before  it  is  in  connection 
with  any  vessels. 

The  vessels  which  are  in  communication  with  the  foetal  heart  are  as  follows: 
In  its  earliest  state  the  circulation  is  external  to  the  embryo.  This  primitive 
circulation  appears  about  the  fifteenth  day,  and  lasts  till  the  fifth  week.  It  con- 
sists of  two  arteries,  the  first  aortic  arches,  which  unite  into  a  single  artery, 
running  down  in  front  of  the  primitive  vertebrae  and  in  the  walls  of  the  intes- 
tinal cavity,  and  joining  in  a  single  artery,  which  again  divides  into  two 
primitive  aortse  or  vertebral  oxtQvies^  and  these  give  off  five  or  six  omphalo-mesenteric 
arteries,  which  ramify  in  the  germinal  area,  forming  with  their  parent  trunks 
a  close  network,  terminating  in  veins,  which  converge  towards  a  venous  trunk, 
the  terminal  sinus.  This  vessel  surrounds  the  vascular  portion  of  the  germinal 
area,  but  does  not  extend  up  to  the  anterior  end  of  the  embryo.  It  terminates 
on  either  side  in  a  vein  called  omphalo-mesenteric.  The  two  omphalo-mesen- 
teric veins  open  by  a  single  trunk  into  the  auricular  extremity  of  the  heart. 
This  primitive  circulation  extends  gradually  from  the  germinal  area  over  the 
whole  of  the  umbilical  vesicle,  and  disappears  as  the  latter  becomes  atrophied. 
In  a  more  advanced  state  of  the  embryo,  the  position  of  this  first  pair  of  aortic 
arches,  corresponds  to  the  first  pharyngeal  arch.  Next  in  succession,  other 
pairs  of  arches  are  formed  behind  the  first'  (Fig.  65).  The  total  number  is  five, 
but  the  whole  five  pairs  do  not  exist  together,  for  the  first  two  have  disappeared 
before  the  others  are  formed.  These  two  have  no  representatives  in  the  per- 
manent structures.  The  third  pair  gives  origin  to  the  carotids,  the  fourth  pair 
forms  the  innominata  and  subclavian  on  the  right,  the  arch  of  the  aorta  and 
subclavian  on  the  left.  The  fifth  forms  on  the  left  side  the  pulmonary  artery, 
the  ductus  arteriosus  and  the  descending  portion  of  the  thoracic  aorta.  Its 
right  branch  disappears. 

The  ascending  portion  of  the  arch  of  the  aorta,  and  the  root  of  the  pulmo- 
nary artery,  are  at  first  blended  together  in  the  common  dilatation  (aortic 
sinus),  which  has  been  above  spoken  of  as  connected  with  the  ventricular  end 
of  the  rudimentary  heart  (Fig.  64, 1).  The  septum  which  divides  this  common 
artery  into  two  begins  to  appear  very  earlj'-,  even  before  the  interventricular 
septum.  The  formation  of  the  permanent  vessels  is  shown  by  the  following 
diagram : — 

Fig.  65. 


I 


Diagram  of  the  formation  of  the  aortic  arches  and  the  liir<;e  arteries.  I.  II.  III.  IV.  V.  First,  second, 
third,  fourth  and  fifth  aortic  arches.  A.  Common  trunk  from  which  the  first  pair  spring;  the  place  uhero 
the  succeeding  pair.<  are  formed  is  indicated  by  dotted  lines.  B.  Common  trunlc,  with  four  arches  and  a  tr.TCO 
of  the  fifth.  C.  Common  trunk  with  tlie  tliree  last  pairs,  the  flriit  two  having  been  obliterated.  D.  The  per- 
sistent arteries,  those  which  have  dis.ippeared  being  indicated  by  dotted  lines.  1.  Common  arterial  trunk. 
2.  Thor.icio  iiorta.  3.  Right  branch  of  the  common  trunk,  which  is  only  temporary.  4.  Left  branch,  per- 
manent. 5.  Axillary  artery.  6.  Vertebrnl.  7.  8.  Subclavian.  9.  Common  carotid.  10.  External;  and 
11,  Internal  carotid.     12.  Aorta.     13.  Pulmonary  artery.     14,  15.  Right  and  left  pulmonary  arteries. 


•  The  position  of  the  first  fotir  of  these  aortio  arches  is  behind  the  corresponding  pharyns-eal 
arches,  and  that  of  the  fifth  behind  the  fourth  pharyngeal  cleft. 


DEVELOPMENT    OF    THE    VESSELS.  1C5 

The  descending  aorta  appears  to  be  the  remnant  of  the  artery  formed  by  the 
union  of  the  two  primitive  aortse.  The  omphalo-mesenteric  arteries,  which 
spring  from  these  latter,  all  disappear  except  one,  which  remains  as  the  superior 
mesenteric  artery.  The  umbilical  arteries  are  at  first  the  terminations  of  the 
two  primitive  aortse,  but  when  these  vessels  are  united  into  one,  the  umbilical 
arteries  appear  as  branches,  and  the  aorta  itself  ends  in  a  caudal  prolongation, 
which  afterwards  becomes  the  middle  sacral.  The  common  and  internal  iliac 
arteries  are  the  only  permanent  remains  of  the  umbilical  arteries  {see  Internal 
Iliac  Arteries.) 

Veins. — The  primitive  venous  circulation  has  been  described  above,  the  two 
omphalo-mesenteric  veins  opening  by  a  common  trunk  into  the  lower  end  of 
the  tube,  which  represents  the  heart.  The  next  state  of  the  venous  circulation 
is,  that  at  about  four  weeks  there  is  found  a  single  vein  lying  behind  the  in- 
testinal cavity  (not  in  front  of  it,  as  the  temporary  omphalo-mesenteric  veins 
do),  and  receiving  the  trunk  vein  from  the  intestine  (mesenteric).  Two  um- 
bilical veins  are  early  formed,  and  open  together  into  the  common  trunk  of 
the  omphalo-mesenteric  vein.  They  receive  branches  from  the  allantois  and 
anterior  surface  of  the  embryo.  The  right  vein  soon  disappears ;  the  left  um- 
bilical vein,  on  the  contrary,  grows  till  it  becomes  the  trunk  vessel  into  which 
the  omphalo-mesenteric  vein  and  its  mesenteric  branch  appear  to  open.  Next 
the  liver  begins  to  be  formed  around  the  umbilical  vein,  and  then  this  vein 
sends  branches  into  that  gland  (afferent  veins)  which  afterwards  become  the 
portal  veins  in  the  interior  of  the  liver,  and  which  give  origin  to  other  veins 
(efferent),  which  return  the  blood  from  the  liver,  and  form  afterwards  the 
hepatic  veins.  The  portion  of  the  umbilical  vein  between  the  giving  off  of 
the  future  portal  vessels  and  the  reception  of  the  hepatic,  forms  the  ductus 
venosus.  The  mesenteric  vein  communicates  at  first  with  the  omphalo-mesen- 
teric ;  when  the  veins  of  the  liver  are  formed,  the  omphalo-mesenteric  is  trans- 
ferred from  the  umbilical  vein  to  the  right  afferent  hepatic.  A  portion  of  it 
persists  and  forms  the  trunk  of  the  portal  vein. 

The  systemic  veins  are  developed  from  four  trunk  veins,  two  on  either  side, 
above  and  below,  which  appear  before  the  formation  of  the  allantois  or  the 
umbilical  vessels.  These  unite  into  one  canal  on  either  side  (canal  of  Cuvier), 
which  open  into  the  common  trunk  of  the  omphalo-mesenteric  veins,  and  so 
into  the  auricular  portion  of  the  rudimentary  heart.  These  four  primitive 
veins  lie,  two  of  them  in  front,  the  anterior  cardinal,  or  jugular  veins,  and  the 
other  two  behind,  the  posterior  cardinal  veins.  As  the  umbilical  vein  increases, 
and  the  omphalo-mesenteric  diminishes  in  volume,  the  sinuses  of  Cuvier  are 
transferred  to  the  former  vein,  and  when  the  inferior  cava  is  formed  and  the 
umbilical  vein  becomes  merely  its  tributary,  the  sinuses  of  Cuvier  open  into 
the  inferior  vena  cava.  At  a  later  period  the  portion  of  the  vena  cava  inferior, 
between  the  opening  of  the  sinuses  of  Cuvier  and  the  auricle,  disappears,  and 
then  the  auricle  receives  three  veins — viz.,  the  inferior  cava,  and  the  two  sinuses 
of  Cuvier,  which  are  now  called  right  and  left  superior  vena  cava  (Fig.  66). 
The  superior  cardinal,  or  jugular  veins,  which  form  the  upper  branches  of  the 
sinuses  of  Cuvier  on  either  side,  unite  about  the  second  month  by  a  transverse 
anastomosing  branch.  The  left  superior  vena  cava  assumes  an  oblique  posi- 
tion, and  empties  itself  into  the  lower  and  left  end  of  the  auricle.  Finally,  its 
trunk  disappears,  while  its  orifice  is  transformed  into  the  coronary  sinus,  in 
which  the  great  cardiac  vein  opens.  The  right  sinus  of  Cuvier,  or  superior 
vena  cava,  persists ;  the  transverse  anastomosing  branch  between  the  two  jugu- 
lars becomes  the  left  innominate  vein,  and  the  end  of  the  right  jugular  the 
right  innominate.  The  venous  circulation  in  the  lower  part  of  the  embryo  is 
at  first  carried  on  by  the  inferior  cardinal  veins,  which  return  the  blood  from 
the  Wolffian  bodies,  and  receives  branches  corresponding  to  the  intercostal, 
lumbar,  and  crural  veins. 


lOG 


GENERAL    ANATOMY, 


Between  the  fourth  and  fifth  week,  the  inferior  vena  cava  begins  to  appear 
in  the  form  of  a  vessel  which  passes  upwards  behind  the  liver  and  between  the 

Fig.  66. 


Diagram  of  the  formation  of  the  main  systemic  veins.  A.  Heart  and  venous  system  at  the  period  when 
there  are  two  ven89  cavse  siiperiores,  posterior  view.  1.  Left  superior  cava.  2.  Right  superior  cava.  3. 
Inferior  cava.  4.  Left  inferior  cardinal.  6.  Right  inferior  cardinal.  6.  Right  jugular.  7.  Anastomosing 
branch  between  the  jugulars  (left  innominate).  8.  Subclavians.  9.  Internal  jugular.  10.  External  jugu- 
lar. 11.  Middle  obliterated  portion  of  the  posterior  cardinal  veins.  12.  Newly  formed  posterior  vertebral 
veins.  13.  Anastomosis  between  the  two  vertebrals — trunk  of  small  azygos.  14.  Iliac  veins,  proceeding 
from  anastomosis  between  the  inferior  cava  and  posterior  cardinals.  15.  Crural.  16.  Hj'pogastric — origin- 
ally the  distal  ends  of  the  cardinals.  B.  Heart  and  permanent  vein,  posterior  view.  1.  Obliterated  left 
superior  cava.  6.  Right  innominate.  7.  Left  innominate.  8.  Subclavian.  10.  Jugular.  13.  Trunk  of 
the  small  a/ygos.  17.  Coronary  sinus  receiving  the  coronary  vein.  18.  Superior  intercostal.  19.  Su[ 
small  azygos.     20.  Inferior  small  asygos. 


ipe^l 


two  Wolffian  bodies.     It  anastomoses  below  with  the  two  cardinal  veins,  and 
with  the  crural  veins,  which  gradually  come  to  open  into  it. 

The  middle  part  of  the  cardinal  veins  disappears ;  their  distal  extremities 
persist  as  the  hypogastric  veins,  which  open  along  with  the  crural  into  the 
vena  cava,  forming  the  iliac  and  other  veins  of  the  lower  extremities.  The 
termination  of  each  cardinal  vein  above,  in  the  sinus  of  Cuvier,  or  superior 
cava,  also  persists.  The  central  atrophied  portion  of  the  cardinal  veins  is  re- 
placed by  a  vein  on  either  side,  called  posterior  vertebral,  which  receive  the 
intercostal  and  lumbar  veins,  and  are  soon  united  by  an  oblique  anastomosing 
branch.  The  right  vertebral  vein,  together  with  the  persistent  termination  of 
the  right  cardinal  vein,  forms  the  great  azygos  vein.  The  distal  portion  of  the 
left  vertebral  vein  with  the  oblique  anastomosing  branch,  forms  the  small 
azygos ;  and  the  upper  part  of  the  left  vertebral,  with  the  persistent  termina- 
tion of  the  left  cardinal,  forms  the  left  superior  intercostal  vein. 

The  Foetal  Circulation  is  spoken  of  in  the  body  of  the  work,  under  the 
subject  of  the  Thorax. 

Development  of  the  Alimentary  Canal. — The  development  of  the  intestinal 
cavity  is,  as  shown  above,  p.  97,  one  of  the  earliest  phenomena  of  embryonic 
life.  This  original  intestine  is  closed  at  either  end,  and  is  at  first  in  free  com- 
munication with  the  umbilical  vesicle  (Fig.  59,  3).  It  is  divided  into  three 
oarts:  the  anterior  or  cephalic  portion  of  the  primitive  intestine;  the  middle, 


DEVELOPMENT    OF    THE    ALIMENTARY    CANAL.       lOT 

and  the  posterior  or  pelvic.  From  the  first  is  formed  the  pharynx  and  oeso- 
phagus ;  from  the  second,  the  stomach,  small  intestine  and  large  intestine,  as  far 
as  the  upper  part  of  the  rectum ;  from  the  third,  the  middle  third  of  the  rec- 
tum. The  buccal  cavity,  on  the  one  hand,  and  the  lower  portion  of  the  rectum 
on  the  other,  are  separate  productions  from  the  external  layer  of  the  blasto- 
dermic membrane,  and  do  not  communicate  with  the  common  cavity  till  a  later 
period.  The  permanence  of  the  foetal  septum  in  either  case  constitutes  a  well 
known  deformity — imperforate  oesophagus  or  imperforate  rectum,  as  the  case 
may  be.  The  anal  cavity  is  at  first  common  to  the  urogenital,  as  well  as  to  the 
digestive  organs. 

The  development  of  the  palate  has  been  spoken  of  above. 

The  tongue  appears  about  the  fifth  week  as  a  small  elevation,  behind  the 
inferior  maxillary  arch,  to  which  is  united  another  projection  from  the  second 
pharyngeal  arch.  The  epithelial  layer  is  furnished  by  the  external  blastoder- 
mic membrane. 

The  tonsils  appear  about  the  fourth  month. 

The  middle  portion  of  the  primitive  intestine  is  at  first  a  straight  tube,  com- 
municating freely  with  the  umbilical  vesicle.  It  then  leaves  the  vertebral 
column  in  the  middle,  and  forms  a  curve  attached  to  that  column  by  the  mesen- 
tery. A  portion  of  the  intestine  above  this  mesentery  dilates  into  the  stomach, 
which  gradually  also  acquires  a  mesentery  of  its  own ;  the  rest  remains  at- 
tached to  the  spine,  and  forms  the  duodenum.  The  curve  of  the  intestine  ap- 
pears as  it  were  drawn  out  from  the  body  by  its  attachment  to  the  vitelline 
duct,  and  lies  external  to  the  parietes,  and  in  the  umbilical  cord,  until  the  end 
of  the  third  month,  when  it  passes  back  again  into  the  abdomen.  While  still 
forming  a  portion  of  the  cord,  the  intestine  begins  to  be  distinguished  into  large 
and  small,  for  the  anterior  or  upper  part,  corresponding  to  the  small  intestine, 
begins  to  assume  a  convoluted  arrangement  about  the  eighth  wxek,  whilst  the 
lower  part,  which  had  been  posterior,  passes  to  the  front  and  right  side  of  the 
other,  and  becomes  dilated  at  a  short -distance  from  the  insertion  of  the  vitelline 
duct,  to  form  the  rudiment  of  the  caecum.  When  the  intestine  lies  wholly  in 
the  belly,  the  curve  of  the  large  intestine  begins  rapidly  "to  form;  but  the 
caecum  lies  for  some  time  in  the  middle  line,  and  the  ascending  colon  is  not 
fully  formed  till  the  sixth  month. 

The  source  of  each  layer  of  the  intestine,  and  the  closure  of  the  omphalo- 
mesenteric or  vitelline  duct  have  been  spoken  of  (above  pp.  91,  94). 

The  liver  appears  after  the  Wolffian  bodies,  about  the  third  week,  in  the  form 
of  two  depressions  formed  by  the  epithelial  and  fibro-intestinal  layers  of  the 
blastodermic  membrane,  and  projecting  from  the  intestine  at  the  part  which 
afterwards  forms  the  duodenum.  These  depressions  are  developed  into  the 
right  and  left  lobes.  They  grow  very  rapidly  around  the  omphalo-raeseuteric 
vein,  from  which  they  receive  the  branches  enumerated  on  p.  106,  and  about 
the  third  month  the  liver  almost  fills  the  abdominal  cavity.  From  this  period 
the  relative  development  of  the  liver  is  less  active,  more  especially  that  of  the 
left  lobe,  which  now  becomes  smaller  than  the  right ;  but  the  liver  remains  up 
to  the  end  of  foetal  life  relatively  larger  than  in  the  adult. 

The  gall-bladder  appears  about  the  second  month,  and  bile  is  detected  in  the 
intestine  in  the  third  month. 

The  pancreas  is  also  an  early  formation,  being  far  advanced  in  the  second 
month.  It,  as  well  as  the  other  salivary  glands,  which  appear  about  the  same 
period,  originates  in  a  projection  from  the  epithelial  layer,  which  afterwards 
forms  a  cavity,  from  the  ramifications  of  which  the  lobules  of  the  gland  are 
formed. 

Development  of  the  Respiratory  Organs. — The  lungs  appear  somewhat  later 
than  the  liver.  They  are  developed  from  a  small  cul-de-sao  which  is  formed 
on  either  side  as  a  projection  from  the  epithelial  and  fibrous  laminae  of  the  in- 


108  GENERAL    ANATOMY. 

testine.  During  the  fourth  week  these  depressions  are  found  on  either  side, 
opening  freely  into  the  pharynx,  and  from  the  original  pouches  other  secondary 
pouches  are  given  off,  so  that  by  the  eighth  week  the  form  of  the  lobes  of  the 
lungs  may  be  made  out.  The  two  primary  pouches  have  a  common  pedicle  of 
communication  with  the  pharynx.  This  is  developed  into  the  trachea  (Fig. 
64),  the  cartilaginous  rings  of  which  are  perceptible  about  the  seventh  week. 
The  parts  which  afterwards  form  the  larynx  are  recognized  as  early  as  in  the 
sixth  week,  viz :  a  projection  on  either  side  of  the  pharyngeal  opening,  the 
rudiment  of  the  arytenoid  cartilages,  and  a  transverse  elevation  from  the  third 
pharyngeal  arch,  which  afterwards  become  the  epiglottis :  the  vocal  cords  and 
ventricles  of  the  larynx  are  seen  about  the  fourth  month.  The  traces  of  the 
diaphragm  appear  early,  in  the  form  of  a  fine  membrane,  separating  the  lungs 
from  the  Wolffian  bodies,  the  stomach  and  liver,  but  the  source  of  its  formation 
has  not  been  ascertained.  The  pleural  and  peritoneal  cavities  are  then  sepa- 
rated, having  been  common  up  to  this  time.  The  serous  membrane  of  the 
pleura  is  formed  about  the  tenth  week ;  but  its  development  is  also  unknown. 

Development  of  the  Oenito-urinary  Organs. — The  allantois  communicates  at 
first  with  the  lower  part  of  the  primitive  intestine  by  a  canal — the  urachus. 
After  the  second  month  the  lower  part  of  the  urachus  dilates,  so  as  to  form  the 
bladder,  which  then  communicates  above  with  the  cavity  of  the  urachus,  and 
below  with  the  rectum,  by  a  canal  of  communication  which  is  afterwards  trans- 
formed into  the  urethra.  The  urachus  is  obliterated  before  the  termination  of 
foetal  life;  but  the  cord  formed  by  its  obliteration  is  perceptible  throughout 
life,  passing  from  the  upper  part  of  the  bladder  to  the  umbilicus. 

The  kidneys  are  also  formed  from  the  lower  end  of  the  urachus.  They  are  at 
first  hollow  organs  lying  behind  and  below  the  Wolffian  body.  As  their  dis- 
tance from  the  bladder  increases,  the  ureters  become  developed,  and  the  simple 
cul-de-sacs  in  which  the  foetal  kidneys  commence,  divide  and  subdivide  so  as  to 
form  lobulated  organs  provided  with  calices  in  thejr  interior.  This  lobulation 
is  perceptible  for  some  time  after  birth. 

The  suprarenal  bodies  are  formed  independently  both  of  the  kidneys  and 
Wolffian  bodies. 

The  Wolffian  body,  or  primordial  kidney,  is  perceptible  about  the  third  week, 
forming  a  mass  of  cells  which  soon  give  rise  to  a  hollow  organ,  situated  on 
either  side  of  the  primitive  vertebrae,  and  extending  from  the  heart  to  the  lower 
end  of  the  embryo,  terminating  above  in  a  cul-de-sac  and  opening  below  into 
the  bladder.  The  structure  of  the  Wolffian  body  is  in  many  respects  analogous 
to  that  of  the  permanent  kidney.  It  is  composed  partly  of  an  excretory  canal 
into  which  open  numerous  "conduits,"  rectilinear  at  first,  but  afterwards  tor- 
tuous, and  partly  of  a  cellular  or  glandular  structure,  in  which  Malpighian  tufts 
are  found.  It  is  fixed  to  the  diaphragm  by  a  superior  ligament,  and  to  the 
spinal  column  by  an  inferior  or  lumbar  ligament.  Its  office  is  the  same  as  that 
of  the  kidneys,  viz.,  to  secrete  fluid  containing  urea,  which  accumulates  in  the 
bladder.  When  the  permanent  kidneys  are  formed,  the  greater  part  of  the 
Wolffian  body  disappears.  The  rest  takes  part  in  the  formation  of  the  genital 
organs. 

The  internal  genital  organs  have  at  first  no  distinctive  signs  of  sex.  They  are 
developed  from  the  Wolffian  body,  the  genital  gland,  and  the  conduit  of  Muller. 
The  genital  glands  are  masses  of  cells  which  are  formed  towards  the  sixth  week 
of  foetal  life.  They  are  produced  from  the  middle  blastodermic  layer,  and  lie 
on  the  inside  of  the  Wolffian  V)ody,  to  which  they  are  attached  by  a  mesenteric 
layer  of  peritoneum.  The  conduit  of  Miiller,  or  genital  duct,  is  formed  at  the 
same  time  as  the  genital  gland,  and  like  it  from  the  middle  blastodermic  layer. 
It  is  at  first  a  mere  cellular  cord,  and  then  represents  a  canal,  the  upper  part 
of  which  is  closed;  the  lower  opens  into  the  bladder.  It  lies  internal  and 
anterior  to  the  duct  of  the  Wolffian  body. 


DEVELOPMENT    OF    THE    GENITAL    ORGANS.  109 

Up  to  this  point  no  difference  of  sex  is  perceptible;  but  from  this  stage, 
towards  the  commencement  of  the  third  month,  the  internal  organs  of  the 
female  and  male  begin  to  assume  a  different  appearance. 

Female  Organs. — The  genital  gland,  in  its  development  into  an  ovary,  becomes 
more  lengthened  and  assumes  an  oblique  position,  by  which  characters  it  can 
be  distinguished  from  the  testicle,  about  the  ninth  or  tenth  week.  The  ovary 
is  at  first  situated  internal  and  anterior  to  the  Wolffian  body.  As  that  bodV 
disappears  the  ovary  descends  towards  the  inguinal  region.  It  passes  into  the 
pelvis  towards  the  end  of  foetal  life.  The  ovules  and  Graafian  follicles  are 
derived  from  the  genital  gland,  but  according  to  His  the  stroma  of  the  ovary  is 
furnished  by  the  Wolffian  body. 

The  Fallopian  tube  is  formed  by  the  portion  of  the  duct  of  Miiller,  which  lies 
above  the  lumbar  ligament  of  the  Wolffian  body.  This  duct  is  at  first  com- 
pletely closed,  and  its  closed  extremity  remains  permanent,  forming  a  small 
cystic  body  attached  to  the  fimbriated  end  of  the  Fallopian  tube,  and  called  the 
"  hydatid  of  Morgagni."  Below  this,  a  cleft  forms  in  the  duct,  and  is  developed 
into  the  fimbriated  opening  of  the  Fallopian  tube. 

Below  this  portion  of  the  duct  of  Miiller,  that  body  on  either  side,  and  the 
ducts  of  the  Wolffian  body,  are  united  together  in  a  structure  called  "the  genital 
cord,"  in  which  the  two  Mullerian  ducts  approach  each  other,  lying  side  by 
side  and  finally  coalescing  to  form  the  cavity  of  the  vagina  and  uterus.  This 
coalescence  commences  in  the  middle,  corresponding  to  the  body  of  the  uterus. 
The  upper  parts  of  the  Mullerian  ducts  in  the  genital  cord  constitute  the  cornua 
of  the  uterus,  little  developed  in  the  human  species.  The  only  remains  of  the 
Wolffian  body  consist  in  a  structure  (parovarium  or  organ  of  Rosenmiiller) 
which  can  usually  be  detected  lying  between  the  ovary  and  Fallopian  tube,  and 
consisting  of  a  group  of  tubules  converging  to  a  single  duct,  which  is  some- 
times of  considerable  size  and  runs  for  some  distance  in  the  broad  ligament. 

About  the  fifth  month  an  annular  constriction  marks  the  position  of  the  neck 
of  the  uterus,  and  after  the  sixth  month  the  walls  of  the  uterus  begin  to  thicken. 

The  round  ligament  is  derived  from  the  lumbar  ligament  of  the  Wolffian 
body,  the  superior  ligament  of  the  genital  gland  becomes  the  cord  which 
attaches  the  ovary  to  the  fimbriated  extremity  of  the  Fallopian  tube,  the  peri- 
toneum constitutes  the  broad  ligaments,  the  superior  ligament  of  the  Wolffian 
body  disappears  with  that  structure. 

Internal  Organs  in  the  Male. — 1.  The  genital  gland,  in  its  development  Into  a 
testicle,  becomes  rounded  and  thick,  and  is  more  vertical  than  the  ovary  is  in 
its  early  state.  The  tubuli  seminiferi  are  early  visible,  being  at  first  short  and 
straight,  and  then  gradually  assume  a  coiled  arrangement.  The  tunica  albu- 
ginea  is  formed  about  the  third  month. 

2.  The  Mullerian  ducts  disappear  in  the  male  sex,  with  the  exception  of  their 
lower  ends.  These  unite  in  the  middle  line,  and  open  by  a  common  orifice  into 
the  uro-genital  sinus.     This  constitutes  the  utriculus  hominis  or  sinus  2:>rostaticus. 

3.  The  head  of  the  epididymis,  its  canal,  the  vas  deferens  and  ejaculatory 
duct,  are  formed  from  the  canals  and  from  the  duct  of  the  Wolffian  body.- 

The  remains  of  the  Wolffian  bodies  also  form  the  vas  aberrans,  and  a  struc- 
ture described  by  Girald^s^  and  called  after  him,  "  the  organ  of  Giraldes," 
which  bears  a  good  deal  of  resemblance  to  the  organ  of  Rosenmiiller  in  the 
other  sex.  It  consists  of  a  number  of  convoluted  tubules  lying  in  the  cellular 
tissue  in  front  of  the  cord  and  close  to  the  head  of  the  epididymis. 

The  descent  of  the  testis  and  the  formation  of  the  gubernaculum  are  de- 
scribed under  the  Male  Generative  Organs,  in  the  body  of  the  work. 

The  external  organs  of  generation^  like  the  internal,  pass  through  a  stage  in 
which  there  is  no  distinction  of  sex  (Fig.  67,  I,  II,  III).     We  must  therefore 

'  Journ.  de  Phys.,  18G1. 


110 


GENERAL    ANATOMY. 


first  describe  this  stage,  and  then  follow  the  development  of  the  female  and 
male  organs  respectively. 

As  stated  above,  the  anal  depression  at  an  early  period  is  formed  by  an  in- 
volution of  the  external  epithelium  apart  from  the  intestine,    which  is  still 


Development  of  the  external  genital  organs.  Lullfferent  type,  I.  II.  III.  Femnh.  A  B.  At  the  middle 
of  the  fifth  month.  0.  At  the  beginning  of  the  sixth.  Male.  A'.  At  the  beginning  of  the  fourth  month. 
B'.  At  the  middle  of  the  fourth  month.  C.  At  the  end  of  the  fourth  month.  I.  Cloaca.  2.  Genital  tur 
bercle.  3.  Glans  penis  or  clitoridis.  4.  Genital  furrow.  5.  External  genitnl  folds  (labia  majora  or  scrotum). 
6.  Umbilical  cord.  7.  Anus.  8.  Caud:il  extremity  and  coccygeal  tubercle.  9.  Labia  minora.  10.  Uro- 
genital sinus.  II.  Fraonum  clitoridis.  12.  Prcputiuin  penis  or  clitoridis.  13.  Opening  of  the  urethra.  14. 
Opening  of  the  vagina.     15.  Hymen.     16.  Scrotal  raphe. 

closed  at  its  lower  end.  When  the  septum  between  the  two  opens,  which  is 
about  the  fourth  week,  the  urachus  in  front  and  the  intestine  behind  both  com- 
municate with  the  cloaca.     About  the  second  month  a  transverse  division  (the 


DEVELOPMENT    OF    THE    GENITAL    ORGANS.  Ill 

perineum)  begins  to  form  and  divides  the  cloaca  into  the  anal  cavity  behind, 
the  urogenital  sinus  in  front.  In  the  sixth  week  a  tubercle,  the  genital  tubercle, 
is  formed  in  front  of  the  cloaca,  and  this  is  soon  surrounded  by  two  folds  of 
skin,  the  genital  folds.  Towards  the  end  of  the  second  month  the  tubercle  pre- 
sents, on  its  lower  aspect,  a  groove,  the  genital  furrow,  turned  towards  the 
cloaca.  All  these  parts  are  well  developed  at  the  period  shown  by  No.  III.  of 
the  following  diagrams,  where  the  anus  is  separated  from  the  urogenital  sinus, 
yet  no  distinction  of  sex  is  possible. 

Female  Organs  (Fig.  67,  A,  B,  C). — The  female  organs  are  developed  by  an 
easy  transition  from  the  above  form.  The  urogenital  sinus  persists  as  the  ves- 
tibule of  the  vagina,  and  forms  a  single  tube  with  the  upper  part  of  the  vagina, 
which  we  have  already  seen  developed  from  the  united  MUllerian  ducts.  The 
genital  tubercle  forms  the  clitoris,  the  genital  folds  the  labia  majora,  the  lips  of 
the  genital  furrow,  the  labia  minora,  the  genital  furrow  remaining  open,  except 
below  where  it  unites  with  the  perineum,  constituting  the  raph^. 

Male  Organs. — In  the  male,  the  changes  are  greater  from  the  indifferent  type. 
The  genital  tubercle  is  developed  into  the  penis,  the  glans  appearing  in  the 
third  month,  the  prepuce  and  corpora  cavernosa  in  the  fourth.  The  genital 
furrow  closes,  and  thus  forms  a  canal,  the  spongy  portion  of  the  urethra.  The 
urogenital  sinus  becomes  elongated,  and  forms  the  prostatic  and  membranous 
urethra.  The  genital  folds  unite  in  the  middle  line,  to  form  the  scrotum,  at 
about  the  same  time  as  the  genital  furrow  closes,  viz.,  between  the  third  and 
fourth  month. 


CHEOITOLOGICAL  TABLE 

OF 

THE  deyelopme:n^t  of  the  fcetus. 


(The  following  table  is  translated  from  the  work  of  Beaunis  and  Bouchard, 
with  some  very  unimportant  alterations.'  It  will  serve  to  present  a  resume  of 
the  preceding  facts  in  an  easily  accessible  form.) 

End  of  second  week. — Formation  of  the  amnion  and  umbilical  vesicle.  Chorda  dorsalis  and 
medullary  groove.     Heart. 

Beginning  of  third  week. — The  vitelline  membrane  has  entirely  disappeared.  Protovertebral 
disks.     First  pharyngeal  arch.     Buccal  depression.     Primitive  circulation. 

End  of  third  week. — The  allantois  and  Wolffian  body  appear.  The  amnion  is  closed.  Cerebral 
vesicles.  Primitive  ocular  and  auditory  vesicles.  Coalescence  of  the  inferior  maxillary 
protuberances.     Liver.     Formation  of  the  three  last  pharyngeal  arches. 

Fourth  week. — 'I'he  umbilical  vesicle  has  attained  its  full  development.  Projection  of  the  caudal 
extremity.  Projection  of  the  upper  and  lower  limbs.  Cloaca!  aperture.  The  heart  sepa- 
rates into  a  right  and  left  heart.  Spinal  ganglia  and  anterior  roots.  Olfactory  fossae. 
Lungs.     Pancreas. 

Fifth  week. — Vascularity  of  the  allantois  in  its  whole  extent.  First  trace  of  hands  and  feet. 
The  primitive  aorta  divides  into  primitive  aorta  and  pulmonary  artery.  Conduit  of  MUller 
and  genital  gland.     Ossification  of  clavicle  and  lower  jaw.     Cartilage  of  Meckel. 

Sixth  week. — The  activity  of  the  umbilical  vesicle  ceases.  The  pharyngeal  clefts  disappear. 
The  vertebral  column,  primitive  cranium  and  ribs  assume  the  cartilaginous  condition. 
Posterior  roots  of  the  nerves.  Membranes  of  the  nervous  centres.  Bladder.  Kidneys. 
Tongue.     Larynx.     Thyroid  glands     Germs  of  teeth.     Uenital  tubercle  and  folds. 

Seventh  week. — The  muscles  begin  to  be  perceptible.  Points  of  ossification  of  the  ribs,  scapula, 
shafts  of  humerus,  femur,  tibia,  intermaxillary  bone,  palate,  upper  jaw  (its  first  four  points). 

Eighth  week. — Distinction  of  arm  and  forearm,  and  of  thigh  and  leg.  Appearance  of  the  inter- 
digital  clefts.  Capsule  of  the  lens  and  pupillary  membrane.  Completion  of  the  interven- 
tricular and  commencement  of  the  interauricular  septum.  Salivary  glands.  Spleen.  Su- 
prarenal capsules.  The  larynx  begins  to  become  cartilaginous.  AH  the  vertebral  bodies 
are  cartilaginous.  Points  of  ossification  for  the  ulna,  radius,  fibula,  and  ilium.  The  two 
halves  of  the  bony  palate  unite.     Sympathetic  nerve. 

Ninth  week. — Corpus  striatum.  Pericardium.  Distinction  between  ovary  and  testicle.  Forma- 
tion of  the  genital  furrow.  Osseous  nuclei  of  vertebral  bodies  and  arches,  frontal,  vomer, 
malar  bone,  shafts  of  metacarpal  bones,  metatarsal  bones  and  phalanges.  The  union  of  the 
hard  palate  is  completed.     Gall-bladder. 

Third  month. — Formation  of  the  foetal  placenta.  The  projection  of  the  caudal  extremity  disap- 
pears. It  is  possible  to  distinguish  the  male  and  female  organs  at  the  commencement  of  the 
third  month-  The  cloacal  aperture  divided  into  two  parts.  The  cartilaginous  arches  on 
the  dorsal  region  of  the  spine  close.  Points  of  ossification  for  the  occipital,  sphenoid,  os 
unguis,  nasal  bones,  squamous  portion  of  temporal  and  ischium.  Orbital  centre  of  superior 
maxillary  bone.  Commencement  of  formation  of  maxillary  sinus.  Pons  Varolii.  Fissure 
of  Sylvius.  Formation  of  eyelids  and  of  hairs  and  nails.  Mammary  gland.  Epiglottis. 
Union  of  the  testicle  with  the  canals  of  the  Wolfiian  body.     Prostate. 

Fourth  month. — The  closure  of  the  cartilaginous  arches  of  the  spine  is  complete.  Osseous 
points  for  the  first  sacral  vertebra  and  pubes.  Os.sification  of  the  malleus  and  incus. 
Corpus  calloaum.  Membranous  lamina  spiralis :  cartilage  of  the  Eustachian  tube.  Tym- 
panic ring.  Fat  in  subcutaneous  cellular  tissue.  Tonsils.  Closure  of  genital  furrow  and 
formation  of  scrotum  and  prepuce. 


'  It  will  be  noticed  that  the  time  assigned  in  this  table  for  the  appearance  of  the  first  rudinient 
of  some  of  the  bones  (e.  r/.,  the  ilium)  varies  in  some  cases  from  that  assigned  on  p.  52.  'J'his  is 
t  point  on  which  anatomists  differ,  and  which  probably  varies  in  difl'crent  cases. 

S  112 


CHRONOLOGICAL    TABLE.  113 

Fifth  month. — The  two  layers  of  decidua  begin  to  coalesce.  Osseous  nuclei  of  axis  and  odontoid 
process.  Lateral  points  of  first  sacral  vertebra  ;  median  points  of  second.  Osseous  points 
of  lateral  masses  of  ethmoid.  Ossification  of  stapes  and  petrous  bone.  Ossification  of 
germs  of  teeth.  Appearance  of  germs  of  permanent  teeth.  Eruption  of  hair  on  head. 
Sudoriferous  glands.  Glands  of  B runner.  Follicles  of  tonsils  and  base  of  tongue.  Lym- 
phatic glands.     Commencement  of  limitation  of  uterus  and  vagina. 

Sixth  month. — Points  of  ossification  for  the  anterior  root  of  the  transverse  process  of  the  seventh 
cervical  vertebra.  Lateral  points  of  second  sacral  vertebra;  median  points  of  third.  The 
sacro-vertebral  angle  forms.  Osseous  points  of  the  manubrium  sterni  and  of  the  os  calcis. 
The  cerebral  hemisphere  covers  the  cerebellum.  Papilla;  of  the  skin.  Sebaceous  glands, 
''.'he  free  border  of  the  nail  projects  from  the  corium  of  the  dermis.  Peyer's  patches.  The 
walls  of  the  uterus  thicken. 

Seventh  month. — Additional  points  of  first  sacral  vertebra;  lateral  points  of  third,  median  point 
of  fourth.  First  osseous  point  of  body  of  sternum.  Osseous  point  for  astragalus.  X^isap- 
pearance  of  Meckel's  cartilage.  Cerebral  convolutions.  Insula  of  Reil.  Separation  of 
tubercula  quadrigemina.  Disappearance  of  pupillary  membrane.  The  testicle  passes  into 
the  vaginal  process  of  the  peritoneum. 

Eighth  month. — Additional  points  for  the  second  sacral  vertebra;  lateral  points  for  the  fourth; 
median  points  for  the  fifth. 

Ninth  month. — Additional  points  for  the  third  sacral  vertebra;  lateral  points  for  the  fifth. 
Osseous  point  for  the  middle  turbinated  bone;  for  the  body  and  great  cornu  of  the  hyoid; 
for  the  second  and  third  pieces  of  the  body  of  the  sternum  ;  for  the  lower  end  of  the  femur. 
Ossification  of  the  bony  lamina  spiralis  and  axis  of  the  cochlea.  Opening  of  the  eyelids. 
The  testicles  are  in  the  scrotum. 


DESCRIPTIVE  AND  SURGICAL  ANATOMY. 


The  Skeleton. 

The  entire  skeleton  in  the  adult  consists  of  200  distinct  bones.     These  are — 

The  Spine  or  vertebral  column  (sacrum  and  coccyx  included,  26 

Cranium 8 

Face 14 

Os  hyoides,  sternum,  and  ribs 26 

Upper  extremities 64 

Lower  extremities 62 


200 


In  this  enumeration,  the  patellae  are  included  as  separate  bones,  but  the 
smaller  sesamoid  bones,  and  the  ossicula  auditus,  are  not  reckoned.  The  teeth 
belong  to  the  tegumentary  system. 

These  bones  are  divisible  into  four  classes:   Long,  Short,  Flat,  and  Irregular. 

The  Long  Bones  are  found  in  the  limbs,  where  they  form  a  system  of  levers, 
which  have  to  sustain  the  weight  of  the  trunk,  and  to  confer  the  power  of 
locomotion.  A  long  bone  consists  of  a  lengthened  cylinder  or  shaft,  and  two 
extremities.  The  shaft  is  a  hollow  cylinder,  the  walls  consisting  of  dense  com- 
pact tissue  of  great  thicknes's  in  the  middle,  and  becoming  thinner  towards  the 
extremities ;  the  spongy  tissue  is  scanty,  and  the  bone  is  hollowed  out  in  its 
interior  to  form  the  medullary  canal.  The  extremities  are  generally  somewhat 
expanded  for  greater  convenience  of  mutual  connection,  for  the  purposes  of 
articulation,  and  to  afford  a  broad  surface  for  muscular  attachment.  Here  the 
bone  is  made  up  of  spongy  tissue  with  only  a  thin  coating  of  compact  sub- 
stance. The  long  bones  are,  the  humerus,  radius,  tdna,  femur,  tibia,  Jibula, 
metacarpal,  and  metatarsal  bones,  and  the  phalanges.  The  clavicle  is  also  usually 
reckoned  as  a  long  bone. 

Short  Bones.  Where  a  part  of  the  skeleton  is  intended  for  strength  and 
compactness,  and  its  motion  is  at  the  same  time  slight  and  limited,  it  is  divided 
into  a  number  of  small  pieces,  united  together  by  ligaments,  and  the  separate 
bones  are  short  and  compressed,  such  as  the  bones  of  the  carpus  and  tarsus. 
These  bones,  in  their  structure,  are  spongy  throughout,  excepting  at  their  sur- 
face, where  there  is  a  thin  crust  of  compact  substance. 

Flat  Bones.  Where  the  principal  requirement  is  either  extensive  protection, 
or  the  provision  of  broad  surfaces  for  muscular  attachment,  we  find  the  osseous 
structure  expanded  into  broad  flat  plates,  as  is  seen  in  the  bones  of  the  skull 
and  the  shoulder-blade.  These  bones  are  composed  of  two  thin  layers  of  com- 
pact tissue  inclosing  between  them  a  variable  quantity  of  cancellous  tissue. 
In  the  cranial  bones,  these  layers  of  compact  tissue  are  familiarly  known  as 
the  tables  of  the  skull ;  the  outer  one  is  thick  and  tough ;  the  inner  one  thinner, 
denser,  and  more  brittle,  and  hence  termed  the  vitreous  table.  The  intervening 
cancellous  tissue  is  called  the  diploe.  The  flat  bones  are,  the  occipital,  parietal, 
frontal,  nasal,  lachrymal,  vomer,  scap)ulac,  ossa  innominata,  sternum,  and  ribs. 

115 


116  THE    SKELETON. 

"The  Irregular  or  Mixed  Bones  are  such  as,  from  their  peculiar  form,  cannot 
be  grouped  under  either  of  the  preceding  heads.  Their  structure  is  similar  to 
that  of  other  bones,  consisting  of  a  layer  of  compact  tissue  externally,  and  of 
spongy,  cancellous  tissue  within.  The  irregular  bones  are,  the  vertehrve,  sacrum, 
coccyx,  temporal,  sphenoid,  ethmoid,  superior  maxillary,  inferior  maxillary,  palate, 
inferior  turbinated,  and  hyoid. 

Surfaces  of  Bones.  If  the  surface  of  any  bone  is  examined,  certain  eminences 
and  depressions  are  seen,  to  which  descriptive  anatomists  have  given  the  fol- 
lowing names. 

A  prominent  process  projecting  from  the  surface  of  a  bone,  which  it  has 
never  been  separate  from,  or  movable  upon,  is  termed  an  apophysis  (from  anotvatj, 
an  excrescence);  but  if  such  process  is  developed  as  a  separate  piece  from  the 
rest  of  the  bone,  to  which  it  is  afterwards  joined,  it  is  termed  an  epiiphysis  (from 
irti^Moii,  an  accretion). 

These  eminences  and  depressions  are  of  two  kinds:  articular,  and  non- 
articular.  Well-marked  examples  of  articular  eminences  are  found  in  the 
heads  of  the  humerus  and  femur ;  and  of  articular  depressions,  in  the  glenoid 
cavity  of  the  scapula,  and  the  acetabulum.  Non-articular  eminences  are  desig- 
nated according  to  their  form.  Thus,  a  broad,  rough,  uneven  elevation  is  called 
a  tuberosity;  a  small  rough  prominence,  a  tubercle;  a  sharp,  slender,  pointed 
eminence,  a  spine ;  a  narrow  rough  elevation,  running  some  way  along  the  sur- 
face, a  ridge,  or  line. 

The  non-articular  depressions  are  also  of  very  variable  form,  and  are  de- 
scribed as  fossae,  grooves,  furrows,  fissures,  notches,  etc.  These  non-articular 
eminences  and  depressions  serve  to  increase  the  extent  of  surface  for  the  attach- 
ment of  ligaments  and  muscles,  and  are  usually  well  marked  in  proportion  to 
the  muscularity  of  the  subject. 

THE   SPINE. 

The  Spine  is  a  flexuous  and  flexible  column,  formed  of  a  series  of  bones 
called  Vertebrse. 

The  Vertebrae  are  thirty-three  in  number,  exclusive  of  those  which  form  the 
skull,  and  have  received  the  names  cervical,  dorsal,  lumbar,  sacral,  and  coccygeal, 
according  to  the  position  which  they  occupy ;  seven  being  found  in  the  cervical 
region,  twelve  in  the  dorsal,  five  in  the  lumbar,  five  in  the  sacral,  and  four  in 
the  coccygeal. 

This  number  is  sometimes  increased  by  an  additional  vertebra  in  one  region, 
or  the  number  may  be  diminished  in  one  region,  the  deficiency  being  supplied 
by  an  additional  vertebra  in  another.  These  observations  do  not  apply  to  the 
cervical  portion  of  the  spine,  the  number  of  bones  forming  which  is  seldom 
increased  or  diminished. 

The  vertebra9  in  the  three  uppermost  regions  of  the  spine  are  separate 
throughout  the  whole  of  life;  but  those  found  in  the  sacral  and  coccygeal 
regions  are,  in  the  adult,  firmly  united,  so  as  to  form  two  bones— five  entering 
into  the  formation  of  the  upper  bone  or  sacrum,  and  four  into  the  terminal 
bone  of  the  spine  or  coccyx. 

General  Characters  of  a  Vertebra. 

Each  vertebra  consists  of  two  essential  parts,  an  interior  solid  segment  or 
body,  and  a  posterior  segment  or  arch.  The  arch  is  formed  of  two  pedicles 
and  two  laminae,  supporting  seven  processes,  viz.,  four  articular,  two  transverse, 
and  one  spinous  process. 

The  bodies  of  the  vertebrae  are  piled  one  upon  the  other,  forming  a  strong 
pillar,  for  the  support  of  the  cranium  and  trunk;  the  arches  forming  a  hollow 
cylinder  behind  for  the  protection  of  the  spinal  cord.  The  different  vertebrae 
are  connected  together  by  means  of  the  articular  processes,  and  the  interverte- 


I 


CHARACTERS    OF    THE    CERVICAL    VERTEBRA.        117 

bral  cartilages ;  while  the  transverse  and  spinous  processes  serve  as  levers  for 
the  attachment  of  muscles  which  move  the  different  parts  of  the  spine.  Lastly, 
between  each  pair  of  vertebrae,  apertures  exist  through  which  the  spinal  nerves 
pass  from  the  cord.  Each  of  these  constituent  parts  must  now  be  separately 
examined. 

The  Body  is  the  largo^t  and  most  solid  part  of  a  vertebra.  Above  and  below, 
it  is  slightly  concave,  presenting  a  rim  around  its  circumference;  and  its  upper 
and  lower  surfaces  are  rough,  for  the  attachment  of  the  intervertebral  fibro- 
"  cartilages.  In  front,  it  is  convex  from  side  to  side,  concave  from  above  down- 
wards. Behind,  it  is  flat  from  above  downwards  and  slightly  concave  from 
side  to  side.  Its  anterior  surface  is  perforated  by  a  few  small  apertures,  for 
the  passage  of  nutrient  vessels;  whilst,  on  the  posterior  surface,  is  a  single 
large  irregular  aperture,  or  occasionally  more  than  one,  for  the  exit  of  veins 
from  the  body  of  the  vertebra,  the  vense  basis  vertehrve. 

The  Pedicles  project  backwards,  one  on  each  side,  from  the  upper  part  of  the 
body  of  the  vertebra,  at  the  line  of  junction  of  its  posterior  and  lateral  surfaces. 
The  concavities  above  and  below  the  pedicles  are  t\\Q  intervertebral  notches ;  they 
are  four  in  number,  two  on  each  side,  the  inferior  ones  being  generally  the 
deeper.  When  the  vertebras  are  articulated,  the  notches  of  each  contiguous 
pair  of  bones  form  the  intervertebral  foramina  which  communicate  with  the 
spinal  canal  and  transmit  the  spinal  nerves. 

The  Larainw  are  two  broad  plates  of  bone,  which  complete  the  vertebral 
arch  behind,  inclosing  a  foramen  which  serves  for  the  protection  of  the  spinal 
cord ;  they  are  connected  to  the  body  by  means  of  the  pedicles.  Their  upper 
and  lower  borders  are  rough,  for  the  attachment  of  the  ligamenta  sub/lava. 

The  Articular  Processes,  four  in  number,  two  on  each  side,  spring  from  the 
junction  of  the  pedicles  with  the  laminae.  The  two  superior  project  upwards, 
their  articular  surfaces  being  directed  more  or  less  backwards,  the  two  inferior 
project  downwards,  their  articular  surfaces  looking  more  or  less  forwards.' 

The  Spinous  Process  projects  backwards  from  the  junction  of  the  two  laminae, 
and  serves  for  the  attachment  of  muscles. 

The  Transverse  Processes,  two  in  number,  project  one  at  each  side  from  the 
point  where  the  articular  processes  join  the  pedicle.  They  also  serve  for  the 
attachment  of  muscles. 

Chaeacters  of  the  Cervical  Vertebra  (Fig.  68). 

The  Body  is  smaller  than  in  any  other  region  of  the  spine,  and  broader  from 
side  to  side  than  from  before  backwards.     The  anterior  and  posterior  surfaces 

Fig.  68. — ^A  Cervical  Vertebra. 

Toittri^Tulcnh  o}  Trans.  trccrJt^S^^^--^:;^^,,^l^^ 

)lupirurr  Articular  Trocett 

TnfcMT Articular  £roctss 


'  It  may,  perhaps,  be  as  well  to  remind  the  reader,  that  the  direction  of  a  surface  is  determined 
by  that  of  a  line  drawn  at  right  angles  to  it. 


118 


THE    SKELETON. 


are  flattened  and  of  equal  depth ;  the  former  is  placed  on  a  lower  level  than 
the  latter,  and  its  inferior  border  is  prolonged  downwards  so  as  to  overlap  the 
upper  and  fore  part  of  the  vertebra  below.  Its  upper  surface  is  concave  trans- 
versely, and  presents  a  projecting  lip  on  each  side;  its  lower  surface  being 
convex  from  side  to  side,  concave  from  before  backwards,  and  presenting  late- 
rally a  shallow  concavity,  which  receives  the  corresponding  projecting  lip  of 
the  adjacent  vertebra.  The  pedicles  are  directed  obliquely  outwards,  and  the 
superior  intervertebral  notches  are  deeper,  but  narrower,  than  the  inferior. 
The  laminse  are  narrow,  long,  thinner  above  than  below,  and  overlap  each 
other ;  inclosing  the  spinal  foramen,  which  is  very  large,  and  of  a  triangular 
form.  The  spinous  processes  are  short  and  bifid  at  the  extremity,  to  afford 
greater  extent  of  surface  for  the  attachment  of  muscles,  the  two  divisions  being 
often  of  unequal  size.  They  increase  in  length  from  the  fourth  to  the  seventh. 
The  transverse  processes  are  short,  directed  downwards,  outwards,  and  forwards, 
bifid  at  their  extremity,  and  marked  by  a  groove  along  their  upper  surface, 
which  runs  downwards  and  outwards  from  the  superior  intervertebral  notch, 
and  serves  for  the  transmission  of  one  of  the  cervical  nerves.  The  transverse 
processes  are  pierced  at  their  base  by  a  foramen,  for  the  transmission  of  the 
vertebral  artery,  vein,  and  plexus  of  nerves.  Each  process  is  formed  by  two 
roots :  the  anterior  root  arises  from  the  side  of  the  body,  and  corresponds  to 
the  ribs:  the  posterior  root  springs  from  the  junction  of  the  pedicle  with  the 
lamina,  and  corresponds  with  the  transverse  processes  in  the  dorsal  region.  It 
is  by  the  junction  of  the  two  that  the  foramen  for  the  vertebral  vessels  is  formed. 
The  extremities  of  each  of  these  roots  form  the  anterior  and  posterior  tubercles  of 
the  transverse  processes.  The  articular  processes  are  oblique ;  the  superior  are 
of  an  oval  form,  flattened  and  directed  upwards  and  backwards ;  the  inferior 
downwards  and  forwards. 

The  peculiar  vertebrae  in  the  cervical  region  are  the  first  or  ^.^Zas;  the  second 
or  Axis;  and  the  seventh  or  Vertebra  prominens.  The  great  modifications  in 
the  form  of  the  atlas  and  axis  are  designed  to  admit  of  the  nodding  and  rota- 
tory movements  of  the  head. 

The  AUas  (Fig.  69)  (so  named  from  supporting  the  globe  of  the  head).     The 

Fig.  69.— Ist  Cervical  Vertebra,  or  Atlas. 
Tiiberclfi- 


Trani.ProcfW 


J'orafnen  for 
Vcrrtehrai  Aril 


Rudimentary  Spin.  Proc 
a.  Diagram  of  Section  of  Adontoid  Process 


Qrooife  fcr  V^rP^^.  Art ." 
anW^l-'  Cerv.N«rvt 


h.  Diagram  of  Section  of  Transverse  Ligaments 


chief  peculiarities  of  this  bone  are,  that  it  has  neither  body  nor  spinous  process. 
The  body  is  detached  from  the  rest  of  the  bone,  and  forms  the  odontoid  process 
of  the  second  vertebra;  while  the  parts  corresponding  to  the  pedicles  pass  in 
front,  and  join  to  form  the  anterior  arch.  The  atlas  consists  of  an  anterior 
arch,  a  posterior  arch,  and  two  lateral  masses.  The  anterior  arch  forms  about 
one-fifth  of  the  bone  ;  its  anterior  surface  is  convex,  and  presents  about  its 
centre  a  tubercle,  for  the  attachment  of  the  Longus  Colli  muscle ;  posteriorly 


CERVICAL    VERTEBRA.  119 

it  is  concave,  and  marked  by  a  smooth  oval  or  circular  facet,  for  articulation 
with  the  odontoid  process  of  the  axis.  The  posterior  arch  forms  about  two-fifths 
of  the  circumference  of  the  bone ;  it  terminates  behind  in  a  tubercle,  which  is 
the  rudiment  of  a  spinous  process,  and  gives  origin  to  the  Eectus  Capitis  Pos- 
ticus Minor.  The  diminutive  size  of  this  process  prevents  any  interference  in 
the  movements  between  it  and  the  cranium.  The  posterior  part  of  the  arch 
presents,  above,  a  rounded  edge ;  whilst,  in  front,  immediately  behind  each  su- 
perior articular  process,  is  a  groove,  sometimes  converted  into  a  foramen  by  a 
delicate  bony  spicula  which  arches  backwards  from  the  posterior  extremity  of 
the  superior  articular  process.  These  grooves  represent  the  superior  interver- 
tebral notches,  and  are  peculiar  from  being  situated  behind  the  articular  pro- 
cesses, instead  of  before  them,  as  in  the  other  vertebrae.  They  serve  for  the 
transmission  of  the  vertebral  artery,  which,  ascending  through  the  foramen  in 
the  transverse  process,  winds  round  the  lateral  mass  in  a  direction  backwards 
and  inwards.  They  also  transmit  the  sub-occipital  nerves.  On  the  under  sur- 
face of  the  posterior  arch,  in  the  same  situation,  are  two  other  grooves,  placed 
behind  the  lateral  masses,  and  representing  the  inferior  intervertebral  notches 
of  other  vertebrae.  They  are  much  less  marked  than  the  superior.  The  lateral 
masses  are  the  most  bulky  and  solid  parts  of  the  atlas,  in  order  to  support  the 
weight  of  the  head ;  they  present  two  articulating  processes  above,  and  two 
below.  The  two  superior  are  of  large  size,  oval,  concave,  and  approach  to- 
wards one  another  in  front,  but  diverge  behind ;  they  are  directed  upwards, 
inwards,  and  a  little  backwards,  forming  a  kind  of  cup  for  the  condyles  of  the 
occipital  bone,  and  are  admirably  adapted  to  the  nodding  movements  of  the 
head.  Not  unfrequently  they  are  partially  subdivided  by  a  more  or  less  deep 
indentation  which  encroaches  upon  each  lateral  margin.  The  inferior  articular 
processes  are  circular  in  form,  flattened,  or  slightly  concave,  and  directed  down- 
wards, inwards,  and  a  little  backwards,  articulating  with  the  axis,  and  permit- 
ting the  rotatory  movements.  Just  below  the  inner  margin  of  each  superior 
articular  surface  is  a  small  tubercle,  for  the  attachment  of  a  ligament  which, 
stretching  across  the  ring  of  the  atlas,  divides  it  into  two  unequal  parts ;  the 
anterior  or  smaller  segment  receiving  the  odontoid  process  of  the  axis,  the  pos- 
terior allowing  the  transmission  of  the  spinal  cord  and  its  membranes.  This 
part  of  the  spinal  canal  is  of  considerable  size,  to  afford  space  for  the  spinal 
cord ;  and  hence  lateral  displacement  of  the  atlas  may  occur  without  compres- 
sion of  the  spinal  cord.  The  transverse  processes  are  of  large  size,  for  the  at- 
tachment of  special  muscles  which  assist  in  rotating  the  head — long,  not  bifid, 
perforated  at  their  base  by  a  canal  for  the  vertebral  artery,  which  is  directed 
from  below,  upwards,  and  backwards. 

The  Axis  (Fig.  70),  (so  named  from  forming  the  pivot  upon  which  the  head 
rotates).  The  most  distinctive  character  of  this  bone  is  the  strong  prominent 
process,  tooth-like  in  form  (hence  the  name  odontoid),  which  rises  perpendicu- 
larly from  the  upper  part  of  the  body.  The  body  is  of  a  triangular  form ;  deeper 
in  front  than  behind,  and  prolonged  downwards  anteriorly  so  as  to  overlap  the 
upper  and  fore  part  of  the  adjacent  vertebra.  It  presents  in  front  a  median 
longitudinal  ridge,  separating  two  lateral  depressions  for  the  attachment  of  the 
Longus  colli  muscles  of  each  side.  The  odontoid  process  presents  two  articu-" 
lating  surfaces:  one  in  front  of  an  oval  form,  for  articulation  with  the  atlas; 
another  behind,  for  the  transverse  ligament;  the  latter  frequently  encroaching 
on  the  sides  of  the  process;  the  apex  is  pointed.  Below  the  apex,  the  process 
is  somewhat  enlarged,  and  presents  on  either  side  a  rough  impression  for  the 
attachment  of  the  odontoid  or  check  ligaments,  which  connect  it  to  the  occipital 
bone;  the  base  of  the  process,  where  it  is  attached  to  the  body,  is  constricted, 
so  as  to  prevent  displacement  from  the  transverse  ligament,  which  binds  it  in 
this  situation  to  the  anterior  arch  of  the  atlas.  Sometimes,  however,  this  pro- 
cess does  become  displaced,  especially  in  children,  in  whom  the  ligaments  are 
more  relaxed:  instant  death  is  the  result  of  this  accident.     The  pedicles  are 


120 


•\ 


THE    SKELETON. 


broad  and  strong,  especially  their  anterior  extremities,  which  coalesce  with  the 
sides  of  the  body  and  the  root  of  the  odontoid  process.  The  laminae  are  thick 
and  strong,  and  the  spinal  foramen  very  large.     The  superior  articular  surfaces 

Fig,  70. — 2d  Cervical  Vertebra,  or  Axis. 
Odontoid  I^att  ^ 


Ronffh  Surf.fffT  CAeeJt  Lt'g^ 
Arttc,  Swrf.fcr  Trant.LijI 


Spm.FrocA 


Artie,  Surf,  for  Atlas 


Body 


Tran.t  .Proa. 
InJor.A.  rtit.Pratf, 


ntlioct. 


are  sound,  slightly  convex,  directed  upwards  and  outwards,  and  are  peculiar  in 
being  supported  on  the  body,  pedicles,  and  transverse  processes.     The  inferior 

articular  surfaces  have  the  same 
Fig.  71.— 7th  Cervical  Vertebra,  or  Vertebra  Pro-    direction  as  those  of  the  other 
"^°®°^'  cervical  vertebrae.   The  superior 

intervertebral  notches  are  very 
shallow,  and  lie  behind  the  arti- 
cular processes;  the  inferior  in 
front  of  them,  as  in  the  other 
cervical  vertebrae.  The  trans- 
verse processes  are  very  small, 
not  bifid,  and  perforated  by  the 
vertebral  foramen,  or  foramen 
for  the  vertebral  artery,  which  is 
directed  obliquely  upwards  and 
outwards.  The  spinous  process 
is  of  large  size,  very  strong, 
deeply  channelled  on  its  under 
surface,  and  presents  a  bifid  tu- 
bercular extremity  for  the  attach- 
ment of  muscles,  which  serve  to 
rotate  the  head  upon  the  spine. 

Seventh  Cervical  (Fig.  71).  The 
most  distinctive  character  of  this 
vertebra  is  the  existence  of  a  very 
long  and  prominent  spinous  process;  hence  the  name  "Vertebra  prominens." 
This  process  is  thick,  nearly  horizontal  in  direction,  not  bifurcated,  and  has, 
attached  to  it  the  ligameutum  nuchae.  The  transverse  process  is  usually  of 
large  size,  especially  its  posterior  root;  its  upper  surface  has  usually  a  shallow 
groove,  and  it  seldom  presents  more  than  a  trace  of  bifurcation  at  its  extremity. 
The  vertebral  foramen  is  sometimes  as  large  as  in  the  other  cervical  vertebrae, 
usually  smaller,  on  one  or  both  sides,  and  sometimes  wanting.  On  the  left  sid(3 
it  occasionally  gives  passage  to  the  vertebral  artery;  more  frequently  the  ver- 
tebral vein  traverses  it  on  both  sides;  but  the  usual  arrangement  is  for  both 
artery  and  vein  to  pass  through  the  foramen  in  the  transverse  process  of  the 
sixth  cervical. 


»^i,i,ous  Froe^ 


DORSAL    VERTEBRA.  121 

Characters  of  the  Dorsal  Vertebra. 

The  bodies  of  the  Dorsal  Vertebrae  resemble  those  in  the  cervical  and  lumbar 
regions  at  the  respective  ends  of  this  portion  of  the  spine;  but  in  the  middle 
of  the  dorsal  region,  their  form  is  very  characteristic,  being  heart-shaped,  and 
broader  in  the  antero-posterior  than  in  the  lateral  direction.  .They  are  thicker 
behind  than  in  front,  flat  above  and  below,  convex  and  prominent  in  front, 
deeply  concave  behind,  slightly  constricted  in  front  and  at  the  sides,  and  marked 
on  each  side,  near  the  root  of  the  pedicle,  by  two  demi-facets,  one  above,  the 
other  below.  These  are  covered  with  cartilage  in  the  recent  state;  and,  when 
articulated  with  the  adjoining  vertebrae,  form  oval  surfaces  for  the  reception 
of  the  heads  of  the  corresponding  ribs.  The  pedicles  are  directed  backwards, 
and  the  inferior  intervertebral  notches  are  of  large  size,  and  deeper  than  in  any 
other  region  of  the  spine.  The  laminse  are  broad  and  thick,  and  the  spinal 
foramen  small,  and  of  a  circular  form.  The  articular  processes  are  flat,  nearly 
vertical  in  direction,  and  project  from  the  upper  and  lower  part  of  the  pedicles, 
the  superior  being  directed  backwards  and  a  little  outwards  and  upwards,  the 
inferior  forwards  and  a  little  inwards  and  downwards.  The  transverse  processes 
arise  from  the  same  parts  of  the  arch  as  the  posterior  roots  of  the  transverse 
processes  in  the  neck;  they  are  thick,  strong,  and  of  great  length,  directed 
obliquely  backwards  and  outwards,  presenting  a  clubbed  extremity,  which  is 
tipped  on  its  anterior  part  by  a  small  concave  surface,  for  articulation  with  the 
tubercle  of  a  rib.  Besides  the  articular  facet  for  the  rib,  two  indistinct  tuber- 
cles may  be  seen  rising  from  the  extremity  of  the  transverse  processes,  one  near 
the  upper,  the  other  near  the  lower  border.  In  man,  they  are  comparatively 
of  small  size,  and  serve  only  for  the  attachment  of  muscles.  Bat,  in  some 
animals,  they  attain  considerable  magnitude  either  for  the  purpose  of  more 
closely  connecting  the  segments  of  this  portion  of  the  spine,  or  for  muscular 
and  ligamentous  attachment.  The  spinous  processes  are  long,  triangular  in 
form,  directed  obliquely  downwards,  and  terminating  by  a  tubercular  margin. 
They  overlap  one  another  from  the  fifth  to  the  eighth,  but  are  less  oblique  in 
direction  above  and  below. 

Fig.  72. — A  Dorsal  Vertebra. 
^tijacrim  AOie.  ^^'"*—-^-§^^  Demi,  faucet  for  Tiead  ofHH 

I* 


Facet  Jor  Tulercle  ofEil 


iFrorJ 


DemifacetforlieaJ/  ojRil 
Infer.  Artie  .Froc. 


The  peculiar  dorsal  vertebra  are  the  first,  ninth,  tenth,  eleventh,  and  twelfth 
(Fig.  73). 


122 


THE    SKELETON. 


The  First  Dorsal  Vertebra  presents,  on  each  side  of  the  body,  a  single  entire 
articular  facet  for  the  head  of  the  first  rib,  and  a  half  facet  for  the  upper  half 
of  the  second.  The  upper  surface  of  the  body  is  like  that  of  a  cervical  verte- 
bra, being  broad  transversely,  concave,  and  lipped  on  each  side.  The  articular 
surfaces  are  oblique  and  the  spinous  process  thick,  long,  and  almost  horizontal. 


Fig.  73. — Peculiar  Dorsal  Vertebraj. 


(An  entire  fa  re  f  a7>fltfe 
[AJjcmifa^et  heiouf 


— AUemi-farrt'  a^ove 


— One  ent4.re  farei 


An  entire  faeeC 
No  facet  on  Trans.Pro». 
which  is  rudimenta-^nj 


An  entiraftieet 
Nofa-r/!tonTra  nsjin 
Infer.Artie.  Pro« 
eon  i/e^and  tit  rnai 
outward 


The  Ninth  Dorsal  has  no  demi-facet  below.  In  some  subjects,  however,  the 
ninth  has  two  demi-facets  on  each  side,  then  the  tenth  has  a  demi-facet  at  the 
upper  part ;  none  below. 

The  Tenth  Dorsal  has  (except  in  the  cases  just  mentioned)  an  entire  articular 
facet  on  each  side  above ;  it  has  no  demi-facet  below. 

In  the  Eleventh  Dorsal^  the  body  approaches  in  its  form  and  size  to  the  lumbar. 
The  articular  facets  for  the  heads  of  the  ribs,  one  on  each  side,  are  of  large  size, 
and  placed  chiefly  on  the  pedicles,  which  are  thicker  and  stronger  in  this  and 


LUMBAR    VERTEBRA. 


123 


the  next  vertebra,  than  in  any  other  part  of  the  dorsal  region.  The  transverse 
processes  are  very  short,  tubercular  at  their  extremities,  and  have  no  articular 
facets  for  the  tubercles  of  the  ribs.  The  spinous  process  is  short,  nearly  hori- 
zontal in  direction,  and  presents  a  slight  tendency  to  bifurcation  at  its  extremity. 
The  Twelfth  Dorsal  has  the  same  general  characters  as  the  eleventh  ;  but  may 
be  distinguished  from  it  by  the  inferior  articular  processes  being  convex  and 
turned  outwards,  like  those  of  the  lumbar  vertebrae ;  by  the  general  form  of 
the  body,  laminae,  and  spinous  process,  approaching  to  that  of  the  lumbar 
vertebras ;  and  by  the  transverse  processes  being  shorter,  and  the  tubercles  at 
their  extremities  more  marked. 

Characters  of  the  Lumbar  Yertebe^. 

The  Lumbar  Vertebree  (Fig.  74)  are  the  largest  segments  of  the  vertebral 
column.  The  body  is  large,  broader  from  side  to  side  than  from  before  back- 
wards, about  equal  in  depth  in  front  and  behind,  flattened  or  slightly  concave 
above  and  below,  concave  behind,  and  deeply  constricted  in  front  and  at  the 


74. — A  Lumbar  Vertebra 


Super.  Artie.  Proc. 


sides,  presenting  prominent  margins,  which  afford  a  broad  basis  for  the  support 
of  the  superincumbent  weight.  The  pedicles  are  very  strong,  directed  back- 
wards from  the  upper  part  of  the  bodies ;  consequently  the  inferior  interverte- 
bral notches  are  of  large  size.  The  laminae  are  short"  but  broad  and  strong; 
and  the  foramen  triangular,  larger  than  in  the  dorsal,  smaller  than  in  the  cer- 
vical region.  The  superior  articular  processes  are  concave,  and  look  almost 
directly  inwards ;  the  inferior,  convex,  look  outwards  and  a  little  forwards ;  the 
former  are  separated  by  a  much  wider  interval  than  the  latter,  embracing  the 
lower  articulating  processes  of  the  vertebra  above.  The  transverse  processes 
are  long,  slender,  directed  transversely  outwards  in  the  upper  three  lumbar 
vertebrae,  slanting  a  little  upwards  in  the  lower  two.  By  some  anatomists  they 
are  considered  homologous  with  the  ribs.  Of  the  two  tubercles  noticed  in  con- 
nection with  the  transverse  processes  in  the  dorsal  region,  the  superior  ones 
become  connected  in  this  region  with  the  back  part  of  the  superior  articular 
processes.  Although  in  man  they  are  comparatively  small,  in  some  animals 
they  attain  considerable  size,  and  serve  to  locl^  the  vertebrae  more  closely  to- 
gether. The  spinous  processes  are  thick  and  broad,  somewhat  quadri-lateral, 
horizontal  in  direction,  thicker  below  than  above,  and  terminating  by  a  rough 
uneven  border. 

^  The  Fifth  Lumbar  vertebra  is  characterized  by  having  the  body  much  thicker 
m  front  than  behind,  which  accords  with  the  prominence  of  the  sacro-vertebr.al 
articulation,  by  the  smaller  size  of  its  spinous  process,  by  the  wide  interval 
between  the  inferior  articulating  processes,  and  by  the  greater  size  and  thick- 
ness of  its  transverse  processes. 


124 


THE    SKELETON". 


Structure  and  Development  of  the  VERTEBRiB. 


The  structure  of  a  vertebra  differs 
in  different  parts.  The  body  is  com- 
posed of  light  spongy  cancellous  tis- 
sue, having  a  thin  coating  of  compact 
tissue  on  its  external  suface  perforated 
by  numerous  orifices,  some  of  large 
size,  for  the  passage  of  vessels;  its 
interior  is  traversed  by  one  or  two 
large  canals  for  the  reception  of  veins, 
which  converge  towards  a  single  large 
irregular  or  several  small  apertures 
at  the  posterior  part  of  the  body  of 
each  bone.  The  arch  and  processes 
projecting  from  it  have,  on  the  con- 
trary, an  exceedingly  thick  covering 
of  compact  tissue. 

Development.  Each  vertebra  is 
formed  of  three  primary  cartilaginous 
portions  (Fig.  75) ;  one  for  each  lami- 
na and  its  processes,  and  one  for  the 
body.  Ossification  commences  in  the 
lamina9  about  the  sixth  week  of  foetal 
life,  in  the  situation  where  the  trans- 
verse processes  afterwards  project, 
the  ossifio  granules  shooting  back- 
wards to  the  spine,  forwards  to  the 
body,  and  outwards  into  the  trans- 
verse and  articular  processes.  Ossi- 
fication in  the  body  commences  in  the 
middle  of  the  cartilage  about  the 
eighth  week.  At  birth  these  three 
pieces  are  perfectly  separate.  During 
the  first  year  the  laminae  become 
united  behind,  by  a  portion  of  carti- 
lage in  which  the  spinous  process  is 
ultimately  formed,  and  thus  the  arch 
is  completed.  About  the  third  year 
the  body  is  joined  to  the  arch  on  each 
side,  in  such  a  manner  that  the  body 
is  formed  from  the  three  original 
centres  of  ossification,  the  amount 
contributed  by  the  pedicles  increasing 
in  extent  from  below  upwards.  Thus 
the  bodies  of  the  sacral  vertebrae  are 
formed  almost  entirely  from  the  cen- 
tral nuclei,  the  bodies  of  the  lumbax 
segments  are  formed  laterally  and 
behind  by  the  pedicles ;  in  the  dorsal 
region,  the  pedicles  advance  as  far 
forwards  as  the  articular  depressions 
for  the  heads  of  the  ribs,  forming 
these  cavities  of  reception;  and  in 
the  neck  the  whole  of  the  lateral 
portions  of  the  bodies  are  formed  by 
the  advance  of  the  pedicles.     Before 


Fig.  75. — Development  of  a  Vertebra, 
j^y  S ^^rimar'j  etntrst 

.  JfvrBody  (&'?.'  ufcok) 


ffor  each  lavuntt,  (6  -  we^Jij 

Fig.  7G. 
jS^  /fSecondartj  Centre* 


^  f  i  for  earJi 
^  iTranit.Proo. 
I    f6  yTi 


2.  tonutimet  /  j  for  Spin, vtoo.  (f6yTf) 

Fig.  77. 

Stf_2  additiona/  pla te t 

-ifoTiivper  turf'act\ 
of  lody        L/ 

h" 

■IJoT  u  ?idc  r  xu  TfiZeA 
vf  body 


Fig.  78.— Atlas. 

By  S   ccTitrea  not 

fforanur.aTrh  fl-y']  con- 
'       '  y  ttanl 

t literal  nuusY'!!^'-''^'^ 


i 


Fig.  79. — Axis. 

By  G  emtrBi 

■  Zfor  odontciJ jproe  /iff-*?  moj 

/for  ta-eli  la  tern  I  matt 

'ffor  lody  (6^  mo.) 

Fig.  80. — Lumbar  Vertebra. 

Jt    adJi/ioTUl  I  cernt  nj 


i 


XOf 


far  tuhtrclc*  on  Sop.Artic.Brue 


I 


DEVELOPMENT  OF  THE  VERTEBRA.        125 

puberty,  no  other  changes  occur,  excepting  a  gradual  increase  in  the  growth 
of  these  primary  centres,  the  upper  and  under  surface  of  the  bodies,  and  the 
ends  of  the  transverse  and  spinous  processes,  being  tipped  with  cartilage,  in 
which  ossific  granules  are  not  as  yet  deposited.  At  sixteen  years  (Fig,  76), 
four  secondary  centres  appear,  one  for  the  tip  of  each  transverse  process,  and 
two  (sometimes  united  into  one)  for  the  end  of  the  spinous  process.  At  twenty- 
one  years  (Fig.  77),  a  thin  circular  plate  of  bone  is  formed  in  the  layer  of  car- 
tilage situated  on  the  upper  and  under  surface  of  the  body,  the  former  being 
the  thicker  of  the  two.  All  these  become  joined ;  and  the  bone  is  completely 
formed  about  the  thirtieth  year  of  life. 

Exceptions  to  this  mode  of  development  occur  in  the  first,  second,  and  seventh 
cervical,  and  in  the  vertebrae  of  the  lumbar  region. 

The  Atlas  (Fig.  78)  is  developed  by  two  primary  centres,  and  by  one  or  more 
epiphyses.  The  two  primary  centres  are  destined  for  the  two  lateral  or  neural 
masses,  the  ossification  of  which  commences  before  birth,  near  the  articular 
processes,  and  extends  backwards :  these  portions  of  bone  are  separated  from 
one  another  behind,  at  birth,  by  a  narrow  interval  filled  in  with  cartilage. 
Between  the  second  and  third  years,  they  unite  either  directly  or  through  the 
medium  of  an  epiphysal  centre,  developed  in  the  cartilage  near  their  point 
of  junction.  The  anterior  arch,  at  birth,  is  altogether  cartilaginous,  and  this 
portion  of  the  atlas  is  completed  by  the  gradual  extension  forwards  and  ulti- 
mate junction  of  the  two  neural  processes.  Occasionally,  a  separate  nucleus  is 
developed  in  the  anterior  arch,  which,  extending  laterally,  joins  the  neural  pro- 
cesses in  front  of  the  pedicles;  or,  there  are  two  nuclei  developed  in  the  anterior 
arch,  one  on  either  side  of  the  median  line,  which  join  to  form,  a  single  mass, 
afterwards  united  to  the  lateral  portions  in  front  of  the  articulating  processes. 

The  Axis  (Fig.  79)  is  developed  by  six  centres.  The  body  and  arch  of  this 
bone  are  formed  in  the  same  manner  as  the  corresponding  parts  in  the  other 
vertebrae:  one  centre  for  the  lower  part  of  the  body,  and  one  for  each  lamina. 
The  odontoid  process  consists  originally  of  an  extension  upwards  of  the  cartila- 
ginous mass,  in  which  the  lower  part  of  the  body  is  formed.  At  about  the 
sixth  month  of  foetal  life,  two  osseous  nuclei  make  their  appearance  in  the  base 
of  this  process:  they  are  placed  laterally,  and  join  before  birth  to  form  a  conical 
bi-lobed  mass  deeply  cleft  above ;  the  interval  between  the  cleft  and  the  summit 
of  the  process,  is  formed  by  a  wedge-shaped  piece  of  cartilage ;  the  base  of  the 
process  being  separated  from  the  body  by  a  cartilaginous  interval,  which  gradually 
becomes  ossified,  sometimes  by  a  separate  epiphysal  nucleus.  Finally,  as  Dr.  Hum- 
phry has  demonstrated,  the  apex  of  the  odontoid  process  has  a  separate  nucleus. 

The  Seventh  Cervical.  The  anterior  or  costal  part  of  the  transverse  process 
of  the  seventh  cervical,  is  developed  from  a  separate  osseous  centre  at  about 
the  sixth  month  of  foetal  life,  and  joins  the  body  and  posterior  division  of  the 
transverse  process  between  the  fifth  and  sixth  years.  Sometimes  this  process 
continues  as  a  separate  piece,  and,  becoming  lengthened  outwards,  constitutes 
what  is  known  as  a  cervical  rib. 

The  Lumbar  Vertebrse  (Fig.  80)  have  two  additional  centres  (besides  those  pecu- 
liar to  the  vertebrae  generally),  for  the  tubercles,  which  project  from  the  back 
part  of  the  superior  articular  processes.  The  transverse  process  of  the  first 
lumbar  is  sometimes  developed  as  a  separate  piece,  which  may  remain  perma- 
nently unconnected  with  the  remaining  portion  of  the  bone;  thus  forming  a 
lumbar  rib,  a  peculiarity  which  is  rarely  met  with. 

Progress  of  Ossification  in  the  Spine  generally.  Ossification  of  the  laminee  of 
the  vertebrae  commences  at  the  upper  part  of  the  spine,  and  proceeds  gradually 
downwards;  hence  the  frequent  occurrence  of  spina  bifida  in  the  lower  part  of 
the  spinal  column.  Ossification  of  the  bodies,  on  the  other  hand,  commences  a 
little  below  the  centre  of  tile  spinal  column  (about  the  ninth  or  tenth  dorsal 
vertebras),  and  extends  both  upwards  and  downwards.  Although,  however,  the 
ossific  nuclei  make  their  first  appearance  in  the  lower  dorsal  vertebrae,  the 
lumbar  and  first  sacral  are  those  in  which  these  nuclei  are  largest  at  birth. 


126 


THE    SKELETON. 


Attachment  of  Muscles.  To  the  Atlas  are  attached  the  Longus  Colli,  Rectus 
Anticus  Minor,  Rectus  Lateralis,  Rectus  Posticus  Minor,  Obliquus  Superior  and 
Inferior,  Splenius  Colli,  Levator  Anguli  Scapulae,  Interspinous,  and  Inter- 
transverse. 

To  the  Axis  are  attached  the  Longus  Colli,  Obliquus  Inferior,  Rectus  Posticus 
Major,  Serai-spinalis  Colli,  Multifidus  Spinae,  Levator  Anguli  Scapulae,  Splenius 
Colli,  Transversalis  Colli,  Scalenus  Posticus,  Intertransversales,  Interspinales. 

'To  the  remaining  Vertebrae  generally  are  attached,  anteriorly,  the  Rectus 
Anticus  Major,  Longus  Colli,  Scalenus  Anticus  and  Posticus,  Psoas  Magnus, 
Psoas  Parvus,  Quadratus  Lumborum,  Diaphragm,  Obliquus  Internus  and  Trans- 
versalis ;  posteriorly,  the  Trapezius,  Latissimus  Dorsi,  Levator  Anguli  Scapulae, 
Rhomboideus  Major  and  Minor,  Serratus  Posticus  Superior  and  Inferior,  Sple- 
nius, Sacro-lumbalis,  Longissimus  Dorsi,  Spinalis  Dorsi,  Cervicalis  Ascendens, 
Transversalis  Collis,  Trachelo-mastoid,  Complexus,  Semi-Spinalis  Dorsi  and 
Colli,  Multifidus  Spinae,  Interspinales,  Supraspinales,  Intertransversaies,  Leva- 
tores  Costarura. 

The  Sacral  and  Coccygeal  Vertebrae  consist,  at  an  early  period  of  life,  of  nine 
separate  pieces,  which  are  united  in  the  adult,  so  as  to  form  two  bones,  five 
entering  into  the  formation  of  the  sacrum,  four  into  that  of  the  coccyx.  Occa- 
sionally, the  coccyx  consists  of  five  bones.^ 

The  Sacrum. 

The  Sacrum  (Fig.  81)  is  a  large  triangular  bone,  situated  at  the  lower  part] 
of  the  vertebral  column,  and  at  the  upper  and  back  part  of  the  pelvic  cavity,! 

Fig.  81. — Sacrum,  Anterior  Surface. 
I\uiiujntoru 


'  Dr.  Humphry  describes  this  as  the  usual  composition  of  the  Coccyx. — On  the  Skeleton,  p.  j 
4.56. 


SACRUM. 


127 


Fig.  82. — Vertical  Section  of  the  Sacrum. 


where  it  is  inserted  like  a  wedge  between  the  two  ossa  innominata;  its  upper 
part,  or  base,  articulating  with  the  last  lumbar  vertebra,  its  apex  with  the 
coccyx.  The  sacrum  is  curved  upon  itself,  and  placed  very  obliquely,  its 
upper  extremity  projecting  forwards,  and  forming,  with  the  last  lumbar  verte- 
bra, a  very  prominent  angle,  called  the  promonlory  or  sacro -vertebral  angle,  whilst 
its  central  part  is  directed  backwards,  so  as  to  give  increased  capacity  to  the 
pelvic  cavity.  It  presents  for  examination  an  anterior  and  posterior  surface, 
two  lateral  surfaces,  a  base,  an  apex,  and  a  central  canal. 

The  Anterior  Surface  is  concave  from  above  downwards,  and  slightly  so  from 
side  to  side.  In  the  middle  are  seen  four  transverse  ridges,  indicating  the 
original  division  of  the  bone  into  five  separate  pieces.  The  portions  of  bone 
intervening  between  the  ridges  correspond  to  the  bodies  of  the  vertebrae.  The 
body  of  the  first  segment  is  of  large  size,  and  in  form  resembles  that  of  a  lum- 
bar vertebra;  the  succeeding  ones  diminish  in  size  from  above  downwards,  are 
flattened  from  before  backwards,  and 
curved  so  as  to  accommodate  themselves 
to  the  form  of  the  sacrum,  being  concave 
in  front,  convex  behind.  At  each  end 
of  the  ridges  above  mentioned,  are  seen 
the  anterior  sacral  foramina,  analogous 
to  the  intervertebral  foramina,  four  in 
number  on  each  side,  somewhat  rounded 
in  form,  diminishing  in  size  from  above 
downwards,  and  directed  outwards  and 
forwards ;  they  transmit  the  anterior 
branches  of  the  sacral  nerves.  External 
to  these  foramina  is  the  lateral  mass, 
consisting,  at  an  early  period  of  life,  of 
separate  segments,  which  correspond  to 
the  anterior  transverse  processes.  These 
become  blended,  in  the  adult,  with  the 
bodies,  with  each  other,  and  with  the 
posterior  transverse  processes.  Bach 
lateral  mass  is  traversed  by  four  broad 
shallow  grooves,  which  lodge  the  ante- 
rior sacral  nerves  as  they  pass  outwards, 
the  grooves  being  separated  by  promi- 
nent ridges  of  bone,  which  give  attach- 
ment to  the  slips  of  the  Pyriformis 
muscle. 

If  a  vertical  section  is  made  through 
the  centre  of  the  bone  (Fig.  82),  the 
bodies  are  seen  to  be  united  at  their 
cirumference  by  bone,  a  wide  interval 
being  left  centrally,  which,  in  the  recent 
state,  is  filled  by  intervertebral  sub- 
stance. In  some  bones,  this  union  is 
more  complete  between  the  lower  segments,  than  between  the  upper  ones. 

The  Posterior  Surface  (Fig.  83)  is  convex  and  much  narrower  than  the  ante- 
rior. In  the  middle  line,  are  three  or  four  tubercles,  which  represent  the  rudi- 
mentary spinous  processes  of  the  sacral  vertebras.  Of  these  tubercles,  the  first 
is  usually  prominent,  and  perfectly  distinct  from  the  rest ;  the  second  and 
third  are  either  separate  or  united  into  a  tubercular  ridge,  which  diminishes  in 
size  from  above  downwards ;  the  fourth  usually,  and  the  fifth  always,  remain- 
ing undeveloped.  External  to  the  spinous  processes  on  each  side,  are  the 
laminse,  broad  and  well  marked  in  the  three  first  pieces;  sometimes  the  fourth, 
and  generally  the  fifth,  being  undeveloped ;  in  this  situation  the  lower  end  of 


1S8 


THE    SKELETON. 


the  sacral  canal  is  exposed.  External  to  the  laminae  are  a  linear  series  of  in- 
distinct tubercles  representing  the  articular  processes;  the  upper  pair  are  large, 
well  developed,  and  correspond  in  shape  and  direction  to  the  superior  articu- 
lating processes  of  a  lumbar  vertebra;  the  second  and  third  are  small;  the 

Fig.  83. — Sacrum,  Posterior  Surface. 


Jiott. Sacral  far. 


fourth  and  fifth  (usually  blended  together)  are  situated  on  each  side  of  tl 
sacral  canal.  They  are  called  the  sacral  cornua^  and  articulate  with  the  corni 
of  the  coccyx.  External  to  the  articular  processes  are  the  four  posterior  sacral 
foramina;  they  are  smaller  in  size  and  less  regular  in  form  than  the  anterior, 
and  transmit  the  posterior  branches  of  the  sacral  nerves.  On  the  outer  side  of 
the  posterior  sacral  foramina  are  a  series  of  tubercles,  the  rudimentary  posterior 
transverse  processes  of  the  sacral  vertebrae.  The  first  pair  of  transverse  tubercles 
are  of  large  size,  very  distinct,  and  correspond  with  each  superior  angle  of  the 
bone;  the  second,  small  in  size,  enter  into  the  formation  of  the  sacro-iliac 
articulation;  the  third  give  attachment  to  the  oblique  sacro-iliac  ligaments;  and 
the  fourth  and  fifth  to  the  great  sacro-ischiatic  ligaments.  The  interspace  be- 
tween the  spinous  and  transverse  processes  on  the  back  of  the  sacrum,  presents 
a  wide  shallow  concavity,  called  the  sacral  groove;  it  is  continuous  above  witi||fl 
the  vertebral  groove,  and  lodges  the  origin  of  the  Erector  Spinas.  ll 

The  Lateral  Surface,  broad  above,  becomes  narrowed  into  a  thin  edge  below. 
Its  upper  half  presents  in  front  a  broad  ear-shaped  surface  for  articulation  wit 
the  ilium.  This  is  called  the  auricular  surface,  and  in  the  fresh  state  is  coatc 
with  cartilage.  It  is  bounded  posteriorly  by  deep  and  uneven  impressions,  foi 
the  attachment  of  the  posterior  sacro-iliac  ligaments.  The  lower  half  is  thin 
and  sharp,  and  gives  attachment  to  the  greater  and  lesser  sacro-ischiatic  liga- 
ments, and  to  some  fibres  of  the  Gluteus  Maximus;  below,  it  presents  a  deep 
notch,  which  is  converted  into  a  foramen  by  articulation  with  the  transverse 


foi* 


SACRUM. 


129 


Fig.  84. 


-Development  of  the  Sacrum. 

Additloiutl  ventres 
Jhr    the  first  3  pieces  * 


at  hcrth 


Fig.  8.5. 


process  of  the  upper  piece  of  tlie  coccyx,  and  transmits  the  anterior  branch  of 
the  fifth  sacral  nerve. 

The  Base  of  the  sacrum,  which  is  broad  and  expanded,  is  directed  upwards 
and  forwards.  In  the  middle  is  seen  an  oval  articular  surface,  which  corres- 
ponds with  the  under  surface  of  the  body  of  the  last  lumbar  vertebra,  bound- 
ed behind  by  the  Jarge  triangular  orifice  of  the  sacral  canal.  This  orifice  is 
formed  behind  by  the  spinous  process  and  laminge  of  the  first  sacral  vertebra, 
whilst  projecting  from  it  on  each  side  are  the  superior  articular  processes;  they 
are  oval,  concave,  directed  backwards  and  inwards,  like  the  superior  articular 
processes  of  a  lumbar  vertebra  ;  and  in  front  of  each  articular  process  is  an  in- 
tervertebral notch,  which  forms  the  lower  half  of  the  last  intervertebral  fora- 
men. Lastly,  on  each  side  of  the  articular 
surface  is  a  broad  and  flat  triangular 
surface  of  bone,  which  extends  outwards, 
and  is  continuous  on  each  side  with  the 
iliac  fossa. 

The  Aiiex^  directed  downwards  and 
forwards,  presents  a  small  oval  concave 
surface  for  articulation  with  the  coccyx. 

The  Sacral  Canal  runs  throughout  the 
greater  part  of  the  bone ;  it  is  large  and 
triangular  in  form  above,  small  and  flat- 
tened from  before  backwards  below.  In 
this  situation,  its  posterior  wall  is  incom- 
plete, from  the  non-development  of  the 
laminge  and  spinous  processes.  It  lodges 
the  sacral  nerves,  and  is  perforated  by 
the  anterior  and  posterior  sacral  fora- 
mina, through  which  these  pass  out. 

Structure.  It  consists  of  much  loose 
spongy  tissue  within,  invested  externally 
by  a  thin  layer  of  compact  tissue. 

Differences  in  the  Sacrum  of  the  Male 
and  Female.  The  sacrum  in  the  female 
is  usually  wider  than  in  the  male ;  and 
it  is  much  less  curved,  the  upper  half  of 
the  bone  being  nearly  straight,  the  lower 
half  presenting  the  greatest  amount  of 
curvature.  The  bone  is  also  directed 
more  obliquely  backwards;  which  in- 
creases the  size  of  the  pelvic  cavity,  and 
forms  a  more  prominent  sacro-vertebral 
angle.  In  the  male,  the  curvature  is 
more  evenly  distributed  over  the  whole 
length  of  the  bone,  and  is  altogether 
greater  than  in  the  female. 

Peculiarities  of  the  Sacrum.  This  bone, 
in  some  cases,  consists  of  six  pieces; 
occasionally  the  number  is  reduced  to 
four.  Sometimes  the  bodies  of  the  first 
and  second  segments  are  not  joined,  or 
the  laminae  and  spinous  processes  have 
not  coalesced.  Occasionally,  the  upper 
pair  of  transverse  tubercles  are  not 
joined  to  the  rest  of  the  bone  on  one  or 

both  sides ;  and  lastly,  the  sacral  canal  may  be  open  for  nearly  the  lower  half 
of  the  bone,  in  consequence  of  the  imperfect  development  of  the  laminae  and 


At  i\  Yei.rs. 


Fig.  86. 


2       EuipJiiisal 


I  am  tills 


for  eac/t   la  feral   surfa.ce. 


at  25 


.1  # 


130  THE    SKELETON. 

spinous  processes.  The  sacrum,  also,  varies  considerably  with  respect  to  its 
degree  of  curvature.  From  the  examination  of  a  large  number  of  skeletons, 
it  would  appear  that,  in  one  set  of  cases,  the  anterior  surface  of  this  bone  was 
nearly  straight,  the  curvature,  which  was  very  slight,  affecting  only  its  lower 
end.  In  another  set  of  cases,  the  bone  was  curved  throughout  its  whole  length, 
but  especially  towards  its  middle.  In  a  third  set  the  degree  of  curvature  was 
less  marked,  and  affected  especially  the  lower  third  of  the  bone. 

Development  (Fig  84).  The  sacrum,  formed  by  the  union  of  five  vertebrae, 
has  thirty-five  centres  of  ossification. 

The  bodies  of  the  sacral  vertebrae  have  each  three  ossific  centres ;  one  for  the 
central  part,  and  one  for  the  epiphysal  plates  on  its  upper  and  under  surface. 

The  laminse  of  the  sacral  vertebrae  are  each  developed  by  two  centres ;  these 
meet  behind  to  form  the  arch,  and  subsequently  join  the  body. 

"The  lateral  masses  have  six  additional  centres,  two  for  each  of  the  first  three 
vertebrae.  These  centres  make  their  appearance  above  and  to  the  outer  side  of 
the  anterior  sacral  foramina  (Fig.  84),  and  are  developed  into  separate  segments, 
which  correspond  with  the  anterior  transverse  processes  (Fig.  85) ;  they  are 
subsequently  blended  with  each  other,  and  with  the  bodies  and  the  posterior 
transverse  processes  to  form  the  lateral  mass. 

Lastly,  each  lateral  surface  of  the  sacrum  is  developed  by  two  epiphysal  plates 
(Fig.  86) ;  one  for  the  auricular  surface,  and  one  for  the  remaining  part  of  the 
thin  lateral  edge  of  the  bone. 

Period  of  Development.  At  about  the  eighth  or  ninth  week  of  foetal  life, 
ossification  of  the  central  part  of  the  bodies  of  the  first  three  vertebrae  com- 
mences; and,  at  a  somewhat  later  period,  that  of  the  last  two.  Between  the 
sixth  and  eighth  months  ossification  of  the  laminae  takes  place,  and,  at  about 
the  same  period,  the  characteristic  osseous  tubercles  for  the  three  first  sacral 
vertebrae  make  their  appearance.  The  laminae  join  to  form  the  arch,  and  are 
united  to  the  bodies,  first,  in  the  lowest  vertebrae.  This  occurs  about  the  second 
year,  the  uppermost  segment  appearing  as  a  single  piece  about  the  fifth  or  sixth 
year.  About  the  sixteenth  year  the  epiphyses  for  the  upper  and  under  surfaces 
of  the  bodies  are  formed ;  and,  between  the  eighteenth  and  twentieth  years, 
those  for  each  lateral  surface  of  the  sacrum  make  their  appearance.  At  about 
this  period  the  last  two  segments  are  joined  to  one  another ;  and  this  process 
gradually  extending  upwards,  all  the  pieces  become  united,  and  the  bone  com- 
pletely formed  from  the  twenty-fifth  to  the  thirtieth  year  of  life. 

Articulations.  With  four  bones ;  the  last  lumbar  vertebra,  coccyx,  and  tho 
two  ossa  innominata. 

Attachment  of  Muscles.  In  front,  the  Pyriformis  and  Coccygeus;  behind,  tbo 
Gluteus  Maximus  and  Erector  Spinse. 

The  Coccyx.  ™| 

The  Coccyx  (xdxxvl,  cuchoo\  so  called  from  having  been  compared  to  a  cuckoo's] 
beak  (Fig.  87),  is  usually  formed  of  four  small  segments  of  bone,  the  mostj 
rudimentary  parts  of  the  vertebral  column.  In  each  of  the  first  three  segments] 
may  be  traced  a  rudimentary  body,  articular  and  transverse  processes;  the  last] 
piece  (sometimes  the  third)  is  a  mere  nodule  of  bone,  without  distinct  processes.! 
All  the  segments  are  destitute  of  laminae  and  spinous  processes;  and,  conse- 
quently, of  spinal  canal  and  intervertebral  foramina.  The  first  segment  is  thej 
largest ;  it  resembles  the  lowermost  sacral  vertebra,  and  often  exists  as  a  sepa- 
rate piece  ;  the  last  three,  diminishing  in  size  from  above  downwards,  are  usually! 
blended  together  so  as  to  form  a  single  bone.  The  gradual  diminution  in  the! 
size  of  the  pieces  gives  this  bone  a  triangular  form,  the  base  of  the  triangle] 
joining  the  end  of  the  sacrum.  It  presents  for  examination  an  anterior  andj 
posterior  surface,  two  borders,  a  base,  and  an  apex.  The  anterior  surface  isj 
slightly  concave,  and  marked  with  three  transverse  grooves,  indicating  thej 


I 


THE    SPINE    IN    GENERAL. 


131 


Fig.  87. — Coccyx. 
Comwa 


Cs^ 


points  of  junction  of  the  different  pieces.  It  has  attached  to  it  the  anterior 
sacro-coccjgeal  ligament  and  Levator  Ani  muscle,  and  supports  the  lower  end 
of  the  rectum.  The  posterior  surface  is  convex, 
marked  by  transverse  grooves  similar  to  those  on 
the  anterior  surface;  and  presents  on  each  side  a 
lineal  row  of  tubercles,  the  rudimentary  articular 
processes  of  the  coccygeal  vertebrae.  Of  these,  the 
superior  pair  are  very  large;  and  are  called  the 
cornua  of  the  coccyx;  they  project  upwards,  and 
articulate  with  the  cornua  of  the  sacrum,  the  junc- 
tion between  these  two  bones  completing  the  fifth 
sacral  foramen  for  the  transmission  of  the  posterior 
branch  of  the  fifth  sacral  nerve.  The  lateral  borders 
are  thin,  and  present  a  series  of  small  eminences, 
which  represent  the  transverse  processes  of  the  coccy- 
geal vertebrae.  Of  these,  the  first  on  each  side  is  of 
large  size,  flattened  from  before  backwards ;  and  often 
ascends  to  join  the  lower  part  of  the  thin  lateral 
edge  of  the  sacrum,  thus  completing  the  fifth  sacral 
foramen:  the  others  diminish  in  size  from  above 
downwards,  and  are  often  wanting.  The  borders  of 
the  coccyx  are  narrow,  and  give  attachment  on  each 
side  to  the  sacro-sciatic  ligaments  and  Coccygeus 
muscle.  The  base  presents  an  oval  surface  for  articu- 
lation with  the  sacrum.  The  apex  is  rounded,  and 
has  attached  to  it  the  tendon  of  the  External  Sphinc- 
ter muscle.  It  is  occasionally  bifid,  and  sometimes 
deflected  to  one  or  other  side. 

Developm.ent.  The  coccyx  is  developed  by  four 
centres,  one  for  each  piece.  Occasionally,  one  of  the 
first  three  pieces  of  this  bone  is  developed  by  two 
centres,  placed  side  by  side.  The  ossifi«  nuclei  make  their  appearance  in  the 
following  order :  in  the  first  segment,  at  birth ;  in  the  second  piece,  at  from 
five  to  ten  years;  in  the  third,  from  ten  to  fifteen  years;  in  the  fourth,  from 
fifteen  to  twenty  years.  As  age  advances,  these  various  segments  become 
united  in  the  following  order :  the  first  two  pieces  join ;  then  the  third  and 
fourth;  and,  lastly,  the  bone  is  completed  by  the  union  of  the  second  and  third. 
At  a  later  period  of  life,  especially  in  females,  the  coccyx  often  becomes  joined 
to  the  end  of  the  sacrum. 

Articulation.     With  the  sacrum. 

Attachment  of  Mxiscles.     On  either  side,  the  Coccygeus ;  behind,  the  Gluteus 
Maximus;  at  the  apex,  the  Sphincter  Ani;  and  in  front,  the  Levator  Ani. 


Posterior  iSfic-rfa.oa 


Of  the  Spine  in  General. 

The  Spinal  Column,  formed  by  the  junction  of  the  vertebrae,  is  situated  in 
the  median  line,  at  the  posterior  part  of  the  trunk :  its  average  length  is  about 
two  feet  two  or  three  inches,  measured  along  the  curved  anterior  surface  of  the 
column.  Of  this  length  the  cervical  part  measures  about  five,  the  dorsal  about 
eleven,  the  lumbar  about  seven  inches,  and  the  sacrum  and  coccyx  the  remain- 
der. 

Viewed  in  front,  it  presents  two  pyramids  joined  together  at  their  bases,  the 
upper  one  being  formed  by  all  the  vertebrae  from  the  second  cervical  to  the 
last  lumbar;  the  lower  one  by  the  sacrum  and  coccyx.  When  examined  more 
closely,  the  upper  pyramid  is  seen  to  be  formed  of  three  smaller  pyramids. 
The  uppermost  of  these  consists  of  the  six  lower  cervical  vertebrae ;  its  apex 
being  formed  by  the  axis  or  second  cervical ;  its  base,  by  the  first  dorsal.     The 


132 


THE    SKELETOX 


Fij?.  88.— Lateral  View  of  the  Spine. 


lit  Ctrviecd 
or  Atias 

2d  Cervical 
or  Axit. 


i*.'  l)orsai.-\ 


4- 


10- 


l^  Lum6nr.^ 


A 


:s 


second  pyramid,  which  is  inverted,  is  formed 
by  the  four  upper  dorsal  vertebrae,  the  base 
being  at  the  first  dorsal,  the  smaller  end  at  the 
fourth.  The  third  pyramid  commences  at  the 
fourth  dorsal,  and  gradually  increases  in  size 
to  the  fifth  lumbar. 

Viewed  laterally  (Fig.  88),  the  spinal  column 
presents  several  curves,  which  correspond  to  the 
different  regions  of  the  column,  and  are  called 
cervical,  dorsal,  lumbar,  and  pelvic.  The  cer- 
vical curve  commences  at  the  apex  of  the  odon- 
toid process,  and  terminates  at  the  middle  of  the 
second  dorsal  vertebra ;  it  is  convex  in  front, 
and  is  the  least  marked  of  all  the  curves.  The 
dorsal  curve,  which  is  concave  forwards,  com- 
mences at  the  middle  of  the  second,  and  ter- 
minates at  the  middle  of  the  twelfth  dorsal. 
Its  most  prominent  point  behind  corresponds 
to  the  body  of  the  seventh  or  eighth  vertebra. 
The  lumbar  curve  commences  at  the  middle 
of  the  last  dorsal  vertebra,  and  terminates  at 
the  sacro-vertebral  angle.  It  is  convex  ante- 
riorly ;  the  convexity  of  the  lower  three  ver- 
tebrae being  much  greater  than  that  of  the 
upper  ones.  The  pelvic  curve  commences  at 
the  sacro-vertebral  articulation,  and  terminates 
at  the  point  of  the  coccyx.  It  is  concave  an- 
teriorly. These  curves  are  partly  due  to  tho 
shape  of  the  bodies  of  the  vertebrae,  and  partly 
to  the  intervertebral  substances,  as  will  be 
explained  in  the  Articulatiom  of  the  Spine. 

The  spine  has  also  a  slight  lateral  curva- 
ture, the  convexity  of  which  is  directed  to- 
ward the  right  side.  This  is  most  probably 
produced,  as  Bichat  first  explained,  chiefly 
by  muscular  action ;  most  persons  using  the 
right  arm  in  preference  to  the  left,  especially 
in  making  long-continued  efforts,  when  the 
body  is  curved  to  the  right  side.  In  support 
of  this  explanation,  it  has  been  found,  by  B^- 
clard,  that  in  one  or  two  individuals  who  were 
left-handed,  the  lateral  curvature  was  directed 
to  the  left  side. 

The  spinal  column  presents  for  examina- 
tion an  anterior,  a  posterior,  and  two  lateral 
surfaces;  a  base,  summit,  and  vertebral  canal. 

The  anterior  surface  present  the  bodies  of 
the  vertebra)  separated  in  the  recent  state  by 
the  intervertebral  disks.  The  bodies  are  broad 
in  the  cervical  region,  narrow  in  the  upper 
part  of  the  dorsal,  and  broadest  in  the  lumbar 
region.  The  whole  of  this  surface  is  convex 
transversely,  concave  from  above  downwards 
in  the  dorsal  region,  and  convex  in  the  same 
direction  in  the  cervical  and  lumbar  regions. 

The  posterior  surface  presents  in  the  median 
line  the  spinous  processes.     These  are  short, 


J 


THE    SKULL.  133 

horizontal,  with  bifid  extremities  in  the  cervical  region.  In  the  dorsal  region, 
they  are  directed  obliquely  above,  assume  almost  a  vertical  direction  in  the 
middle,  and  are  horizontal  below,  as  are  also  the  spines  of  the  lumbar  vertebrae. 
They  are  separated  by  considerable  intervals  in  the  loins,  by  narrower  intervals 
in  the  neck,  and  are  closely  approximated  in  the  middle  of  the  dorsal  region. 
Occasionally  one  of  these  processes  deviates  a  little  from  the  median  line,  a  fact 
to  be  remembered  in  practice,  as  irregularities  of  this  sort  are  attendant  also  on 
fractures  or  displacements  of  the  spine.  On  either  side  of  the  spinous  processes, 
extending  the  whole  length  of  the  column,  is  the  vertebral  groove,  formed  by 
the  laminae  in  the  cervical  and  lumbar  regions,  where  it  is  shallow,  and  by  the 
laminas  and  transverse  processes  in  the  dorsal  region,  where  it  is  deep  and  broad. 
In  the  recent  state,  these  grooves  lodge  the  deep  muscles  of  the  back.  External 
to  the  vertebral  grooves  are  the  articular  processes,  and  still  more  externally 
the  transverse  processes.  In  the  dorsal  region,  the  latter  processes  stand  back- 
wards, on  a  plane  considerably  posterior  to  the  same  processes  in  the  cervical 
and  lumbar  regions.  In  the  cervical  region,  the  transverse  processes  are  placed 
in  front  of  the  articular  processes,  and  between  the  intervertebral  foramina.  In 
the  lumbar,  they  aje  placed  also  in  front  of  the  articular  processes,  but  behind 
the  intervertebral  foramina.  In  the  dorsal  region,  they  are  posterior  both  to 
the  articular  processes  and  foramina. 

The  lateral  surfaces  are  separated  from  the  posterior  by  the  articular  processes 
in  the  cervical  and  lumbar  regions,  and  by  the  transverse  processes  in  the  dorsal. 
These  surfaces  present  in  front  the  sides  of  the  bodies  of  the  vertebrae,  marked 
in  the  dorsal  region  by  the  facets  for  articulation  with  the  heads  of  the  ribs. 
More  posteriorly  are  the  intervertebral  foramina,  formed  by  the  juxtaposition 
of  the  intervertebral  notches,  oval  in  shape,  smallest  in  the  cervical  and  upper 
part  of  the  dorsal  regions,  and  gradually  increasing  in  size  to  the  last  lumbar. 
They  are  situated  between  the  transverse  processes  in  the  neck,  and  in  front  of 
them  in  the  back  and  loins,  and  transmit  the  spinal  nerves.  The  base  of  the 
vertical  column  is  formed  by  the  under  surface  of  the  body  of  the  fifth  lumbar 
vertebra ;  and  the  summit  by  the  upper  surface  of  the  atlas.  The  vertebral  canal 
follows  the  different  curves  of  the  spine;  it  is  largest  in  those  regions  in  which 
the  spine  enjoys  the  greatest  freedom  of  movement,  as  in  the  neck  and  loins, 
where  it  is  wide  and  triangular ;  and  narrow  and  rounded  in  the  back,  where 
motion  is  more  limited. 

THE  SKULL. 

The  Skull,  or  superior  expansion  of  the  vertebral  column,  is  composed  of  four 
vertebrae,  the  elementary  parts  of  which  are  specially  modified  in  form  and  size, 
and  almost  immovably  connected,  for  the  reception  of  the  brain,  and  special 
organs  of  the  senses.  These  vertebrae  are  the  occipital,  parietal,  frontal,  and 
nasal.  Descriptive  anatomists,  however,  divide  the  skull  into  two  parts,  the 
Cranium  and  the  Face.  The  Cranium  (xpavos,  a  helmet)  is  composed  of  eight  bones : 
viz.,  the  occipital^  two  parietal^  frontal^  two  temporal,  sphenoid,  and  ethmoid.  The 
Face  is  composed  oi  fourteen  bones:  viz.,  the  two  nasal,  two  superior  maxillary, 
two  lachrymal,  two  malar,  two  palate,  two  inferior  turbinated,  vomer,  and  inferior 
maxillary.  The  ossicula  auditlUs,  the  teeth^  and  Wormian  bones,  are  not  included 
in  this  enumeration. 


134  THE    SKELETON. 


Cranium^  8  hones. 


f  Occipital. 
Two  Parietal. 
)Frontal. 
I  Two  Temporal. 
Sphenoid. 
^Ethmoid. 


Skull,  22  hones.  I  /'^wo  ^'^sal. 

Two  Superior  Maxillary. 
iTwo  Lachrymal. 
JTwo  Malar. 
Face,  14  hones.    \Two  Palate. 

/Two  Inferior  Turbinated. 
Vomer. 
^Inferior  Maxillary. 

BONES  OF  THE  CRANIUM. 
The  Occipital  Bone. 

The  Occipital  5one  (Fig.  89)  is  situated  at  the  back  part  and  base  of  the 
cranium,  is  trapezoid  in  form,  curved  upon  itself,  and  presents  for  examination 
two  surfaces,  four  borders,  and  four  angles. 

The  External  Surface  is  convex.  Midway  between  the  summit  of  the  bone 
and  the  posterior  margin  of  the  foramen  magnum  is  a  prominent  tubercle,  the 
external  occipital  protuberance,  for  the  attachment  of  the  Ligamentum  Nuchse; 
and  descending  from  it  as  far  as  the  foramen,  a  vertical  ridge,  the  external 
occipital  crest.  This  tubercle  and  crest  vary  in  prominence  in  different  skulls. 
Passing  outwards  from  the  occipital  protuberance  on  each  side  are  two  semi- 
circular ridges,  the  superior  curved  lines ;  and  running  parallel  with  these  from 
the  middle  of  the  crest,  are  the  two  inferior  curved  lines.  The  surface  of  the 
bone  above  the  superior  curved  lines  is  smooth  on  each  side,  and,  in  the  recent 
state,  is  covered  by  the  Occipito-frontalis  muscle,  whilst  the  ridges,  as  well  as 
the  surface  of  the  bone  between  them,  serve  for  the  attachment  of  numerous 
muscles.  The  superior  curved  line  gives  attachment  internally  to  the  Trapezius, 
externally  to  the  Occipito-frontalis  and  Sterno  cleido-mastoid,  to  the  extent 
shown  in  Fig.  89 ;  the  depressions  between  the  curved  lines  to  the  Complexus 
internally,  the  Splenius  Capitis  and  Obliquus  Capitis  Superior  externally.  The 
inferior  curved  line,  and  the  depressions  below  it,  afford  insertion  to  the  Rectus 
Capitis  Posticus  Major  and  Rectus  Capitis  Posticus  Minor  muscles. 

'T\\Q  foramen  magnum  is  a  large  oval  aperture,  its  long  diameter  extending 
from  before  backwards.  It  transmits  the  spinal  cord  and  its  membranes,  the 
spinal  accessory  nerves,  and  the  vertebral  arteries.  Its  back  part  is  wide  for 
the  transmission  of  the  cord,  and  the  corresponding  margin  rough  for  the 
attachment  of  the  dura  mater  inclosing  the  cord  ;  the  forepart  is  narrower,  being 
encroached  upon  by  the  condyles;  it  has  projecting  towards  it  from  below  the 
odontoid  process,  and  its  margins  are  smooth  and  bevelled  internally  to  support 
the  medulla  oblongata.  On  each  side  of  the  foramen  magnum  are  the  condyles, 
for  articulation  with  the  atlas ;  they  are  convex,  oblong,  or  reniform  in  shape, 
and  directed  downwards  and  outwards;  they  converge  in  front,  and  encroach 
slightly  upon  the  anterior  segment  of  the  foramen.  On  the  inner  border  of 
each  condyle  is  a  rough  tubercle  for  the  attachment  of  the  ligaments  (check) 
which  connect  this  bone  with  the  odontoid  process  of  the  axis;  whilst  external 
to  them  is  a  rough  tubercular  prominence,  the  transverse  or  jugular  process 
(the  representative  of  the  transverse  process  of  a  vertebra)  channelled  in  front 
by  a  deep  notch,  which  forms  part  of  the  jugular  foramen.  The  under  surface 
of  this  process  affords  attachment  to  the  Rectus  Capitis  Lateralis;  its  upper  or 
cerebral  surface  presents  a  deep  groove  which  lodges  part  of  the  lateral  sinus. 


OCCIPITAL    BONE. 


135 


whilst  its  prominent  extremity  is  marked  by  a  quadrilateral  rough  surface, 
covered  with  cartilage  in  the  fresh  state,  and  articulating  with  a  similar  surface 
on  the  petrous  portion  of  the  temporal  bone.  On  the  outer  side  of  each  con- 
dyle, near  its  forepart,  is  a  foramen,  the  anterior  condyloid ;  it  is  directed  down- 


Fig.  89. — Occipital  Bone.     Outer  Surface. 


of£1ktryrue 


wards,  outwards,  and  forwards,  and  transmits  the  hypoglossal  nerve.  This 
foramen  is  sometimes  double.  Behind  each  condyle  is  a  fossa, ^  sometimes 
perforated  at  the  bottom  by  a  foramen,  the  posterior  condyloid,  for  the  trans- 
mission of  a  vein  to  the  lateral  sinus.  In  front  of  the  foramen  magnum  is  a 
strong  quadrilateral  plate  of  bone,  the  basilar  process,  wider  behind  than  in 
front ;  its  under  surface,  which  is  rough,  presenting  in  the  median  line  a  tuber- 
cular ridge,  the  pharyngeal  spine,  for  the  attachment  of  the  tendinous  raph^ 
and  Superior  Constrictor  of  the  pharynx ;  and,  on  each  side  of  it,  rough  depres- 
sions for  the  attachment  of  the  Rectus  Capitis  Anticus  Major  and  Rectus  Capitis 
Anticus  Minor  muscles. 

The  Internal  or  Cerebral  Surface  (Fig.  90)  is  deeply  concave.  The  posterior 
or  occipital  part  is  divided  by  a  crucial  ridge  into  four  fossae.  The  two  supe- 
rior fossae  receive  the  posterior  lobes  of  the  cerebrum,  and  present  slight  emi- 
nences and  depressions  corresponding  to  their  convolutions.  The  two  inferior, 
which  receive  the  lateral  lobes  of  the  cerebellum,  are  larger  than  the  former, 
and  comparatively  smooth ;  both  are  marked  by  slight  grooves  for  the  lodg- 
ment of  arteries.  At  the  point  of  meeting  of  the  four  divisions  of  the  crucial 
ridge  is  an  eminence,  the  internal  occipital  protuberance.  It  nearly  corresponds 
to  that  on  the  outer  surface,  and  is  perforated  by  one  or  more  large  vascular 

'  This  fossa  presents  many  variations  in  size.  It  is  usually  shallow ;  and  the  foramen  small ; 
occasionally  wanting,  on  one,  or  both  sides.  Sometimes  both  fossa  and  foramen  are  large,  but 
confined  to  one  side  only ;  more  rarely,  the  fossa  and  foramen  are  very  large  on  both  sides. 


136 


THE    SKELETON. 


foramina.  From  this  eminence,  the  superior  division  of  the  crucial  ridge  runs 
upward  to  the  superior  angle  of  the  bone;  it  presents  occasionally  a  deep  groove 
for  the  superior  longitudinal  sinus,  the  margins  of  which  give  attachment  to 
the  falx  cerebri.     The  inferior  division,  the  internal  occipital  crest,  runs  to  the 

Fig.  90. — Occipital  Bone.    Inner  Surface. 
Sufiepiof  Allele 


Jaiferioi'  An  alp 


posterior  margin  of  the  foramen  magnum,  on  the  edge  of  which  it  becomes 
gradually  lost;  this  ridge,  which  is  bifurcated  below,  serves  for  the  attachment 
of  the  falx  cerebelli.  It  is  usually  marked  by  two  small  grooves,  which  com- 
mence on  either  side  of  the  posterior  margin  of  the  foramen  magnum,  join 
together  above,  and  run  into  the  depression  for  the  Torcular  Herophili.  They 
lodge  the  occipital  sinuses.  The  transverse  grooves  pass  outwards  to  the  lateral 
angles;  they  are  deeply  channelled,  for  the  lodgment  of  the  lateral  sinuses, 
their  prominent  margins  affording  attachment  to  the  tentorium  cerebelli.*  At 
the  point  of  meeting  of  these  grooves  is  a  depression,  the  "Torcular  Hero- 
phili,"* placed  a  little  to  one  or  the  other  side  of  the  internal  occipital  pro- 
tuberance. More  anteriorly  is  the  foramen  magnum,  and  on  each  side  of  it, 
but  nearer  its  anterior  than  its  posterior  part,  the  internal  openings  of  the  ante- 

'  Usually  ono  of  the  transverse  proovoa  is  deeper  and  broader  than  the  other ;  occasionally 
both  grooves  arc  of  equal  dc'])th  aud  breadth,  or  both  equally  indistinct.  The  broader  of  the 
two  transverse  grooves  is  nearly  always  continuous  with  the  vertical  groove  for  the  superior 
longitudinal  sinus,  and  occupies  the  corresponding  side  of  the  median  line. 

*  The  columns  of  blood  coming  in  different  directions  were  supposed  to  be  pressed  together  at 
this  point. 


OCCIPITAL    BONE.  137 

rior  condyloid  foramina ;  the  internal  openings  of  the  posterior  condyloid  fora- 
mina being  a  little  external  and  posterior  to  them,  protected  by  a  small  arch  of 
bone.  At  this  part  of  the  internal  surface  there  is  a  very  deep  groove,  in  which 
the  posterior  condyloid  foramen,  when  it  exists,  has  its  internal  termination. 
This  groove  is  continuous  in  the  complete  skull  with  that  which  separates  the 
upper  from  the  lower  fossae,  and  lodges  the  end  of  the  same  sinus,  the  lateral. 
In  front  of  the  foramen  magnum  is  the  basilar  process,  presenting  a  shallow 
depression,  the  basilar  groove,  which  slopes  from  behind,  upwards  and  forwards, 
and  supports  the  medulla  oblongata ;  and  on  each  side  of  the  basilar  process  is  a 
narrow  channel,  which,  when  united  with  a  similar  channel  on  the  petrous  por- 
tion of  the  temporal  bone,  forms  a  groove,  which  lodges  the  inferior  petrosal  sinus. 

Angles.  The  s^iperior  angle  is  received  into  the  interval  between  the  poste- 
rior superior  angles  of  the  two  parietal  bones :  it  corresponds  with  that  part 
of  the  skull  in  the  foetus  which  is  called  the  posterior  fontancUe.  The  inferior 
angle  is  represented  by  the  square-shaped  surface  of  the  basilar  process.  At 
an  early  period  of  life,  a  layer  of  cartilage  separates  this  part  of  the  bone  from 
the  sphenoid;  but  in  the  adult,  the  union  between  them  is  osseous.  The  lateral 
angles  correspond  to  the  outer  ends  of  the  transverse  grooves,  and  are  received 
into  the  interval  between  the  posterior  inferior  angles  of  the  parietal  and  the 
mastoid  portion  of  the  temporal. 

Borders.  The  superior  extends  on  each  side  from  the  superior  to  the  lateral 
angle,  is  deeply  serrated  for  articulation  with  the  parietal  bone,  and  forms,  by 
this  union,  the  lambdoid  suture.  The  inferior  border  extends  from  the  lateral 
to  the  inferior  angle;  its  upper  half  is  rough,  and  articulates  with  the  mastoid 
portion  of  the  temporal,  forming  the  masto-occipital  suture:  the  inferior  half 
articulates  with  the  petrous  portion  of  the  temporal,  forming  the  petro-occipital 
suture;  these  two  portions  are  separated  from  one  another  by  the  jugular  process. 
In  front  of  this  process  is  a  deep  notch,  which,  with  a  similar  one  on  the  petrous 
portion  of  the  temporal,  forms  the  foramen  lacerum  posterius.  This  notch  is  occa- 
sionally subdivided  into  two  parts  by  a  small  process  of  bone,  and  presents  an 
aperture  at  its  upper  part,  the  internal  opening  of  the  posterior  condyloid  foramen. 

Structure.  The  occipital  bone  consists  of  two  compact  laminae,  called  the 
outer  and  inner  tables,  having  between  them  the  diploic  tissue:  this  bone  is  espe- 
cially  thick   at    the  ridges, 

protuberances,  condyles,  and  Fig-  91.— Development  of  Occipital  Bone, 

anterior  part  of  the  basilar  i?y  ^  centrei 

process;    whilst  at   the  bot- 
tom of  the  fossae,  especially  ,^^^_^.^^«« 
the  inferior,  it  is  thin,  semi-                        ^BPWJWBBJik     ^  /"^  occipital 
transparent,  and  destitute  of                    ^^P"  '1    ""'    ^SL  /^'•«'^« 
diploe. 

Development  (Fig.  91).   The 
occipital  bone  has/o?«-  centres 

of  development:  one  for  the  

posterior   or    occipital    part,  at  lira     m      '  ^    ,  f,^  ,„,f,  ,,^jr^ 

which    is    formed    in    mem-      ^'^  ^> pt^^e*  /-- 1  )   f)  portion 

brane;    one    for   the   basilar        '^J><-'-^^^ 

portion,    and    one    for    each  V^^^ ^/"^  hcvsdcr  j>o,tion 

condyloid  portion,  which  are 
formed  in  cartilage. 

The  centre  for  the  occipital  portion  appears  aboul  the  tenth  week  of  foetal  life; 
and  consists,  according  to  Blandin  and  Cruveilhier,  of  a  small  oblong  plate  which 
appears  in  the  situation  of  the  occipital  protuberance.'     The  condyloid  portions 

'  B6clard  considers  this  segment  to  have  four  centres  of  ossification,  arranged  in  pairs,  two 
above  and  two  below  thp  curved  lines,  and  Meckel  describes  eight,  four  of  which  correspond  in 
situation  with  those  aliove  described  :  of  the  other  four,  two  are  placed  in  juxtaposition,  at  the 
upper  angle  of  the  bone,  and  the  remaining  two,  one  at  each  side,  in  the  lateral  angles. 


•»s 


138 


THE    SKELETON. 


then  ossify,  and  lastly  the  basilar  portion.  At  birth,  the  bone  consists  of  four  parts, 
separate  from  one  another,  the  occipital  portion  being  fissured  in  the  direction 
indicated  in  the  plate  above.  At  about  the  fourth  year,  the  occipital  and  the 
two  condyloid  pieces  join;  and  about  the  sixth  year  the  bone  consists  of  a 
single  piece.  At  a  later  period,  between  the  eighteenth  and  twenty-fifth  years, 
the  occipital  and  sphenoid  become  united,  forming  a  single  bone. 

Articulations.  With  six  bones;  two  parietal,  two  temporal,  sphenoid,  and 
atlas. 

Attachment  of  Muscles.  To  the  superior  curved  line  are  attached  the  Occipito- 
frontalis.  Trapezius,  and  Sterno-cleido-mastoid.  To  the  space  between  the 
curved  lines,  the  Complexus,  Splenius  Capitis,  and  Obliquus  Superior;  to  the 
inferior  curved  line,  and  the  space  between  it  and  the  foramen  magnum,  the 
Eectus  Capitis  Posticus  (Major  and  Minor);  to  the  transverse  process,  the  Rectus 
Lateralis;  and  to  the  basilar  process,  the  Rectus  Capitis  Anticus  Major,  Rectus 
Anticus  Minor,  and  Superior  Constrictor  of  the  pharynx. 

The  Parietal  Bones. 

The  Parietal  Bones  {paries,  a  wall)  form  by  their  union  the  sides  and  roof  of 
the  skull.  Each  bone  is  of  an  irregular  quadrilateral  form,  and  presents  for 
examination  two  surfaces,  four  borders  and  four  angles. 

Surfaces.  The  external  surface  (Fig.  92)  is  convex,  smooth,  and  marked  about 
its  centre  by  an  eminence,  called  the  parietal  eminence,  which  indicates  the 


1 


Fiff.  92. — Left  Parietal  Bone.    External  Surface. 


"Parieial    ^^,, 


Mm-- 


^l^APORhL      Mu^cc 


point  where  ossification  commenced.  Crossing  the  middle  of  the  bone  in  an 
arched  direction  is  a  curved  ridge,  the  temporal  ridge,  for  the  attachment  of  the 
temporal  fascia.     Above  this  ridge,  the  surface  of  the  bone  is  rough  and  porous. 


PARIETAL    BONES. 


139 


and  covered  by  the  aponeurosis  of  the  Occipito-frontalis;  below  it  the  bone  is 
smooth,  forms  part  of  the  temporal  fossa,  and  affords  attachment  to  the  temporal 
muscle.  At  the  back  part  of  the  superior  border,  close  to  the  sagittal  suture, 
is  a  small  foramen,  the  parietal  foramen,  which  transmits  a  vein  to  the  superior 
longitudinal  sinus.  Its  existence  is  not  constant,  and  its  size  varies  consider- 
ably. 

The  internal  surface  (Fig.  93),  concave,  presents  eminences  and  depressions 
for  lodging  the  convolutions  of  the  cerebrum,  and  numerous  furrows  for  the 


Fig.  93. — Left  Parietal  Bone.     Internal  Surface. 


FastSfuf 


To»l.l»JerJ{n()Lo^ 


,_Anf.  Sup. 
AiuiLe 


Ant.  Infcr.An.ql» 


ramifications  of  the  meningeal  arteries ;  the  latter  run  upwards  and  backwards 
from  the  anterior  inferior  angle,  and  from  the  central  and  posterior  part  of  the 
lower  border  of  the  bone.  Along  the  upper  margin  is  part  of  a  shallow  groove, 
which,  when  joined  to  the  opposite  parietal,  forms  a  channel  for  the  superior 
longitudinal  sinus,  the  elevated  edges  of  which  afford  attachment  to  the  falx 
cerebri.  Near  the  groove  are  seen  several  depressions;  they  lodge  the  Pac- 
chionian bodies.  The  internal  opening  of  the  parietal  foramen  is  also  seen 
when  that  aperture  exists. 

Borders.  The  superior^  the  longest  and  thickest,  is  dentated  to  articulate  with 
its  fellow  of  the  opposite  side,  forming  the  sagittal  suture.  The  inferior  is 
divided  into  three  parts:  of  these,  the  anterior  is  thin  and  pointed,  bevelled  at 
the  expense  of  the  outer  surface,  and  overlapped  by  the  tip  of  the  great  wing 
of  the  sphenoid ;  the  middle  portion  is  arched,  bevelled  at  the  expense  of  the 
outer  surface,  and  overlapped  by  the  squamous  portion  of  the  temporal ;  the 
posterior  portion  is  thick  and  serrated  lor  articulation  with  the  mastoid  portion 
of  the  temporal.  The  anterior  border,  deeply  serrated,  is  bevelled  at  the  expense 
of  the  outer  surface  above,  and  of  the  inner  below ;  it  articulates  with  the  frontal 
bone,  forming  the  coronal  suture.  The  posterior  border,  deeply  denticulated, 
g,rticulates  with  the  occipital,  forming  the  lambdoid  suture. 


140  THE    SKELETON. 

Angles.  The  anterior  superior^  thin  and  pointed,  corresponds  with  that  por- 
tion of  the  skull  which  in  the  foetus  is  membranous,  and  is  called  the  anterior 
fontanelle.  The  anterior  inferior  angle  is  thin  and  lengthened,  being  received  in 
the  interval  between  the  great  wing  of  the  sphenoid  and  the  frontal.  This  point 
will  be  found  about  one  inch  behind  the  upper  and  outer  angle  of  the  orbit. 
Its  inner  surface  is  marked  by  a  deep  groove,  sometimes  a  canal,  for  the  an- 
terior branch  of  the  middle  meningeal  artery.  The  posterior  superior  angle  cor- 
responds with  the  junction  of  the  sagittal  and  lambdoid  sutures.  In  the  foetus 
this  part  of  the  skull  is  membranous,  and  is  called  the  j^osterior  fontanelle.  The 
posterior  inferior  angle  articulates  with  the  mastoid  portion  of  the  temporal  bone, 
and  generally  presents  on  its  inner  surface  a  broad  shallow  groove  for  lodging 
part  of  the  lateral  sinus. 

Development.  The  parietal  bone  is  formed  in  membrane,  being  developed  by 
one  centre,  which  corresponds  with  the  parietal  eminence,  and  makes  its  first 
appearance  about  the  fifth  or  sixth  week  of  foetal  life.  Ossification  gradually 
extends  from  the  centre  to  the  circumference  of  the  bone.  The  angles  are  con- 
sequently the  parts  last  formed,  and  it  is  in  their  situation  that  the  fontanelles 
exist,  previous  to  the  completion  of  the  growth  of  the  bone. 

Articulations.  With  five  bones;  the  opposite  parietal,  the  occipital,  frontal, 
temporal,  and  sphenoid. 

Attachment  of  Muscles.     One  only,  the  Temporal. 

The  Frontal  Bone. 

The  Frontal  Bone,  which  resembles  a  cockle-shell  in  form,  consists  of  two 
portions — a  vertical  or  frontal  portion,  situated  at  the  anterior  part  of  the  cra- 
nium, forming  the  forehead;  and  a  horizontal  or  orhito-nasal  portion,  which 
enters  into  the  formation  of  the  roof  of  the  orbits  and  nose. 

Vertical  Portion.  External  Surface  (Fig.  94).  In  the  median  line,  traversing 
the  bone  from  the  upper  to  the  lower  part,  is  occasionally  seen  a  slightly  ele- 
vated ridge,  and  in  young  subjects  a  suture,  which  represents  the  line  of  union 
of  the  two  lateral  halves  of  which  the  bone  consists  at  an  early  period  of  life. 
In  the  adult,  this  suture  is  usually  obliterated,  and  the  bone  forms  one  piece. 
Traces  of  the  obliterated  suture  are,  however,  generally  perceptible  at  the  lower 
part.  On  either  side  of  this  ridge,  a  little  below  the  centre  of  the  bone,  is  a 
rounded  eminence,  the  frontal  eminence.  These  eminences  vary  in  size  in 
difi'erent  individuals,  and  are  occasionally  unsymmetrical  in  the  same  subject. 
They  are  especially  prominent  in  cases  of  well-marked  cerebral  development. 
The  whole  surface  of  the  bone  above  this  part  is  smooth,  and  covered  by  the 
aponeurosis  of  the  Occipito- frontalis  muscle.  Below  the  frontal  eminence,  and 
separated  from  it  by  a  slight  groove,  is  the  superciliary  ridge,  broad  internally 
where  it  is  continuous  with  the  nasal  eminence,  but  less  distinct  as  it  arches 
outwards.  These  ridges  are  caused  by  the  projection  outwards  of  the  frontal 
sinuses,  and  give  attachment  to  the  Orbicularis  Palpebrarum  and  Corrugator 
Supercilii.'  Beneath  the  superciliary  ridge  is  the  supra-orbital  arch,  a  curved  and 
prominent  margin,  which  forms  the  upper  boundary  of  the  orbit,  and  separates 
the  vertical  from  the  horizontal  portion  of  the  bone.  The  outer  part  of  the 
arch  is  sharp  and  prominent,  affording  to  the  eye,  in  that  situation,  considerable 
protection  from  injury ;  the  inner  part  is  less  prominent.  At  the  inner  third 
of  this  arch  is  a  notch,  sometimes  converted  into  a  foramen  by  a  bony  process. 


'  Some  confusion  is  occasioned  to  students  commencinjr  the  study  of  anatomy,  by  the  name 
"sinuHcs"  havinjr  beca  pivcn  to  two  perfectly  different  kinds  of  spaces  connected  with  the  skull. 
It  may  be  as  well,  therefore,  to  state  here,  at  the  outset,  that  the  "sinuses"  on  the  interior  of  the 
cranium 
the  bloo 

cranium  (the  frontal,  ethmoidal,  snlionoid,  and  maxillary)  are  hollow  spaces  ia  the  bones  them 
■  ith  tne  i         " 


W 


.  marked  by  grooves  on  the  inner  surface  of  the  bones,  are  venous  channels  along  which    ^ 
d  runs  in  its  passage  back  from  the  brain,  while  the  "  sinuses"  on  the  outside  of  thii    H 

(the  frontal,  ethmoidal,  snlionoid,  and  maxillary)  are  *-" ■■  "  -   ' "'^— • 

selves,  which  communicate  with  tne  nostrils,  and  contain  air. 


FRONTAL    BONE. 


141 


and  called  the  supra-orbital  notch  or  foramen.  It  transmits  the  supra-orbital 
artery,  veins,  and  nerve.  A  small  aperture  is  seen  in  the  upper  part  of  the 
notch,  which  transmits  a  vein  from  the  diploe  to  join  the  ophthalmic  vein. 
The  supra-orbital  arch  terminates  externally  in  the  external  angular  process, 


Fiff.  94. — Frontal  .Bone.     Outer  Surface. 


Angular  jiroc. 


Katal 


and  internally  in  the  internal  angular  process.  The  external  angular  process 
is  strong,  prominent,  and  articulates  with  the  malar  bone:  running  upwards  and 
backwards  from  it  is  a  sharp-curved  crest,  the  temporal  ridge,  for  the  attach- 
ment of  the  temporal  fascia;  and  beneath  it  a  slight  concavity,  that  forms  the 
anterior  part  of  the  temporal  fossa,  and  gives  origin  to  the  Temporal  muscle. 
The  internal  angular  processes  are  less  marked  than  the  external,  and  ar- 
ticulate with  the  lachrymal  bones.  Between  the  internal  angular  processes  is  a 
rough  uneven  interval,  the  nasal  notch,  which  articulates  in  the  middle  line 
with  the  nasal  bone,  and  on  either  side  with  the  nasal  process  of  the  superior 
maxillary  bone.  The  notch  is  continuous  below  with  a  long  pointed  process, 
the  nasal  spine. 

Vertical  Portion.  Internal  Surface  (Fig.  95).  Along  the  middle  line  is  a  ver- 
tical groove,  the  edges  of  which  unite  below  to  form  a  ridge,  the  frontal  crest ; 
the  groove  lodges  the  superior  longitudinal  sinus,  whilst  its  edges  afford  attach- 
ment to  the  falx  cerebri.  The  crest  terminates  below  at  a  small  opening,  the 
foramen  coecum,  which  is  generally  completed  behind  by  the  ethmoid.  This 
foramen  varies  in  size  in  different  subjects,  is  usually  partially  or  completely 
impervious,  lodges  a  process  of  the  falx  cerebri,  and,  when  open,  transmits  a 
vein  from  the  lining-membrane  of  the  nose  to  the  superior  longitudinal  sinus. 
On  either  side  of  the  groove,  the  bone  is  deeply  concave,  presenting  eminences 
and  depressions  for  the  convolutions  of  the  brain,  and  numerous  small  furrows 
for  lodging  the  ramifications  of  the  anterior  meningeal  arteries.     Several  small, 


142 


THE    SKELETON. 


irregular  fossae  are  also  seen  on  either  side  of  the  groove,  for  the  reception  of 
the  Pacchionian  bodies. 

Horizontal  Portion.     External  Surface.     This  portion  of  the  bone  consists  of 
two  thin  plates,  which  form  the  vault  of  the  orbits,  separated  from  one  another 

Fig.  95. — Frontal  Bone.     Inner  Surface. 


u'Oh  Sup.Maxm. -^'H^SIIJ^j^  ^FrontaZ    Sinus 

J  j'     If     \Exjpan^<,d  baae  of  Ncvxal  Spnie, 

vfUh  Perpendieular ^laU  of  Mhrnutd      U       ^„rmimj  jpart  cf  B oaf  ^  Nose 

by  the  ethmoidal  notch.  Each  orbital  vault  consists  of  a  smooth,  concave, 
triangular  plate  of  bone,  marked  at  its  anterior  and  external  part  (immediately 
beneath  the  external  angular  process)  by  a  shallow  depression;  the  lachrymal 
fossa,  for  lodging  the  lachrymal  gland ;  and  at  its  anterior  and  internal  part, 
by  a  depression  (sometimes  a  small  tubercle)  for  the  attachment  of  the  fibrous 
pulley  of  the  Superior  Oblique  muscle.  The  ethmoidal  notch  separates  the 
two  orbital  plates;  it  is  quadrilateral ;  and  filled  up,  when  the  bones  are  united, 
by  the  cribriform  plate  of  the  ethmoid.  The  margins  of  this  notch  present 
several  half-cells,  which,  when  united  with  corresponding  half-cells  on  the 
upper  surface  of  the  ethmoid,  complete  the  ethmoidal  cells;  two  grooves  are 
also  seen  crossing  these  edges  transversely ;  they  are  converted  into  canals  by 
articulation  with  the  ethmoid,  and  are  called  the  anterior  and  posterior  ethmoidal 
canals ;  they  open  on  the  inner  walls  of  the  orbit.  The  anterior  one  transmits 
the  nasal  nerve  and  anterior  ethmoidal  vessels,  the  posterior  one  the  posterior 
ethmoidal  vessels.  In  front  of  the  ethmoidal  notch  is  the  nasal  spine,  a  sharp- 
pointed  eminence,  which  projects  downwards  and  forwards,  and  articulates  in 
front  with  the  crest  of  the  nasal  bones;  behind,  it  is  marked  by  two  grooves, 
separated  by  a  vertical  ridge ;  the  ridge  articulates  with  the  perpendicular 
lainellaj  of  the  ethmoid,  the  grooves  form  part  of  the  roof  of  the  nasal  fossae. 
On  either  side  of  the  base  of  the  nasal  spine  are  the  openings  of  the  frontal 
sinuses.  These  are  two  irregular  cavities,  which  extend  upwards  and  outwards, 
a  variable  distance,  between  the  two  tables  of  the  skull,  aud  are  separated  from 


TEMPORAL    BONES. 


143 


one  another  by  a  thin  bony  septum.  They  give  rise  to  the  prominences  above 
the  root  of  the  nose,  called  the  nasal  eminences  and  superciliary  ridges.  In  the 
child  they  are  generally  absent,  and  they  become  gradually  developed  as  age 
advances.  These  cavities  vary  in  size  in  different  persons,  are  larger  in  men 
than  in  women,  and  are  frequently  of  unequal  size  on  the  two  sides,  the  left 
being  commonly  the  larger.  Occasionally  they  are  subdivided  by  incomplete 
bony  laminae.  They  are  lined  by  mucous  membrane,  and  communicate  with 
the  nose  by  the  infundibulum,  and  occasionally  with  each  other  by  apertures 
in  their  septum. 

The  Internal  Surface  of  the  Horizontal  Portion  presents  the  convex  upper 
surfaces  of  the  orbital  plates,  separated  from  each  other  in  the  middle  line  by 
the  ethmoidal  notch,  and  marked  by  eminences  and  depressions  for  the  con- 
volutions of  the  anterior  lobes  of  the  brain. 

Borders.  The  border  of  the  vertical  portion  is  thick,  strongly  serrated, 
bevelled  at  the  expense  of  the  internal  table  above,  where  it  rests  upon  the 
parietal  bones,  and  at  the  expense  of  the  external  table  at  each  side,  where  it 
receives  the  lateral  pressure  of  those  bones :  this  border  is  continued  below 
into  a  triangular  rough  surface,  which  articulates  with  the  great  wing  of  the 
sphenoid.  The  border  of  the  horizontal  portion  is  thin,  serrated,  and  articu- 
lates with  the  lesser  wing  of  the  sphenoid. 

Structure.  The  vertical  portion  and  external  angular  processes  are  very 
thick,  consisting  of  diploic  tissue  contained  between  two  compact  laminae. 
The  horizontal  portion  is  thin^  translucent,  and  composed  entirely  of  compact 
tissue ;  hence  the  facility  with  which  instruments  can  penetrate  the  cranium 
through  this  part  of  the  orbit. 

Development  (Fig.  96).  The  frontal  bone  is  formed  in  membrane,  being  deve- 
loped by  two  centres,  one  for  each  lateral  half,  which  make  their  appearance, 
at  an  early  period  of  foetal  life,  in  the 
situation  of  the  orbital  arches.  From 
this  point  ossification  extends,  in  a  radi- 
ating manner,  upwards  into  the  forehead, 
and  backwards  over  the  orbit.  At  birth 
it  consists  of  two  pieces,  which  after- 
wards become  united,  along  the  middle 
line,  by  a  suture  which  runs  from  the 
vertex  to  the  root  of  the  nose.  This  su- 
ture usually  becomes  obliterated  within 
a  few  years  after  birth :  but  it  occasion- 
ally remains  throughout  life. 

Articulations.  With  twelve  bones: 
two  parietal,  sphenoid,  ethmoid;  two 
nasal,  two  superior  maxillary,  two  lach- 
rymal, and  two  malar. 

Attachment  of  Muscles.  The  Corrugator  Supercilii,  Orbicularis  Palpebrarum, 
and  Temporal,  on  each  side. 


Fig.  96.— Frontal  Bone  at  Birth. 
Developed  hy  two  lateral  Halves. 


The  Tempoeal  Bones. 

The  Temporal  Bones  are  situated  at  the  side  and  base  of  the  skull,  and 
present  for  examination  a  squamous^  mastoid,  and  petrous  portion. 

The  Squamous  Portion  {squama,  a  scale),  (Fig.  97),  the  anterior  and  upper  part 
of  the  bone,  is  scale-like  in  form,  and  thin  and  translucent  in  texture.  Its 
outer  surface  is  smooth,  convex,  and  grooved  at  its  back  part  for  the  deep  tem- 
poral arteries ;  it  affords  attachment  to  the  Temporal  muscle,  and  form.s  part 
of  the  temporal  fossa.  At  its  back  part  may  be  seen  a  curved  ridge — part  of 
the  temporal  ridge ;  it  serves  for  the  attachment  of  the  temporal  fascia,  limits 
the  origin  of  the  Temporal  muscle,  and  marks  the  boundary  between  the 


144 


THE    SKELETON. 


squamous  and  mastoid  portion  of  the  bone.  Projecting  from  the  lower  part 
of  the  squamous  portion  is  a  long  arched  outgrowth  of  bone,  the  zygomatic 
process.  This  process  is  at  first  directed  outwards,  its  two  surfaces  looking 
upwards  and  downwards ;  it  then  appears  as  if  twisted  upon  itself,  and  runs 

Fig.  97. — Left  Temporal  Bone.     Outer  Surface. 


'attoi ^  foramsn 


forwards,  its  surfaces  now  looking  inwards  and  outwards.    The  superior  border] 
of  the  process  is  long,  thin,  and  sharp,  and  serves  for  the  attachment  of  thoj 
temporal  fascia.     The  inferior,  short,  thick,  and  arched,  has  attached  to  it  somoj 
fibres  of  the  Masseter  muscle.     Its  outer  surface  is  convex  and  subcutaneous;' 
its  inner  is  concave,  and  also  affords  attachment  to  the  Masseter.     The  ex- 
tremity, broad  and  deeply  serrated,  articulates  with  the  malar  bone.     Tho 
zygomatic  process  is  connected  to  the  temporal  bone  by  three  divisions,  called 
its  roots — an  anterior,  middle,  and  posterior.     The  anterior,  which  is  short,  but] 
broad  and  strong,  runs  transversely  inwards  into  a  rounded  eminence,  the 
eminentia  articularis.     This  eminence  forms  the  front  boundary  of  the  glenoid 
fossa,  and  in  the  recent  state  is  covered  with  cartilage.    The  middle  root  forms! 
the  outer  margin  of  the  glenoid  cavity ;  running  obliquely  inwards,  it  termi- 
nates at  the  commencement  of  a  well-marked  fissure,  the  Glaserian  fissure;] 
whilst  the  posterior  root,  which  is  strongly  marked,  runs  from  the  upper  border 
of  the  zygoma,  in  an  arched  direction,  upwards  and  backwards,  forming  tho 
posterior  part  of  the  temporal  ridge.     At  the  junction  of  the  anterior  root  with] 
the  zygoma  is  a  projection,  called  the  tubercle,  for  the  attachment  of  the  exter- 
nal lateral  ligament  of  the  lower  jaw;  and  between  the  anterior  and  middloj 
roots  is  an  oval  depression,  forming  part  of  the  glenoid  fossa  {y>-r,vr,^  a  socket),, 
for  the  reception  of  the  condyle  of  the  lower  jaw.     This  fossa  is  bounded,  inj 
front,  by  the  eminentia  articularis;  behind,  by  the  vaginal  process;  and,  ex- 
ternally, by  the  auditory  process  and  middle  root  of  the  zygoma;  and  is  di-; 
vided  into  two  parts  by  a  narrow  slit,  the   Glaserian  fissure.     The  anterior] 
part,  formed  by  the  squamous  portion  of  the  bone,  is  smooth,  covered  in  the 


TEMPORAL    BONES.  145 

recent  state  with  cartilage,  and  articulates  with  the  condyle  of  the  lower  jaw. 
This  part  of  the  glenoid  fossa  is  separated  from  the  auditory  process  by  a  small 
tubercle,  the  post-glenoid  process,  the  representative  of  a  prominent  tubercle 
which,  in  some  of  the  mammalia,  descends  behind  the  condyle  of  the  jaw,  and 
prevents  it  being  displaced  backwards  during  mastication  (Humphry).  The 
posterior  part  of  the  glenoid  fossa  is  formed  chiefly  by  the  vaginal  process  of 
the  petrous  portion,  and  lodges  part  of  the  parotid  gland.  The  Glaserian 
fissure,  which  leads  into  the  tympanum,  lodges  the  processus  gracilis  of  the 
malleus,  and  transmits  the  Laxator  Tympaoi  muscle  and  the  tympanic  branch 
of  the  internal  maxillary  artery.  The  chorda  tympani  nerve  passes  through  a 
separate  canal  parallel  to  the  Glaserian  fissure  (canal  of  Huguier),  on  the  outer 
side  of  the  Eustachian  tube,  in  the  retiring  angle  between  the  squamous  and 
petrous  portions  of  the  temporal  bone. 

The  internal  surface  of  the  squamous  portion  (Fig.  98)  is  concave,  presents 
numerous  eminences  and  depressions  for  the  convolutions  of  the  cerebrum,  and 
two  well-marked  grooves  for  the  branches  of  the  middle  meningeal  artery. 

Borders.  The  superior  border  is  thin,  bevelled  at  the  expense  of  the  inter- 
nal surface,  so  as  to  overlap  the  lower  border  of  the  parietal  bone,  forming  the 
squamous  suture.  The  anterior  inferior  border  is  thick,  serrated,  and  bevelled, 
alternately  at  the  expense  of  the  inner  and  outer  surfaces,  for  articulation  with 
the  great  wing  of  the  sphenoid. 

The  Mastoid  Portion  {^aotbi,  a  nipple  or  teat)  is  situated  at  the  posterior  part 
of  the  bone ;  its  outer  surface  is  rough,  and  perforated  by  numerous  foramina : 
one  of  these,  of  large  size,  situated  at  the  posterior  border  of  the  bone,  is 
termed  the  mastoid  foramen  ;  it  transmits  a  vein  to  the  lateral  sinus  and  a  small 
artery.  The  position  and  size  of  this  foramen  are  very  variable.  It  is  not 
always  present :  sometimes  it  is  situated  in  the  occipital  bone,  or  in  the  suture 
between  the  temporal  and  the  occipital.  The  mastoid  portion  is  continued 
below  into  a  conical  projection,  the  mastoid  process,  the  size  and  form  of  which 
vary  somewhat.  This  process  serves  for  the  attachment  of  the  Sterno-mas- 
toid,  Splenius  Capitis,  and  Trachelo-mastoid  muscles.  On  the  inner  side  of 
the  mastoid  process  is  a  deep  groove,  the  digastric  fossa,  for  the  attachment  of 
the  Digastric  muscle;  and  running  parallel  with  it,  but  more  internal,  the 
occipital  groove,  which  lodges  the  occipital  artery.  The  internal  surface  of 
the  mastoid  portion  presents  a  deep  curved  groove,  which  lodges  part  of  the 
lateral  sinus ;  and  into  it  may  be  seen  opening  the  mastoid  foramen.  A  section 
of  the  mastoid  process  shows  it  to  be  hollowed  out  into  a  number  of  cellular 
spaces,  communicating  with  each  other,  called  the  mastoid  cells ;  they  open  by 
a  single  or  double  orifice  into  the  back  of  the  tympanum ;  are  lined  by  a  pro- 
longation of  its  lining  membrane ;  and,  probably,  form  some  secondary  part 
of  the  organ  of  hearing.  The  mastoid  cells,  like  the  other  sinuses  of  the 
cranium,  are  not  developed  until  after  puberty ;  hence  the  prominence  of  this 
process  in  the  adult. 

Borders.  The  superior  border  of  the  mastoid  portion  is  broad  and  rough,  its 
serrated  edge  sloping  outwards,  for  articulation  with  the  posterior  inferior 
angle  of  the  parietal  bone.  The  posterior  border,  also  uneven  and  serrated, 
articulates  with  the  inferior  border  of  the  occipital  bone  between  its  lateral 
angle  and  jugular  process. 

The  Petrous  Portion  {rtitpoi,  a  stone),  so  named  from  its  extreme  density  and 
hardness,  is  a  pyramidal  process  of  bone,  wedged  in  at  the  base  of  the  skull 
between  the  sphenoid  and  occipital  bones.  Its  direction  from  without  is  in- 
wards, forwards,  and  a  little  downwards.  It  presents  for  examination  a  base, 
an  apex,  three  surfaces,  and  three  borders ;  and  contains,  in  its  interior,  the 
essential  parts  of  the  organ  of  hearing.  The  base  is  applied  against  the  internal 
surface  of  the  squamous  and  mastoid  portions,  its  upper  half  being  concealed; 
but  its  lower  half  is  exposed  by  the  divergence  of  those  two  portions  of  the 
10 


146 


THE    SKELETON. 


bone  wbich  brings  into  view  the  oval  expanded  orifice  of  a  canal  leading  into 
the  tympanum,  the  meatus  auditorius  externus.  This  canal  is  situated  between 
the  mastoid  process  and  the  posterior  and  middle  roots  of  the  zygoma;  its 
upper  margin  is  smooth  and  rounded,  but  the  greater  part  of  its  circumference 
is  surrounded  by  a  curved  plate  of  bone,  the  auditory  process,  the  free  margin 
of  which  is  thick  and  rough,  for  the  attachment  of  the  cartilage  of  the  external 
ear. 

The  apex  of  the  petrous  portion,  rough  and  uneven,  is  received  into  the 
angular  interval  between  the  spinous  process  of  the  sphenoid  and  the  basilar 
process  of  the  occipital ;  it  presents  the  anterior  or  internal  orifice  of  the 
carotid  canal,  and  forms  the  posterior  and  external  boundary  of  the  foramen 
lacerum  medium. 

The  anterior  surface  of  the  petrous  portion  (Fig.  98)  forms  the  posterior  bound- 
ary of  the  middle  fossa  of  the  skull.     This  surface  is  continuous  with  the  squa- 

Fig.  98. — Left  Temporal  Bone.    Inner  Surface. 


Aqtiednftu*  Vcshhiti  ' 
Jfejyrcesu/n  for  Dura  water 
Jtitatuf  Auduarma  uiUfnu* 


^liru^fjor  .^upenvr  Se^ddraclar  Canal 
■  Hiatus    FcblUpw 

-O^omnyfor  S^utlUr  Petrotal  A^nre 
VcnresMian  for  Caitertau  gangh<^n. 
-BriitU  pastid  throu</h  Carotid  Catud 


I 


moua  portion,  to  which  it  is  united  by  a  suture,  the  temporal  suture,  the  remains 
of  which  are  distinct  even  at  a  late  period  of  life.  It  presents  six  points  for 
examination.  1.  An  eminence  near  the  centre,  which  indicates  the  situation  of 
the  superior  vertical  semicircular  canal.  2.  On  the  other  side  of  this  eminence 
a  depression,  indicating  the  position  of  the  tympanum,  the  layer  of  bone  which 
separates  the  tympanum  from  the  cranial  cavity  being  extremely  thin,  3.  A 
shallow  groove,  sometimes  double,  leading  backwards  to  an  oblique  opening, 
the  hiatus  Fallopii,  for  the  passage  of  the  petrosal  branch  of  the  Vidian  nerve. 
4.  A  smaller  opening,  occasionally  seen  external  to  the  latter,  for  the  passage 
of  the  smaller  petrosal  nerve.  5,  Near  the  apex  of  the  bone  the  termination 
of  the  carotid  canal,  the  wall  of  which  in  this  situation  is  deficient  in  front. 
6.  Above  this  canal,  a  shallow  depression  for  tlie  reception  of  the  Casserian 
ganglion. 

The  posterior  surface  forms  the  front  boundary  of  the  posterior  fossa  of  the 


TEMPORAL    BONES. 


14T 


skull,  and  is  continuous  with  the  inner  surface  of  the  mastoid  portion  of  the 
bone.  It  presents  three  points  for  examination :  1.  About  its  centre,  a  large 
orifice,  the  meatus  auditorius  internus,  whose  size  varies  considerably  ;  its  mar- 
gins are  smooth  and  rounded;  and  it  leads  into  a  short  canal,  about  four  lines 
in  length,  which  runs  directly  outwards,  and  is  closed  by  a  vertical  plate,  di- 
vided by  a  horizontal  crest  into  two  unequal  portions.  The  canal  transmits  the 
auditory  and  facial  nerves,  and  auditory  artery.  2.  Behind  the  meatus  audi- 
torius, a  small  slit,  almost  hidden  by  a  thin  plate  of  bone,  leading  to  a  canal, 
the  aquaeductus  vestibuli,  which  transmits  a  small  artery  and  vein,  and  lodges 
a  process  of  the  dura  mater.  3.  In  the  interval  between  these  two  openings, 
but  above  them,  an  angular  depression  which  lodges  a  process  of  the  dura  mater, 
and  transmits  a  small  vein  into  the  cancellous  tissue  of  the  bone. 

The  inferior  or  basilar  surface  (Fig,  99)  is  rough  and  irregular,  and  forms  part 
of  the  base  of  the  skull.     Passing  from  the  apex  to  the  base,  this  surface  pre- 

Fi<r.  99. — Petrous  Portion.     Inferior  Surface. 


or  nJ.  Teitsor  tymparii.  muscle 


Canal  for  Jacoh,on\  nerve 
^\aurdiictus  Cor/tfaie. 
(^'^nuL  for  Arnold's  oiervr 
JwjwJar  fvssa 

^(yloid  process- 

St-'/lo-  mastmd  forn  mevt 

Jiiyulnr  £iirfa<-e 

AuHcular  fissure 


STYLO-PflARy^cE«» 


sents  eleven  points  for  examination:  1.  A  rough  surface,  quadrilateral  in  form, 
which  serves  partly  for  the  attachment  of  the  Levator  Palati  and  Tensor  Tym- 
pani  muscles:  2.  The  large  circular  aperture  of  the  carotid  canal,  which  ascends 
at  first  vertically,  and  then,  making  a  bend,  runs  horizontally  forwards  and 
inwards;  it  transmits  the  internal  carotid  artery  and  the  carotid  plexus:  3.  The 
aquseductus  cochleas,  a  small  triangular  opening,  lying  on  the  inner  side  of  the 
latter,  close  to  the  posterior  border  of  the  petrous  portion;  it  transmits  a  vein 
from  the  cochlea,  which  joins  the  internal  jugular:  4.  Behind  these  openings 
a  deep  depression,  the  jugular  fossa,  which  varies  in  depth  and  size  in  different 
skulls  ;  it  lodges  the  internal  jugular  vein,  and,  with  a  similar  depression  on 
the  margin  of  the  occipital  bone,  forms  the  foramen  lacerum  posterius:  5.  A 
small  foramen  for  the  passage  of  Jacobson's  nerve  (the  tympanic  branch  of  the 
glosso-pbaryngeal);  this  foramen  is  seen  in  front  of  the  bony  ridge  dividing 


148 


THE    SKELETON. 


the  carotid  canal  from  the  jugular  fossa:  6.  A  small  foramen  on  the  inner  wall 
of  the  jugular  fossa,  for  the  entrance  of  the  auricular  branch  of  the  pneumogas- 
tric  (Arnold's)  nerve :  7.  Behind  the  jugular  fossa,  a  smooth  square-shaped 
^facet,  the  jugular  surface;  it  is  covered  with  cartilage  in  the  recent  state,  and 
articulates  with  the  jugular  process  of  the  occipital  bone :  8.  The  vaginal  pro- 
cess, a  very  broad  sheath-like  plate  of  bone,  which  extends  from  the  carotid 
canal  to  the  mastoid  process ;  it  divides  behind  into  two  laminae,  receiving 
between  them  the  9th  point  for  examination,  the  styloid  process ;  a  long  sharp 
spina,  about  an  inch  in  length,  continuous  with  the  vaginal  process,  between 
the  laminae  of  which  it  is  received ;  it  is  directed  downwards,  forwards,  and 
inwards,  varies  in  size  and  shape,  and  sometimes  consists  of  several  pieces 
united  by  cartilage;  it  affords  attachment  to  three  muscles,  the  Stylo-pharyn- 
geus,  Stylo-glossus,  and  Stylo-hyoideus ;  and  two  ligaments,  the  stylo-hyoid 
and  stylo-maxillary:  10.  The  stylo-mastoid  foramen,  a  rather  large  orifice, 
placed  between  the  styloid  and  mastoid  processes  ;  it  is  the  termination  of  the 
aquaeductus  Fallopii,  and  transmits  the  facial  nerve  and  stylo-mastoid  artery: 
11.  The  auricular  fissure,  situated  between  the  vaginal  and  mastoid  processes, 
for  the  exit  of  the  auricular  branch  of  the  pneumogastric  nerve. 

Borders  of  the  petrous  portion.  The  superior,  the  longest,  is  grooved  for  the 
superior  petrosal  sinus,  and  has  attached  to  it  the  tentorium  cerebelli ;  at  its 
inner  extremity  is  a  semilunar  notch,  upon  which  the  fifth  nerve  lies.  The 
posterior  hovAoT  is  intermediate  in  length  between  the  superior  and  the  anterior. 
Its  inner  half  is  marked  by  a  groove,  which,  when  completed  by  its  articulation 
with  the  occipital,  forms  the  channel  for  the  inferior  petrosal  sinus.  Its  outer 
half  presents  a  deep  excavation — the  jugular  fossa — which,  with  a  similar  notch 
on  the  occipital,  forms  the  foramen  lacerum  posterius.  A  projecting  eminence 
of  bone  occasionally  stands  out  from  the  centre  of  the  notch,  and  divides  the 
foramen  into  two  parts.  The  anterior  border  is  divided  into  two  parts — an 
outer  joined  to  the  squamous  portion  by  a  suture,  the  remains  of  which  are 
distinct;  an  inner,  free,  articulating  with  the  spinous  process  of  the  sphenoid. 
At  the  angle  of  junction  of  the  petrous  and  squamous  portions  are  seen  two 
canals,  separated  from  one  another  by  a  thin  plate  of  bone,  the  processus  coch- 

leariformis;  they  both  lead  into  the 
Fig.  100.— Development  of  the  Temporal  Bone,    tympanum,  the  upper  one  transmit- 
By  lour  Centres.  ^jj^g  ^^^  Tensor  Tympani  muscle,  the 

lower  one  the  Eustachian  tube. 

Structure,  The  squamous  portion 
is  like  that  of  the  other  cranial  bones, 
the  mastoid  portion  cellular,  and  the 
petrous  portion  dense  and  hard. 

Development  (Fig.  100).  The  tempo- 
ral bone  is  developed  by  yb?^r  centres, 
exclusive  of  those  for  the  internal  ear 
and  the  ossicula,  viz :  one  for  the  squa- 
mous portion  including  the  zygoma, 
one  for  the  petrous  and  mastoid  parts, 
one  for  the  styloid,  and  one  for  the 
auditory  process  (tympanic  bone). 
The  first  traces  of  the  development 
of  this  bone  appear  in  the  squamous 
portion,  about  the  time  when  osseous 
matter  is  deposited  in  the  vertebrae ; 
the  auditory  process  succeeds  next ; 
it  consists  of  a  curved  piece  of  bone, 
forming  about  three-fourths  of  a  cir- 
cle, the  deficiency  being  above;  it  is  grooved  along  its  concave  surface  for 
the  attachment  of  the  membrana  tympani,  and  becomes  united  by  its  extremi- 


1  prr  S^uamotia 
fOTtum  tTuiudiii 
Zygoma^. 
Z^  mo. 


I  for  Auditortf 


/    for  I'etrous 

Ir  Xa,»tui(L 


i  for  StyZoii  pTve. 


SPHENOID    BONE. 


149 


ties  to  the  squamous  portion  during  the  last  months  of  intra-uterine  life. 
The  petrous  and  mastoid  portions  then  become  ossified,  and  lastly  the  styloid 
process,  which  remains  separate  a  considerable  period,  and  is  occasionally 
never  united  to  the  rest  of  the  bone.  At  birth,  the  temporal  bone,  excluding 
the  styloid  process,  is  formed  of  three  pieces — the  squamous  and  zygomatic, 
the  petrous  and  mastoid,  and  the  auditory.  The  auditory  process  joins  with 
the  squamous  about  the  time  of  birth.  The  petrous  and  mastoid  join  with 
the  squamous  during  the  first  year,  and  the  styloid  process  becomes  united 
between  the  second  and  third  years.  The  subsequent  changes  in  this  bone 
are,  that  the  auditory  process  extends  outwards,  so  as  to  form  the  meatus  audi- 
torius ;  the  glenoid  fossa  becomes  deeper ;  and  the  mastoid  part,  which  at  an 
early  period  of  life  is  quite  flat,  enlarges  from  the  development  of  the  cellular 
cavities  in  its  interior. 

Articulations.  With  five  bones — occipital,  parietal,  sphenoid,  inferior  maxil- 
lary, and  malar. 

Attachment  of  Muscles.  To  the  squamous  portion,  the  Temporal ;  to  the  zy- 
goma, the  Masseter ;  to  the  mastoid  portion,  the  Occipito-frontalis,  Sterno-mas- 
toid,  Splenius  Capitis,  Trachelo-mastoid,  Digastricus,  and  Eetrahens  Aurem; 
to  the  styloid  process,  the  Stylo-pharyngeus,  Stylo-hyoideus,  and  Stylo-glos- 
sus ;  and  to  the  petrous  portion,  the  Levator  Palati,  Tensor  Tympani,  and  Sta- 
pedius. 

The  Sphenoid  Bone. 

The  Sphenoid  Bone  {a^riv^  a  wedge)  is  situated  at  the  anterior  part  of  the  base 
of  the  skull,  articulating  with  all  the  other  cranial  bones,  which  it  binds  firmly 
and  solidly  together.  In  its  form  it  somewhat  resembles  a  bat,  with  its  wings 
extended ;  and  is  divided  into  a  central  portion  or  body,  two  greater  and  two 
lesser  wings  extending  outwards  on  each  side  of  the  body ;  and  two  processes, 
the  pterygoid  processes,  which  project  from  it  below. 

The  Body  is  of  large  size,  quadrilateral  in  form,  and  hollowed  out  in  its  inte- 
rior so  as  to  form  a  mere  shell  of  bone.  It  presents  for  examination /owr  sur- 
faces— a  superior,  an  inferior,  an  anterior,  and  a  posterior. 

Fig.  101. — Sphenoid  Bone.     Superior  Surface. 


Tommen  OpUcw 
Torimuiii  ZdCi'ruvi 

Toramnn  J^otii.nliiin. 
H  Vaalii 

,  Ol'llJ4> 


The  superior  surface  (Fig.  101).     In  front  is  seen  a  prominent  spine,  the  eth- 
moidal spine,  for  articulation  with  the  ethmoid ;  behind  this  a  smooth  surface 


150 


THE    SKELETON. 


presenting,  in  the  median  line,  a  slight  longitudinal  eminence,  with  a  depression 
on  each  side,  for  lodging  the  olfactory  nerves.  A  narrow  transverse  groove, 
the  optic  groove,  bounds  the  above-mentioned  surface  behind  ;  it  lodges  the 
optic  commissure,  and  terminates  on  either  side  in  the  optic  foramen,  for  the 
passage  of  the  optic  nerve  and  ophthalmic  artery.  Behind  the  optic  groove  is  a 
small  eminence,  olive-like  in  shape,  the  olivary  process ;  and  still  more  poste- 
riorly, a  deep  depression,  the  pituitary  fossa,  or  "sella  Turcica,"  which  lodges 
the  pituitary  body.  This  fossa  is  perforated  by  numerous  foramina,  for  the 
transmission  of  nutrient  vessels  to  the  substance  of  the  bone.  It  is  bounded 
in  front  by  two  small  eminences,  one  on  either  side,  called  the  middle  clinoid 
processes  (xxtViy,  a  bed),  and  behind  by  a  square-shaped  plate  of  bone,  terminat- 
ing at  each  superior  angle  in  a  tubercle,  the  posterior  clinoid  processes,  the 
size  and  form  of  which  vary  considerably  in  different  individuals.  These  pro- 
cesses deepen  the  pituitary  fossa,  and  serve  for  the  attachment  of  prolongations 
from  the  tentorium  cerebelli.  The  sides  of  the  plate  of  bone  supporting  the 
posterior  clinoid  processes  are  notched  for  the  passage  of  the  sixth  pair  of 
nerves;  and  behind,  this  plate  of  bone  presents  a  shallow  depression,  which 
slopes  obliquely  backwards,  and  is  continuous  with  the  basilar  groove  of  the 
occipital  bone ;  it  supports  the  pons  Varolii.  On  either  side  of  the  body  is  a 
broad  groove,  curved  something  like  the  italic  letter/;  it  lodges  the  internal 
carotid  artery  and  the  cavernous  sinus,  and  is  called  the  cavernous  groove.  The 
posterior  surface,  quadrilateral  in  form,  articulates  with  the  basilar  process  of 
the  occipital  bone.  During  childhood  these  bones  are  separated  by  a  layer  of 
cartilage ;  but  in  after-life  (between  the  eighteenth  and  twenty-fifth  years)  this 
becomes  ossified,  ossification  commencing  above,  and  extending  downward ; 
and  the  two  bones  then  form  one  piece.     The  anterior  surface  (Fig.  102)  pre- 

Fig.  102. — Sphenoid  Bone.    Anterior  Surface.' 


iPt'^i/'jold  Sidyt' 


T/vtti--na7 !Pte-ryif<)i<i  flint* 

sents,  in  the  middle  line,  a  vertical  lamella  of  bone  which  articulates  in  front 
with  the  perpendicular  plate  of  the  ethmoid,  forming  part  of  the  septum  of  the 
nose.  On  either  side  of  it  are  the  irregular  openings  leading  into  the  sphenoid 
cells  or  sinuses.  These  are  two  large  irregular  cavities,  hollowed  out  of  the 
interior  of  the  body  of  the  sphenoid  tjone,  and  separated  from  one  another  by  a 
more  or  less  complete  perpendicular  bony  septum.  Their  form  and  size  vary 
considerably ;  they  are  seldom  symmetrical,  and  are  often  partially  subdivided 


'  In  this  fipure,  bolh  the  nntorior  and  inferior  surfaces  of  the  body  of  the  sphenoid  bone  arc 
shown,  the  bone  being  held  with  the  pterygoid  processes  almost  horizontal. 


SPHENOID    BONE.  161 

by  irregular  osseous  laminae.  Occasionally  they  extend  into  the  basilar  process 
of  the  occipital  nearly  as  far  as  the  foramen  magnum.  The  septum  is  seldom 
quite  vertical,  being  commonly  bent  to  one  or  the  other  side.  These  sinuses 
do  not  exist  in  children,  but  they  increase  in  size  as  age  advances.  They  are 
partially  closed,  in  front  and  below,  by  two  thin  curved  plates  of  bone;  the 
sphenoidal  turbinated  bones,  leaving  a  round  opening  at  their  upper  parts,  by 
which  they  communicate  with  the  upper  and  back  part  of  the  nose,  and  occa- 
sionally with  the  posterior  ethmoidal  cells  or  sinuses.  The  lateral  margins  of 
this  surface  present  a  serrated  edge,  which  articulates  with  the  os  planum  of  the 
ethmoid,  completing  the  posterior  ethmoidal  cells;  the  lower  margin,  also  rough 
and  serrated,  articulates  with  the  orbital  process  of  the  palate  bone ;  and  the 
upper  margin  with  the  orbital  plate  of  the  frontal  bone.  The  inferior  surface 
presents,  in  the  middle  line,  a  triangular  spine,  the  rostrum,  which  is  continuous 
with  the  vertical  plate  on  the  anterior  surface,  and  is  received  into  a  deep  fissure 
between  the  alaa  of  the  vomer.  On  each  side  may  be  seen  a  projecting  lamina 
of  bone,  which  runs  horizontally  inwards  from  near  the  base  of  the  pterygoid 
process :  these  plates,  termed  the  vaginal  processes,  articulate  with  the  edges 
of  the  vomer.  Close  to  the  root  of  the  pterygoid  process  is  a  groove,  formed 
into  a  complete  canal  when  articulated  with  the  sphenoidal  process  of  the  palate 
bone;  it  is  called  the  ptery go-palatine  canal,  and  transmits  the  pterygo-palatine 
vessels  and  pharyngeal  nerve. 

The  Greater  Wings  are  two  strong  processes  of  bone,  which  arise  from  the 
sides  of  the  body,  and  are  curved  in  a  direction  upwards,  outwards,  and  back- 
wards ;  being  prolonged  behind  into  a  sharp-pointed  extremity,  the  spinous 
process  of  the  sphenoid.  Each  wing  presents  three  surfaces  and  a  circumfer- 
ence, The  superior  or  cerebral  surface  (Fig.  101)  forms  part  of  the  middle  fossa 
of  the  skull ;  it  is  deeply  concave,  and  presents  eminences  and  depressions  for 
the  convolutions  of  the  brain.  At  its  anterior  and  internal  part  is  seen  a  cir- 
cular aperture,  the  foramen  rotundum,  for  the  transmission  of  the  second  divi- 
sion of  the  fifth  nerve.  Behind  and  external  to  this  is  a  large  oval  foramen, 
the  foramen  ovale,  for  the  transmission  of  the  third  division  of  the  fifth  nerve, 
the  small  meningeal  artery,  and  the  small  petrosal  nerve.  At  the  inner  side 
of  the  foramen  ovale,  a  small  aperture  may  occasionally  be  seen  opposite  the 
root  of  the  pterygoid  process ;  it  is  the  foramen  Vesalii,  -transmitting  a  small 
vein.  Lastly,  in  the  apex  of  the  spine  of  the  sphenoid  is  a  short  canal,  some- 
times double,  the  foramen  spinosum;  it  transmits  the  middle  meningeal  artery. 
The  external  surface  (Fig.  102)  is  convex,  and  divided  by  a  transverse  ridge, 
the  pterygoid  ridge,  into  two  portions.  The  superior  or  larger,  convex  from 
above  downwards,  concave  from  before  backwards,  enters  into  the  formation 
of  the  temporal  fossa,  and  attaches  part  of  the  temporal  muscle.  The  inferior 
portion,  smaller  in  size  and  concave,  enters  into  the  formation  of  the  zygomatic 
fossa,  and  affords  attachment  to  the  External  Pterygoid  muscle.  It  presents, 
at  its  posterior  part,  a  sharp-pointed  eminence  of  bone,  the  spinous  process,  to 
which  is  connected  the  internal  lateral  ligament  of  the  lower  jaw,  and  the 
Laxator  Tympani  muscle.  The  pterygoid  ridge,  dividing  the  temporal  and 
zygomatic  portions,  gives  attachment  to  part  of  the  External  Pterygoid  muscle. 
At  its  inner  extremity  is  a  triangular  spine  of  bone,  which  serves  to  increase 
the  extent  of  origin  of  this  muscle.  The  anterior  or  orbital  surface,  smooth  and 
quadrilateral  in  form,  assists  in  forming  the  outer  wall  of  the  orbit.  It  is 
bounded  above  by  a  serrated  edge,  for  articulation  with  the  frontal  bone ; 
below,  by  a  rounded  border,  which  enters  into  the  formation  of  the  spheno- 
maxillary fissure ;  internally,  it  enters  into  the  formation  of  the  sphenoidal 
fissure ;  whilst  externally  it  presents  a  serrated  margin,  for  articulation  with 
the  malar  bone.  At  the  upper  part  of  the  inner  border  is  a  notch  for  the  trans- 
mission of  a  branch  of  the  ophthalmic  artery;  and  at  its  lower  part  a  small 
pointed  spine  of  bone,  which  serves  for  the  attachment  of  part  of  the  lower 
head  of  the  External  Eectus.     One  or  two  small  foramina  may  occasionally  be 


152 


THE    SKELETON. 


seen  for  the  passage  of  arteries ;  they  are  called  the  external  orbital  foramina. 
Clrcttraference  of  the  great  wing  {¥\g.  101):  commencing  from  behind,  from  the 
body  of  the  sphenoid  to  the  spine,  the  outer  half  of  this  margin  is  serrated,  for 
articulation  with  the  petrous  portion  of  the  temporal  bone ;  whilst  the  inner 
half  forms  the  anterior  boundary  of  the  foramen  lacerum  medium,  and  presents 
the  posterior  aperture  of  the  Vidian  canal.  In  front  of  the  spine  the  circum- 
ference of  the  great  wing  presents  a  serrated  edge,  bevelled  at  the  expense  of 
the  inner  table  below,  and  of  the  external  above,  which  articulates  with  the 
squamous  portion  of  the  temporal  bone.  At  the  tip  of  the  great  wing  a  trian- 
gular portion  is  seen,  bevelled  at  the  expense  of  the  internal  surface,  for  arti- 
culation with  the  anterior  inferior  angle  of  the  parietal  bone.  Internal  to  this 
is  a  broad  serrated  surface,  for  articulation  with  the  frontal  bone :  this  surface 
is  continuous  internally  with  the  sharp  inner  edge  of  the  orbital  plate,  which 
assists  in  the  formation  of  the  sphenoidal  fissure. 

The  Lesser  Wings  (processes  of  Ingrassias)  (Fig.  101)  are  two  thin  triangular 
plates  of  bone,  which  arise  from  the  upper  and  lateral  parts  of  the  body  of  the 
sphenoid;  and,  projecting  transversely  outwards,  terminate  in  a  sharp  point. 
The  superior  surface  of  each  is  smooth,  flat,  broader  internally  than  externally, 
and  supports  the  anterior  lobe  of  the  brain.  The  inferior  surface  forms  the 
back  part  of  the  roof  of  the  orbit,  and  the  upper  boundary  of  the  sphenoidal 
fissure  or  foramen  lacerum  anterius.  This  fissure  is  of  a  triangular  form,  and 
leads  from  the  cavity  of  the  cranium  into  the  orbit ;  it  is  bounded  internally 
by  the  body  of  the  sphenoid — above,  by  the  lesser  wing ;  below,  by  the  orbital 
surface  of  the  great  wing — and  is  converted  into  a  foramen  by  the  articulation 
of  this  bone  with  the  frontal.  It  transmits  the  third,  the  fourth,  the  ophthalmic 
division  of  the  fifth  and  the  sixth  nerves,  and  the  ophthalmic  vein.  The  ante- 
rior border  of  the  lesser  wing  is  serrated  for  articulation  with  the  frontal  bone ; 
the  posterior,  smooth  and  rounded,  is  received  into  the  fissure  of  Sylvius  of  the 
brain.  The  inner  extremity  of  this  border  forms  the  anterior  clinoid  process. 
The  lesser  wing  is  connected  to  the  side  of  the  body  by  two  roots,  the  upper 
thin  and  flat,  the  lower  thicker,  obliquely  directed,  and  presenting  on  its  outer 
side,  near  its  junction  with  the  body,  a  small  tubercle,  for  the  attachment  of 
the  common  tendon  of  the  muscles  of  the  eye.  Between  the  two  roots  is  the 
optic  for.amen,  for  the  transmission  of  the  optic  nerve  and  ophthalmic  artery. 

The  Pterygoid  processes  {nrifvi,  a  wing ;  tlboi,  likeness),  (Fig.  103),  one  on  each 
side,  descend  perpendicularly  from  the  point  where  the  body  and  great  wing 
unite.     Each  process  consists  of  an  external  and  an  internal  plate,  separated 

behind    by   an    intervening 
Fig.  103.    Sphenoid  Bone.    Posterior  Surface.  notch — the  pterygoid  fossa; 

but  joined  partially  in  front. 
The  external  pterygoid  2)late 
is  broad  and  thin,  turned  a 
little  outwards,  and  forms 
part  of  the  inner  wall  of  the 
zygomatic  fossa.  It  gives 
attachment,  by  its  outer  sur- 
face, to  the  External  Ptery- 
goid muscle;  its  inner  sur- 
face forms  part  of  the  ptery- 
goid fossa,  and  gives  attach- 
ment to  the  Internal  Ptery- 
goid. The  internal  pterygoid 
plate  is  much  narrower  and 
longer,  curving  outwards,  at 
its  extremity,  into  a  hook- 
like process  of  bone,  the  hamular  process,  around  which  turns  the  tendon  of 
the  Tensor  Palati  muscle.     At  the  base  of  this  plate  is  a  small,  oval,  shallow 


SPHENOID    BONE.  153 

depression,  the  scaphoid  fossa,  from  which  arises  the  Tensor  Palati,  and  above 
which  is  seen  the  posterior  orifice  of  the  Vidian  canal.  The  outer  surface  of 
this  pLate  forms  part  of  the  pterygoid  fossa,  the  inner  surface  forming  the  outer 
boundary  of  the  posterior  aperture  of  the  nares.  The  Superior  Constrictor  of 
the  pharynx  is  attached  to  its  posterior  edge.  The  two  pterygoid  plates  are 
separated  below  by  an  angular  interval,  in  which  the  pterygoid  process,  or 
tuberosity,  of  the  palate  bone  is  received.  The  anterior  surface  of  the  ptery- 
goid  process  is  very  broad  at  its  base,  and  forms  the  posterior  wall  of  the 
spheno-raaxillary  fossa.  It  supports  Meckel's  ganglion.  It  presents,  above, 
the  anterior  orifice  of  the  Vidian  canal;  and  below,  a  rough  margin,  which 
articulates  with  the  perpendicular  plate  of  the  palate-bone. 

The  Sphenoidal  Spongy  Bones  are  two  thin  curved  plates  of  bone,  which  exist 
as  separate  pieces  until  puberty,  and  occasionally  are  not  joined  to  the  sphenoid 
in  the  adult.  They  are  situated  at  the  anterior  and  inferior  part  of  the  body 
of  the  sphenoid,  an  aperture  of  variable  size  being  left  in  their  anterior  wall, 
through  which  the  sphenoidal  sinuses  open  into  the  nasal  fossae.  They  are 
irregular  in  form,  and  taper  to  a  point  behind,  being  broader  and  thinner  in 
front.  Their  inner  surface,  which  looks  towards  the  cavity  of  the  sinus,  is 
concave ;  their  outer  surface  convex.  Bach  bone  articulates  in  front  with  the 
ethmoid,  externally  with  the  palate;  behind,  its  point  is  placed  above  the 
vomer,  and  is  received  between  the  root  of  the  pterygoid  process  on  the  outer 
side,  and  the  rostrum  of  the  sphenoid  on 
the  inner.  Fig.  104.— Plan  of  the  Development  of  the 

Development     The    sphenoid    bone    is  Sphenoid.    By  ten  Centres, 

developed  by  ten  centres,  six  for  the  pos-      jj^tachUsger-wn^ic^Ant'^jiaTtafliody 
terior   sphenoidal   division,  and   four  for  '    ^ 

the  anterior  sphenoid.  The  six  centres 
for  the  posterior  sphenoid  are — one  for 
each  greater  wing  and  external  pterygoid 
plate;  one  for  each  internal  pterygoid 
plate ;  two  for  the  posterior  part  of  the 

body.    The  four  for  the  anterior  sphenoid  xf<^«^ig^atm:ugyext.^uTygjyi^.f.6 

are,  one  for  each  lesser  wing  and  anterior 
part   of    the    body,    and    one    for    each  xf^^aJi  splunoi^l  turbinated  b^n. 

sphenoidal  turbinated  bone.  Ossification 
takes  place  in  these  pieces  in  the  follow- 
ing order :  the  greater  wing  and  external  pterygoid  plate  are  first  formed,  ossifio 
granules  being  deposited  close  to  the  foramen  rotundum  on  each  side,  at  about 
the  second  month  of  foetal  life ;  from  thence  ossification  spreads  outwards  into 
the  great  wing,  and  downwards  into  the  external  pterygoid  plate.  Each  inter- 
nal pterygoid  plate  is  then  formed,  and  becomes  united  to  the  external  about 
the  middle  of  foetal  life.  The  two  centres  for  the  posterior  part  of  the  body 
appear  as  separate  nuclei,  side  by  side,  beneath  the  sella  Turcica ;  they  join, 
about  the  middle  of  foetal  life,  into  a  single  piece,  which  remains  un-united  to 
the  rest  of  the  bone  until  after  birth.  Each  lesser  wing  is  formed  by  a  separate 
centre,  which  appears  on  the  outer  side  of  the  optic  foramen,  at  about  the  third 
month ;  they  become  united  and  join  with  the  body  at  about  the  eighth  month 
of  foetal  life.  At  about  the  end  of  the  third  year,  ossification  has  "made  its 
appearance  in  the  sphenoidal  spongy  bones. 

At  birth  the  sphenoid  consists  of  three  pieces,  viz.,  the  greater  wing  and 
pterygoid  processes  on  each  side;  the  lesser  wings  and  body  united.  At  the  first 
year  after  birth,  the  greater  wings  and  body  are  united.  From  the  tenth  to  the 
twelfth  year  the  spongy  bones  are  partially  united  to  the  sphenoid,  their  junction 
being  complete  by  the  twentieth  year.     Lastly,  the  sphenoid  joins  the  occipital. 

Articulations.  The  sphenoid  articulates  with  all  the  bones  of  the  cranium, 
and  five  of  the  face;  the  two  malar,  two  palate,  and  vomer:  the  exact  extent 
of  articulation  with  each  bone  is  shown  in  the  accompanying  figures. 


154 


THE    SKELETON. 


Attachment  of  Muscles.  The  Temporal,  External  Pterygoid,  Internal  Ptery- 
goid, Superior  Constrictor,  Tensor  Palati,  Laxator  Tyrapani,  Levator  Palpebrae, 
Obliquus  Superior,  Superior  Kectus,  Internal  Rectus,  Inferior  Rectus,  External 
Rectus. 


The  Ethmoid  Bone. 

The  Ethmoid  (»J'9/*65,  a  sieve)  is  an  exceedingly  light  spongy  bone,  of  a  cubical 
form,  situated  at  the  anterior  part  of  the  base  of  the  cranium,  between  the  two 

orbits,  at  the  root  of  the  nose. 
Fig.  I05.-Ethmoid  Bone^   Outer  Surface  of  Right  Lateral    ^^^  contributing  to  form  each 

^        ^    ''  of  these  cavities.     It  consists 

of  three  parts :  a  horizontal 
plate,  which  forms  part  of  the 
base  of  the  cranium ;  a  per- 
pendicular plate,  which  forms 
part  of  the  septum  nasi ;  and 
two  lateral  masses  of  cells. 

^\\Q  Horizontal  or  Cribriform 
Plate  (Fig.  105)  forms  part  of 
the  anterior  fossa  of  the  base 
of  the  skull,  and  is  received 
into  the  ethmoid  notch  of  the 
frontal  bone  between  the  two 
orbital  plates.  Projecting  up- 
wards from  the  middle  line  of 
this  plate,  is  a  thick,  smooth, 
triangular  process  of  bone, 
the  crista  galli,  so  called  from 
its  resemblance  to  a  cock's  comb.  Its  base  joins  the  cribriform  plate.  Its 
posterior  border,  long,  thin,  and  slightly  curved,  serves  for  the  attachment 
of  the  falx  cerebri.  Its  anterior  border,  short  and  thick,  articulates  with  the 
frontal  bone,  and  presents  two  small  projecting  alse,  which  are  received  into 
corresponding  depressions  in  the  frontal,  completing  the  foramen  coecum  behind 

Its   sides    are   smooth 


i  af.*turbinuted  i. 


Fig.  106. — Perpendicular  Plate  of  Ethmoid  (enlarged),  shown  by 
removing  the  right  Lateral  Mass. 


<ux''J  EikmoiiJtic 


and  sometimes  bulging 
in  which  case  it  is  founc 
to  inclose  a  small  sinua 
On    each    side    of    th( 
crista  galli,  the  cribri 
form    plate  is   narrow^ 
and  deeply  grooved,  tc 
support  the  bulb  of  th« 
olfactory     nerve,     an( 
perforated  by  foraminj 
for  the    passage  of  its 
filaments.     These  fora-11 
mina   are    arranged   iiL^ 
three  rows:  the  inner4j 
most,    which    are    tha!| 
largest  and  least  nume«] 
rous,  are  lost  in  groove* 
on  the  upper  part  of  the] 
septum;    the   foramina; 
of  the  outer   row   are 
continued  on  to  the  surface  of  the  upper  spongy  bone.     The  foramina  of  the 
middle  row  are  the  smallest;  they  perforate  the  bone,  and  transmit  nerves  to 


ETHMOID    BONE.  156 

tlie  roof  of  the  nose.  At  the  front  part  of  the  cribriform  plate,  on  each  side  of 
the  crista  galli,  is  a  small  fissure,  which  transmits  the  nasal  branch  of  the 
ophthalmic  nerve;  and  at  its  posterior  part  a  triangular  notch,  which  receives 
the  ethmoidal  spine  of  the  sphenoid. 

The  Perpendicular  Plate  (Fig.  106)  is  a  thin  flattened  lamella  of  bone,  which 
descends  from  the  under-surface  of  the  cribriform  plate,  and  assists  in  forming 
the  septum  of  the  nose.  It  is  much  thinner  in  the  middle  than  at  the  circum- 
ference, and  is  generally  deflected  a  little  to  one  side.  Its  anterior  border  articu- 
lates with  the  frontal  spine  and  crest  of  the  nasal  bones.  Its  posterior,  divided 
into  two  parts,  is  connected  by  its  upper  half  with  the  rostrum  of  the  sphenoid 
— by  its  lower  half  the  vomer.  The  inferior  border  serves  for  the  attachment 
of  tiie  triangular  cartilage  of  the  nose.  On  each  side  of  the  perpendicular  plate 
numerous  grooves  and  canals  are  seen,  leading  from  foramina  on  the  cribriform 
plate ;  they  lodge  filaments  of  the  olfactory  nerves. 

The  Lateral  Masses  of  the  ethmoid  consist  of  a  number  of  thin-walled  cellular 
cavities,  the  ethmoidal  cells,  interposed  between  two  vertical  plates  of  bone,  the 
outer  one  of  which  forms  part  of  tbe  orbit,  and  the  inner  one  part  of  the  nasal 
fossa  of  the  corresponding  side.  In  the  disarticulated  bone  many  of  these  cells 
appear  to  be  broken;  but  when  the  bones  are  articulated,  they  are  closed  in  at 
every  part.  The  upper  surface  of  each  lateral  mass  presents  a  number  of  appa- 
rently half-broken  cellular  spaces ;  these  are  closed  in  when  articulated  by  the 
edges  of  the  ethmoidal  notch  of  the  frontal  bone.  Crossing  this  surface  are 
two  grooves  on  each  side,  converted  into  canals  by  articulation  with  the  frontal; 
they  are  the  anterior  and  posterior  ethmoidal  foramina,  and  open  on  the  inner 
wall  of  the  orbit.  The  posterior  surface  also  presents  large  irregular  cellular 
cavities,  which  are  closed  in  by  articulation  with  the  sphenoidal  turbinated 
bones,  and  orbital  process  of  the  palate.  The  cells  at  the  anterior  surface  are 
completed  by  the  lachrymal  bone  and  nasal  process  of  the  superior  maxillary, 
and  those  below  also  by  the  superior  maxillary.  The  outer  surface  of  each 
lateral  mass  is  formed  of  a  thin  smooth  square  plate  of  bone,  called  the  os 
j)lanum;  it  forms  part  of  the  inner  Avail  of  the  orbit,  and  articulates  above  with 
the  orbital  plate  of  the  frontal ;  below,  with  the  superior  maxillary  and  orbital 
process  of  the  palate ;  in  front,  with  the  lachrymal ;  and  behind,  with  the  sphenoid. 

From  the  inferior  part  of  each  lateral  mass,  immediately  beneath  the  os 
planum,  there  projects  downwards  and  backwards  an  irregular  lamina  of  bone, 
called  tlie  wnc(/brTOji9?-oces5,  from  its  hook-like  formi  it  serves  to  close  in  the 
upper  part  of  the  orifice  of  the  antrum,  and  articulates  with  the  ethmoidal  pro- 
cess of  the  inferior  turbinated  bone.     It  is  often  broken  in  articulating  the  bones. 

The  inner  surface  of  each  internal  mass  forms  part  of  the  outer  wall  of  the 
nasal  fossa  of  the  corresponding  side.  It  is  formed  of  a  thin  lamella  of  bone, 
which  descends  from  the  under  surface 

of  the  cribriform  plate,  and  terminates       ^ig-  107.— Ethmoid  Bone.    Inner  Surface  of 
below  in  afree  convoluted  margin,  the  Right  Lateral  Mass  (enlarged), 

middle  turbinated  bone.  The  whole 
of  this  surface  is  rough,  and  marked 
above  by  numerous  grooves,  which 
run  nearly  vertically  downwards 
from  the  cribriform  plate :  they  lodge 
branches  of  the  olfactory  nerve, 
which  are  distributed  on  the  mucous 
membrane  covering  the  bone.  The 
back  part  of  this  surface  is  subdivided 
by  a  narrow  oblique  fissure,  the  su- 
perior meatus  of  the  nose,  bounded 
above  by  a  thin  curved  plate  of  bone 
— the  superior  turbinated  bone.  By  means  of  an  orifice  at  the  upper  part 
of  this  fissure,  the  posterior  ethmoidal  cells  open  into  the  nose.     Below,  and 


/ 
156  THE    SKELETON^. 

in  front  of  the  superior  meatus,  is  seen  the  convex  surface  of  the  middle  turbi- 
nated bone.  It  extends  along  the  whole  length  of  the  inner  surface  of  each 
lateral  mass ;  its  lower  margin  is  free  and  thick,  and  its  concavity,  directea 
outwards,  assists  in  forming  the  middle  meatus.  It  is  by  a  large  orifice  at  the 
upper  and  front  part  of  the  middle  meatus,  that  the  anterior  ethmoidal  cells, 
and  through  them  the  frontal  sinuses,  communicate  with  the  nose,  by  means  of 
a  funnel  shaped  canal,  the  infundibulum.  The  cellular  cavities  of  each  lateral 
mass,  thus  walled  in  by  the  os  planum  on  the  outer  side,  and  by  the  other  bones 
already  mentioned,  are  divided  by  a  thin  transverse  bony  partition  into  two 
sets,  which  do  not  communicate  with  each  other ;  they  are  termed  the  anterior 
&nd posterior  ethmoidal  cells,  or  sinuses.  The  former,  smaller  but  more  numerous, 
communicate  with  the  frontal  sinuses  above,  and  the  middle  meatus  below,  by 
means  of  a  long  flexuous  cellular  canal,  the  infundihulum ;  the  posterior,  larger 
but  less  numerous,  open  into  the  superior  meatus,  and  communicate  (occasion- 
ally) with  the  sphenoidal  sinuses. 

Development.  By  three  centres — one  for  the  perpendicular  lamella,  and  one 
for  each  lateral  mass. 

The  lateral  masses  are  first  developed,  ossific  granules  making  their  first 
appearance  in  the  os  planum  between  the  fourth  and  fifth  months  of  foetal  life,} 
and  afterwards  in  the  spongy  bones.  At  birth,  the  bone  consists  of  the  two] 
lateral  masses,  which  are  small  and  ill-developed;  but  when  the  perpendicular 
and  horizontal  plates  begin  to  ossify,  as  they  do  about  the  first  year  after  birth, 
the  lateral  masses  become  joined  to  the  cribriform  plate.  The  formation  and 
increase  in  the  ethmoidal  cells,  which  complete  the  bone,  take  place  about  thej 
fifth  or  sixth  year. 

Articulations.  With  fifteen  bones:  the  sphenoid,  two  sphenoidal  turbinated,! 
the  frontal,  and  eleven  of  the  face — the  two  nasal,  two  superior  maxillary,  two] 
lachryuial,  two  palate,  two  inferior  turbinated,  and  the  vomer. 

Development  op  the  Cranium. 

The  development  of  the  cranium  commences  at  a  very  early  period,  on  account  ofthe  import- 1 
ance  of  the  organ  it  is  intended  to  protect.     In  its  most  rudimentary  state,  it  consists  of  a  thin  i 
membranous  capsule,  inclosing  the  cerebrum,  and  accurately  moulded  upon  its  surface.    This  J 
capsule  is  placed  external  to  the  dura  mater,  and  in  close  contact  with  it ;  its  walls  are  continu-  j 
ous  with  the  canal  for  the  spinal  cord,  and  the  chorda  dorsalis,  or  primitive  part  of  the  vertebral 
column,  is  continued  forwards,  from  the  spine,  along  the  base,  to  its  forepart,  where  it  terminates 
in  a  tapering  point.    The  next  step  in  the  process  of  development  is  the  formation  of  cartilage. 
This  is  deposited  in  the  base  of  the  skull,  in  two  symmetrical  segments,  one  on  either  side  of  the , 
median  line;  these  subsequently  coalesce,  so  as  to  inclose  the  chorda  dorsalis — the  chief  part  of 
the  cerebral  capsule  still  retaining  its  membranous  form.     Ossification  first  takes  place  in  the 
roof,  and  is  preceded  bv  the  deposition  of  a  membranous  blastema  upon  the  surface  of  the  cere- 
bral capsule,  in  which  tlie  ossifying  process  extends  ;  the  primitive  membranous  capsule  becoming 
the  internal  periosteum,  and  being  ultimately  blended  with  the  dura  mater.    Although  the  bones 
of  the  vertex  of  the  skull  appear  before  those  at  the  base,  and  make  considerable  progress  in 
their  growth  :  at  birth  ossification  is  more  advanced  in  the  base,  this  portion  of  the  skull  forming 
a  solid  immovable  groundwork. 

The  Fontanelles  (Figs.  108,  109.) 

Before  birth,  the  bones  at  the  vertex  and  side  of  the  skull  are  separated  from  each  other  by 
membranous  intervals,  in  which  bone  is  deficient.  These  intervals,  at  certain  parts,  are  of  con- 
siderable size,  and  are  termed  the /(mfanellcs,  so  called  from  the  pulsations  of  the  brain,  which 
are  perceptible  at  the  anterior  fontanelle,  and  were  likened  to  the  rising  of  water  in  a  fountain. 
The  fontanelles  are  four  in  number,  and  correspond  to  the  junction  of  the  four  angles  of  the 
parietal  with  the  contiguous  bones.  TTio  anterior  fontanelle  is  the  largest,  and  corresponds  to 
the  junction  of  the  sagittal  and  coronal  sutures ;  the  posterior  fontanelle,  of  smaller  size,  is 
situated  at  the  junction  of  the  sagittal  and  lambdoid  sutures  ;  the  two  remaining  ones  are  situated 
at  the  inferior  angles  of  the  parietal  bone.  The  latter  are  closed  soon  after  birth ;  the  two  at 
the  superior  angles  remain  open  longer :  the  posterior  being  closed  in  a  few  months  after  birth  ; 
the  anterior  remaining  open  until  the  first  or  second  year.    These  spaces  are  gradually  filled  in 


CONGENITAL    FISSURES    AND    GAPS. 


157 


Fig  108.— Skull  at  birth,  showing  the  Anterior 
and  Posterior  Fontanelles. 


Fig.  109. — The  Lateral  Fontanelles. 


by  an  extension  of  the  ossifying  process,  or  by  the  development  of  a  Wormian  bone.  Sometimes 
the  anterior  fontanelle  remains  open  beyond  two  years,  and  is  occasionally  persistent  throughout 
life. 

Supernumerary  or  Wormian^  Bones. 

When  ossification  of  any  of  the  tabular  bones  of  the  skull  proves  abortive,  the  membranous 
interval  which  would  be  left  is  usually  filled  in  by  a  supernumerary  piece  of  bone.  This  is 
developed  from  a  separate  centre,  and  gradually  extends  until  it  fills  the  vacant  space.  These 
supernumerary  pieces  are  called  Wormian  bones :  they  are  called  also,  from  their  usual  form, 
ossa  triquetra  ;  but  they  present  much  variation  in  situation,  number,  and  size. 

They  occasionally  occupy  the  situation  of  the  fontanelles.  Bertin,  Cruveilhier,  and  Cuvier 
have  each  noticed  the  presence  of  one  in  the  anterior  fontanelle.  There  are  two  specimens  in 
the  Museum  of  St.  George's  Hospital,  which  present  Wormian  bones  in  this  situation.  In  one, 
the  skull  of  a  child,  the  supernumerary  piece  is  of  considerable  size,  and  of  a  quadrangular  form. 

They  are  occasionally  found  in  the  posterior  fontanelle,  appearing  to  replace  the  superior  angle 
of  the  occipital  bone.  Not  unfrequently,  there  is  one  replacing  the  extremity  of  the  great  wing 
of  the  sphenoid,  or  the  anterior  inferior  angle  of  the  parietal  bone,  in  the  fontanelle  there  situated. 

They  have  been  found  in  the  different  sutures  on  the  vertex  and  side  of  the  skull,  and  in  some 
of  those  at  the  base.  They  are  most  frequent  in  the  lambdoid  suture.  Mr.  Ward  mentions  an 
instance  "  in  which  one-half  of  the  lambdoid  suture  was  formed  by  large  Wormian  bones  disposed 
in  a  double  row,  and  jutting  deeply  into  each  other ;  and  refers  to  similar  specimens  described 
by  Dumontier  and  Bourgery. 

A  deficiency  in  the  ossification  of  the  flat  bones  would  appear  in  some  cases  to  be  symmetrical 
on  the  two  sides  of  the  skull ;  for  it  is  not  uncommon  to  find  these  supernumerary  bones  corre- 
sponding in  form,  size,  and  situation  on  each  side.  Thus,  in  several  instances,  I  have  seen  a 
pair  of  large  Wormian  bones  symmetrically  placed  in  the  lambdoid  suture ;  in  another  speci- 
men, a  pair  in  the  coronal  suture,  with  a  supernumerary  bone  in  the  spheno-parietal  suture  of 
both  sides. 

The  size  of  these  supernumerary  pieces  varies,  they  being  in  some  cases  not  larger  than  a  pin's 
>head,  and  confined  to  the  outer  table ;  in  other  cases  so  large,  that  one  pair  of  these  bones  may 
form  the  whole  of  the  occipital  bone  above  the  superior  curved  lines,  as  described  by  B6clard 
and  Ward.  Their  number  is  generally  limited  to  two  or  three ;  but  more  than  a  hundred  have 
been  found  in  the  skull  of  an  adult  hydrocephalic  skeleton.  In  their  development,  structure, 
and  mode  of  articulation,  they  resemble  the  other  cranial  bones. 

Congenital  Fissures  and  Gaps. 

Dr.  Humphry  has  called  attention  to  the  not  unfrequent  existence  of  congenital  fissures  in 
the  cranial  bones,  the  result  of  incomplete  ossification.  These  fissures  have  been  noticed  in  the 
frontal,  parietal,  and  squamous  portion  of  the  temporal  bones;  they  extend  from  the  margin 
towards  the  middle  of  the  bone;  and  are  of  great  interest  in  a  medico-legal  point  of  view,  as 
I  they  are  liable  to  be  mistaken  for  fractures.  An  arrest  of  the  ossifying  process  may  also  give 
I  rise  to  the  deficiencies  or  gaps  occasionally  found  in  the  cranial  bones.  Such  deficiencies  are 
Uaid  to  occur  most  frequently  when  ossification  is  imperfect,  and  to  be  situated  near  the  natural 
jipertures  for  vessels.  Dr.  Humphry  describes  such  deficiencies  to  exist  in  a  calvarium,  in  the 
I  Cambridge  Museum,  where  a  gap  sufl5ciently  large  to  admit  the  end  of  the  finger  is  seen  on 


"  Wormius,  a  physician  in  Copenhagen,  is  said  to  have  given  the  first  detailed  description  of 
.liese  bones. 


158 


THE    SKELETON". 


either  side  of  the  sagittal  suture,  in  the  place  of  the  parietal  foramen.  There  is  a  specimen 
precisely  similar  to  this  in  the  Museum  of  St.  George's  Hospital;  and  another,  in  which  a 
small  circular  gap  exists  in  the  parietal  bone  of  a  young  child,  just  above  the  parietal  eminence. 
Similar  de6ciencies  are  not  unfrequentiy  met  with  in  hydrocephalic  skulls ;  being  most  frequent, 
according  to  Dr.  Humphry,  in  the  frontal  bones  ;  and,  in  the  parietal  bones,  on  either  side  of 
the  sagittal  suture. 


Fig.  110.— Right  Nasal  Bone. 
with   Frontal  B* 

— Oppotitt/  bone. 


Fig.  111. — Right  Nasal  Bone. 


Fro  ntaZ  Sjniw- 

CTeaf- 


BONES  OF  THE  FACE. 

The  Facial  Bones  are  fourteen  in  number,  viz.,  the 
Two  Nasal,  Two  Palate, 

Two  Superior  Maxillary,  Two  Inferior  Turbinated, 

Two  Lachrymal,  Vomer, 

Two  Malar,  Inferior  Maxillary. 

Nasal  Bones. 

The  Nasal  are  two  small  oblong  bones,  varying  in  size  and  form  in  different 
individuals ;  they  are  placed  side  by  side  at  the  middle  and  upper  part  of  the 
face,  forming,  by  their  junction,  "the  bridge"  of  the  nose.    Each  bone  presents 

for  examination  two  sur- 
faces, and  four  borders. 
Theow^er  surface  is  con- 
cave from  above  down- 
wards, convex  from  side 
to  side ;  it  is  covered  by 
the  Pyramidal  is  and 
Compressor  nasi  mus- 
cles, marked  by  numer- 
ous small  arterial  fur- 
rows, and  perforated 
about  its  centre  by  a 
foramen,  sometimes 
double,  for  the  trans- 
mission of  a  small  ■vein. 
Sometimes  this  foramen  is  absent  on  one  or  both  sides,  and  occasionally  tho 
foramen  caecum  opens  on  this  surface.  The  inner  surface  is  concave  from 
side  to  side,  convex  from  above  downwards;  in  which  direction  it  is  tra- 
versed by  a  longitudinal  groove  (sometimes  a  canal),  for  the  passage  of  a 
branch  of  the  nasal  nerve.  The  superior  border  is  narrow,  thick,  and  serrated 
for  articulation  with  the  nasal  notch  of  the  frontal  bone.  The  inferior  border 
is  broad,  thin,  sharp,  directed  obliquely  downwards,  outwards,  and  backwards, 
and  serves  for  the  attachment  of  the  lateral  cartilage  of  the  nose.  This  border 
presents  about  its  centre  a  notch,  through  which  passes  the  branch  of  the  nasal 
nerve  above  referred  to ;  and  is  prolonged  at  its  inner  extremity  into  a  sharj) 
spine,  which,  when  articulated  with  the  opposite  bone,  forms  the  nasal  angle. 
The  external  border  is  serrated,  bevelled  at  the  expense  of  the  internal  surface 
above,  and  of  the  external  below,  to  articulate  with  the  nasal  process  of  the 
superior  maxillary.  The  internal  border,  thicker  above  than  below,  articu- 
lates with  its  fellow  of  the  opposite  side,  and  is  prolonged  behind  into  a  ver- 
tical crest,  which  forms  part  of  the  septum  of  the  nose.  This  crest  articulates 
with  the  nasal  spine  of  the  frontal  above,  and  the  perpendicular  plate  of  tho 
ethmoid  below. 

Development.  By  one  centre  for  each  bone,  which  appears  about  the  same 
period  as  in  the  vertebrae. 

Articulations.     With  four  bones.     Two  of  the  cranium,  the  frontal  and  eth- 
moid, and  two  of  the  face,  the  opposite  nasal  and  the  superior  maxillary. 
No  muscles  are  directly  attached  to  this  bone. 


Outer  Surface^ 


Rrocno 
J'lat£  cf Ethmoid, 


groove  for  tiataL  nerve 
Inner  Surface 


SUPERIOR  MAXILLARY  BONE. 


159 


Superior  Maxillary  Bone. 

The  Superior  Maxillary  is  one  of  the  most  important  bones  of  tlie  face  in  a 
surgical  point  of  view,  on  account  of  the  number  of  diseases  to  which  some  of 
its  parts  are  liable.  Its  minute  examination  becomes,  therefore,  a  matter  of 
considerable  interest.  It  is  the  largest  bone  of  the  face,  excepting  the  lower  jaw; 
and  forms,  by  its  union  with  its  fellow  on  the  opposite  side,  the  whole  of  the 
upper  jaw.  Each  bone  assists  in  the  formation  of  three  cavities,  the  roof  of 
the  mouth,  the  floor  and  outer  wall  of  the  nose,  and  the  floor  of  the  orbit ;  and 
also  enters  into  the  formation  of  two  fossae,  the  zygomatic  and  spheno-maxil- 
lary;  and  two  fissures,  the  spheno-maxillary  and  pterygo-maxillary. 

The  bone  presents  for  examination  a  body  and  four  processes,  malar,  nasal, 
alveolar,  and  palatine. 

The  Body  is  somewhat  quadrilateral,  and  is  hollowed  out  in  its  interior  to 
form  a  large  cavity,  the  antrum  of  Highmore.  Its  surfaces  are  four :  an  ex- 
ternal or  facial,  a  posterior  or  zygomatic,  a  superior  or  orbital,  and  an  internal. 

The  external  or  facial  surface  (Fig.  112)  is  directed  forwards  and  outwards. 
In  the  median  line  of  the  bone,  just  above  the  incisor  teeth,  is  a  depression,  the 

Fig.  112. — Left  Superior  Maxillary  Bone.     Outer  Surface. 
Outer        Surface. 


Incisive  Jo  sua 


Posterior  Dental  CunaU 


ILle 


;/y. 


^ors.  Cc 


"'ilM. 


•Bicusidds 


incisive  or  myrtiform  fossa,  which  gives  origin  to  the  Depressor  Alse  Nasi. 
Above  and  a  little  external  to  it,  the  Compressor  Nasi  arises.  More  external, 
is  another  depression,  the  canine  fossa,  larger  and  deeper  than  the  incisive  fossa, 
from  which  it  is  separated  by  a  vertical  ridge,  the  canine  eminence,  correspond- 
ing to  the  socket  of  the  canine  tooth.  The  canine  fossa  gives  origin  to  the 
Levator  Anguli  Oris.  Above  the  canine  fossa  is  the  infra-orbital  foramen,  the 
termination  of  the  infra-orbital  canal;  it  transmits  the  infra-orbital  nerve  and 
artery.  Above  the  infra-orbital  foramen  is  the  margin  of  the  orbit,  which 
affords  partial  attachment  to  the  Levator  Labii  Superioris  Proprius. 

The  posterior  or  zygomatic  surface  is  convex,  directed  backwards  and  out- 
wards, and  forms  part  of  the  zygomatic  fossa.  It  presents  about  its  centre 
several  apertures  leading  to  canals  in  the  substance  of  the  bone;  they  are 


160 


THE    SKELETON. 


termed  the  posterior  dental  canals,  and  transmit  the  posterior  dental  vessels  and 
nerves.  At  the  lower  part  of  this  surface  is  a  rounaed  eminence,  the  maxillary 
tuberosity,  especially  prominent  after  the  growth  of  the  wisdom-tooth,  rough 
on  its  inner  side  for  articulation  with  the  tuberosity  of  the  palate  bone.  Im- 
mediately above  the  rough  surface  is  a  groove,  which,  running  obliquely  down 
on  the  inner  surface  of  the  bone,  is  converted  into  a  canal  by  articulation  with 
the  palate  bone,  forming  the  posterior  palatine  canal. 

The  superior  or  orbital  surface  is  thin,  smooth,  triangular,  and  forms  part  of 
the  floor  of  the  orbit.  It  is  bounded  internally  by  an  irregular  margin  which 
articulates,  in  front,  with  the  lachrymal;  in  the  middle,  with  the  os  planum  of 
the  ethmoid;  behind,  with  the  orbital  process  of  the  palate  bone;  bounded 
externally  by  a  smooth  rounded  edge  which  enters  into  the  formation  of  the 
spheno-maxillary  fissure,  and  which  sometimes  articulates  at  its  anterior  ex- 
tremity with  the  orbital  plate  of  the  sphenoid ;  bounded,  in  front,  by  part  of 
the  circumference  of  the  orbit,  which  is  continuous,  on  the  inner  side  with  the 
nasal,  on  the  outer  side  with  the  malar  process.  Along  the  middle  line  of  the 
orbital  surface  is  a  deep  groove,  the  infra-orbital,  for  the  passage  of  the  infra- 
orbital nerve  and  artery.  This  groove  commences  at  the  middle  of  the  outer 
border  of  the  surface,  and  passing  forwards,  terminates  in  a  canal  which  sub- 
divides into  two  branches;  one  of  the  canals,  the  infra -orbital,  opens  just  be- 
low the  margin  of  the  orbit ;  the  other,  which  is  smaller,  runs  into  the  substance 
of  the  anterior  wall  of  the  antrum ;  it  is  called  the  anterior  dental  canal,  trans- 
mitting the  anterior  dental  vessels  and  nerves  to  the  front  teeth  of  the  upper 
jaw.  At  the  inner  and  fore  part  of  the  orbital  surface,  just  external  to  the 
lachrymal  canal,  is  a  minute  depression,  which  gives  origin  to  the  Inferior 
Oblique  muscle  of  the  eye. 

The  internal  surface  (Fig.  113)  is  unequally  divided  into  two  parts  by  a  hori- 
zontal projection  of  bone,  the  palate  process;  the  portion  above  the  palate  pro- 


Fig.  113. — Left  Superior  Maxillary  Bone.    Inner  Surface. 


— ^ 


murktd    in    ourJnve 


JPi&maCd 
Injitrior  TurlfnrtffJ 


AnC.  Nasal SoiTtt 


BriffJ» 

jjn  its  I  d  rh  rouglt  I 
Ant.f>aUit.Cah 


cess  forms  part  of  the  outer  wall  of  the  nose ;  that  below  it  forms  part  of  the 
cavity  of  the  mouth.     The  superior  division  of  this  surface  presents  a  large 


SUPERIOR    MAXILLARY    BONE.  161 

irregular  opening  leading  into  the  antrum  of  Highmore.  At  the  upper  border 
of  this  aperture  are  numerous  broken  cellular  cavities,  which,  in  the  articulated 
skull,  are  closed  in  by  the  ethmoid  and  lachrymal  bones.  Below  the  aperture 
is  a  smooth  concavity  which  forms  part  of  the  inferior  meatus  of  the  nose,  tra- 
versed by  a  fissure,  the  maxillary  fissure,  which  runs  from  the  lower  part  of 
the  orifice  of  the  antrum  obliquely  downwards  and  forwards,  and  receives  the 
maxillary  process  of  the  palate  bone.  Behind  it  is  a  rough  surface  which  arti- 
culates with  the  perpendicular  plate  of  the  palate  bone,  traversed  by  a  groove, 
which,  commencing  near  the  middle  of  the  posterior  border,  runs  obliquely 
downwards  and  forwards,  and  forms,  when  completed  by  its  articulation  with 
the  palate  bone,  the  posterior  palatine  canal.  In  front  of  the  opening  of  the 
antrum  is  a  deep  groove,  converted  into  a  canal  by  the  lachrymal  and  inferior 
turbinated  bones,  which  is  coated  with  mucous  membrane,  and  called  the  nasal 
duct.  More  anteriorly  is  a  well-marked  rough  ridge,  the  inferior  turbinated 
crest,  for  articulation  with  the  inferior  turbinated  bone.  The  concavity  above 
this  ridge  forms  part  of  the  middle  meatus  of  the  nose ;  whilst  that  below  it 
forms  part  of  the  inferior  meatus.  The  inferior  division  of  this  surface  is  con- 
cave, rough,  and  uneven,  and  perforated  by  numerous  small  foramina  for  the 
passage  of  nutrient  vessels. 

The  A7itru7n  of  Highmore,  or  Maxillary  Sinus,  is  a  large  triangular^ shaped 
cavity,  hollowed  out  of  the  body  of  the  maxillary  bone ;  its  apex,  directed 
outwards,  is  formed  by  the  malar  process;  its  base,  by  the  outer  wall  of  the 
nose.  Its  walls  are  everywhere  exceedingly  thin,  its  roof  being  formed  by  the 
orbital  plate,  its  floor  by  the  alveolar  process,  its  anterior  wall  by  the  facial, 
and  its  posterior  by  the  zygomatic  surface.  Its  inner  wall,  or  base,  presents, 
in  the  disarticulated  bone,  a  large  irregular  aperture,  which  communicates  with 
the  nasal  fossa.  The  margins  of  this  aperture  are  thin  and  ragged,  and  the 
aperture  itself  is  much  contracted  by  its  articulation  with  the  ethmoid  above, 
the  inferior  turbinated  below,  and  the  palate  bone  behind.^  In  the  articulated 
skull,  this  cavity  communicates  with  the  middle  meatus  of  the  nose  generally 
by  two  small  apertures  left  between  the  above-mentioned  bones.  In  the  recent 
state,  usually  only  one  small  opening  exists,  near  the  upper  part  of  the  cavity, 
sufficiently  large  to  admit  the  end  of  a  probe,  the  other  being  closed  by  the 
lining  membrane  of  the  sinus. 

Crossing  the  cavity  of  the  antrum,  are  often  seen  several  projecting  laminae 
of  bone,  similar  to  those  seen  in  the  sinuses  of  the  cranium;  and  on  its  poste- 
rior wall  are  the  posterior  dental  canals,  transmitting  the  posterior  dental 
vessels  and  nerves  to  the  teeth.  Projecting  into  the  floor  are  several  conical 
processes,  corresponding  to  the  roots  of  the  first  and  second  molar  teeth;*  in 
some  cases  the  floor  is  perforated  by  the  teeth  in  this  situation.  It  is  from  the 
extreme  thinness  of  the  walls  of  this  cavity,  that  we  are  enabled  to  explain 
how  a  tumor,  growing  from  the  antrum,  encroaches  upon  the  adjacent  parts, 
pushing  up  the  floor  of  the  orbit,  and  displacing  the  eyeball,  projecting  inward 
into  the  nose,  protruding  forwards  on  to  the  cheek,  and  making  its  way  back- 
wards into  the  zygomatic  fossa,  and  downwards  into  the  mouth. 

The  Malar  Process  is  a  rough  triangular  eminence,  situated  at  the  angle  of 
separation  of  the  facial  from  the  zygomatic  surface.  In  front  it  is  concave, 
forming  part  of  the  facial  surface ;  behind,  it  is  also  concave,  and  forms  part 
of  the  zygomatic  fossa;  above,  it  is  rough  and  serrated  for  articulation  with 
the  malar  bone ;  whilst  below,  a  prominent  ridge  marks  the  division  between 

'  In  some  cases,  at  any  rate,  the  lachrj^mal  bone  encroaches  slightly  on  the  anterior  superior 
portion  of  the  opening,  and  assists  in  forming  the  inner  wall  of  the  antrum. 

*  The  number  of  teeth  whose  fangs  are  in  relation  with  the  floor  of  the  antrum  is  variable. 
The  antrum  ''may  extend  so  as  to  be  in  relation  to  all  the  teeth  of  the  true  maxilla,  from  the 
canine  to  the  dois  sapienticp." — See  Mr.  Salter  on  Abscess  of  the  Antrum,  in  a  Sydtm  of  Stir- 
gtry,  edited  by  T.  Holmes,  vol.  iv,  p.  25. 
11 


I 


162  THE    SKELETON. 

the  facial  and  zygomatic  surfaces.     A  small  part  of  the  Masseter  muscle  arises 
from  this  process. 

The  Nasal  Process  is  a  thick  triangular  plate  of  bone,  which  projects  up- 
wards, inwards,  and  backwards,  by  the  side  of  the  nose,  forming  part  of  its 
lateral  boundary.  Its  external  surface  is  concave,  smooth,  perforated  by 
numerous  foramina,  and  gives  attachment  to  the  Levator  Labii  Superioris, 
Alaeque  Nasi,  the  Orbicularis  Palpebrarum,  and  tendo  oculi.  Its  internal 
surface  forms  part  of  the  outer  wall  of  the  nose ;  it  articulates  above  with  the 
frontal,  and  presents  a  rough  uneven  surface,  which  articulates  with  the  eth- 
moid bone,  closing  in  the  anterior  ethmoid  cells ;  below  this  is  a  transverse  ridge, 
the  superior  turbinated  crest,  for  articulation  with  the  middle  turbinated  bone 
of  the  ethmoid,  bounded  below  by  a  smooth  concavity,  which  forms  part  of 
the  middle  meatus;  below  this  again  is  the  inferior  turbinated  crest  (already 
described),  for  articulation  with  the  inferior  turbinated  bone;  and  still  more 
inferiorly,  the  concavity  which  forms  part  of  the  inferior  meatus.  The  an- 
terior border  of  the  nasal  process  is  thin,  directed  obliquely  downwards  and 
forwards,  and  presents  a  serrated  edge  for  articulation  with  the  nasal  bone :  its 
posterior  border  is  thick,  and  hollowed  into  a  groove  for  the  nasal  duct:  of 
the  two  margins  of  this  groove,  the  inner  one  articulates  with*  the  lachrymal 
bone,  the  outer  one  forms  part  of  the  circumference  of  the  orbit.  Just  where 
the  latter  joins  the  orbital  surface  is  a  small  tubercle,  the  lachrymal  tubercle; 
this  serves  as  a  guide  to  the  surgeon  in  the  performance  of  the  operation  for 
fistula  lachrymalis.  The  lachrymal  groove  in  the  articulated  skull  is  con- 
verted into  a  canal  by  the  lachrymal  bone,  and  lachrymal  process  of  the  in- 
ferior turbinated ;  it  is  directed  downwards,  and  a  little  backwards  and  out- 
wards, is  about  the  diameter  of  a  goose-quill,  slightly  narrower  in  the  middle 
than  at  either  extremity,  and  lodges  the  nasal  duct. 

The  Alveolar  Process  is  the  thickest  and  most  spongy  part  of  the  bone, 
broader  behind  than  in  front,  and  excavated  into  deep  cavities  for  the  recej)tion 
of  the  teeth.  These  cavities  are  eight  in  number,  and  vary  in  size  and  depth 
according  to  the  teeth  they  contain.  That  for  the  canine  tooth  is  the  deepest; 
those  for  the  molars  are  the  widest,  and  subdivided  into  minor  cavities;  those 
for  the  incisors  are  single,  but  deep  and  narrow.  The  Buccinator  muscle  arises 
from  the  outer  surface  of  this  process,  as  far  forward  as  the  first  molar  tooth. 

The  Palate  Process,  thick  and  strong,  projects  horizontally  inwards  from  the 
inner  surface  of  the  bone.  It  is  much  thicker  in  front  than  behind,  and  forms 
a  considerable  part  of  the  floor  of  the  nostril,  and  the  roof  of  the  mouth.  Its 
upper  surface  is  concave  from  side  to  side,  smooth  and  forms  part  of  the  floor 
of  the  nose.  In  front  is  seen  the  upper  orifice  of  the  anterior  palatine  (incisor) 
canal,  which  leads  into  a  fossa  formed  by  the  junction  of  the  two  superior 
maxillary  bones,  and  situated  immediately  behind  the  incisor  teeth.  It  trans- 
mits the  anterior  palatine  vessels,  the  naso-palatitie  nerves  passing  through  the 
intermaxillary  suture.  The  inferior  surface,  also  concave,  is  rough  and  uneven, 
and  forms  part  of  the  roof  of  the  mouth.  Tliis  surface  is  perforated  by 
numerous  foramina  for  the  passage  of  nutritious  vessels,  channelled  at  the 
back  part  of  its  alveolar  border  by  a  longitudinal  groove,  sometimes  a  canal, 
for  the  transmission  of  the  posterior  palatine  vessels,  and  a  large  nerve,  and 
presents  little  depressions  for  the  lodgment  of  the  palatine  glands.  This  sur- 
face presents  anteriorly  the  lower  orifice  of  the  anterior  palatine  fossa.  In 
some  bones,  a  delicate  linear  suture  may  be  seen  extending  from  the  anterior 
palatine  fossa  to  the  interval  between  the  lateral  incisor  and  the  canine  tooth. 
This  marks  out  the  intermaxillary,  or  incisive,  bone,  which  in  some  animals 
exists  permanently  as  a  separate  piece.  It  includes  the  whole  thickness  of  the 
alveolus,  the  corresponding  part  of  the  floor  of  the  nose,  and  the  anterior  nasal 
spine,  and  contains  the  sockets  of  the  incisor  teeth.  The  outer  border  of  the 
palate  process  is  incorporated  with  the  rest  of  the  bone.  The  inner  border  is 
thicker  in  front  than  behind,  and  is  raised  above  into  a  ridge,  which,  with  the 


LACHRYMAL    BONES. 


163 


J  for  Ifa  ual    Sf 
I'lieiaL   portVi 

1  for  Orlital  f^ 
Malar  jtori'-.* 


1    furlncistvt  porf^ 


1  for  Palatal -povV- 


Anterior  Surface. 


at 
BtrtTh 


Inferior  Surfuce. 


corresponding  ridge  in  the  opposite  bone,  forms  a  groove  for  the  reception  of 

the  vomer.     The  anterior  margin  is  bounded  by  the  thin  concave  border  of  the 

opening  of  the  nose,  prolonged 

forwards  internally  into  a  sharp      Fig.  114— Development  of  Superior  Maxillary  Bone. 

process,  forming,  with  a  similar  ^^  ^'''''  Centres. 

process  of   the    opposite  bone, 

the  anterior  nasal  spine.     The 

posterior  border  is  serrated  for 

articulation  with  the  horizontal 

plate  of  the  palate  bone. 

Development.  This  bone  is 
formed  at  such  an  early  period, 
and  ossification  proceeds  in  it 
with  such  rapidity,  that  it  has 
been  found  impracticable  hi- 
therto to  determine  with  ac- 
curacy its  number  of  centres. 
It  appears,  however,  probable 
that  it  has  four  centres  of  de- 
velopment, viz.,  one  for  the 
nasal  and  facial  portions,  one 
for  the  orbital  and  malar,  one 
for  the  incisive,  and  one  for  the 
palatal  portion,  including  the 
entire  palate,  except  the  incisive 
segment.  The  incisive  portion 
is  indicated  in  young  bones  by 

a  fissure,  which  marks  off  a  small  segment  of  the  palate,  including  the  two 
incisor  teeth.  In  some  animals,  this  remains  permanently  as  a  separate  piece, 
constituting  the  intermaxillary  bone ;  and  in  the  human  subject,  where  the  jaw 
is  malformed,  as  in  cleft  palate,  this  segment  may  be  separated  from  the  maxil- 
lary bone  by  a  deep  fissure  extending  backwards  between  the  two  into  the 
palate.  If  the  fissure  be  on  both  sides,  both  segments  are  quite  isolated  from 
the  maxillary  bones,  and  hang  from  the  end  of  the  vomer :  they  are  not  unfre- 
quently  much  displaced,  and  the  deformity  is  often  accompanied  by  congenital 
fissure  of  the  upper  lip,  either  on  one  or  both  sides  of  the  median  line.  The 
maxillary  sinus  appears  at  an  earlier  period  than  any  of  the  other  nasal  sinuses, 
its  development  commencing  about  the  fourth  month  of  foetal  life. 

Articulations.  With  nine  bones ;  two  of  the  cranium — the  frontal  and  eth- 
moid, and  seven  of  the  face,  viz.,  the  nasal,  malar,  lachrymal,  inferior  turbi- 
nated, palate,  vomer,  and  its  fellow  of  the  opposite  side.  Sometimes  it  articu- 
lates with  the  orbital  plate  of  the  sphenoid. 

Attachment  of  Muscles.  Orbicularis  Palpebrarum,  Obliquus  Inferior  Oculi, 
Levator  Labii  Superioris  Alaeque  Nasi,  Levator  Labii  Superioris  Proprius, 
Levator  Anguli  Oris,  Compressor  Nasi,  Depressor  Alae  Nasi,  Masseter, 
Buccinator. 

The  Lachrymal  Bones. 

The  Lachrymal  are  the  smallest  and  most  fragile  bones  of  the  face.  They 
are  situated  at  the  front  part  of  the  inner  wall  of  the  orbit,  and  resemble 
somewhat  in  form,  thinness,  and  size,  a  finger-nail ;  hence  they  are  termed  the 
ossa  unguis.  Each  bone  presents,  for  examination,  two  surfaces  and  four 
borders.  The  external  (Fig.  115)  or  orbital  surface  is  divided  by  a  vertical 
ridge  into  two  parts.  The  portion  of  bone  in  front  of  this  ridge  presents  a 
smooth,  concave,  longitudinal  groove,  the  free  margin  of  which  unites  with 
the  nasal  process  of  the  superior  maxillary  bone,  completing  the  lachrymal 
groove.     The  upper  part  of  this  groove  lodges  the  lachrymal  sac ;  the  lower 


1G4 


THE    SKELETOX. 


Fig.  115. — Left  Lachrymal  Bone 
External  Surface. 


^•rf  FroTttal 


part  assists  in  the  formation  of  the   lachrymal  canal,  and  lodges  the  nasal 
duct.     The  portion  of  bone  behind  the  ridge  is  smooth,  slightly  concave,  and 

forms  part  of  the  inner  wall  of  the  orbit.  The 
ridge,  with  a  part  of  the  orbital  surface  imme- 
diately behind  it,  affords  attachment  to  the  Tensor 
Tarsi ;  the  ridge  terminates  below  in  a  small  hook- 
like process,  which  articulates  with  the  lachrymal 
tubercle  of  the  superior  maxillary  bone,  and 
completes  the  upper  orifice  of  the  lachrymal 
canal.  It  sometimes  exists  as  a  separate  piece, 
which  is  then  called  the  lesser  lachrymal  hone. 
The  internal  or  nasal  surface  presents  a  depressed 
furrow,  corresponding  to  the  ridge  on  its  outer 
surface.  The  surface  of  bone  in  front  of  this  forms 
part  of  the  middle  meatus;  and  that  behind  it 
articulates  with  the  ethmoid  bone,  filling  in  the 
anterior  ethmoidal  cells.  Of  the  four  horde  s, 
the  anterior  is  the  longest,  and  articulates  with 
the  nasal  process  of  the  superior  maxillary  bone. 
The  posterior,  thin  and  uneven,  articulates  with 
the  OS  planum  of  the  ethmoid.  The  superior,  the  shortest  and  thickest,  articu- 
lates with  the  internal  angular  process  of  the  frontal  bone.  The  inferior  is 
divided  by  the  lower  edge  of  the  vertical  crest  into  two  parts ;  the  posterior 
part  articulates  with  the  orbital  plate  of  the  superior  maxillary  bone ;  the  an- 
terior portion  is  prolonged  downwards  into  a  pointed  process,  which  articulates 
with  the  lachrymal  process  of  the  inferior  turbinated  bone,  and  assists  in  -the 
formation  of  the  lachrymal  canal. 

Development.     By  a  single  centre,  which  makes  its  appearance  soon  after 
ossification  of  the  vertebrae  has  commenced. 

Articulations.     With  four  bones;  two  of  the  cranium,  the  frontal  and  ethmoid, 
and  two  of  the  face,  the  superior  maxillary  and  the  inferior  turbinated. 
Attachment  of  Muscles.     The  Tensor  Tarsi. 


{SlicjMy 


The  Malar  Bones. 

The  Malar  are  two  small  quadrangular  bones,  situated  at  the  upper  and  outer 
part  of  the  face:  they  form  the  prominence  of  the  cheek,  part  of  the  outer  wall 
and  floor  of  the  orbit,  and  part  of  the  temporal  and  zygomatic  fossae.  Each 
bone  presents  for  examination  an  external  and  internal  surface;  four  processes, 

the  frontal,  orbital,  maxillary, 
Fig.  116.— Left  Malar  Bone.    Outer  Surface.  and  zygomatic ;  and  four  bor- 

ders. The  external  surface  (Fig. 
116)  is  smooth,  convex,  perfo- 
rated near  its  centre  by  one  or 
two  small  apertures,  the  malar 
foramina,  for  the  passage  of 
nerves  and  vessels,  covered  by 
the  Orbicularis  Palpebrarum 
muscle,  and  affords  attachment 
to  the  Zygomaticus  Major  and 
Zygomaticus  Minor  muscles. 

^he  internal  surface  {^\g.  117), 
directed  backwards  and  in- 
wards, is  concave,  presenting 
internally  a  rough  triangular 
surface,  for  articulation  with 
the   superior  maxillary  bone; 


BTiatlfi  ptuted  tAroughi 
Tcmporo  Miilmr  (ixnnls 


MALAR    BONES. 


165 


Fig.  117.— Left  Malar  Bone. 


and  externally,  a  smootli  con-  fj„.  117.— Left  Malar  Bone.    Inner  Surface, 

cave  surface,  which  forms  the 
anterior  boundary  of  the  tem- 
poral fossa  above;  and  below, 
where  it  is  wider,  forms  part  of 
the  zygomatic  fossa.  This  sur- 
face presents,  a  little  above  its 
centre,  the  aperture  of  one  or 
two  malar  canals,  and  affords 
attachment  to  part  of  two  mus- 
cles, the  Temporal  above  and 
the  Masseter  below.  The  fron- 
tal process  is  thick  and  serrated, 
and  articulates  with  the  exter- 
nal angular  process  of  the  fron- 
tal bone.  The  orbital  process  is 
a  thick  and  strong  plate,  which 
projects  backwards  from  the 
orbital  margin  of  the  bone.  Its 
upper  surface,  smooth  and  concave,  forms,  by  its  junction  with  the  great  ala  of 
the  sphenoid,  the  outer  wall  of  the  orbit.  Its  under  surface,  smooth  and  con- 
vex, forms  part  of  the  temporal  fossa.  Its  anterior  margin  is  smooth  and 
rounded,  forming  part  of  the  circumference  of  the  orbit.  Its  superior  margin, 
rough,  and  directed  horizontally,  articulates  with  the  frontal  bone  behind  the 
external  angular  process.  Its  posterior  margin  is  rough  and  serrated  for  articu- 
lation with  the  sphenoid;  internally  it  is  also  serrated  for  articulation  with  the 
orbital  surface  of  the  superior  maxillary.  At  the  angle  of  junction  of  the 
sphenoidal  and  maxillary  portions,  a  short  rounded  non-articular  margin  is 
generally  seen:  this  forms  the  anterior  boundary  of  the  spheno-maxillary 
fissure ;  occasionally,  no  such  non-articular  margin  exists,  the  fissure  being 
completed  by  the  direct  junction  of  the  maxillary  and  sphenoid  bones,  or  by 
the  interposition  of  a  small  Wormian  bone  in  the  angular  interval  between 
them.  On  the  upper  surface  of  the  orbital  process  are  seen  the  orifices  of  one  or 
two  temporo-malar  canals ;  one  of  these  usually  opens  on  the  posterior  surface, 
the  other  (occasionally  two),  on  the  facial  surface:  they  transmit  filaments 
(temporo-malar)  of  the  orbital  branch  of  the  superior  maxillary  nerve.  The 
maxillary  process  is  a  rough  triangular  surface,  which  articulates  with  the  supe- 
rior maxillary  bone.  The  zygomatic  process,  long,  narrow,  and  serrated,  articu- 
lates with  the  zygomatic  process  of  the  temporal  bone.  Of  the/owr  borders,  the 
superior  or  orbital  is  smooth,  arched,  and  forms  a  considerable  part  of  the 
circumference  of  the  orbit.  The  inferior,  or  zygomatic,  is  continuous  with  the 
lower  border  of  the  zygomatic  arch,  affording  attachment  by  its  rough  edge  to 
the  Masseter  muscle.  The  anterior  or  maxillary  border  is  rough,  and  bevelled 
at  the  expense  of  its  inner  table,  to  articulate  with  the  superior  maxillary  bone; 
affording  attachment  by  its  outer  margin  to  the  Levator  Labii  Superioris  Pro- 
prius,  just  at  its  point  of  junction  with  the  superior  maxillary.  The  posterior 
or  temporal  border,  curved  like  an  italic  /,  is  continuous  above  with  the  com- 
mencement of  the  temporal  ridge;  below,  with  the  upper  border  of  the  zygo- 
matic arch :  it  affords  attachment  to  the  temporal  fascia. 

Development.     By  a  single  centre  of  ossification,  which  appears  at  about  the 
same  period  when  ossification  of  the  vertebrae  commences. 

Articulations.     With  four  bones :   three  of  the  cranium,  frontal,  sphenoid, 
and  temporal ;  and  one  of  the  face,  the  superior  maxillary. 

Attachment  of  Muscles.     Levator   Labii   Superioris   Proprius,   Zygomaticus 
Major,  Zygomaticus  Minor,  Masseter,  and  Temporal. 


166 


THE    SKELETON. 


The  Palate  Bones. 

Tlie  Palate  Bones  are  situated  at  the  back  part  of  the  nasal  fossae ;  they  are 
wedged  in  between  the  superior  maxillary  and  the  pterygoid  process  of  the 
sphenoid.  Each  bone  assists  in  the  formation  of  three  cavities ;  the  floor  and 
outer  wall  of  the  nose,  the  roof  of  the  mouth,  and  the  floor  of  the  orbit ;  and 
enters  into  the  formation  of  three  fossae :  the  zygomatic,  spheno-maxillary, 
and  pterygoid.  In  form  the  palate  bone  somewhat  resembles  the  letter  L, 
and  may  be  divided  into  an  inferior  or  horizontal  plate,  and  a  superior  or  ver- 
tical plate 

The  Inferior  or  Horizontal  Plate  is  thick,  of  a  quadrilateral  form,  and  presents 
two  surfaces  and  four  borders.  The  superior  surface,  concave  from  side  to 
side,  forms  the  back  part  of  the  floor  of  the  nostril.  The  inferior  surface, 
slightly  concave  and  rough,  forms  the  back  part  of  the  hard  palate.  At  its 
posterior  part  may  be  seen  a  transverse  ridge,  more  or  less  marked,  for  the 
attachment  of  the  aponeurosis  of  the  Tensor  Palati  muscle.  At  the  outer  ex- 
tremity of  this  ridge  is  a  deep  groove,  converted  into  a  canal  by  its  articulation 
with  the  tuberosity  of  the  superior  maxillary  bone,  and  forming  the  posterior 
palatine  canal.  Near  this  groove,  the  orifices  of  one  or  two  small  canals, 
accessory  posterior  palatine,  may  frequently  be  seen.  The  anterior  border  is 
serrated,  bevelled  at  the  expense  of  its  inferior  surface,  and  articulates  with 
the  palate  process  of  the  superior  maxillary  bone.  The  posterior  border  is 
concave,  free,  and  serves  for  the  attachment  of  the  soft  palate.  Its  inner  ex- 
tremity is  sharp  and  pointed,  and,  when  united  with  the  opposite  bone,  forms 
a  projecting  process,  the  posterior  nasal  spine,  for  the  attachment  of  the  Azygos 
Uvulae.  The  external  border  is  united  with  the  lower  part  of  the  perpendicu- 
lar plate  almost  at  right 

Fig.  118.— Left  Palate  Bone.    Internal  View  (enlarged).  "         —-     - 


id  -?> 


SujttrUr  ilea. 
JSpt%»na.  ^ftlafinc  JTtnraituHi — 


angles.  The  internal  bor- 
der, the  thickest,  is  ser- 
rated for  articulation  with 
its  fellow  of  the  opposite 
side ;  its  superior  edge  is 
raised  into  a  ridge,  which, 
united  with  the  opposite 
bone,  forms  a  crest  in 
which  the  vomer  is  re- 
ceived. 

The  Superior  or  Vertical 
PZa/e  (Fig.  118)  is  thin,  of 
an  oblong  form,  and  di- 
rected upwards  and  a  lit- 
tle inwards.  It  presents 
two  surfaces,  an  external 
and  an  internal,  and  four 
borders. 

The  internal  surface 
presents,  at  it  lower  part, 
a  broad  shallow  depres- 
sion, which  forms  part  of 
the  inferior  meatus  of  the  nose.  Immediately  above  this  is  a  well-marked 
horizontal  ridge,  the  inferior  turbinated  crest,  for  articulation  with  the  inferior 
turbinated  bone;  above  this,  a  second  broad  shallow  depression,  which  forms 
part  of  the  middle  meatus,  surmounted  above  by  a  horizontal  ridge  less  pro- 
minent than  the  inferior,  the  superior  turbinated  crest,  for  articulation  with 
the  middle  turbinated  bone.  Above  the  superior  turbinated  crest  is  a  narrow 
horizontal  groove,  which  forms  part  of  the  superior  meatus. 

The  external  surface  is  rough  and  irregular  throughout  the  greater  part  of  its 


HORIZONTAL      PLATC 


PALATE    BONES. 


16T 


Fio:. 


119.— Left  Palate   Bone. 
View  (enlarged). 


Posterior 


S/iheruiidtiJ.  /irocess. 


extent,  for  articulation  with  the  inner  surface  of  the  superior  maxillary  bone, 
its  upper  and  back  part  being  smooth  where  it  enters  into  the  formation  of  the 
spheno-maxillary  fossa;  it  is  also  smooth  in  front,  where  it  covers  the  orifice 
of  the  antrum.  Towards  the  back  part  of  this  surface  is  a  deep  groove,  con- 
verted into  a  canal,  the  posterior  palatine,  by  its  articulation  with  the  superior 
maxillary  bone.  It  transmits  the  posterior,  or  descending  palatine  vessels,  and 
a  large  nerve. 

The  anterior  border  is  thin,  irregular,  and  presents  opposite  the  inferior 
turbinated  crest  a  pointed  projecting  lamina,  the  maxillary  process,  which  is 
directed  forwards,  and  closes  in  the  lower 
and  back  part  of  the  opening  of  the  an- 
trum, being  received  into  a  fissure  that 
exists  at  the  inferior  part  of  this  aper- 
ture. The  posterior  border  (Fig.  119) 
presents  a  deep  groove,  the  edges  of 
which  are  serrated  for  articulation  with 
the  pterygoid  process  of  the  sphenoid. 
At  the  lower  part  of  this  border  is  seen 
a  pyramidal  process  of  bone,  the  ptery- 
goid process  or  tuberosity  of  the  palate, 
which  is  received  into  the  angular  in- 
terval between  the  two  pterygoid  plates 
of  the  sphenoid  at  their  inferior  ex- 
tremity. This  process  presents,  at  its 
back  part,  three  grooves,  a  median,  and 
two  lateral  ones.  The  former  is  smooth, 
and  forms  part  of  the  pterygoid  fossa, 
affording  attachment  to  the  Internal 
Pterygoid  muscle;  whilst  the  lateral 
grooves  are  rough  and  uneven,  for  ar- 
ticulation with  the  anterior  border  of 
each  pterygoid  plate.     A  few  fibres  of 

the  External  Pterygoid  muscle  also  arise  from  the  tuberosity  of  the  palate 
bone.  The  base  of  this  process,  continuous  with  the  horizontal  portion  of  the 
bone,  presents  the  apertures  of  the  accessory  descending  palatine  canals;  whilst 
its  outer  surface  is  rough  for  articulation  with  the  inner  surface  of  the  body  of 
the  superior  maxillary  bone. 

The  superior  border  of  the  vertical  plate  presents  two  well-marked  processes 
separated  by  an  intervening  notch  or  foramen.  The  anterior,  or  larger,  is  called 
the  orbital  process ;  the  posterior,  the  sphenoidal. 

The  Orhital  Process^  directed  upwards  and  outwards,  is  placed  on  a  higher 
level  than  the  sphenoidal.  It  presents  five  surfaces,  which  inclose  a  hollow 
cellular  cavity,  and  is  connected  to  the  perpendicular  plate  by  a  narrow  con- 
stricted neck.  Of  these  five  surfaces  three  are  articular,  two  non-articular,  or 
free  surfaces.  The  three  articular  are  the  anterior  or  maxillary  surface,  which 
is  directed  forwards,  outwards,  and  downwards,  is  of  an  oblong  form,  and  rough 
for  articulation  with  the  superior  maxillary  bone.  The  posterior  or  sp)henoidat 
surface  is  directed  backwards,  upwards,  and  inwards.  It  ordinarily  presents  a 
small  open  cell,  which  communicates  with  the  sphenoidal  sinus,  and  the  mar- 
gins of  which  are  serrated  for  articulation  with  the  vertical  part  of  the  sphe- 
noidal turbinated  bone.  The  internal  or  ethmoidal  surface  is  directed  inwards^ 
upwards,  and  forwards,  and  articulates  with  the  lateral  mass  of  the  ethmoid 
bone.  In  some  cases,  the  cellular  cavity  above-mentioned  opens  on  this  sur- 
face of  the  bone ;  it  then  communicates  with  the  posterior  ethmoid  cells.  More 
rarely  it  opens  on  both  surfaces,  and  then  communicates  both  with  the  pos- 
terior ethmoidal  cells,  and  the  sphenoidal  sinus.  The  non-articular  or  free  sur- 
faces are  the  superior  or  orhital^  directed  upwards  and  outwards,  of  triangular 


HORIZONTAL 
PLATE 


168 


THE    SKELETON. 


form,  concave,  smooth,  and  forming  the  back  part  of  the  floor  of  the  orbit,  and 
the  external  or  zygomatic  surface,  directed  outwards,  backwards,  and  down- 
wards, of  an  oblong  form,  smooth,  lying  in  the  spheno-maxillary  fossa,  and 
looking  into  the  zygomatic  fossa.  The  latter  surface  is  separated  from  the 
orbital  by  a  smooth  rounded  border,  which  enters  into  the  formation  of  the 
spheno-maxillary  fissure. 

The  Sphenoidal  Process  of  the  palate  bone  is  a  thin  compressed  plate,  much 
smaller  than  the  orbital,  and  directed  upwards  and  inwards.  It  presents  three 
surfaces  and  two  borders.  The  superior  surface,  the  smallest  of  the  three, 
articulates  with  the  horizontal  part  of  the  sphenoidal  turbinated  bone ;  it  pre- 
sents a  groove  which  contributes  to  the  formation  of  the  ptery go- palatine  canal. 
The  internal  surface  is  concave,  and  forms  part  of  the  outer  wall  of  the  nasal 
fossa.  The  external  surface  is  divided  into  an  articular  and  a  non-articular 
portion ;  the  former  is  rough  for  articulation  with  the  inner  surface  of  the 
Pterygoid  process  of  the  sphenoid;  the  latter  is  smooth,  and  forms  part  of  the 
zygomatic  fossa.  The  anterior  border  forms  the  posterior  boundary  of  the 
spheno-palatine  foramen.  The  posterior  border,  serrated  at  the  expense  of  the 
outer  table,  articulates  with  the  inner  surface  of  the  pterygoid  process. 

The  orbital  and  sphenoidal  processes  are  separated  from  one  another  by  a 
deep  notch,  which  is  converted  into  a  foramen,  the  spheno-palatine,  by  articu- 
lation with  the  sphenoidal  turbinated  bone.  Sometimes  the  two  processes  are 
united  above,  and  form  between  them  a  complete  foramen,  or  the  notch  is 
crossed  by  one  or  more  spiculaB  of  bone,  so  as  to  form  two  or  more  foramina. 
In  the  articulated  skull  this  foramen  opens  into  the  back  part  of  the  outer  wall 
of  the  superior  meatus,  and  transmits  the  spheno-palatine  vessels  and  nerves. 

Development.  From  a  single  centre,  which  makes  its  ap])earance  at  the  angle 
of  junction  of  the  two  plates  of  the  bone.  From  this  point  ossification  spreads 
inwards  to  the  horizontal  plate,  downwards  into  the  tuberosity,  and  upwards 
into  the  vertical  plate.  In  the  foetus,  the  horizontal  plate  is  much  longer  than 
the  vertical ;  and  even  after  it  is  fully  ossified,  the  whole  bone  is  at  first  re- 
markable for  its  shortness. 

Artic7ilations.  With  six  bones ;  the  sphenoid,  ethmoid,  superior  maxillary, 
inferior  turbinated,  vomer,  and  opposite  palate. 

Attachment  of  Muscles.  The  Tensor  Palati,  Azygos  UvulaB,  Internal  and  Ex- 
ternal Pterygoid. 

The  Inferior  Turbinated  Bones. 

The  Inferior  Turbinated  Bones  are  situated  one  on  each  side  of  the  outer 
wall  of  the  nasal  fossae.  Each  consists  of  a  layer  of  thin  spongy  bone,  curled 
upon  itself  like  a  scroll,  hence  its  name  "turbinated;"  and  extends  horizontally 
along  the  outer  wall  of  the  nasal  fossa,  immediately  below  the  orifice  of  the 
antrum.     Each  bone  presents  two  surfaces,  two  borders,  and  two  extremities. 


Fig.  120. 


-Right  Inferior  Turbinated  Bone. 
Inner  Surface. 


Fig.  121. — Right  Inferior  Turbinated 
Bone.     Outer  Surface. 


The  internal  surface  (Fig.  120)  is  convex,  perforated  by  numerous  apertures, 
and  traversed  by  longitudinal  grooves  and  canals  for  the  lodgment  of  arteries 


THE    VOMER. 


169 


and  veins.  In  the  recent  state  it  is  covered  by  the  lining  membrane  of  the 
nose.  The  external  surface  is  concave  (Fig.  121),  and  forms  part  of  the  inferior 
meatus.  Its  upper  border  is  thin,  irregular,  and  connected  to  various  bones 
along  the  outer  wall  of  the  nose.  It  may  be  divided  into  three  portions ;  of 
these,  the  anterior  articulates  with  the  inferior  turbinated  crest  of  the  superior 
maxillary  bone;  the  posterior  with  the  inferior  turbinated  crest  of  the  palate 
bone ;  the  middle  portion  of  the  superior  border  presents  three  well-marked 
processes,  which  vary  much  in  their  size  and  form.  •  Of  these,  the  anterior  and 
smallest  is  situated  at  the  junction  of  the  anterior  fourth  with  the  posterior 
three-fourths  of  the  bone ;  it  is  small  and  pointed,  and  is  called  the  lachrymal 
process^  for  it  articulates  with  the  anterior  inferior  angle  of  the  lachrymal  bone, 
and  by  its  margins,  with  the  groove  on  the  back  of  the  nasal  process  ot  the 
superior  maxillary,  and  thus  assists  in  forming  the  lachrymal  canal.  At  the 
junction  of  the  two  middle  fourths  of  the  bone,  but  encroaching  on  its  posterior 
fourth,  a  broad  thin  plate,  the  ethmoidal  process^  ascends  to  join  the  unciform 
process  of  the  ethmoid :  from  the  lower  border  of  this  process  a  thin  lamina 
of  bone  curves  downwards  and  outwards,  hooking  over  the  lower  edge  ot  the 
orifice  of  the  antrum,  which  it  narrows  below  :  it  is  called  the  maxillary  process, 
and  fixes  the  bone  firmly  on  to  the  outer  wall  of  the  nasal  fossa.  The  inferior 
border  is  free,  thick,  and  cellular  in  structure,  more  especially  in  the  middle 
of  the  bone.  Both  extremities  are  more  or  less  narrow  and  pointed.  If  the 
bone  is  held  so  that  its  outer  concave  surface  is  directed  backwards  {i.e.,  towards 
the  holder),  and  its  superior  border,  from  which  the  lachrymal  and  ethmoidal 
processes  project,  upwards,  the  lachrymal  process  will  be  directed  to  the  side 
to  which  the  bone  belongs. 

Development.  By  a  single  centre  which  makes  its  appearance  about  the 
middle  of  foetal  life. 

Articulations.  With  four  bones ;  one  of  the  cranium,  the  ethmoid,  and  tihree 
of  the  face,  the  superior  maxillary,  lachrymal,  and  palate. 

No  muscles  are  attached  to  this  bone. 


Al<^' 


The  Vomer. 

The  Vomer  is  a  single  bone,  situated  vertically  at  the  back  part  of  the  nasal 
fossae,  forming  part  of  the  septum  of  the  nose.  It  is  thin,  somewhat  like  a 
ploughshare   in  form ;  but  it 

varies  in  different  individuals.  Fig.  122. — Vomer. 

being  frequently  bent  to  one 
or  the  other  side ;  it  presents 
for  examination  two  surfaces 
and  four  borders.  The  lateral 
surfaces  are  smooth,  marked 
by  small  furrows  for  the  lodg- 
ment of  bloodvessels,  and  by 
a  groove  on  each  side,  some- 
times a  canal,  the  naso-pala- 
tine,  which  runs  obliquely 
downwards  and  forwards  to 
the  intermaxillary  suture  be- 
tween the  two  anterior  pala 
tine  canals;  it  transmits  the 
naso-palatine  nerve.  The  su- 
perior   border,    the   thickest, 

presents  a  deep  groove,  bounded  on  each  side  by  a  horizontal  projecting  ala  of 
bone:  the  groove  receives  the  rostrum  of  the  sphenoid,  whilst  the  alae  are 
overlapped  and  retained  by  laminae  (the  vaginal  processes)  which  project  from 
the  under  surface  of  the  body  of  the  sphenoid  at  the  base  of  the  pterygoid  pro- 
cesses. At  the  front  of  the  groove  a  fissure  is  left  for  the  transmission  of  blood- 


^i-tk   Sup-Ma^ 


vli.  t" 


ITO 


THE    SKELETON. 


vessels  to  the  substance  of  the  bone.  The  inferior  border,  the  longest,  is  broad 
and  uneven  in  front,  where  it  articulates  with  the  two  superior  maxillary  bones; 
thin  and  sharp  behind,  where  it  joins  with  the  palate  bones.  The  upper  half 
of  the  anterior  border  usually  consists  of  two  laminie  of  bone,  between  which 
is  received  the  perpendicular  plate  of  the  ethmoid,  the  lower  half  consisting  of 
a  single  rough  edge,  also  occasionally  channelled,  which  is  united  to  the  tri- 
angular cartilage  of  the  nose.  The  posterior  border  is  free,  concave,  and  sepa- 
rates the  nasal  fossae  behind.     It  is  thick  and  bifid  above,  thin  below. 

Development.  The  vomer  at  an  early  period  consists  of  two  laminae  separated 
bya  very  considerable  interval,  and  inclosing  between  them  a  plate  of  cartilage 
which  is  prolonged  forwards  to  form  the  remainder  of  the  septum.  Ossification 
commences  in  it  at  about  the  same  period  as  in  the  vertebrae  (the  coalescence 
ot  the  laminae  taking  place  from  behind  forwards),  but  is  not  complete  until 
after  puberty. 

Articulations.  "With  six  bones ;  two  of  the  cranium,  the  sphenoid  and  eth- 
moid ;  and  four  of  the  face,  the  two  superior  maxillary  and  the  two  palate 
bones,  and  with  the  cartilage  of  the  septum. 

The  vomer  has  no  muscles  attached  to  it. 


The  Inferior  Maxillary  Bone. 

The  Inferior  Maxillary  Bone,  the  largest  and  strongest  bone  of  the  face, 
serves  for  the  reception  of  the  lower  teeth.  It  consists  of  a  curved  horizontal 
portion,  or  body,  and  two  perpendicular  portions,  or  rami,  which  join  the  back 
part  of  the  body  nearly  at  right  angles. 

The  Horizontal  Portion,  or  Body  (Fig.  123),  is  convex  in  its  general  outline, 
and  curved  somewhat  like  a  horseshoe.  It  presents  for  examination  two  sur- 
faces and  two  borders.     The  external  surface  is  convex  from  side  to  side,  concave 

Fig.  123. — Inferior  Maxillary  Bone.    Outer  Surface.     Side  View. 


o'V/, 


Afr-nful 
/troees* 


from  above  downwards.  In  the  median  line  is  a  vertical  ridge,  the  symphysii 
which  extends  from  the  upper  to  the  lower  border  of  the  bone,  and  indicate 
the  point  of  junction  of  the  two  pieces  of  which  the  bone  is  composed  at  a 
early  period  of  life.  The  lower  part  of  the  ridge  terminates  in  a  prominet 
triangular  eminence,  the  mental  process.  On  either  side  of  the  symphysis,  ju« 
below  the  roots  of  the  incisor  teeth,  is  a  depression,  the  incisive  fossa,  for  t 
attachment  of  the  Levator  Menti ;  and  still  more  externally,  a  foramen,  t 
mental  foramen,  for  the  passage  of  the  mental  nerve  and  artery.  Tiiis  foramen 
is  placed  just  below  the  root  of  the  second  bicuspid  tooth.     Running  outwards 


INFERIOR    MAXILLARY    BONE.  171 

from  the  base  of  the  mental  process  on  each  side,  is  a  well-marked  ridge,  the 
external  oblique  line.  This  ridge  is  at  first  nearly  horizontal,  but  afterwards 
inclines  upwards  and  backwards,  and  is  continuous  with  the  anterior  border 
of  the  ramus ;  it  affords  attachment  to  the  Depressor  Labii  Inferioris  and 
Depressor  Anguli  Oris,  below  which  the  Platysma  Myoides  is  inserted.  The 
external  oblique  line  and  the  internal  or  mylo-hyoidean  line  (to  be  afterwards 
described),  divide  the  body  of  the  bone  into  a  superior  or  alveolar,  and  an 
inferior  or  basilar  portion. 

The  internal  surface  (Fig.  124)  is  concave  from  side  to  side,  convex  from 
above  downwards.  In  the  middle  line  is  an  indistinct  linear  depression,  cor- 
responding to  the  symphysis  externally ;  on  either  side  of  this  depression,  just 

Fig.  124. — Inferior  Maxillary  Bone.     Inner  Surface.     Side  Yicw. 


CENIO-HYO-GLOSSUS 
CENIO-HYOIDEUS 


Ilylo-Iiuoiii  Ridge 

B  0  dy 

below  its  centre,  are  four  prominent  tubercles,  placed  in  pairs,  two  above  and 
two  below;  they  are  called  the  genial  tubercles^  and  afford  attachment,  the  upper 
pair  to  the  Genio-hyoglossi  muscles,  the  lower  pair  to  the  Grenio-hyoidei  mus- 
cles. Sometimes  the  tubercles  on  each  side  are  blended  into  one,  or  they  all 
unite  into  an  irregular  eminence  of  bone,  or  nothing  but  an  irregularity  may 
be  seen  on  the  surface  of  the  bone  at  this  part.  On  either  side  of  the  genial 
tubercles  is  an  oval  depression,  the  sublingual  fossa,  for  lodging  the  sublingual 
gland ;  and  beneath  the  fossa,  a  rough  depression  on  each  side,  which  gives 
attachment  to  the  anterior  belly  of  the  Digastric  muscle.  At  the  back  part  of 
the  sublingual  fossa,  the  internal  oblique  line  (mylo-hyoidean)  commences ;  it 
is  at  first  faintly  marked,  but  becomes  more  distinct  as  it  passes  upwards  and 
outwards,  and  is  especially  prominent  opposite  the  last  two  molar  teeth ;  it 
divides  the  lateral  surface  of  the  bone  into  two  portions,  and  affords  attachment 
throughout  its  whole  extent  to  the  Mylo-hyoid  muscle,  the  Superior  Constrictor 
being  attached  above  its  posterior  extremity,  nearer  the  alveolar  margin.  The 
portion  of  bone  above  this  ridge  is  smooth,  and  covered  by  the  mucous  mem- 
brane of  the  mouth :  whilst  that  below  it  presents  an  oblong  depression,  the 
submaxillary  fossa,  wider  behind  than  in  front,  for  the  lodgment  of  the  sub- 
maxillary gland. 

The  superior  or  alveolar  border  is  wider,  and  its  margins  thicker  behind  than 
in  front.  It  is  hollowed  into  numerous  cavities,  for  the  reception  of  the  teeth ; 
these  cavities  are  sixteen  in  number,  and  vary  in  depth  and  size  according  to 
the  teeth  which  they  contain.  To  its  outer  side,  the  Buccinator  muscle  is 
attached  as  far  forward  as  the  first  molar  tooth.     The  inferior  border  is  rounded, 


172  THE    SKELETON. 

longer  tlian  the  superior,  and  thicker  in  front  than  behind;  it  presents  a 
shallow  groove,  just  where  the  body  joins  the  ramus,  over  which  the  facial 
artery  tarns. 

The  Perpendicular  Portions,  or  Rami,  are  of  a  quadrilateral  form.  Each 
presents  for  examination  two  surfaces,  four  borders,  and  two  processes.  The 
external  surface  is  flat,  marked  with  ridges,  and  gives  attachment  throughout 
nearly  the  whole  of  its  extent  to  the  "Masseter  muscle.  The  internal  surface 
presents  about  its  centre  the  oblique  aperture  of  the  inferior  dental  canal,  for 
the  passage  of  the  inferior  dental  vessels  and  nerve.  The  margin  of  this  open- 
ing is  irregular ;  it  presents  in  front  a  prominent  ridge,  surmounted  by  a  sharp 
spine,  which  gives  attachment  to  the  internal  lateral  ligament  of  the  lower 
jaw ;  and  at  its  lower  and  back  part  a  notch  leading  to  a  groove,  the  mylo- 
hyoidean,  which  runs  obliquely  downwards  to  the  back  part  of  the  submaxil- 
lary fossa ;  and  lodges  the  mylo-hyoid  vessels  and  nerve.  Behind  the  groove 
is  a  rough  surface,  for  the  insertion  of  the  Internal  Pterygoid  muscle.  The 
inferior  dental  canal  runs  obliquely  downwards  and  forwards  in  the  sub- 
stance of  the  ramus,  and  then  horizontally  forwards  in  the  body ;  it  is  here 
placed  under  the  alveoli,  with  which  it  communicates  by  small  openings.  On 
arriving  at  the  incisor  teeth,  it  turns  back  to  communicate  with  the  mental 
foramen,  giving  off  two  small  canals,  which  run  forward,  to  be  lost  in  the  can- 
cellous tissue  of  the  bone  beneath  the  incisor  teeth.  This  canal,  in  the  posterior 
two-thirds  of  the  bone,  is  situated  nearer  the  internal  surface  of  the  jaw  ;  and 
in  the  anterior  third,  nearer  its  external  surface.  Its  walls  are  composed  of 
compact  tissue  at  either  extremity,  and  of  cancellous  in  the  centre.  It  contains 
the  inferior  dental  vessels  and  nerve,  from  which  branches  are  distributed  to 
the  teeth  through  small  apertures  at  the  bases  of  the  alveoli.  The  upper  border 
of  the  ramus  is  thin,  and  presents  two  processes,  separated  by  a  deep  concavity, 
the  sigmoid  notch.  Of  these  processes,  the  anterior  is  the  coronoid,  the  poste- 
rior the  condyloid. 

The  coronoid  process  is  a  thin,  flattened,  triangular  eminence  of  bone,  which 
varies  in  shape  and  size  in  different  subjects,  and  serves  chiefly  for  the  attach- 
ment of  the  Temporal  muscle.  Its  external  surface  is  smooth,  and  afford-^ 
attachment  to  the  Masseter  and  Temporal  muscles.  Its  internal  surface  givt 
attachment  to  the  Temporal  muscle,  and  presents  the  commencement  of  a  lou 
gitudinal  ridge,  which  is  continued  to  the  posterior  part  of  the  alveolar  procesj 
On  the  outer  side  of  this  ridge  is  a  deep  groove,  continued  below  on  the  out  I 
side  of  the  alveolar  process ;  this  ridge  and  part  of  the  groove  afford  attad  | 
ment,  above,  to  the  Temporal;  below,  to  the  Buccinator  muscle. 

The  condyloid  process,  shorter  but  thicker  than  the  coronoid,  consists  of  tv?! 
portions:  the  condyle,  and  the  constricted  portion  which  supports  the  condyle, 
the  neck.  The  condyle  is  of  an  oblong  form,  its  long  axis  being  transverse, 
and  set  obliquely  on  the  neck  in  such  a  manner  that  its  outer  end  is  a  little 
more  forward  and  a  little  higher  than  its  inner.  It  is  convex  from  before  back- 
wards, and  from  side  to  side,  the  articular  surface  extending  further  on  the 
posterior  than  on  the  anterior  surface.  The  neck  of  the  condyle  is  flattened 
from  before  backwards,  and  strengthened  by  ridges  which  descend  from  the 
fore  part  and  sides  of  the  condyle.  Its  lateral  margins  are  narrow,  and  present 
externally  a  tubercle  for  the  external  lateral  ligament.  Its  posterior  surface  is 
convex ;  its  anterior  is  hollowed  out  on  its  inner  side  by  a  depression  (the 
pterygoid  fossa)  for  the  attachment  of  the  External  Pterygoid. 

The  lower  border  of  the  ramus  is  thick,  straight,  and  continuous  with  the  body 
of  the  bone.  At  its  junction  with  the  posterior  border  is  the  angle  of  the  jaw, 
which  is  either  inverted  or  everted,  and  marked  by  rough  oblique  ridges  on 
each  side  for  the  attachment  of  the  Masseter  externally,  and  the  Internal 
Pterygoid  internally ;  the  stylo-maxillary  ligament  is  attached  to  the  bone  be- 
tween these  muscles.  The  anterior  border  is  thin  above,  thicker  below,  and 
continuous  with  the  external  oblique  line.  lHhQ  posterior  border  is  thick,  smooth, 
rounded  and  covered  by  the  parotid  gland. 


SIDE-YIEW    OF    LOWER    JAW. 

Side-view  op  the  Lower  Jaw  at  different  Periods  of  Life. 

Fiff.  125.— At  Birth. 


113 


Fig.  126.— At  Puberty, 


Fig.  127.— In  the  Adult 


Fig.  128.— In  Old  Aj-e. 


174  THE    SKELETON. 

The  Sigmoid  Notch,  separating  the  two  processes,  is  a  deep  semilunar  depres- 
sion,  crossed  by  the  masseteric  artery  and  nerve. 

Development.  This  bone  is  formed  at  such  an  early  period  of  life,  before  in- 
deed, any  other  bone  except  the  clavicle,  that  it  has  been  found  impossible  at 
present  to  determine  its  earliest  condition.  It  appears  probable,  however  that 
it  is  developed  by  two  centres,  one  for  each  lateral  half,  the  two  segments 
meeting  at  the  symphysis,  where  they  become  united.  Additional  centres  have 
also  been  described  for  the  coronoid  process,  the  condyle,  the  angle,  and  the 
thin  plate  of  bone,  which  forms  the  inner  side  of  the  alveolus. 

Changes  Produced  in  the  Lower  Jaw  by  Age. 

The  changes  •which  the  Lower  Jaw  undergoes  after  birth,  relate— 1.  To  the  alterations  effected 
in  the  body  of  the  bone  by  the  first  and  second  dentitions,  the  loss  of  the  teeth  in  the  aged,  and 
the  subsequent  absorption  of  the  alveoli.  2.  To  the  size  and  situation  of  the  dental  canal;  and, 
3.  To  the  angle  at  which  the  ramus  joins  with  the  body. 

At  birth  (Fig.  125),  the  bone  consists  of  two  lateral  halves,  united  by  fibro-cartilaginous  ti;?- 
8ue,  in  which  one  or  two  osseous  nuclei  are  generally  found.  The  body  is  a  mere  shell  of  bone 
containing  the  sockets  of  the  two  incisor,  the  canine,  and  the  two  temporary  molar  teeth,  imper- 
fectly partitioned  from  one  another.  The  dental  canal  is  of  large  size,  and  runs  near  the  lower 
border  of  the  bone,  the  mental  foramen  opening  beneath  the  socket  of  the  first  molar.  The 
angle  is  obtuse,  from  the  jaws  not  being  as  yet  separated  by  the  eruption  of  the  teeth. 

After  birth  (Fig.  12()),  the  two  segments  of  the  bone  become  joined  at  the  symphysis,  from 
below  upwards,  in  the  first  year;  but  a  trace  of  separation  may  be  visible  in  the  beginning  of  the 
second  year,  near  the  alveolar  margin.  The  body  becomes  elongated  in  its  whole  length  but 
more  especially  behind  the  mental  foramen,  to  provide  space  for  the  three  additional  teeth  devi 
loped  in  this  part.  The  depth  of  the  body  becomes  greater,  owing  to  increased  growth  of  tL 
alveolar  part,  to  afford  room  for  the  fangs  of  the  teeth,  and  by  thickening  of  the  subdental  por- 
tion which  enables  the  jaw  to  withstand  the  powerful  action  of  the  masticatory  muscles  ;  but  tlie 
alveolar  portion  is  the  deeper  of  the  two,  and,  consequently,  the  chief  part  of  the  body  lies 
above  the  oblique  line.  The  dental  canal,  after  the  second  dentition,  is  situated  just  above  the 
level  of  the  mylo-hyoid  ridge ;  and  the  mental  foramen  occupies  the  position  usual  to  it  in  the 
adult.     The  angle  becomes  less  obtuse,  owing  to  the  separation  of  the  jaws  by  the  teeth. 

In  the  adult  (Fig,  127),  the  alveolar  and  basilar  portions  of  the  body  are  usually  of  equal  depth. 
The  mental  foramen  opens  midway  between  the  upper  and  lower  border  of  the  bone,  and  the 
dental  canal  runs  nearly  parallel  with  the  mylo-hyoid  line.  The  ramus  is  almost  vertical  in  direc- 
tion, and  joins  the  body  at  nearly  right  angles, 

Jn  old  age  (Fig,  128),  the  bone  becomes  greatly  reduced  in  size;  for,  with  the  loss-of  the  teeth, 
the  alveolar  process  is  absorbed,  and  the  basilar  part  of  the  bone  alone  remains ;  consequently 
the  chief  part  of  the  bone  is  below  the  oblique  line.     The  dental  canal,  with  the  mental  foramei: 
opening  from  it,  is  close  to  the  alveolar  border.    The  rami  are  oblique  in  direction,  and  the  angl 
obtuse. 

Articulations.    With  the  glenoid  fossse  of  the  two  temporary  bones. 

Attachment  of  Muscles.  To  its  external  surface,  commencing  at  the  symphysi 
and  proceeding  backwards:  Levator  Menti,  Depressor  Labii  Inferioris,  J) 
pressor  Anguli  Oris,  Platysma  Myoides,  Buccinator,  Masseter.  To  its  intern 
surface,  commencing  at  the  same  point:  Genio-hyo-glossus,  Genio-hyoideui 
Mylo-hyoideus,  Digastric,  Superior  Constrictor,  Temporal,  Internal  Pterygoi 
External  Pterygoid. 

THE  SUTURES. 

The  bones  of  the  cranium  and  face  are  connected  to  each  other  by  means 
Sutures.     The  sutures  are  rows  of  dentated  processes  of  bone,  projecting  fro 
the  edge  of  either  bone,  and  locking  into  each  other;  the  dentations,  howeve 
are  confined  to  the  external  table,  the  edges  of  the  internal  table  lying  merely 
in  apposition.     The  Cranial  Sut^ires  may  be  divided  into  three  sets :    1.    Those 
at  the  vertex  of  the  skull.     2.  Those  at  the  side  of  the  skull.     8.  Those  at  th 
base. 

The  sutures  at  the  vertex  of  the  skull  are  three ;  the  sagittal,  coronal,  am 
lambdoid. 

The  Sagittal  Suture  (interparietal)  is  formed  by  the  junction  of  the  two  parieta! 
bones,  and  extends  from  the  middle  of  the  frontal  bone,  backwards  to  the  su 


SUTURES    OF    THE    SKULL.  115 

perior  angle  of  the  occipital.  In  childhood,  and  occasionally  in  the  adult,  when 
the  two  halves  of  the  frontal  bone  are  not  united,  it  is  continued  forwards  to 
the  root  of  the  nose.  This  suture  sometimes  presents,  near  its  posterior  ex- 
tremity, the  parietal  foramen  on  each  side;  and  in  front,  where  it  joins  the 
coronal  suture,  a  space  is  occasionally  left,  which  incloses  a  large  Wormian 
bone. 

The  Coronal  Suture  [fronto-parietal]  extends  transversely  across  the  vertex  of 
the  skull,  and  connects  the  frontal  with  the  parietal  bones.  It  commences  at 
the  extremity  of  the  great  wing  of  the  sphenoid  on  one  side,  and  terminates  at 
the  same  point  on  the  opposite  side.  The  dentations  of  this  suture  are  more 
marked  at  the  sides  than  at  the  summit,  and  are  so  constructed  that  the  frontal 
rests  on  the  parietal  above,  whilst  laterally  the  frontal  supports  the  parietal. 

The  Lamhdoid  Suture  {occipito-parietal)  so  called  from  its  resemblance  to  the 
Greek  letter  a,  connects  the  occipital  with  the  parietal  bones.  It  commences 
on  each  side  at  the  mastoid  portion  of  the  temporal  bone,  and  inclines  upwards 
to  the  end  of  the  sagittal  suture.  The  dentations  of  this  suture  are  very  deep 
and  distinct,  and  are  often  interrupted  by  several  small  Wormian  bones. 

The  sutures  at  the  side  of  the  skull  are  also  three  in  number;  the  spheno- 
parietal, squamo-parietal,  and  masto-parietal.  They  are  subdivisions  of  a  single 
suture,  formed  between  the  lower  border  of  the  parietal,  and  the  temporal  and 
sphenoid  bones,  and  which  extends  from  the  lower  end  of  the  lambdoid  suture 
behind,  to  the  lower  end  of  the  coronal  suture  in  front. 

The  Spheno-parietal  is  very  short ;  it  is  formed  by  the  tip  of  the  great  wing 
of  the  sphenoid,  which  overlaps  the  anterior  inferior  angle  of  the  parietal 
bone. 

The  Squamo-parietal^  or  squamous  suture,  is  arched.  It  is  formed  by  the 
squamous  portion  of  the  temporal  bone  overlapping  the  middle  division  of  the 
lower  border  of  the  parietal. 

The  Masto-parietal  is  a  short  suture,  deeply  dentated,  formed  by  the  posterior 
inferior  angle  of  the  parietal,  and  the  superior  border  of  the  mastoid  portion  of 
the  temporal. 

The  sutures  at  the  base  of  the  skull  are,  the  basilar  in  the  centre,  and  on 
each  side,  the  petro-occipital,  the  masto-occipital,  the  petro-sphenoidal,  and  the 
squamo-sphenoidal. 

The  Basilar  Stiture  is  formed  by  the  junction  of  the  basilar  surface  of  the 
occipital  bone  with  the  posterior  surface  of  the  body  of  the  sphenoid.  At  an 
early  period  of  life,  a  thin  plate  of  cartilage  exists  between  these  bones ;  but  in 
the  adult  they  become  fused  into  one.  Between  the  outer  extremity  of  the 
basilar  suture,  and  the  termination  of  the  lambdoid,  an  irregular  suture  exists, 
which  is  subdivided  into  two  portions.  The  inner  portion,  formed  by  the  union 
of  the  petrous  part  of  the  temporal  with  the  occipital  bone,  is  termed  the^e^ro- 
occipital.  The  outer  portion,  formed  by  the  junction  of  the  mastoid  part  of  the 
temporal  with  the  occipital,  is  called  the  masto-occipital.  Between  the  bones 
forming  the  petro-occipital  suture,  a  thin  plaite  of  cartilage  exists ;  in  the  masto- 
occipital  is  occasionally  found  the  opening  of  the  mastoid  foramen.  Between 
the  outer  extremity  of  the  basilar  suture  and  the  spheno-parietal,  an  irregular 
suture  may  be  seen,  formed  by  the  union  of  the  sphenoid  with  the  temporal 
bone.  The  inner  and  smaller  portion  of  this  suture  is  termed  the  petro-sphe- 
noidal;  it  is  formed  between  the  petrous  portion  of  the  temporal  and  the  great 
wing  of  the  sphenoid ;  the  outer  portion,  of  greater  length,  and  arched,  is 
formed  between  the  squamous  portion  of  the  temporal  and  the  great  wing  of 
the  sphenoid ;  it  is  called  the  squamo-sphevoidal. 

The  cranial  bones  are  connected  with  those  of  the  face,  and  the  facial  bones 
with  each  other,  by  numerous  sutures,  which,  though  distinctly  marked,  have 
received  no  special  names.  The  only  remaining  suture  deserving  especial  con- 
sideration, is  the  transverse.     This  extends  across  the  upper  part  of  the  face, 


116  THE    SKELETON. 

and  is  formed  by  the  junction  of  the  frontal  with  the  facial  bones ;  it  extends 
from  the  external  angular  process  of  one  side,  to  the  same  point  on  the  opposite 
side,  and  connects  the  frontal  with  the  malar,  the  sphenoid,  the  ethmoid,  the 
lachrymal,  the  superior  ma'xillary,  and  the  nasal  bones  on  each  side. 

The  sutures  remain  separate  for  a  considerable  period  after  the  complete 
formation  of  the  skull.  It  is  probable  that  they  serve  the  purpose  of  permitting 
the  growth  of  the  bones  at  their  margins ;  while  their  peculiar  formation,  and 
the  interposition  of  the  sutural  ligament  between  the  bones  forming  them, 
prevents  the  dispersion  of  blows  or  jars  received  upon  the  skull.  Dr.  Humphry 
remarks,  "  that,  as  a  general  rule,  the  sutures  are  first  obliterated  at  the  parts 
in  which  the  ossification  of  the  skull  was  last  completed,  viz.,  in  the  neighbor- 
hood of  the  fontanelles;  and  the  cranial  bones  seem  in  this  respect  to  observe 
a  similar  law  to  that  which  regulates  the  union  of  the  epiphyses  to  the  shafts 
of  the  long  bones." 

THE  SKULL. 

The  Skull,  formed  by  the  union  of  the  several  cranial  and  facial  bones  already 
described,  when  considered  as  a  whole,  is  divisible  into  five  regions:  a  superior 
region  or  vertex,  an  inferior  region  or  base,  two  lateral  regions,  and  an  anterior 
region,  the  face. 

Vertex  of  the  Skull. 

The  Superior  Eegion,  or  Yertex,  presents  two  surfaces,  an  external  and  an 
internal. 

The  External  Surface  is  bounded,  in  front,  by  the  nasal  eminences  and  super- 
ciliary ridges ;  behind,  by  the  occipital  protuberance  and  superior  curved  lines 
of  the  occipital  bone;  laterally,  by  an  imaginary  line  extending  from  the  outer 
end  of  the  superior  curved  line,  along  the  temporal  ridge,  to  the  external  angular 
process  of  the  frontal.  This  surface  includes  the  vertical  portion  of  the  frontal, 
the  greater  part  of  the  parietal,  and  the  superior  third  of  the  occipital  bone ;  it 
is  smooth,  convex,  of  an  elongated  oval  form,  crossed  transversely  by  the 
coronal  suture,  and  from  before  backwards  by  the  sagittal,  which  terminates 
behind  in  the  lambdoid.  From  before  backwards  may  be  seen  the  frontal 
eminences  and  remains  of  the  suture  connecting  the  two  lateral  halves  of  the 
frontal  bone ;  on  each  side  of  the  sagittal  suture  is  the  parietal  foramen  anc 
parietal  eminence,  and  still  more  posteriorly  the  smooth  convex  surface  of  thi 
occipital  bone. 

The  Internal  Surface  is  concave,  presents  eminences  and  depressions  for  tbi 
convolutions  of  the  cerebrum,  and  numerous  furrows  for  the  lodgment  o; 
branches  of  the  meningeal  arteries.  Along  the  middle  line  of  this  surface  is  i 
longitudinal  groove,  narrow  in  front,  where  it  terminates  in  the  frontal  crest 
broader  behind;  it  lodges  the  superior  longitudinal  sinus,  and  its  margins  affor 
attachment  to  the  falx  cerebri.  On  either  side  of  it  are  several  depressions  fo 
the  Pacchionian  bodies,  and  at  its  back  part,  the  internal  openings  of  the  parieta 
foramina.  This  surface  is  crossed,  in  front,  by  the  coronal  suture ;  from  befor< 
backwards,  by  the  sagittal ;  behind,  by  the  lambdoid. 

Base  of  the  Skull. 

The  Inferior  Region,  or  Base  of  the  Skull,  presents  two  surfaces,  an  interna 
or  cerebral,  and  an  external  or  basilar. 

The  Internal,  or  Cerebral  Surface  (Fig.  129),  presents  three  fossae  on  each  sidej 
called  the  anterior^  middle^  and  posterior  fnssse  of  the  cranium.  i 

The  Anterior  Fossa  is  formed  by  the  orbital  plate  of  the  frontal,  the  cribriform? 

flate  of  the  ethmoid,  the  ethmoidal  process  and  lesser  wing  of  the  sphenoid., 
t  is  the  most  elevated  of  the  three  fossae,  convex  externally  where  it  corre- 


BASE    OF    THE    SKULL.  177 

sponds  to  the  roof  of  the  orbit,  concave  in  the  median  line  in  the  situation  of 
the  cribriform  plate  of  the  ethmoid.     It  is  traversed  by  three  sutures,  the 

Fig.  129. — Base  of  Skull.     Inner  or  Cerebral  Surface. 

6>-om:-e.  fnr  S'ujvr.  hniaitijJ.Sinu. 

Qioovespr  Anf^r.  Msm'.nyealA 

Foramtn  t.'a:rirm. 

Cn'xtn,  Gnl/.i 

Slit  Jor  7^'/i.ffi.l  rur*tf^ 

Oromi-f,  jm-Nit/ntl,  Tterv/. 

A-nUriOT  JEtbrnoiAnl  Su, 


iirifioet  fo,-  OlfactoTij  ■ncn-f,s- 
£otUrior  EthvLnidiil  Fon 

litJim^'cdul  Spine- 


Olfactory  Groovts- 

Ojift'e    foravicn 

Cjitic  OrouiK- f 

Oliitiry  proo, 
Anterior  Clinnid  jjrae. 

Middle  Clinoid  jiroc 

Title  rior  Clin/ifJ,  jrroa 

Groove  foT  6^  ne-n'tt 

Tor  a  laeerum  medium. 

Ori/U'e  of  Carotid  Canal 

Depui6i>yn  for  CasjirCan  Ganglia 


Xftatut  Audittyr.  Intcrnnx 

Slit  for  Durn-M'^itf  r 

iSup.  Petrosal  groart 

Fnr.  JaceruTn  poattritii 


Anlerior  CondyhtdJ'. 
Aqueduct.  Vestibuli 
PoetM-iar  Condyloid  For. 


Mastoid  FiTK 
£l>st,  MeuLiiQcul  Orooi/ex. 


ethmoidal-frontal,  ethmo-sphenoidal,  and  fronto-sphenoidal ;  and  lodges  the 
anterior  lobe  of  the  cerebrum.  It  presents,  in  the  median  line,  from  before 
backwards,  the  commencement  of  the  groove  for  the  superior  longitudinal 
sinus,  and  the  crest  for  the  attachment  of  the  falx  cerebri ;  the  foramen  coecum, 
12 


178  THE    SKELETON. 

an  aperture  formed  by  the  frontal  bone  and  the  crista  galli  of  the  ethmoid,  which, 
if  pervious,  transmits  a  small  vein  from  the  nose  to  the  superior  longitudinal 
sinus;  behind  the  foramen  coecura,  the  crista  galli,  the  posterior  margin  of  which 
affords  attachment  to  the  falx  cerebri ;  on  either  side  of  the  crista  galli,  the 
olfactory  groove,  which  supports  the  bulb  of  the  olfactory  nerve,  and  is  per- 
forated by  three  rows  of  orifices  for  its  filaments,  and  in  front  by  a  slit-like 
opening,  for  the  nasal  branch  of  the  ophthalmic  nerve.  On  the  outer  side  of 
each  olfactory  groove  are  the  internal  openings  of  the  anterior  and  posterior 
ethmoidal  foramina;  the  former,  situated  about  the  middle  of  the  outer  margin 
of  the  olfactory  groove,  transmits  the  anterior  ethmoidal  artery  and  the  nasal 
nerve,  which  runs  in  a  depression  along  the  surface  of  the  ethmoid,  to  the  slit- 
like opening  above  mentioned ;  whilst  the  posterior  etlimoidal  foramen  opens 
at  the  back  part  of  this  margin  under  cover  of  the  projecting  lamina  of  the 
sphenoid,  and  transmits  the  posterior  ethmoidal  artery  and  vein  to  the  posterior 
ethmoidal  cells.  Further  back  in  the  middle  line  is  the  ethmoidal  spine,  bounded 
behind  by  an  elevated  ridge,  separating  a  longitudinal  groove  on  each  side  which 
supports  the  olfactory  nerve.  The  anterior  fossa  presents  laterally  eminences 
and  depressions  for  the  convolutions  of  the  brain,  and  grooves  for  the  lodgment 
of  the  anterior  meningeal  arteries. 

The  Middle  Fossa,  somewhat  deeper  than  the  preceding,  is  narrow  in  the 
middle,  and  becomes  wider  as  it  expands  laterally.  It  is  bounded  in  front  by 
the  posterior  margin  of  the  lesser  wing  of  the  sphenoid,  the  anterior  clinoid 
process,  and  the  anterior  margin  of  the  optic  groove ;  behind,  by  the  petrous 
portion  of  the  temporal,  and  basilar  suture ;  externally,  by  the  squamous  por- 
tion of  the  temporal,  and  anterior  inferior  angle  of  the  parietal  bone,  and  is 
separated  from  its  fellow  by  the  sella  Turcica.  It  is  traversed  by  four  sutures, 
the  squamous,  spheno-parietal,  spheno-temporal,  and  petro-sphenoidal. 

In  the  middle  line,  from  before  backwards,  is  the  optic  groove,  which  sup- 
ports the  optic  commissure,  and  terminates  on  each  side  in  the  optic  foramen, 
for  the  passage  of  the  optic  nerve  and  ophthalmic  artery ;  behind  the  optic 
groove  is  the  olivary  process,  and  laterally  the  anterior  clinoid  processes,  to 
which  are  attached  the  folds  of  the  dura  mater,  which  form  the  cavernous 
sinuses.  Separating  the  middle  fossaB  is  the  sella  Turcica,  a  deep  depression, 
which  lodges  the  pituitary  gland,  bounded  in  front  by  a  small  eminence  on 
either  side,  the  middle  clinoid  process,  and  behind  by  a  broad  square  plate  of 
bone,  surmounted  at  each  superior  angle  by  a  tubercle,  the  posterior  clinoid 
process ;  beneath  the  latter  process  is  a  groove,  for  the  sixth  nerve.  On  each 
side  of  the  sella  Turcica  is  the  cavernous  groove ;  it  is  broad,  shallow,  and 
curved  somewhat  like  the  italic  letter  /;  it  commences  behind  at  the  foramen 
lacerum  medium,  and  terminates  on  the  inner  side  of  the  anterior  clinoid  pro- 
cess. This  groove  lodges  the  cavernous  sinus,  the  internal  carotid  artery,  and 
the  nerves  of  the  orbit.  The  sides  of  the  middle  fossa  are  of  considerable 
depth;  they  present  eminences  and  depressions  for  the  middle  lobes  of  the 
brain,  and  grooves  for  the  branches  of  the  middle  meningeal  artery ;  the  latter 
commence  on  the  outer  side  of  the  foramen  spinosum,  and  consist  of  two  largo 
branches,  an  anterior  and  a  posterior;  the  former  passing  upwards  and  for- 
wards to  the  anterior  inferior  angle  of  the  parietal  bone,  the  latter  passing 
upwards  and  backwards.  The  following  foramina  may  also  be  seen  from  before 
backwards.  Most  anteriorly  is  the  foramen  lacerum  anterius,  or  sphenoidal 
fissure,  formed  above  by  the  lesser  wing  of  the  sphenoid ;  below,  by  the  greater 
wing;  internally,  by  the  body  of  the  sphenoid;  and  completed  externally  by 
the  orbital  plate  of  the  frontal  bone.  It  transmits  the  third,  fourth,  the  three 
branches  of  the  ophthalmic  division  of  the  fifth,  the  sixth  nerve,  and  the 
ophthalmic  vein.  Behind  the  inner  extremity  of  the  sphenoidal  fissure  is  the 
foramen  rotundum,  for  the  passage  of  the  second  division  of  the  fifth  or 
superior  maxillary  nerve;  still  more  posteriorly  is  seen  a  small  orifice,  the 
foramen  Vesalii,  an  opening,  situated  between  the  foramen  rotundum  and  ovale, 


BASE    OF    THE    SKULL.  179 

a  little  internal  to  both ;  it  varies  in  size  in  different  individuals,  and  is  often 
absent;  when  present,  it  transmits  a  small  vein.  It  opens  below  in  the  ptery- 
goid fossa,  just  at  the  outer  side  of  the  scaphoid  depression.  Behind  and  ex- 
ternal to  the  latter  opening  is  the  foramen  ovale,  which  transmits  the  third 
division  of  the  fifth  or  inferior  maxillary  nerve,  the  small  meningeal  artery, 
and  the  small  petrosal  nerve.  On  the  outer  side  of  the  foramen  ovale  is  the 
foramen  spinosum,  for  the  passage  of  the  middle  meningeal  artery ;  and  on  the 
inner  side  of  the  foramen  ovale,  the  foramen  lacerura  medium.  The  lower 
part  of  this  aperture  is  filled  up  with  cartilage  in  the  recent  •  state.  On  the 
anterior  surface  of  the  petrous  portion  of  the  temporal  bone  is  seen,  from 
without  inwards,  the  eminence  caused  by  the  projection  of  the  superior  semi- 
circular canal,  the  groove  leading  to  the  hiatus  Fallopii,  for  the  transmission  of 
the  petrosal  branch  of  the  Vidian  nerve ;  beneath  it,  the  smaller  groove,  for 
the  passage  of  the  smaller  petrosal  nerve ;  and,  near  the  apex  of  the  bone,  the 
depression  for  the  Casserian  ganglion,  and  the  orifice  of  the  carotid  canal,  for 
the  passage  of  the  internal  carotid  artery  and  carotid  plexus  of  nerves. 

The  Posterior  Fossa,  deeply  concave,  is  the  largest  of  the  three,  and  situated 
on  a  lower  level  than  either  of  the  preceding.  It  is  formed  by  the  occipital, 
the  petrous,  and  mastoid  portions  of  the  temporal,  and  the  posterior  inferior 
angle  of  the  parietal  bone ;  is  crossed  by  three  sutures,  the  petro-occipital, 
masto-occipital,  and  masto-parietal ;  and  lodges  the  cerebellum,  pons  Varolii, 
and  medulla  oblongata.  It  is  separated  from  the  middle  fossa  in  the  median 
line  by  the  basilar  suture,  and  on  each  side  by  the  superior  border  of  the 
petrous  portion  of  the  temporal  bone.  This  serves  for  the  attachment  of  the 
tentorium  cerebelli,  is  grooved  externally  for  the  superior  petrosal  sinus,  and 
at  its  inner  extremity  presents  a  notch,  upon  which  rests  the  fifth  nerve.  Its 
circumference  is  bounded  posteriorly  by  the  grooves  for  the  lateral  sinuses. 
In  the  centre  of  this  fossa  is  the  foramen  magnum,  bounded  on  either  side  by 
a  rough  tubercle,  which  gives  attachment  to  the  odontoid  ligaments;  and  a 
little  above  these  are  seen  the  internal  openings  of  the  anterior  condyloid 
foramina.  In  front  of  the  foramen  magnum  is  the  basilar  process,  grooved  for 
the  support  of  the  medulla  oblongata  and  pons  Varolii,  and  articulating  on 
each  side  with  the  petrous  portion  of  the  temporal  bone,  forming  the  petro- 
occipital  suture,  the  anterior  half  of  which  is  grooved  for  the  inferior  petrosal 
sinus,  the  posterior  half  being  encroached  upon  by  the  foramen  lacerum  pos- 
terius,  or  jugular  foramen.  This  foramen  is  partially  subdivided  into  two 
parts;  the  posterior  and  larger  division  transmitting  the  internal  jugular  vein, 
the  anterior  the  eighth  pair  of  nerves.  Above  the  jugular  foramen  is  the 
internal  auditory  foramen,  for  the  auditory  and  facial  nerves  and  auditory 
artery;  behind  and  external  to  this  is  the  slit-like  opening  leading  into  the 
aquaeductus  vestibuli ;  whilst  between  the  two  latter,  and  near  the  superior 
border  of  the  petrous  portion,  is  a  small  triangular  depression,  which  lodges  a 
process  of  the  dura  mater,  and  occasionally  transmits  a  small  vein  into  the 
substance  of  the  bone.  Behind  the  foramen  magnum  are  the  inferior  occipital 
fossse,  which  lodge  the  lateral  lobes  of  the  cerebellum,  separated  from  one 
another  by  the  internal  occipital  crest,  which  serves  for  the  attachment  of  the 
falx  cerebelli,  and  lodges  the  occipital  sinuses.  The  posterior  fossae  are  sur- 
mounted, above,  by  the  deep  transverse  grooves  for  the  lodgment  of  the  lateral 
sinuses.  These  channels,  in  their  passage  outwards,  groove  the  occipital  bone, 
the  posterior  inferior  angle  of  the  parietal,  the  mastoid  portion  of  the  temporal, 
and  the  occipital  just  behind  the  jugular  foramen,  at  the  back  part  of  which 
they  terminate.  Where  this  sinus  grooves  the  mastoid  part  of  the  temporal 
bone,  the  orifice  of  the  mastoid  foramen  may  be  seen ;  and,  just  previous  to  its 
termination,  it  has  opening  into  it  the  posterior  condyloid  foramen. 

The  External  Surface  of  the  base  of  the  skull  (Fig,  130)  is  extremely 
irregular.  It  is  bounded  in  front  by  the  incisor  teeth  in  the  upper  jaws; 
behind,  b}'-  the  superior  curved  lines  of  the  occipital  bone;  and  laterally,  by 


180 


THE    SKELETON. 


the  alveolar  arch,  the  lower  border  of  the  malar  bone,  the  zygoma,  and  an 
imaginary  line,  extending  from  the  zygoma  to  the  mastoid  process  and  ex- 
Fig.  130.— Base  of  the  Skull.     External  Surface. 


,  Axt  palo/tinf  /ossa 

'rrtfisTTuff  left  Naso-pal-cct.  n. 
-TmnsmitsA'mpalat  t'css. 
TmnsmiCi  rig  lit  NasopalaJL.  n . 


Aeees  sary  palatcnt 
Ftfra  mt  run . 

Poft.Narul  Sj>L>ie. 
azyoo*    uvula 

Ha  mula  r  j>  tpc 
SflictioCd.pToe.  tf  Palwtt. 


-TCNSOR    TVMPANI. 


FJuirifTUfcal Sj)Lnf.fuT  i\iV.  CONSTRICC 


LAXATOR    TVMPANI. 
Caiial  for  Jamt/jinii  n. 

-Anurdu^.  Ct/chUfi. 

Fo-r^l^wtrumpustmH  s. 

CaimZfi/rArnalil:/  tL, 

uxicul«r  fitture. 


BASE    OF    THE    SKULL.  181 

tremity  of  the  superior  curved  line  of  the  occiput.  Tt  is  formed  by  the  palate 
processes  of  the  superior  maxillary  and  palate  bones,  the  vomer,  the  pterygoid, 
under  surface  of  the  great  wing,  spinous  process  and  part  of  the  body  of  the 
sphenoid,  the  under  surface  of  the  squamous,  mastoid,  and  petrous  portions 
of  the  temporal,  and  the  under  surface  of  the  occipital  bone.  The  anterior 
part  of  the  base  of  the  skull  is  raised  above  the  level  of  the  rest  of  this  surface 
(when  the  skull  is  turned  over  for  the  purpose  of  examination),  surrounded  by 
the  alveolar  process,  which  is  thicker  behind  than  in  front,  and  excavated  by 
sixteen  depressions  for  lodging  the  teeth  of  the  upper  jaw ;  the  cavities  varying 
in  depth  and  size  according  to  the  teeth  they  contain.  Immediately  behind 
the  incisor  teeth  is  the  anterior  palatine  fossa.  At  the  bottom  of  this  fossa 
may  usually  be  seen  four  apertures,  two  placed  laterally,  which  open  above, 
one  in  the  floor  of  each  nostril,  and  transmit  the  anterior  palatine  vessels,  and 
two  in  the  median  line  of  the  intermaxillary  suture,  one  in  front  of  the  other, 
the  anterior  transmitting  the  left,  and  the  posterior  (the  larger)  the  right  naso- 
palatine nerve.  These  two  latter  canals  are  sometimes  wanting,  or  they  may 
join  to  form  a  single  one,  or  one  of  them  may  open  into  one  of  the  lateral 
canals  above  referred  to.  The  palatine  vault  is  concave,  uneven,  perforated 
by  numerous  foramina,  marked  by  depressions  for  the  palatal  glands,  and 
crossed  by  a  crucial  suture,  formed  by  the  junction  of  the  four  bones  of  which 
it  is  composed.  One  or  two  small  foramina,  in  the  alveolar  margin  behind  the 
incisor  teeth,  occasionally  seen  in  the  adult,  almost  constant  in  young  subjects, 
are  called  the  incisive  foramina ;  they  transmit  nerves  and  vessels  to  the  incisor 
teeth.  At  each  posterior  angle  of  the  hard  palate  is  the  posterior  palatine 
foramen,  for  the  transmission  of  the  posterior  palatine  vessels  and  descending 
palatine  nerve,  and  running  forwards  and  inwards  from  it  a  groove,  which 
lodges  the  same  vessels  and  nerve.  Behind  the  posterior  palatine  foramen  is  the 
tuberosity  of  the  palate  bone,  perforated  by  one  or  more  accessory  posterior 
palatine  canals,  and  marked  by  the  commencement  of  a  ridge,  which  runs  trans- 
versely inwards,  and  serves  for  the  attachment  of  the  tendinous  expansion  of 
the  Tensor  Palati  muscle.  Projecting  backwards  from  the  centre  of  the  pos- 
terior border  of  the  hard  palate  is  the  posterior  nasal  spine,  for  the  attachment 
of  the  Azygos  Uvulae.  Behind  and  above  the  hard  palate  is  the  posterior 
aperture  of  the  nares,  divided  into  two  parts  by  the  vomer,  bounded  above  by 
the  body  of  the  sphenoid,  below  by  the  horizontal  plate  of  the  palate  bone, 
and  laterally  by  the  pterygoid  processes  of  the  sphenoid.  Each  aperture 
measures  about  an  inch  in  the  vertical,  and  half  an  inch  in  the  transverse 
direction.  At  the  base  of  the  vomer  may  be  seen  the  expanded  alas  of  this 
bone,  receiving  between  them  the  rostrum  of  the  sphenoid.  Near  the  lateral 
margins  of  the  vomer,  at  the  root  of  the  pterygoid  processes,  are  the  pterygo- 
palatine canals.  The  pterygoid  process,  which  bounds  the  posterior  nares  on 
each  side,  presents  near  its  base  the  pterygoid  or  Vidian  canal,  for  the  Vidian 
nerve  and  artery.  Each  process  consists  of  two  plates,  which  bifurcate  at  the 
extremity  to  receive  the  tuberosity  of  the  palate  bone,  and  are  separated 
behind  by  the  pterygoid  fossa,  which  lodges  the  Internal  Pterygoid  muscle.  The 
internal  plate  is  long  and  narrow,  presenting  on  the  outer  side  of  its  base  the 
scaphoid  fossa,  for  the  origin  of  the  Tensor  Palati  muscle,  and  at  its  extremity 
the  hamular  process,  around  which  the  tendon  of  this  muscle  turns.  The 
external  pterygoid  plate  is  broad,  forms  the  inner  boundary  of  the  zygomatic 
fossa,  and  afibrds  attachment,  by  its  outer  surface,  to  the  External  Pterygoid 
muscle. 

Behind  the  nasal  fossae  in  the  middle  line  is  the  basilar  surface  of  the  occi- 
pital bone,  presenting  in  its  centre  the  pharyngeal  spine  for  the  attachment  of 
the  Superior  Constrictor  muscle  of  the  pharynx,  with  depressions  on  each  side 
for  the  insertion  of  the  Kectus  Capitis  Anticus  (major  and  minor).  At  the  base 
of  the  external  pterygoid  plate  is  the  foramen  ovale ;  behind  this,  the  foramen 
spinosum,  and  the  prominent  spinous  process  of  the  sphenoid,  which  gives 


U2  THE    SKELETON. 

attachment  to  the  internal  lateral  ligament  of  the  lower  jaw,  and  the  Laxatoi 
Tympani  muscle.     External  to  the  spinous  process  is  the  glenoid  fossa,  divided 
into  two  parts  by  the  Glaserian  fissure  (p.  144),  the  anterior  portion  concave, 
smooth,  bounded  in  front  by  the  eminentia  articularis,  and  serving  for  the  articu- 
lation of  the  condyle  of  the  lower  jaw ;  the  posterior  portion  rough,  bounded 
behind  by  the  vaginal  process,  and  serving  for  the  reception  of  part  of  the 
parotid  gland.     Emerging  from  between  the  laminae  of  the  vaginal  process  is 
the  styloid  process ;  and  at  the  base  of  this  process  is  the  stylo-mastoid  foramen, 
for  the  exit  of  the  facial  nerve,  and  entrance  of  the  stylo-mastoid  artery.     Ex- 
ternal to  the  stylo-mastoid  foramen  is  the  auricular  fissure  for  the  auricular 
branch  of  the  pneumogastric,  bounded  behind  by  the  mastoid  process.     Upon 
the  inner  side  of  the  mastoid  process  is  a  deep  groove,  the  digastric  fossa ;  and 
a  little  more  internally,  the  occipital  groove,  for  the  occipital  artery.     At  the 
base  of  the  internal  pterygoid  plate  is  a  large  and  somewhat  triangular  aper- 
ture, the  foramen  lacerura  medium,  bounded  in  front  by  the  great  wing  of  the 
sphenoid,  behind  by  tlie  apex  of  the  petrous  portion  of  the  temporal  bone,  and 
internally  by  the  body  of  the  sphenoid  and  basilar  process  of  the  occipital  bone ; 
it  presents  in  front  the  posterior  orifice  of  the  Vidian  canal,  behind  the  aper- 
ture of  the  carotid  canal.     The  basilar  surface  of  this  opening  is  filled  up  in 
the  recent  state  by  a  fibro- cartilaginous  substance;  across  its  upper  or  cerebral 
aspect  passes  the  internal  carotid  artery  and  Vidian  nerve.     External  to  this 
aperture,  the  petro-sphenoidal  suture  is  observed,  at  the  outer  termination  of 
which  is  seen  the  orifice  of  the  canal  for  the  Eustachian  tube,  and  that  for  the 
Tensor  Tympani  muscle.     Behind  this  suture  is  seen  the  under  surface  of  the 
petrous  portion  of  the  temporal  bone,  presenting,  from  within  outwards,  the 
quadrilateral  rough  surface,  part  of  which  affords  attachment  to  the  Levator 
Palati  and  Tensor  Tympani  muscles ;  external  to  this  surface  the  orifices  of  the 
carotid  canal  and  the  aquseductus  cochleae,  the  former  transmitting  the  internal 
carotid  artery  and  the  ascending  branches  of  the  superior  cervical  ganglion  of 
the  sympathetic,  the  latter  serving  for  the  passage  of  a  small  artery  and  vein 
to  the  cochlea.     Behind  the  carotid  canal  is  a  large  aperture,  the  jugular  fossa, 
formed  in  front  by  the  petrous  portion  of  the  temporal,  and  behind  by  the 
occipital ;  it  is  generally  larger  on  the  right  than  on  the  left  side;  and  towards 
its  cerebral  aspect  is  divided  into  two  parts  by  a  ridge  of  bone,  which  projects 
usually  from  the  temporal,  the  anterior,  or  smaller  portion,  transmitting  the 
three  divisions  of  the  eighth  pair  of  nerves;  the  posterior,  transmitting  the  in- 
ternal jugular  vein  and  the  ascending  meningeal  vessels,  from  the  occipital  and 
ascending  pharyngeal  arteries.     On  the  ridge  of  bone  dividing  the  carotid  canal 
from  the  jugular  fossa,  is  the  small  foramen  for  the  transmission  of  the  tym- 
panic nerve;  and  on  the  outer  wall  of  the  jugular  foramen,  near  the  root  of  the 
styloid  process,  is  the  small  aperture  for  the  transmission  of  Arnold's  nerve. 
Behind  the  basilar  surface  of  the  occipital  bone  is  the  foramen  magnum,  bound- 
ed on  each  side  by  the  condyles,  rough  internally  for  the  attachment  of  the 
alar  ligaments,  and  presenting  externally  a  rough  surface,  the  jugular  process, 
which  serves  for  the  attachment  of  the  Rectus  Lateralis.     On  cither  side  of 
each  condyle  anteriorly  is  the  anterior  condyloid  fossa,  perforated  by  the  an- 
terior condyloid  foramen,  for  the  passage  of  the  hypoglossal  nerve.     Behind 
each  condyle  are  the  posterior  condyloid  fossae,  perforated  on  one  or  both  sides 
by  the  posterior  cosdyloid  foramina,  for  the  transmission  of  a  vein  to  the  lateral 
sinus.     Behind  the  foramen  magnum  is  the  external  occipital  crest,  terminating 
above  at  the  external  occipital  protuberance,  whilst  on  each  side  are  seen  the 
superior  and  inferior  curved  lines ;  these,  as  well  as  the  surfaces  of  the  bone 
between  them,  being  rough  for  the  attachment  of  the  muscles,  which  are  enu- 
merated on  page  134. 


1 


LATERAL  REGION  OF  THE  SKULL. 


183 


Lateral  Region  of  the  Skull. 

The  Lateral  Region  of  the  Skull  is  of  a  somewhat  triangular  form,  the  base 
of  the  triangle  being  formed  by  a  line  extending  from  the  external  angular 
process  of  the  frontal  bone  along  the  temporal  ridge  backwards  to  the  outer 
extremity  of  the  superior  curved  line  of  the  occiput :  and  the  sides  by  two 
lines,  the  one  drawn  downwards  and  backwards  from  the  external  angular  pro- 
cess of  the  frontal  bone  to  the  angle  of  the  lower  jaw,  the  other  from  the  angle 
of  the  .jaw  upwards  and  backwards  to  the  extremity  of  the  superior  curved 
line.  This  region  is  divisible  into  three  portions,  temporal,  mastoid,  and 
zygomatic. 

The  Temporal  Fossa  is  bounded  above  and  behind  by  the  temporal  ridge, 
which  extends  from  the  external  angular  process  of  the  frontal  upwards  and 
backwards  across  the  frontal  and  parietal  bones,  curving  downwards  behind  to 
terminate  at  the  root  of  the  zygomatic  process.  In  front,  it  is  bounded  by  the 
frontal,  malar,  and  great  wing  of  the  sphenoid:  externally,  by  the  zygomatic 
arch,  formed  conjointly  by  the  malar  and  temporal  bones ;  below  it  is  separated 
from  the  zygomatic  fossa  by  the  pterygoid  ridge,  seen  on  the  outer  surface  of 
the  great  wing  of  the  sphenoid.     This  fossa  is  formed  by  five  bones,  part  of 

Fig.  131.— Side  Yiew  of  the  Skull. 


//Y  // 1(7  I 


Par  I  el  ah 


the  frontal,  great  wing  of  the  sphenoid,  parietal,  squamous  portion  of  the 
temporal  and  malar  bones,  and  is  traversed  by  five  sutures,  the  transverse  facial, 
coronal,  spheno-parietal,  squamo-parietal,  and  squamo-sphenoidal.  It  is  deeply 
concave  in  front,  convex  behind,  traversed  by  grooves  which  lodge  branches 
of  the  deep  temporal  arteries,  and  filled  by  the  Temporal  muscle. 


184  THE    SKELETON. 

The  Mastoid  Portion  of  the  side  of  the  skull  is  bounded  in  front  by  the  an 
terior  root  of  the  zygoma ;  above,  by  a  line  which  runs  from  the  posterior  root 
of  the  zygoma  to  the  end  of  the  masto-parietal  suture ;  behind  and  below,  by 
the  masto-occipital  suture.  It  is  formed  by  the  mastoid  and  part  of  the  squa- 
mous portion  of  the  temporal  bone ;  its  surface  is  convex  and  rough  for  tlie 
attachment  of  muscles,  and  presents,  from  behind  forwards,  the  mastoid  fora- 
men, the  mastoid  process,  the  external  auditory  meatus,  surrounded  by  the 
auditory  process,  and,  most  anteriorly,  the  glenoid  fossa,  bounded  in  front  by 
the  -eminentia  articularis,  behind  by  the  vaginal  process. 

The  Zygomatic  Fossa  is  an  irregularly-shaped  cavity,  situated  below,  and  on 
the  inner  side  of  the  zygoma ;  bounded,  in  front,  by  the  tuberosity  of  the 
superior  maxillary  bone  and  the  ridge  which  descends  from  its  malar  process; 
behind,  by  the  posterior  border  of  the  pterygoid  process;  above,  by  the  ptery- 
goid ridge  on  the  outer  surface  of  the  great  wing  of  the  sphenoid  and  squamous 
portion  of  the  temporal ;  below,  by  the  alveolar  border  of  the  superior  maxilla; 
internally,  by  the  external  pterygoid  plate ;  and  externally,  by  the  zygomatic 
arch  and  ramus  of  the  jaw.  It  contains  the  lower  part  of  the  Temporal,  the 
External,  and  Internal  pterygoid  muscles,  the  internal  maxillary  artery,  the 
inferior  maxillary  nerve,  and  their  branches.  At  its  upper  and  inner  part  may 
be  observed  two  fissures,  the  spheno-maxillary  and  pterygo-maxillary. 

The  spheno-maxillary  Jissure,  horizontal  in  direction,  opens  into  the  outer  and 
back  part  of  the  orbit.  It  is  formed  above  by  the  lower  border  of  the  orbital 
surface  of  the  great  wing  of  the  sphenoid ;  below,  by  the  external  border  of 
the  orbital  surface  of  the  superior  maxilla  and  a  small  part  of  the  palate  bone; 
externally,  by  a  small  part  of  the  malar  bone;  internally,  it  joins  at  right 
angles  with  the  pterygo-maxillary  fissure.  This  fissure  opens  a  communica- 
tion from  the  orbit  into  tbree  fossae,  the  temporal,  zygomatic,  and  spheno- 
maxillary; it  transmits  the  superior  maxillary  nerve,  infraorbital  artery,  and 
ascending  branches  from  Meckel's  ganglion. 

The  ])teryfjo-maxilla7-y  Jissure  is  vertical,  and  descends  at  right  angles  from 
the  inner  extremitjr  of  the  preceding ;  it  is  an  elongated  interval,  formed  by 
the  divergence  of  the  superior  maxillary  bone  from  the  pterygoid  process  of 
the  sphenoid.  It  serves  to  connect  the  spheno-maxillary  fossa  with  the  zygo- 
matic, and  transmits  "branches  of  the  internal  maxillary  artery. 

The  Spheno-maxillary  Fossa  is  a  small  triangular  space  situated  at  the  angle  o:' 
junction  of  the  spheno-maxillary  and  pterygo-maxillary  fissures,  and  placed 
beneath  the  apex  of  the  orbit.  It  is  formed  above  by  the  under  surface  of  the  body 
of  the  sphenoid  ;  in  front,  by  the  superior  maxillary  bone  ;  behind,  by  the  ptery- 
goid process  of  the  sphenoid ;  internally,  by  the  vertical  plate  of  the  palate.  This 
fossa  has  three  fissures  terminating  in  it,  the  sphenoidal,  spheno-maxillary,  and 
pterygo-maxillary;  it  communicates  with  three  fossae,  the  orbital,  nasal,  and 
zygomatic,  and  with  the  cavity  of  the  cranium,  and  has  opening  into  it  five 
foramina.  Of  these  there  are  three  on  the  posterior  wall ;  the  foramen  rotun- 
dum  above;  below,  and  internal  to  this,  the  Vidian,  and  still  more  inferior  and 
internal,  the  pterygo-palatine.  On  the  inner  wall  is  the  spheno-palatine  fora- 
men by  which  the  spheno-maxillary  communicates  with  the  nasal  fossa,  and 
below  is  the  superior  orifice  of  the  posterior  palatine  canal,  besides  occasionally 
the  orifices  of  two  or  three  accessory  posterior  palatine  canals. 


Anterior  REaioN  of  the  Skull. 


I 


The  Anterior  Region  of  the  Skull,  which  forms  the  Face,  is  of  an  oval  form, 
presents  an  irregular  surface,  and  is  excavated  for  the  reception  of  the  two 
principal  organs  of  sense,  the  eye  and  the  nose.  It  is  bounded  above  by  the 
nasal  eminences  and  margins  of  the  orbit ;  below,  by  the  prominence  of  the 
chin;  on  each  side,  by  the  malar  bone,  and  anterior  margin  of  the  ramus  of  the 
jaw.     In  the  median  line  are  seen  from  above  downwards,  the  nasal  eminences. 


ANTERIOR    REGION    OF    THE    SKULL.  185 

which  indicate  the  situation  of  the  frontal  sinuses;  and  diverging  from  which 
are  the  superciliary  ridges  which  support  the  eyebrows.  Beneath  the  nasal 
eminences  is  the  arch  of  the  nose,  formed  by  the  nasal  bones,  and  the  nasal 
processes  of  the  superior  maxillary.  The  nasal  arch  is  convex  from  side  to 
side,  concave  from  above  downwards,  presenting  in  the  median  line  the  inter- 
nasal  suture,  formed  between  the  nasal  bones,  laterally  the  naso-maxillary 
suture,  formed  between  the  nasal  bone  and  the  nasal  process  of  the  superior 
maxillary  bone,  both  these  sutures  terminating  above  in  that  part  of  the  trans- 
verse suture  which  connects  the  nasal  bones  and  nasal  processes  of  the  superior 
maxillary  with  the  frontal.  Below  the  nose  is  seen  the  opening  of  the  anterior 
nares,  which  is  heart-shaped,  with  the  narrow  end  upwards,  and  presents  late- 
rally, the  thin  sharp  margins  serving  for  the  attachment  of  the  lateral  cartilages 
of  the  nose,  and  in  the  middle  line  below,  a  prominent  process,  the  anterior 
nasal  spine,  bounded  by  two  deep  notches.  Below  this  is  the  intermaxillary 
suture,  and  on  each  side  of  it  the  incisive  fossa.  Beneath  this  fossa  is  the 
alveolar  process  of  the  upper  and  lower  jaw,  containing  the  incisor  teeth,  and 
at  the  lower  part  of  the  median  line,  the  symphysis  of  the  chin,  the  mental 
eminence,  and  the  incisive  fossa  of  the  lower  jaw. 

On  each  side,  proceeding  from  above  downwards,  is  the  supraorbital  ridge, 
terminating  externally  in  the  external  angular  process  at  its  junction  with  the 
malar,  and  internally  in  the  internal  angular  process ;  towards  the  inner  third 
of  this  ridge  is  the  supraorbital  notch  or  foramen,  for  the  passage  of  the  supra- 
orbital vessels  and  nerve,  and  at  its  inner  side  ^  slight  depression  for  the 
attachment  of  the  pulley  of  the  Superior  Oblique  muscle.  Beneath  the  supra- 
orbital ridge  is  the  opening  of  the  orbit,  bounded  externally  by  the  orbital 
ridge  of  the  malar  bone ;  below,  by  the  orbital  ridge  formed  by  the  malar, 
superior  maxillary,  and  lachrymal  bones ;  internally,  by  the  nasal  process  of 
the  superior  maxillary,  and  the  internal  angular  process  of  the  frontal  bone. 
On  the  outer  side  of  the  orbit,  is  the  quadrilateral  anterior  surface  of  the  malar 
bone,  perforated  by  one  or  two  small  malar  foramina.  Below  the  inferior 
margin  of  the  orbit,  is  the  infraorbital  foramen,  the  termination  of  the  infra- 
orbital canal,  and  beneath  this,  the  canine  fossa,  which  gives  attachment  to  the 
Levator  Anguli  Oris ;  bounded  below  by  the  alveolar  processes,  containing  the 
teeth  of  the  upper  jaw.  Beneath  the  alveolar  arch  of  the  lower  jaw  is  the 
mental  foramen  for  the  passage  of  the  mental  nerve  and  artery,  the  external 
oblique  line,  and  at  the  lower  border  of  the  bone,  at  the  point  of  junction  of 
the  body  with  the  ramus,  a  shallow  groove  for  the  passage  of  the  facial  artery. 

The  Orbits. 

The  Orbits  (Fig.  132)  are  two  quadrilateral  pyramidal  cavities,  situated  at  thb 
upper  and  anterior  part  of  the  face,  their  bases  being  directed  forwards  and  out- 
wards, and  their  apices  backwards  and  inwards.  Each  orbit  is  formed  of  seven 
bones,  the  frontal,  sphenoid,  ethmoid,  superior  maxillary,  malar,  lachrymal,  and 
palate ;  but  three  of  these,  the  frontal,  ethmoid,  and  sphenoid,  enter  into  the 
formation  of  both  orbits,  so  that  the  two  cavities  are  formed  of  eleven  bones  only. 
Each  cavity  presents  for  examination,  a  roof,  a  floor,  an  inner  and  a  outer  wall, 
four  angles,  a  circumference  or  base,  and  an  apex.  The  Boo/ is  concave,  directed 
downwards  and  forwards,  and  formed  in  front  by  the  orbital  plate  of  the  frontal; 
behind,  by  the  lesser  wing  of  the  sphenoid.  This  surface  presents  internally 
the  depression  for  the  fibro-cartilaginous  pulley  of  the  Superior  Oblique  mus- 
cle; externally,  the  depression  for  the  lachrymal  gland,  and  posteriorly,  the 
suture  connecting  the  frontal  and  lesser  wing  of  the  sphenoid. 

The  Floor  is  nearly  flat,  and  of  less  extent  than  the  roof;  it  is  formed  chiefly 
by  the  orbital  surface  of  the  superior  maxillary;  in  front,  to  a  small  extent,  by 
the  orbital  process  of  the  malar,  and  behind,  by  the  orbital  surface  of  the  palate. 
This  surface  presents  at  its  anterior  and  internal  part,  just  external  to  the 


186 


THE    SKELETON. 


lachrymal  canal,  a  depression  for  the  attachment  of  the  Inferior  Oblique  muscle: 
externally,  the  suture  between  the  malar  and  superior  maxillary  bones ;  near 

Fig.  132. — Anterior  Eegion  of  the  Skull. 


TCNOO   OCULI 


Ant.  Ntisal  Spine 
Incisive  JosscL 


its  middle,  the  infraorbital  groove;  and  posteriorly,  the  suture  between 
maxillary  and  palate  bones. 

The  Inner  Wall  is  flattened,  and  formed  from  before  backwards  by  the  na.sa 
process  of  the  superior  maxillary,  the  lachrymal,  os  planum  of  the  ethmoid 
and  a  small  part  of  the  body  of  the  sphenoid.     This  surface  presents  the' 
lachrymal  groove,  and  crest  of  the  lachrymal  bone,  and  the  sutures  connecting 
the  ethmoid  with  the  lachrymal  bone  in  front,  and  the  sphenoid  behind.  . 

The  Outer  Wall  is  formed  in  front  by  the  orbital  process  of  the  malar  bone|3 
behind,  by  the  orbital  plate  of  the  sphenoid.  On  it  are  seen  the  orifices  of  onei 
or  two  malar  canals,  and  the  suture  connecting  the  sphenoid  and  malar  bones. 

Angles.  The  superior  external  angle  is  formed  by  the  junction  of  the  upper 
and  outer  walLs;  it  presents,  from  before  backwards,  the  suture  connecting  tha 
frontal  with  the  malar  in  front,  and  with  the  orbital  plate  of  the  sphenoid  be-j 
hind ;  quite  posteriorly  is  the  foramen  lacerum  anterius,  or  sphenoidal  fissure,^ 
which  transmits  the  third,  fourth,  the  ophthalmic  division  of  the  fifth  and  the] 
sixth  nerves,  and  the  ophthalmic  vein.  The  superior  internal  angle  is  formed  by^] 
the  junction  of  the  upper  and  inner  wall,  and  presents  the  suture  connecting 
the  frontal  bone  with  the  lachrymal  in  front,  and  with  the  ethmoid  behind. 
This  suture  is  perforated  by  two  foramina,  the  anterior  and  posterior  ethmoidal, 


I 
I 

I 


NASAL    FOSS^.  187 

the  former  transmitting  the  anterior  ethmoidal  artery  and  nasal  nerve,  the  latter 
the  posterior  ethmoidal  artery  and  vein.  The  inferior  external  angle^  formed  by 
the  junction  of  the  outer  wall  or  floor,  presents  the  spheno-maxillary  fissure, 
which  transmits  the  infraorbital  vessels  and  nerve,  and  the  ascending  branches 
from  the  spheno-palatine  ganglion.  The  inferior  internal  angle  is  formed  by 
the  union  of  the  lachrymal  and  os  planum  of  the  ethmoid,  with  the  superior 
maxillary  and  palate  bones.  The  circumference,  or  base,  of  the  orbit,  quadri- 
lateral in  form,  is  bounded  above  by  the  supraorbital  arch ;  below,  by  the 
anterior  border  of  the  orbital  plate  of  the  malar,  superior  maxillary,  and 
lachrymal  bones;  externally,  by  the  external  angular  process  of  the  frontal  and 
the  malar  bone ;  internally,  by  the  internal  angular  process  of  the  frontal,  and 
the  nasal  process  of  the  superior  maxillary.  The  circumference  is  marked  by 
three  sutures,  the  fronto-maxillary  internally,  the  fronto-malar  externally,  and 
the  malo-maxillary  below;  it  contributes  to  the  formation  of  the  lachrymal 
groove,  and  presents  above,  the  supraorbital  notch  (or  foramen),  for  the  passage 
of  the  supraorbital  artery,  veins  and  nerve.  The  apex,  situated  at  the  back  of 
the  orbit,  corresponds  to  the  optic  foramen,  a  short  circular  canal,  which  trans- 
mits the  optic  nerve  and  ophthalmic  artery.  It  will  thus  be  seen  that  there  are 
nine  openings  communicating  with  each  orbit,  viz.,  the  optic,  foramen  lacerum 
anterius,  spheno-maxillary  fissure,  supraorbital  foramen,  infraorbital  canal, 
anterior  and  posterior  ethmoidal  foramina,  malar  foramina,  and  lachrymal  canal. 

The  Nasal  Foss^. 

The  Nasal  Fossae  are  two  large  irregular  cavities,  situated  in  the  middle  line 
of  the  face,  extending  from  the  base  of  the  cranium  to  the  roof  of  the  mouth, 
and  separated  from  each  other  by  a  thm  vertical  septum.  They  communicate 
by  two  large  apertures,  the  anterior  nares,  with  the  front  of  the  face ;  and  with 
the  pharynx  behind  by  two  posterior  nares.  These  fossae  are  much  narrower 
above  than  below,  and  in  the  middle  than  at  the  anterior  or  posterior  openings: 
their  depth,  which  is  considerable,  is  much  greater  in  the  middle  than  at  either 
extremity.  Each  nasal  fossa  communicates  with  four  sinuses,  the  frontal  above, 
the  sphenoidal  behind,  and  the  maxillary  and  ethmoidal  on  either  side.  Each 
fossa  also  communicates  with  four  cavities :  with  the  orbit  by  the  lachrymal 
canal,  with  the  mouth  by  the  anterior  palatine  canal,  with  the  cranium  by  the 
olfactory  foramina,  and  with  the  spheno-maxillary  fossa  by  the  spheno-palatine 
foramen;  and  they  occasionally  communicate  with  each  other  by  an  aperture 
in  the  septum.  The  bones  entering  into  their  formation  are  fourteen  in  num- 
ber: three  of  the  cranium,  the  frontal,  sphenoid,  the  ethmoid,  and  all  the  bones 
of  the  face,  excepting  the  malar  and  lower  jaw.  Each  cavity  is  bounded  by  a 
roof,  an  inner  and  an  outer  wall. 

The  upper  wall,  or  roof  (Fig.  133),  is  long,  narrow,  and  concave  from  before 
backwards ;  it  is  formed  in  front  by  the  nasal  bones  and  nasal  spine  of  the 
frontal,  which  are  directed  downwards  and  forwards;  in  the  middle,  by  the 
cribriform  lamella  of  the  ethmoid,  which  is  horizontal ;  and  behind,  by  the 
under  surface  of  the  body  of  the  sphenoid,  and  sphenoidal  turbinated  bones, 
which  are  directed  downwards  and  backwards.  This  surface  presents,  from" 
before  backwards,  the  internal  aspect  of  the  nasal  bones ;  on  the  outer  side,  the 
suture  formed  between  the  nasal  bone  and  the  nasal  process  of  the  superior 
maxillary;  on  their  inner  side,  the  elevated  crest  which  receives  the  nasal 
spine  of  the  frontal,  and  the  perpendicular  plate  of  the  ethmoid,  and  articulates 
with  its  fellow  of  the  opposite  side;  whilst  the  surface  of  the  bones  is  perforated 
by  a  few  small  vascular  apertures,  and  presents  the  longitudinal  groove  for  the 
nasal  nerve :  further  back  is  the  transverse  suture,  connecting  the  frontal  with 
the  nasal  in  front,  and  the  ethmoid  behind,  the  olfactory  foramina  and  nasal  slit 
on  the  under  surface  of  the  cribriform  plate,  and  the  suture  between  it  and  the 


188 


THE    SKELETON. 


sphenoid  behind :  quite  posteriorly  are  seen  the  sphenoidal  turbinated  bonei , 
the  orifices  of  the  sphenoidal  sinuses  and  the  articulation  of  the  alae  of  the 
vomer  with  the  under  surface  of  the  body  of  the  sphenoid. 


J 


Fig.  133.— Roof,  Floor,  and  Outer  Wall  of  Nasal  Fossa. 
Hoaf 

Nasal  ^nt 
Xasal  S/pine  of  FroTital  Bone 
EffrvztmtaLPlaU  cfEtJimttd  ^\       j/ /    Jr^* 

Sphnioii 


Prole  passed  tkrjugh 
TiJate-Utehrymal  Caaal 

Brittle  fuaudtkwugk 
IrJundLhuiam  ■ 


OdUr  \Jcdl 
^Mal  ProcafSufXia. 

U,u:ifo7mI>oe  ,^  ditto 
InfivicT  TurbiJutcd 
htlatt 

Sujjcru/r  Meatus 

—yfiddU  Hcatus 
-  Inferior  Meatur 


Floor 

Ant.  Natal  S'jntte 

falatt  rroc.ofiSufMax. 

Palate  Proc.  ofFalaU 

Par. Nasal  S^i'u 

AnC.  FalaUiu  Canal 


i 


The  fioor  is  flattened  from  before  backwards,  concave  from  side  to  side,  an 
wider  in  the  middle  than  at  either  extremity.  It  is  formed  in  front  by  the 
palate  process  of  the  superior  maxillary;  behind,  by  the  palate  process  of  the 
palate  bone.  This  surface  presents,  from  before  backwards,  the  anterior  nasal 
spine;  behind  this,  the  upper  orifice  of  the  anterior  palatine  canal;  internally, 
the  elevated  crest  which  articulates  with  the  vomer ;  and  behind,  the  sutun^ 
between  the  palate  and  superior  maxillary  bones,  and  the  posterior  nasal  spinfH 

The  inner  wall,  or  sep/wm(Fig.l34),  is  a  thin  vertical  partition,  which  separates" 
the  nasal  fossae  from  one  another;  it  is  occasionally  perforated,  so  that  the  fosi 
communicate,  and  it  is  frequently  deflected  considerably  to  one  side.  It 
formed,  in  front,  by  the  crest  of  the  nasal  bones  and  nasal  «pine  of  the  fronta 
in  the  middle,  by  the  perpendicular  lamella  of  the  ethmoid;  behind,  by  t' 
vomer  and  rostrum  of  the  sphenoid;  below,  by  the  crest  of  the  superior  maxi 
lary  and  palate  bones.  It  presents,  in  front,  a  large  triangular  notch,  whic 
receives  the  triangular  cartilage  of  the  nose;  above,  the  lower  orifices  of  the 
olfactory  canals;  and  behind,  the  guttural  edge  of  the  vomer.  Its  surface  ij^ 
marked  by  numerous  vascular  and  nervous  canals  and  the  groove  for  the  nasofl 
palatine  nerve,  and  is  traversed  by  sutures  connecting  the  bones  of  which  it  i^^ 
formed. 

The  outer  wall  (Fig.  133)  is  formed,  in  front,  by  the  nasal  process  of  the 
superior  maxillary  and  lachrymal  bones;  in  the  middle,  by  the  ethmoid  and 
inner  surface  of  the  superior  maxillary  and  inferior  turbinated  bones;  behind, 
by  the  vertical  plate  of  the  palate  bone,  and  the  internal  pterygoid  process  of 
the  sphenoid.     This  surface  presents  three  irregular  longitudinal  passages,  or 


I 


OS    HYOIDES. 


189 


meatuses,  formed  between  three  horizontal  plates  of  bone  that  spring  from  it; 
they  are  termed  the  superior,  middle,  and  inferior  meatuses  of  the  nose.  The 
superior  meatus^  the  smallest  of  the  three,  is  situated  at  the  upper  and  back  part 
of  each  nasal  fossa,  occupying  the  posterior  third  of  the  outer  wall.     It  is 

Fig.  134. — Inner  Wall  of  Nasal  Fossae,  or  Septum  of  Nose. 


Crext  of  Nasal   Ion 
Kaaal  S^ipt  ct fronted  B. 


Space  for  TTiaii^uJar 
Cartilaqe  oj  Septum 


Great  oJ"  Palate  Li(nif 
Crest  of  Siip.MwxM.Jana 


situated  between  the  superior  and  middle  turbinated  bones,  and  has  opening 
into  it  two  foramina,  the  spheno-palatine  at  the  back  of  its  outer  wall,  the  pos- 
terior ethmoidal  cells  at  the  front  part  of  the  upper  wall.  The  opening  of  the 
sphenoidal  sinuses  is  usually  at  the  upper  and  back  part  of  the  nasal  fossae,  im- 
mediately behind  the  superior  turbinated  bone.  The  middle  meatus  is  situated 
between  the  middle  and  inferior  turbinated  bones,  and  occupies  the  posterior 
two-thirds  of  the  outer  wall  of  the  nasal  fossa.  It  presents  two  apertures.  In 
front  is  the  orifice  of  the  infundibulum,  by  which  the  middle  meatus  communi- 
cates with  the  anterior  ethmoidal  cells,  and  through  these  with  the  frontal 
sinuses.  At  the  centre  of  the  outer  wall  is  the  orifice  of  the  antrum,  which 
varies  somewhat  as  to  its  exact  position  in  different  skulls.  The  inferior  meatus, 
the  largest  of  the  three,  is  the  space  between  the  inferior  turbinated  bone  and 
the  floor  of  the  nasal  fossa.  It  extends  along  the  entire  length  of  the  outer 
wall  of  the  nose,  is  broader  in  front  than  behind,  and  presents  anteriorly  the 
lower  orifice  of  the  lachrymal  canal. 

Os  Hyoides. 

The  Hyoid  Bone  is  named  from  its  resemblance  to  the  Greek  Upsilon;  it  is 
also  called  the  lingual  hone,  because  it  supports  the  tongue,  and  gives  attach- 
ment to  its  numerous  muscles.  It  is  a  bony  arch,  shaped  like  a  horseshoe,  and 
consisting  of  five  segments,  a  body,  two  greater  cornua,  and  two  lesser  cornua. 

The  Body  forms  the  central  part  of  the  bone,  and  is  of  a  quadrilateral  form: 
its  anterior  surface  (Fig.  135)  convex,  directed  forwards  and  upwards,  is  divided 


190  THE    SKELETON. 

into  two  parts  by  a  vertical  ridge,  which  descends  along  the  median  line,  ana 
crossed  at  right  angles  by  a  horizontal  ridge,  so  that  this  surface  is  divided 

into  four  muscular  depressions. 
Fig.  IHn.— Hyoid  Bone.    Anterior  Surface  (onlar<iecl).     At  the  point  of  meeting  of  these 

two  lines  is  a  prominent  eleva- 
tion, the  tubercle.     The  portion 
above   the   horizontal    ridge  is 
directed  upwards,  and  is  some- 
times described  as  the  superior 
border.      The    anterior    surface 
gives  attachment  to  the  Genio- 
hyoid in  the  greater  part  of  its 
extent;  above,  to  the  Genio-hyo- 
^Thyro-fhioid    glossus;  bclow,  to  the  Mylo-hy- 
siijio-Hyoid     oid,  Stylo-hyoid,  and  aponeurosis 
of  the   Digastric ;   and  between 
\         omo-Hijoid        these  to  part  of  the  Hyo-glossus. 
Genioihjoid      stemo-Hyoid       Myio-Hyoid  The  iwsterior  snrface  is  smooth, 

concave,  directed  backwards  and 
downwards,  and  separated  from  the  epiglottis  by  the  thyro-hyoid  membrane, 
and  by  a  quantity  of  loose  areolar  tissue.  The  superior  border  is  rounded,  and 
gives  attachment  to  the  thyro-hyoid  membrane,  and  part  of  the  Genio-hvo- 
glossi  muscles.  The  inferior  border  gives  attachment,  in  front,  to  the  Sterno- 
hyoid; behind,  to  part  of  the  Thyro-hyoid,  and  to  the  Omo-hyoid  at  its  junction 
with  the  great  cornu.  The  lateral  surfaces  are  small,  oval,  convex  facets,  covered 
with  cartilage  for  articulation  with  the  greater  cornua. 

The  Greater  Cornua  project  backwards  from  the  lateral  surfaces  of  the  body; 
they  are  flattened  from  above  downwards,  diminish  in  size  from  before  back- 
wards, and  terminate  posteriorly  in  a  tubercle  for  the  attachment  of  the  thyro- 
hyoid ligament.  Their  outer  surface  gives  attachment  to  the  Hyo-glossus;  tlieir 
upper  border  to  the  Middle  Constrictor  of  the  pharynx ;  their  lower  border,  to 
part  of  the  Thyro-hyoid  muscle. 

The  Lesser  Cornua  are  two  small  conical-shaped  eminences,  attached  by  their 
bases  to  the  angles  of  junction  between  the  body  and  greater  cornua,  and  givii  g 
attachment  by  their  apices  to  the  stylo-hyoid  ligaments.  In  youth,  the  cornua 
are  connected  to  the  body  by  cartilaginous  surfaces,  and  held  together  by  liga- 
ments; in  middle  life,  the  body  and  greater  cornua  usually  become  joined ;  and 
in  old  age,  all  the  segments  are  united  together,  forming  a  single  bone. 

Development.  "By  five  centres;  one  for  the  body,  and  one  for  each  cornu. 
Ossification  commences  in  the  body  and  greater  cornua  towards  the  end  of  foetal 
life,  those  of  the  cornua  first  appearing.  Ossification  of  the  lesser  cornua 
commences  some  months  after  birtli. 

Attachment  of  Muscles.  Sterno-hyoid,  Thyro-hyoid,  Omo-hyoid,  aponeur 
of  the  Digastricus,  Stylo-hyoid,  Mylo-hyoid,  Genio-hyoid,  Genio-hyo-gloss 
Hyo-glossus,  Middle  Constrictor  of  the  pharynx,  and  occasionally  a  few  fibrtsa 
of  the  Lingualis.  It  also  gives  attachment  to  the  thyro-hyoidean  membrane, 
and  the  stylo-hyoid,  thyro-hyoid,  and  hyo-epiglottic  ligaments. 

THE  THORAX. 

The  Thorax,  or  Chest,  is  an  osseo-cartilaginous  cage,  intended  to  contain  and 
protect  the  principal  organs  of  respiration  and  circulation.  It  is  the  second  in 
size  of  the  three  cavities  connected  with  the  spine,  and  is  formed  by  the  sternum 
and  costal  cartilages  in  front,  the  twelve  ribs  on  each  side,  and  the  bodies  of 
the  dorsal  vertebras  behind. 

The  Sternitm. 

The  Sternum  (Figs.  186,  137'\  is  a  flat  narrow  bone,  situated  in  the  medinn 
line  of  the  front  of  the  chest,  and  consisting,  in  the  adult,  of  three  portions.    It 


M 


STERNUM. 


191 


Fig.  136. — Sternum  and  Costal  Cartilages. 

STtRNO-CttlOO  M/lSTOrD        ^ 
8U8.;LAV.US  \  ■?5  ^cr_ 


Fig.  137. — Posterior  Surface  of  Sternum. 


193  THE    SKELETON. 

has  been  likened  to  an  ancient  sword:  the  upper  piece,  representing  the  handle, 
is  termed  the  manubrium;  the  middle  and  largest  piece,  which  represents  the 
chief  part  of  the  blade,  is  termed  the  gladiolus ;  and  the  inferior  piece,  which 
is  likened  to  the  point  of  the  sword,  is  termed  the  ensifonn  or  xij^hoid  appendix. 
In  its  natural  position,  its  inclination  is  oblique  from  above,  downwards,  and 
forwards.  It  is  flattened  in  front,  concave  behind,  broad  above,  becoming  nar- 
rowed at  the  point  where  the  first  and  second  pieces  are  connected;  after  which 
it  again  widens  a  little,  and  is  pointed  at  its  extremity.  Its  average  length 
in  the  adult  is  six  inches,  being  rather  longer  in  the  male  than  in  the  female. 

The  First  Piece  of  the  sternum,  or  Manubrium,  is  of  a  somewhat  triangular 
form,  broad  and  thick  above,  narrow  below  at  its  junction  with  the  middle 
piece.  Its  anterior  surface,  convex  from  side  to  side,  concave  from  above  down- 
wards, is  smooth,  and  affords  attachment  on  each  side  to  the  Pectoralis  major 
and  sternal  origin  of  the  sterno-cleido-mastoid  muscle.  In  well-marked  bones, 
the  ridges  limiting  the  attachment  of  these  muscles  are  very  distinct.  Its 
posterior  swface,  concave  and  smooth,  affords  attachment  on  each  side  to  the 
Sterno-hyoid  and  Sterno-thyroid  muscles.  The  superior  border,  the  thickest, 
presents  at  its  centre  the  interclavicular  notch;  and  on  each  side,  an  oval 
articular  surface,  directed  upwards,  backwards,  and  outwards,  for  articulation 
with  the  sternal  end  of  the  clavicle.  The  inferior  border  presents  an  oval  rough 
surface,  covered  in  the  recent  state  with  a  thin  layer  of  cartilage,  for  articula- 
tion with  the  second  portion  of  the  bone.  The  lateral  borders  are  marked  above 
by  an  articular  depression  for  the  first  costal  cartilage,  and  below  by  a  small 
facet,  which,  with  a  similar  facet  on  the  upper  angle  of  the  middle  portion  of 
the  bone,  forms  a  notch  for  the  reception  of  the  costal  cartilage  of  the  second 
rib.  These  articular  surfaces  are  separated  by  a  narrow  curved  edge  which 
slopes  from  above  downwards  and  inwards. 

The  Second  Piece  of  the  sternum,  or  Gladiolus,  considerably  longer,  narrower, 
and  thinner  than  the  first  piece,  is  broader  below  than  above.  Its  anterior  sur- 
face is  nearly  flat,  directed  upwards  and  forwards,  and  marked  by  three  trans- 
verse lines  which  cross  the  bone  opposite  the  third,  fourth,  and  fifth  articular 
depressions.  These  lines  are  produced  by  the  union  of  the  four  separate 
pieces  of  which  this  part  of  the  bone  consists  at  an  early  period  of  life.  At 
the  junction  of  the  third  and  fourth  pieces,  is  occasionally  seen  an  orifice,  th(} 
sternal  foramen ;  it  varies  in  size  and  form  in  different  individuals,  and  pierce;? 
the  bone  from  before  backwards.  This  surface  affords  attachment  on  each  side 
to  the  sternal  origin  of  the  Pectoralis  major.  The  posterior  surface,  slight Ij-- 
concave,  is  also  marked  by  three  transverse  lines ;  but  they  are  less  distinct 
than  those  in  front :  this  surface  affords  attachment  below,  on  each  side,  to  the 
Triangularis  sterni  muscle,  and  occasionally  presents  the  posterior  opening  of 
the  sternal  foramen.  The  superior  border  presents  an  oval  surface  for  articula- 
tion with  the  manubrium.  The  inferior  border  is  narrow,  and  articulates  with 
the  ensiform  appendix.  Each  lateral  border  presents  at  each  superior  angle  a 
small  facet,  which,  with  a  similar  facet  on  the  manubrium,  forms  a  cavity  for 
the  cartilage  of  the  second  rib;  the  four  succeeding  angular  depressions  receive 
the  cartilages  of  the  third,  fourth,  fifth,  and  sixth  ribs,  whilst  each  inferior  angle 
presents  a  small  facet,  which,  with  a  corresponding  one  on  the  ensiform  appen- 
dix, forms  a  notch  for  the  cartilage  of  the  seventh  rib.  These  articular  depres- 
sions are  separated  by  a  series  of  curved  inter-articular  intervals,  which  diminish 
in  length  from  above  downwards,  and  correspond  to  the  intercostal  spaces. 
Most  of  the  cartilages  belonging  to  the  true  ribs,  as  will  be  seen  from  the  fore- 
going description,  articulate  with  the  sternum  at  the  line  of  junction  of  two  of 
its  primitive  component  segments.  This  is  well  seen  in  many  of  the  lower 
animals,  where  the  separate  parts  of  the  bone  remain  ununited  longer  than  in 
man.  In  this  respect  a  striking  analogy  exists  between  the  mode  of  connection 
of  the  ribs  with  the  vertebral  column,  and  the  connection  of  their  cartilages 
with  the  sternal  column. 


STERNUM. 


193 


The  Third  Piece  of  the 
sternum,  the  Ensiform  or 
Xiphoid  Appendix^  is  the 
smallest  of  the  three;  it  is 
thin  and  elongated  in  form, 
cartilaginous  in  structure  in 
youth,  but  more  or  less  os- 
sified at  its  upper  part  in  the 
adult.  Its  anterior  surface 
affords  attachment  to  the 
costo-xiphoid  ligament;  its 
posterior  surface^  to  some  of 
the  fibres  of  the  Diaphragm 
and  Triangularis  Sterni 
muscles:  its  lateral  borders, 
to  the  aponeurosis  of  the 
abdominal  muscles.  Above, 
it  is  continuous  with  the 
lower  end  of  the  gladiolus; 
below,  by  its  pointed  ex- 
tremity, it  gives  attachment 
to  the  linea  alba,  and  at  each 
superior  angle  presents  a  fa- 
cet for  the  lower  half  of  the 
cartilage  of  the  seventh  rib. 
This  portion  of  the  sternum 
is  very  various  in  appear 
ance,  being  sometimes  point- 
ed, broad,  and  thin,  some- 
times bifid,  or  perforated  by 
a  round  hole,  occasionally 
curved,  or  deflected  conside- 
rably to  one  or  the  other 
side. 

Structure.  The  bone  is 
composed  of  delicate  cancel- 
lated texture,  covered  by  a 
thin  layer  of  compact  tissue, 
which  is  thickest  in  the 
manubrium,  between  the  ar- 
ticular facets  for  the  clavi- 
cles. 

Development.  The  ster- 
num, including  the  ensiform 
appendix,  is  developed  by 
six  centres;  one  for  the  first 
piece,  or  manubrium,  four 
for  tlie  second  piece  or  gla- 
diolus, and  one  for  the  en- 
siform appendix.  Up  to  the 
middle  of  foetal  life,  the  ster- 
num is  entirely  cartilaginous, 
and  when  ossification  takes 
place,  the  ossific  granules 
are  deposited  in  the  middle 
of  the  intervals  between  the 
articular  depressions  for  the 
13 


Fig.  188. — Development  of  the  Sternum,  by  Six  Centres. 


"J 
Apjy  e>  a  ra  7ice 


numl>&r  of 
C  cnZTes 


And  in 

Mode  oj' 

Vnion 


i fori ff puce  ^S-emo.fcUa.l' 
ey  MdruLbrium 


2  )    . 

Ci — \         "^  I 

)     ~-'        OhxxUolws         \i^     ifth  mr. 

5.  if^u'^ after 
hii^tA 

Fig.  139. 


rcbnrelti  ii-nlte  , 
except  in  old  age 

3S-l,0. 
20-ZSfhyear 

I   soon  after pahcrtij 

■partly  cartda^iiwus  in. 
adi/anr^  life 

Fig.  140. — Peculiarities. 

for  1'-j)uee  Zor  7/10  re  renZrcs 
;2''.    ■piece,  ti,aiiaJI If  one 

A(^  I   Zjotaccd  laterali-j 

6^ 


Fig.  141. 


Arrest  of  De'tfelojj7iient 

erf  lateraJ  jjccccs   jrroducinci 

Sternal  fissare  k 


-Sternal  fora  mt  ■n 


194  THE    SKELETON. 

costal  cartilages,  in  the  following  order  (Fig  138).  In  the  first  piece,  between 
the  fifth  and  sixth  months ;  in  the  second  and  third,  between  the  sixth  and 
seventh  months;  in  the  fourth  piece,  at  the  ninth  month;  in  the  fifth,  within 
the  first  year,  or  between  the  first  and  second  years  after  birth ;  and  in  the 
ensiform  appendix,  between  the  second  and  the  seventeenth  or  eighteenth 
years,  by  a  single  centre  which  makes  its  appearance  at  the  upper  part,  and 
proceeds  gradually  doAvnwards.  To  these  may  be  added  the  occasional  exist- 
ence, as  described  by  Breschet,  of  two  small  episternal  centres,  which  make 
their  appearance  one  on  each  side  of  the  interclavicular  notch.  These  are  re- 
garded by  him  as  the  anterior  rudiments  of  a  rib,  of  which  the  posterior  rudi- 
ment is  the  anterior  lamina  of  the  transverse  process  of  the  seventh  cervical 
vertebra.  It  occasionally  happens  that  some  of  the  segments  are  formed  from 
more  than  one  centre,  the  number  and  position  of  which  vary  (Fig.  140).  Thus 
the  first  piece  may  have  two,  three,  or  even  six  centres.  When  two  are  pre- 
sent, they  are  generally  situated  one  above  the  other,  the  upper  one  being  the 
larger ;  the  second  piece  has  seldom  more  than  one ;  the  third,  fourth,  and  fifth 
pieces  are  often  formed  from  two  centres  placed  laterally,  the  irregular 
union  of  which  will  serve  to  explain  the  occasional  occurrence  of  the  sternal 
foramen  (Fig.  141),  or  of  the  vertical  fissure  which  occasionally  intersects  this 
part  of  the  bone.  Union  of  the  various  centres  commences  from  below,  and 
proceeds  upwards,  taking  place  in  the  following  order  (Fig.  139).  The  fifth 
piece  is  joined  to  the  fourth  soon  after  puberty ;  the  fourth  to  the  third,  be- 
tween the  twentieth  and  twenty-fifth  years ;  the  third  to  the  second,  between 
the  thirty-fifth  and  fortieth  years;  the  second  is  rarely  joined  to  the  first  except 
in  very  advanced  age. 

Arliculations.     With  the  clavicles,  and  seven  costal  cartilages  on  each  side. 

Attachment  of  Muscles.  The  Pectoralis  Major,  Sterno-cleido-mastoid,  Sterno- 
hyoid, Sterno-thyroid,  Triangularis  Sterni,  aponeurosis  of  the  Obliquus  Ex- 
ternus,  Obliquus  Internus,  and  Transversalis  muscles,  Eectus  Abdominis  and 
Diaphragm. 

The  Kibs. 

The  Eibs  are  elastic  arches  of  bone,  which  form  the  chief  part  of  the  thoracic 
walls.  They  are  twelve  in  number  on  each  side;  but  this  number  may  be  ir-- 
creased  by  the  development  of  a  cervical  or  lumbar  rib,  or  may  be  diminished 
to  eleven.  The  first  seven  are  connected  behind  with  the  spine,  and  in  front 
with  the  sternum,  through  the  intervention  of  the  costal  cartilages,  they  ar3 
called  vertebrosternal,  or  true  ribs.  The  remaining  five  are  false  ribs ;  of  thesa 
the  first  three,  being  connected  behind  with  the  spine,  and  in  front  with  tli'S 
costal  cartilages,  are  called  the  vertebro-costal  ribs;  the  last  two  are  connected 
with  the  vertebrae  only,  being  free  at  their  anterior  extremities;  they  are  termed 
vertebral  or  jloating  ribs.  The  ribs  vary  in  their  direction,  the  upper  ones  bei: 
placed  nearly  at  right  angles  with  the  spine,  the  lower  ones  obliquely,  so  th 
the  anterior  extremity  is  lower  than  the  posterior.  The  extent  of  obliquil 
reaches  its  maximum  at  the  ninth  rib,  and  gradually  decreases  from  that  ri 
to  the  twelfth.  The  ribs  are  situated  one  beneath  the  other  in  such  a  manner 
that  spaces  are  left  between  them,  which  are  called  intercostal  spaces.  Their 
length  corresponds  to  the  length  of  the  ribs,  their  breadth  is  more  considerable 
in  front  than  behind,  and  between  the  upper  than  between  the  lower  ribs.  The 
ribs  increase  in  length  from  the  first  to  the  seventh,  when  they  again  diminis 
to  the  twelfth.  In  breadth  they  decrease  from  above  downwards ;  in  each  ri 
the  greatest  breadth  is  at  the  sternal  extremity. 

Common   Characters  of  the  Ribs  (Fig.  142).     A  rib  from  the  middle  of  t 
series  should  be  taken  in  order  to  study  the  common  characters  of  the  ribs. 

Each  rib  presents  two  extremities,  a  posterior  or  vertebral,  an  interior 
iSternal,  and  an  intervening  portion,  the  body  or  shaft.    The  posterior  or  vertebral 
extremity  presents  for  examination  a  head,  neck,  and  tuberosity.     The  head 


led 

I 


THE    RIBS. 


195 


^ 


(Fig.  143)  is  marked  by  a  kidney-shaped  articu-    Fig.  142.— A  Central  Rib  of  Right 
]ar  surface,   divided  by  a  horizontal  ridge  into  ^^^^-    ^^^^^  Surface. 

two  facets  for  articulation  with  the  costal  cavity  ^■""v, 

formed  by  the  junction  of  the  bodies  of  two 

contiguous  dorsal  vertebrae;  the  upper  facet  is 

small,  the  inferior  one  of  laro-e  size:  the  rido-e 

separatmg  them  serves  for  the  attachment  of 

the  inter-articular  ligament. 

The  neck  is  that  flattened  portion  of  the  rib 

which   extends  outwards  from  the  head;   it  is 

about  an  inch  long,  and  rests  upon  the  trans- 
verse process  of  the  lower  of  the  two  vertebrae 

with  which   the  head  articulates.     Its    anterior 

surface  is  flat  and  smooth,  its  posterior  rough,  for 

the  attachment  of  the  middle  costo-transverse 

ligament,  and  perforated  by  numerous  foramina, 

the  direction  of  which  is  less  constant  than  those 

found  on  the  inner  surface  of  the  shaft.     Of  its 

two  borders,  the  superior  presents  a  rough  crest 

for  the  attachment  of  the  anterior  costo-trans- 
verse   ligament ;    its  inferior  border  is  rounded. 

On  the  posterior  surface  of  the  neck,  just  where 

it  joins  the  shaft,  and  nearer  the  lower  than  the 

upper  border,  is  an  eminence — the  tuberosity  or 

tubercle ;  it  consists  of  an  articular  and  a  non- 
articular  portion.    The  articular  portion^  the  most 

internal  and  inferior  of  the  two,  presents  a  small 

oval  surface,  for  articulation  with  the  extremity 

of  the  transverse  process  of  the  lower  of  the  two 

vertebraB  to  which  the  head  is  connected.     The 

non-articular  portion  is  a  rough  elevation,  which 

affords  attachment  to  the  posterior  costo-trans- 
verse ligament.     The   tubercle    is   much   more 

prominent  in  the  upper  than  in  the  lower  ribs. 
The  shaft  is  thin  and  flat,  so  as  to  present  two 

surfaces,  an  external  and  an  internal ;  and  two    - 

borders,  a  superior  and  an  inferior.     The  exter- 
nal surface  is  convex,  smooth,  and  marked,  at  its 

back  part,  a  little  in  front  of  the  tuberosity,  by 

a  prominent  line,  directed  obliquely  from  above, 

downwards  and  outwards;  this  gives  attachment 

to  a  tendon  of  the  Sacro-lumbalis  muscle,  and  is 

called  the  angle.     At  this  point,  the  rib  is  bent 
I  in  two  directions.     If  the  rib  is  laid  upon  its 

lower  border,  it  wall  be  seen  that  the  anterior 

portion  of  the  shaft,  as  far  as  the  angle,  rests 
;  upon  this  margin,  while  the  vertebral  end  of  the 
i  bone,  beyond  the  angle,  is  bent  inwards,  and  at 
I  the  same  time  tilted  upwards.  The  interval  be- 
;  tween  the  angle  and  the  tuberosity  increases  gra- 
dually from  the  second  to  the  tenth  rib.  The  por- 
I  tion  of  bone  between  these  two  parts  is  rounded, 
j  rough,  and  irregular,  and  serves  for  the  attach- 
ment of  the  Longissimus  Dorsi.  The  portion  of 
I  bone  between  the  angle  and  sternal  extremity  is 
I  also  slightly  twisted  upon  its  own  axis,  the  external  surface  looking  downwards 

behind  the  angle,  a  little  upwards  in  front  of  it.    This  surface  presents,  towards 


196  THE    SKELETON. 

its  sternal  extremity,  an  oblique  line,  the  anterior  angle.     The  internal  surface 
is  concave,  smooth,  directed  a  little  upwards  behind  the  angle ;  a  little  down- 
Fig.  143. — Vertebral  Extremity  of  a  Rib.     External  Surface. 

Taeti  ftiT  hod'ii  tf  ujf^er  J)or*al  Vfiftelra 
Jiidae  fi-iT  fnU  r-articular  Li^^- 
F^Ctt  for  liorly  of  lout,r  Dprsal  Vert 

Jot  tratuv.proc.  ef  lotmr  SotiO-''  ' ^ 


•wards  in  front  of  it.  This  surface  is  marked  by  a  ridge,  which  commences  at 
the  lower  extremity  of  the  head ;  it  is  strongly  marked  as  far  as  the  inner  side 
of  the  angle,  and  gradually  becomes  lost  at  the  junction  of  the  anterior  with 
the  middle  third  of  the  bone.  The  interval  between  it  and  the  inferior  border 
is  deeply  grooved,  to  lodge  the  intercostal  vessels  and  nerve.  At  the  back  part 
of  the  bone,  this  groove  belongs  to  the  inferior  border,  but  just  in  front  of  the 
angle,  where  it  is  deepest  and  broadest,  it  corresponds  to  the  internal  surface. 
The  superior  edge  of  the  groove  is  rounded ;  it  serves  for  the  attachment  of 
the  Internal  Intercostal  muscle.  The  inferior  edge  corresponds  to  the  lower 
margin  of  the  rib,  and  gives  attachment  to  the  External  Intercostal.  Withiu 
the  groove  are  seen  the  orifices  of  numerous  small  foramina,  which  traverse 
the  wall  of  the  shaft  obliquely  from  before  backwards.  The  superior  border, 
thick  and  rounded,  is  marked  by  an  external  and  an  internal  lip,  more  distinct 
behind  than  in  front ;  they  serve  for  tlie  attachment  of  the  External  and  Inter- 
nal Intercostal  muscles.  The  inferior  border,  thin  and  sharp,  has  attached  the 
External  Intercostal  muscle.  The  anterior  or  sternal  extremity  is  flattened, 
and  presents  a  porous  oval  concave  depression,  into  which  the  costal  cartilage 
is  received. 

Pecxdiar  Bibs.  The  ribs  which  require  especial  consideration  are  five  in 
number,  viz.,  the  first,  second,  tenth,  eleventh,  and  twelfth. 

The  first  rib  (Fig.  144)  is  one  of  the  shortest  and  the  most  curved  of  all  the 
ribs;  it  is  broad,  flat,  and  placed  horizontally  at  the  upper  part  of  the  thorax, 
its  surfaces  looking  upwards  and  downwards,  and  its  borders  inwards  and  out- 
wards. The  head  is  of  small  size,  rounded,  and  presents  only  a  single  articular 
facet  for  articulation  with  the  body  of  the  first  dorsal  vertebra.  The  neck  is 
narrow  and  rounded.  The  tuberosity,  thick  and  prominent,  rests  on  the  outer 
border.  There  is  no  angle,  and  the  shaft  is  not  twisted  on  its  axis.  The  upper 
surface  of  the  shaft  is  marked  by  two  shallow  depressions,  separated  from  one 
another  by  a  ridge,  which  becomes  more  prominent  towards  the  internal  border, 
where  it  terminates  in  a  tubercle:  this  tubercle  and  ridge  serve  for  the  attach- 
ment of  the  Scalenus  Anticus  muscle,  the  groove  in  front  of  it  transmitting  the 
subclavian  vein;  that  behind  it,  the  subclavian  artery.  Between  the  groove 
for  the  subclavian  artery  and  the  tuberosity  is  a  depression  for  the  attachment 
of  the  Scalenus  Medius  muscle.  The  under  surface  is  smooth,  and  destitute  of 
the  groove  observed  on  the  other  ribs.  The  outer  border  is  convex,  thick,  and 
rounded;  the  inner,  concave,  thin,  and  sharp,  and  marked  about  its  centre  b}' 
the  tubercle  before  mentioned.  The  anterior  extremity  is  larger  and  thicker  than 
any  of  the  other  ribs. 

The  second  rib  (Fig.  145)  is  much  longer  than  the  first,  but  bears  a  very  con- 
siderable resemblance  to  it  in  the  direction  of  its  curvature.  The  non-articular 
portion  of  the  tuberosity  is  occasionally  only  slightly  marked.  The  angle  is 
slight,  and  situated  close  to  the  tuberosity,  and  the  shaft  is  not  twisted,  so  that 
both  ends  touch  any  plane  surface  upon  which  it  may  be  laid.  The  shaft  is  not 
horizontal,  like  that  of  the  first  rib;  its  outer  surface,  which  is  convex,  looking 


THE    RIBS. 


197 


upwards  and  a  little  outwards.  It  presents,  near  the  middle,  a  rough  eminence 
for  the  attachment  of  part  of  the  second  and  third  digitations  of  the  Serratus 
Magnus.  The  inner  surface^  smooth  and  concave,  is  directed  downwards  and  a 
little  inwards:  it  presents  a  short  groove  towards  its  posterior  part. 


Fig.  144 


Fig.  145 


Unclose  to  tuMcrosi 


fiun^ 


U  <n^*' 


Fig.  146. 
Si>i<f  Ic  u/rUr.  Ula/r  ffted: 

Fig.  147. 


^inglt  artie.  Jkee;t  ^ 

Fig.  148, 
,y<V?y/c    or  tic.  fae. 


The  tenth  rib  (Fig.  146)  has  only  a  single  articular  facet  on  its  head. 

The  eleventh  and  twelfth  ribs  (Figs.  147  and  148)  have  each  a  single  articular 
facet  on  the  head,  which  is  of  rather  large  size;  they  have  no  neck  or  tuber- 
osity, and  are  pointed  at  the  extremity.  The  eleventh  has  a  slight  angle  and 
a  shallow  groove  on  the  lower  border.  The  twelfth  has  neither,  and  is  much 
shorter  than  the  eleventh. 


198  THE    SKELETON. 

Structure.  The  ribs  consist  of  cancellous  tissue,  inclosed  in  a  thin  compact 
layer. 

Development.  Each  rib,  with  the  exception  of  the  last  two,  is  developed  by 
three  centres,  one  for  the  shaft,  one  for  the  head,  and  one  for  the  tubercle.  The 
last  two  have  only  two  centres,  that  for  the  tubercle  being  wanting.  Ossification 
commences  in  the  body  of  the  ribs  at  a  very  early  period,  before  its  appearance 
in  the  vertebrae.  The  epiphysis  of  the  head,  which  is  of  a  slightly  angular 
shape,  and  that  for  the  tubercle,  of  a  lenticular  form,  make  their  appearance 
between  the  sixteenth  and  twentieth  years,  and  are  not  united  to  the  rest  of  the 
bone  until  about  the  twenty-fifth  year. 

Attachment  of  Muschs.  The  Intercostals,  Scalenus  Anticus,  Scalenus  Medius, 
Scalenus  Posticus,  Pectoralis  Minor,  Serratus  Magnus,  Obliquus  Externus, 
Trans-versalis,  Quadratus  Lumborum,  Diaphragm,  Latissimus  Dorsi,  Serratus 
Posticus  Superior,  Serratus  Posticus  Inferior,  Sacro-lumbalis,  Musculus  Acces- 
sorius  ad  Sacro-lumbalera,  Longissimus  Dorsi,  Cervicalis  Ascendens,  Levatores 
Costarum. 

The  Costal  Caetilages. 

The  Costal  Cartilages  (Fig.  136)  are  white  elastic  structures,  which  serve  to 
prolong  the  ribs,  forward  to  the  front  of  the  chest,  and  contribute  very  ma- 
terially to  the  elasticity  of  its  walls.  The  first  seven  are  connected  with  the 
sternum,  the  next  three  with  the  lower  border  of  the  cartilage  of  the  preceding 
rib.  The  cartilages  of  the  last  two  ribs,  which  have  pointed  extremities,  float 
freely  in  the  walls  of  the  abdomen.  Like  the  ribs,  the  costal  cartilages  vary 
in  their  length,  breadth,  and  direction.  They  increase  in  length  from  the  first 
to  the  seventh,  then  gradually  diminish  to  the  last.  They  diminish  in  breadth, 
as  well  as  the-  intervals  between  them,  from  the  first  to  the  last.  They  are 
broad  at  their  attachment  to  the  ribs,  and  taper  towards  their  sternal  extremi- 
ties, excepting  the  first  two,  which  are  of  the  same  breadth  throughout,  and  the 
sixth,  seventh,  and  eighth,  which  are  enlarged  where  their  margins  are  in  con- 
tact. In  direction  they  also  vary;  the  first  descends  a  little,  the  second  is  hori- 
zontal, the  third  ascends  slightly,  whilst  all  the  rest  follow  the  course  of  the 
ribs  for  a  short  extent,  and  then  ascend  to  the  sternum  or  preceding  cartilage. 
Each  costal  cartilage  presents  two  surfaces,  two  borders,  and  two  extremities. 
The  anterior  surface  is  convex,  and  looks  forwards  and  upwards;  that  of  the 
first  gives  attachment  to  the  costo-clavicular  ligament;  that  of  the  first,  second, 
third,  fourth,  fifth,  and  sixth,  at  their  sternal  ends,  to  the  Pectoralis  Major.  The 
others  are  covered  by,  and  give  partial  attachment  to,  some  of  the  great  flat 
muscles  of  the  abdomen.  The  posterior  surface  is  concave,  and  directed  back- 
wards and  downwards,  the  six  or  seven  inferior  ones  aftbrding  attachment  to 
the  Transversalis  muscle  and  the  Diaphragm.  Of  the  two  borders,  the  superior 
is  concave;  the  inferior  convex;  they  afford  attachment  to  the  Intercostal 
muscles,  the  upper  border  of  the  sixth  giving  attachment  to  the  Pectoralis 
Major  muscle.  The  contiguous  borders  of  the  sixth,  seventh,  and  eighth,  and 
sometimes  the  ninth  and  tenth  costal  cartilages  present  smooth  oblong  surfaces 
at  the  points  where  they  articulate.  Of  the  two  extremities,  the  outer  one  is 
continuous  with  the  osseous  tissue  of  the  rib  to  which  it  belongs.  The  inner 
extremity  of  the  first  is  continuous  with  the  sternum;  the  six  succeeding  ones 
have  rounded  extremities,  which  are  received  into  shallow  concavities  on  thai 
lateral  margins  of  the  sternum.  The  inner  extremities  of  the  eighth,  ninth,  and  * 
tenth  costal  cartilages  are  pointed,  and  lie  in  contact  with  the  cartilage  above. 
Those  of  the  eleventh  and  twelfth  are  free,  and  pointed. 

The  costal  cartilages  are  most  elastic  in  youth,  those  of  the  false  ribs  being 
more  so  than  the  true.  In  old  age,  they  become  of  a  deep  yellow  color.  Under 
certain  diseased  conditions  they  are  prone  to  ossify.  Dr.  Humphry's  observa- 
tions on  this  subject  have  led  him  to  regard  the  ossification  of  the  costal  car- 
tilages as  a  sign  of  disease  rather  than  of  age.     "The  ossification  takes  place 


I 


CLAYICLE.  199 

in  the  first  cartilage  sooner  than  in  the  others ;  and  in  men  more  frequently, 
and  at  an  earlier  period  of  life  than  in  women." 

Attachment  of  Mxiscles.  The  Subclavius,  Sterno-thyroid,  Pectoralis  Major, 
Internal  Oblique,  Transversalis,  Rectus,  Diaphragm,  Triangularis  Sterni,  Inter- 
nal and  External  Intercostals. 

OF  THE  EXTREMITIES. 

The  Extremities,  or  limbs,  are  those  long-jointed  appendages  of  the  body, 
which  are  connected  to  the  trunk  by  one  end,  and  free  in  the  rest  of  their  ex- 
tent. They  axQfour  in  number  :  an  upper  or  thoracic  pair,  connected  with  the 
thorax  through  the  intervention  of  the  shoulder,  and  subservient  mainly  to 
tact  and  prehension ;  and  a  lower  pair,  connected  with  the  pelvis,  intended  for 
support  and  locomotion.  Both  pairs  of  limbs  are  constructed  after  one  common 
type,  so  that  they  present  numerous  analogies  ;  while  at  the  same  time  certain 
differences  are  observed  in  each,  dependent  on  the  peculiar  offices  they  perform. 

OF  THE  UPPER  EXTREMITY. 

The  Upper  Extremity  consists  of  the  Arm,  the  Forearm,  and  the  Hand.  Its 
continuity  with  the  trunk  is  established  by  means  of  the  Shoulder,  which  is 
homologous  with  the  innominate  or  haunch  bone  in  the  lower  limb. 

The  Shoulder  is  placed  upon  the  upper  part  and  side  of  the  chest,  connect- 
ing the  upper  extremity  to  the  trunk ;  it  consists  of  two  bones,  the  Clavicle, 
and  the  Scapula. 

The  Clavicle. 

The  Clavicle  {clavis,  a  "key"),  or  collar-bone,  forms  the  anterior  portion  of 
the  shoulder.  It  is  a  long  bone,  curved  somewhat  like  the  italic  letter/,  and 
placed  nearly  horizontally  at  the  upper  and  anterior  part  of  the  thorax,  imme- 
diately above  the  first  rib.  It  articulates  by  its  inner  extremity  with  the  upper 
border  of  the  sternum,  and,  by  its  outer  extremity,  with  the  acromion  process 
of  the  scapula ;  serving  to  sustain  the  upper  extremity  in  the  various  positions 
which  it  assumes,  whilst,  at  the  same  time,  it  allows  of  great  latitude  of  motion 
in  the  arm.  The  clavicle  is  nearly  horizontal.  It  presents  a  double  curvature, 
when  looked  at  in  front;  the  convexity  being  forwards  at  the  sternal  end,  and 
the  concavity  at  the  scapular  end.  Its  outer  third  is  flattened  from  above  down- 
wards, and  extends  in  the  natural  position  of  the  bone,  from  the  coracoid  pro- 
cess to  the  acromion.  Its  inner  two-thirds  are  of  a  cylindrical  form,  and  extend 
from  the  sternum  to  the  coracoid  process  of  the  scapula. 

External  or  Flattened  Portion.  The  outer  third  is  flattened  from  above  down- 
wards, so  as  to  present  two  surfaces,  an  upper  and  a  lower ;  and  two  borders, 
an  anterior  and  a  posterior.  The  iqyper  surface  is  flattened,  rough,  marked  by 
impressions  for  the  attachment  of  the  Deltoid  in  front,  and  the  Trapezius  be- 
hind :  between  these  two  impressions,  externally,  a  small  portion  of  the  bone 
is  subcutaneous.  The  under  surface  is  flattened.  At  its  posterior  border,  where 
the  prismatic  joins  with  the  flattened  portion,  is  a  rough  eminence,  the  conoid 
tubercle ;  this,  in  the  natural  position  of  the  bone,  surmounts  the  coracoid  pro- 
cess of  the  scapula,  and  gives  attachment  to  the  conoid  ligament.  From  this 
tubercle,  an  oblique  line,  occasionally  a  depression,  passes  forward's  and  out- 
wards to  near  the  outer  end  of  the  anterior  border ;  it  is  called  the  oblique  line^ 
and  affords  attachment  to  the  trapezoid  ligament.  The  anterior  border  is  con- 
cave, thin,  and  rough ;  it  limits  the  attachment  of  the  Deltoid,  and  occasionall}/ 
presents,  near  the  centre,  a  tubercle,  the  deltoid  tubercle^  which  is  sometimes  dis- 
tinct in  the  living  subject.  The  posterior  border  is  convex,  rough,  broader  than 
the  anterior,  and  gives  attachment  to  the  Trapezius. 


200 


THE    SKELETON. 


Internal  or  Cylindrical  Portion.  The  cylindrical  portion  forms  the  inner  two- 
thirds  of  the  bone.  It  is  curved,  so  as  be  convex  in  front,  concave  behind,  and 
is  marked  by  three  borders  separating  three  surfaces.  The  anterior  border  is 
continuous  with  the  anterior  margin  of  the  flat  portion.  At  its  commencement 
it  is  smooth  and  corresponds  to  the  interval  between  the  attachment  of  the  Pec- 
toralis  Major  and  Deltoid  muscles;  about  the  centre  of  the  clavicle  it  divides 
to  inclose  an  elliptical  space  for  the  attachment  of  the  clavicular  portion  of  the 
Pectoralis  Major.  This  space  extends  inwards  as  far  as  the  anterior  margin  of 
the  sternal  extremity.  The  superior  harder  is  continuous  with  the  posterior 
margin  of  the  flat  portion,  and  separates  the  anterior  from  the  posterior  surface. 
At  its  commencement  it  is  smooth  and  rounded,  becomes  rough  towards  the 
inner  third  for  the  attachment  of  the  Sterno-mastoid  muscle,  and  terminates  at 
the  upper  angle  of  the  sternal  extremity.  The  jyosterior  or  subclavian  border 
separates  the  posterior  from  the  inferior  surface,  and  extends  from  the  conoid 
tubercle  to  the  rhomboid  impression.  It  forms  the  posterior  boundary  of  the 
groove  for  the  Subclavius  muscle,  and  gives  attachment  to  the  fascia  which 
incloses  that  muscle.  The  anterior  surface  is  included  between  the  superior  and 
anterior  borders.  It  is  directed  forwards  and  a  little  upwards  at  the  sternal 
end,  outwards  and  still  more  upwards  at  the  acromial  extremity,  where  it  be- 
comes continuous  with  the  upper  surface  of  the  flat  portion.  Externally,  it  is 
smooth,  convex,  nearly  subcutaneous,  being  covered  only  by  the  Platysma; 
but  corresponding  to  the  inner  half  of  the  bone,  it  is  divided  by  a  more  or  less 
prominent  line  into  two  parts :  an  anterior  portion,  elliptical  in  form,  rough, 
and  slightly  convex,  for  the  attachment  of  the  Pectoralis  Major;  and  an  upper 
part,  which  is  rough  behind,  for  the  attachment  of  the  Sterno-cleido-mastoid. 
Between  the  two  muscular  impressions  is  a  small  subcutaneous  interval.     The 


Fig.  149. — Left  Clavicle.    Anterior  Surface. 


Ster^tilJExi, 


rfmtty 


Fromitt.1  I^xtJf 


Fig.  150. — Left  Clavicle.     Inferior  Surface. 


posterior  or  cervical  surface  is  smooth,  flat,  directed  vertically,  and  looks  back! 
wards  towards  the  root  of  the  neck.  It  is  limited,  above,  by  the  superior  bor* 
der;  below,  by  the  subclavian  border;  internally,  by  the  margin  of  the  sternal 
extremity ;  externally,  it  is  continuous  with  the  posterior  border  of  the  flat 
portion.  It  is  concave  from  within  outwards,  and  is  in  relation,  by  its  lower 
part,  with  the  suprascapular  vessels.     It  gives  attachment,  near  the  sternal 


CLAVICLE.  201 

extremity,  to  part  of  the  Sterno-hyoid  muscle ;  and  presents,  at  or  near  the 
middle,  a  foramen,  directed  obliquely  outwards,  which  transmits  the  chief 
nutrient  artery  of  the  bone.  Sometimes,  there  are  two  foramina  on  the  poste- 
rior surface,  or  one  on  the  posterior,  the  other  on  the  inferior  surface.  The 
inferior  or  subclavian  surface  is  bounded,  in  front,  by  the  anterior  border;  be- 
hind by  the  subclavian  border.  It  is  narrow  internally,  but  gradually  increases 
in  width  externally,  and  is  continuous  with  the  under  surface  of  the  flat  por- 
tion. Commencing  at  the  sternal  extremity  may  be  seen  a  small  facet  for  arti- 
culation with  the  cartilage  of  the  first  rib.  This  is  continuous  with  the  articular 
surface  at  the  sternal  end  of  the  bone.  External  to  this  is  a  broad  rough  im- 
pression, the  rhomboid,  rather  more  than  an  inch  in  length,  for  the  attachment 
of  the  costa-clavicular  (rhomboid)  ligament.  The  remaining  part  of  this  sur- 
face is  occupied  by  a  longitudinal  groove,  the  subclavian  groove,  broad  and 
smooth  externally;  narrow  and  more  uneven  internally;  it  gives  attachment 
to  the  Subclavius  muscle,  and,  by  its  anterior  margin,  to  the  strong  aponeu- 
rosis which  incloses  it.  Not  unfrequently  this  groove  is  subdivided  into  two 
parts,  by  a  longitudinal  line,  which  gives  attachment  to  the  intermuscular 
septum  of  the  Subclavius  muscle. 

The  internal  or  sternal  end  of  the  clavicle  is  triangular  in  form,  directed  in- 
wards, and  a  little  downwards  and  forwards;  and  presents  an  articular  facet, 
concave  from  before  backwards,  convex  from  above  downwards,  which  articu- 
lates with  the  sternum  through  the  intervention  of  an  inter-articular  fibro-car- 
tilage;  the  circumference  of  the  articular  surface  is  rough,  for  the  attachment 
of  numerous  ligaments.  This  surface  is  continuous  with  the  costal  facet  on  the 
inner  end  of  the  inferior  or  subclavian  surface,  which  articulates  with  the  car- 
tilage of  the  first  rib. 

The  outer  or  acromial  extremity,  directed  outwards  and  forwards,  presents  a 
small,  flattened,  oval  facet,  which  looks  obliquely  downwards  and  inwards,  for 
articulation  with  the  acromion  process  of  the  scapula.  The  direction  of  this 
surface  serves  to  explain  the  greater  frequency  of  dislocation  upwards  rather 
than  downwards,  beneath  the  acromion  process.  The  circumference  of  the  arti- 
cular facet  is  rough,  especially  above,  for  the  attachment  of  the  acromio-clavi- 
cular  ligaments. 

Peculiarities  of  the  Bone  in  the  Sexes  and  in  Individuals.  In  the  female,  the 
clavicle  is  generally  less  curved,  smoother,  and  more  slender  than  in  the  male. 
In  those  persons  who  perform  considerable  manual  labor,  which  brings  into 
constant  action  the  muscles  connected  with  this  bone,  it  acquires  considerable 
bulk,  becomes  shorter,  more  curved,  its  ridges  for  muscular  attachment  become 
prominently  marked,  and  its  sternal  end  of  a  prismatic  form.  The  right  cla- 
vicle is  generally  heavier,  thicker,  and  rougher,  and  often  shorter,  than  the  left. 

Structure.  The  shaft,  as  well  as  the  extremities,  consists  of  cancellous  tissue, 
invested  in  a  compact  layer  much  thicker  in  the  centre  than  at  either  end.  The 
clavicle  is  highly  elastic,  by  reason  of  its  curves.  From  the  experiments  of  Mr. 
Ward,  it  has  been  shown  that  it  possesses  sufficient  longitudinal  elastic  force  to 
project  its  own  weight  nearly  two  feet  on  a  level  surface,  when  a  smart  blow  is 
struck  on  it,  and  sufficient  transverse  elastic  force,  opposite  the  centre  of  its 
anterior  convexity,  to  throw  its  own  weight  about  a  foot.  This  extent  of  elastic 
power  must  serve  to  moderate  very  considerably  the  effect  of  concussions  re- 
ceived upon  the  point  of  the  shoulder. 

Development.  By  two  centres:  one  for  the  shaft,  and  one  for  the  sternal 
extremity.  The  centre  for  the  shaft  appears  very  early,  before  any  other  bone ; 
the  centre  for  the  sternal  end  makes  its  appearance  about  the  eighteenth  or 
twentieth  year,  and  unites  with  the  rest  of  the  bone  a  few  years  after. 

Articulations.     With  the  sternum,  scapula,  and  cartilage  of  the  first  rib. 

Attachment  of  Mtiscles.  The  Sterno-cleido-mastoid,  Trapezius,  Pectoralis 
Major,  Deltoid,  Subclavius,  and  Sterno-hyoid. 


202 


THE    SKELETON. 


The  Scapula.     ' 

The  Scapula  forms  the  back  part  of  the  shoulder.  It  is  a  large  flat  bone, 
triangular  in  shape,  situated  at  the  posterior  aspect  and  side  of  the  thorax,  be- 
tween the  first  and  eighth  ribs,  its  posterior  border  or  base  being  about  an  inch 
from,  and  nearly  parallel  with,  the  spinous  processes  of  the  vertebrae.  It  pre- 
sents for  examination  two  surfaces,  three  borders,  and  three  angles. 

The  anterior  surface^  or  venter  (Fig.  151),  presents  a  broad  concavity,  the  sub- 
scapular fossa.     It  is  marked,  in  the  posterior  two-thirds,  by  several  oblique 

Fig.  151. — Left  Scapula.    Anterior  Surface,  or  Venter. 


1 


ridges,  which  pass  from  behind  obliquely  outwards  and  upwards,  the  anterior 
third  being  smooth.  The  oblique  ridges  give  attachment  to  the  tendinous  in- 
tersections, and  the  surfaces  between  them,  to  tlie  fleshy  fibres,  of  the  Sub- 
scapularis  muscle.  The  anterior  third  of  the  fossa,  which  is  smooth,  is  covered 
by,  but  does  not  afford  attachment  to,  the  fibres  of  this  muscle.  This  surface 
is  separated  from  tlie  po.sterior  border  by  a  smooth  triangular  margin  at  the 
superior  and  inferior  angles,  and  in  the  interval  between  these  by  a  narrow 


I 


SCAPULA. 


203 


edge  wliicli  is  often  deficient.  This  marginal  surface  affords  attachment  through- 
out its  entire  extent  to  the  Serratus  Magnus  muscle.  The  subscapular  fossa 
presents  a  transverse  depression  at  its  upper  part,  called  the  subscapular  angle ; 
it  is  in  this  situation  that  the  fossa  is  deepest ;  so  that  the  thickest  part  of  the 
Subscapularis  muscle  lies  in  a  line  parallel  with  the  glenoid  cavity,  and  must 
consequently  operate  most  eflectively  on  the  humerus  which  is  contained  in 
that  cavity. 

The  posterior  surface,  or  dorsum  (Fig.  152),  is  arched  from  above  downwards, 
alternately  convex  and  concave  from  side  to  side.     It  is  subdivided  unequally 


ee^g 


Fig.  152. — Left  Scapula.    Posterior  Surface,  or  Dorsum. 
Co  reeco  »V 


eftQif 


into  two  parts  by  the  spine ;  the  portion  above  the  spine  is  called  the  supra- 
spinous fossa,  and  that  below  it,  the  infraspinous  fossa. 

The  supraspinous  fossa,  the  smaller  of  the  two,  is  concave,  smooth,  and 
broader,  at  the  vertebral  than  at  the  humeral  extremity.  It  affords  attachment 
by  its  inner  two-thirds  to  the  Supraspinatus  muscle. 


204  THE    SKELETON. 

The  infraspinous  fossa  is  much  larger  than  the  preceding ;  towards  its  verte- 
bral margin  a  shallow  concavity  is  seen  at  its  upper  part ;  its  centre  presents  a 
prominent  convexity,  whilst  towards  the  axillary  border  is  a  deep  groove, 
which  runs  from  the  upper  towards  the  lower  part.  The  inner  two-thirds 
of  this  surface  afford  attachment  to  the  infraspinatus  muscle;  the  outer  fourth 
is  only  covered  by  it,  without  giving  origin  to  its  fibres.  This  surface  is 
separated  from  the  axillary  border  by  an  elevated  ridge,  which  runs  from  the 
lower  part  of  the  glenoid  cavity,  downwards  and  backwards  to  the  posterior 
border,  about  an  inch  above  the  inferior  angle.  The  ridge  serves  for  the 
attachment  of  a  strong  aponeurosis,  which  separates  the  Infraspinatus  from  the 
two  Teres  muscles.  The  surface  of  bone  between  this  line  and  the  axillary 
border  is  narrow  in  the  upper  two-thirds  of  its  extent,  and  traversed  near  its 
centre  by  a  groove  for  the  passage  of  the  dorsalis  scapula)  vessels ;  it  affords 
attachment  to  the  Teres  Minor.  Its  lower  third  presents  a  broader,  somewhat 
triangular  surface,  which  gives  origin  to  the  Teres  Major,  and  over  Avhich 
glides  the  Latissimus  Dorsi ;  sometimes  the  latter  muscle  takes  origin  by  a  few 
fibres  from  this  part.  The  broad  and  narrow  portions  of  bone  above  alluded 
to  are  separated  by  an  oblique  line,  which  runs  from  the  axillary  border, 
downwards  and  backwards;  to  it  is  attached  the  aponeurosis  separating  the 
two  Teres  muscles  from  each  other. 

The  spine  is  a  prominent  plate  of  bone,  which  crosses  obliquely  the  inner 
four-fifths  of  the  dorsum  of  the  scapula  at  its  upper  part,  and  separates  the 
supra  from  the  infraspinous  fossa ;  it  commences  at  the  vertebral  border  by  a 
smooth  triangular  surface,  over  which  the  Trapezius  glides,  separated  from  the 
bone  by  a  bursa;  and,  gradually  becoming  more  elevated  as  it  passes  forwards, 
terminates  in  the  acromion  process  which  overhangs  the  shoulder  joint.  The 
spine  is  triangular  and  flattened  from  above  downwards,  its  apex  corresponding 
to  the  posterior  border ;  its  base,  which  is  directed  outwards,  to  the  neck  of 
the  scapula.  It  presents  two  surfaces  and  three  borders.  Its  superior  surface 
is  concave,  assists  in  forming  the  supraspinous  fossa,  and  affords  attachment  to 
part  of  the  Supraspinatus  muscle.  Its  inferior  surface  forms  part  of  the  infra- 
spinous fossa,  gives  origin  to  part  of  the  Infraspinatus  muscle,  and  presents 
near  its  centre  the  orifice  of  a  nutrient  canal.  Of  the  three  borders,  the 
anterior  is  attached  to  the  dorsum  of  the  bone ;  the  posterior,  or  crest  of  the 
spine,  is  broad,  and  presents  two  lips,  and  an  intervening  rough  interval.  I'o 
the  superior  lip  is  attached  the  Trapezius,  to  the  extent  shown  in  the  figure. 
A  very  rough  prominence  is  generally  seen  occupying  that  portion  of  the 
spine  which  receives  the  insertion  of  the  middle  and  inferior  fibres  of  this 
muscle.  To  the  inferior  lip,  throughout  its  whole  length,  is  attached  the 
Deltoid.  The  interval  between  the  lips  is  also  partly  covered  by  the  fibres  of 
these  muscles.  The  external  border,  the  .shortest  of  the  three,  is  slightly  con- 
cave, its  edges  thick  and  round,  continuous  above  with  the  under  surface  of 
the  acromion  process;  below,  with  the  neck  of  the  scapula.  The  narrow 
portion  of  bone  external  to  this  border  serves  to  connect  the  supraspinous 
and  infraspinous  fossee. 

The  acromion  process,  so  called  from  forming  the  summit  of  the  shoulder 
(oxpov,  a  summit;  ^^not,  the  shoulder),  is  a  large  and  somewhat  triangular  process, 
flattened  from  behind  forwards,  directed  at  first  a  little  outwards,  and  then 
curving  forwards  and  upwards,  so  as  to  overhang  the  glenoid  cavity.  Its  upper 
surface,  directed  upwards,  backwards,  and  outwards,  is  convex,  rough,  and  gives 
attachment  to  some  fibres  of  the  Deltoid.  Its  under  surface  is  smooth  and  con- 
cave. Its  outer  border,  which  is  thick  and  irregular,  affords  attachment  to  the 
Deltoid  muscle.  Its  inner  margin,  shorter  than  the  outer,  is  concave,  gives 
attachment  to  a  portion  of  the  Trapezius  muscle,  and  presents  about  its  centre 
a  small  oval  surface,  for  articulation  with  the  scapular  end  of  the  clavicle.  Its 
apex,  which  corresponds  to  the  point  of  meeting  of  these  two  borders  in  front, 
is  thin,  and  has  attached  to  it  the  coraco-acromial  ligament. 


SCAPULA.  205 

Of  the  three  borders  or  coslse  of  the  scapula,  the  superior  is  the  shortest  and 
thinnest;  it  is  concave,  terminating  at  its  inner  extremity  at  the  superior  angle, 
at  its  outer  extremity  at  the  coracoid  process.  At  its  outer  part  is  a  deep  semi- 
circular notch,  the  suprascapular,  formed  partly  by  the  base  of  the  coracoid 
process.  This  notch  is  converted  into  a  foramen  by  the  transverse  ligament, 
and  serves  for  the  passage  of  the  suprascapular  nerve.  The  adjacent  margin 
of  the  superior  border  affords  attachment  to  the  Omo-hyoid  muscle.  The 
external  or  axillary  border  is  the  thickest  of  the  three.  It  commences  above  at 
the  lower  margin  of  the  glenoid  cavity,  and  inclines  obliquely  downwards  and 
backwards  to  the  inferior  angle.  Immediately  below  the  glenoid  cavity  is  a 
rough  depression  about  an  inch  in  length,  which  affords  attachment  to  the  long 
head  of  the  Triceps  muscle ;  to  this  succeeds  a  longitudinal  groove,  which 
extends  as  far  as  its  lower  third,  and  affords  origin  to  part  of  the  Subscapularis 
muscle.  The  inferior  third  of  this  border  which  is  thin  and  sharp,  serves  for 
the  attachment  of  a  few  fibres  of  the  Teres  Major  behind,  and  of  the  Subscapu- 
laris in  front.  The  internal  or  vertebral  border^  also  named  the  base,  is  the 
longest  of  the  three,  and  extends  from  the  superior  to  the  inferior  angle  of 
the  bone.  It  is  arched,  intermediate  in  thickness  between  the  superior  and 
the  external  borders,  and  the  portion  of  it  above  the  spine  is  bent  considerably 
outwards,  so  as  to  form  an  obtuse  angle  with  the  lower  part.  The  vertebral 
border  presents  an  anterior  lip,  a  posterior  lip,  and  an  intermediate  space.  The 
anterior  lip  affords  attachment  to  the  Serratus  Magnus;  the  posterior  lip^  to  the 
Supraspinatus  above  the  spine,  the  Infraspinatus  below;  the  interval  between 
the  two  lips,  to  the  Levator  Anguli  Scapulae  above  the  triangular  surface  at 
the  commencement  of  the  spine;  the  Ehomboideus  Minor,  to  the  edge  of  that 
surface ;  the  Ehomboideus  Major  being  attached  by  means  of  a  fibrous  arch, 
connected  above  to  the  lower  part  of  the  triangular  surface  at  the  base  of  the 
spine,  and  below  to  the  lower  part  of  the  posterior  border. 

Of  the  three  angles^  the  superior^  formed  by  the  junction  of  the  superior  and 
internal  borders,  is  thin,  smooth,  rounded,  somewhat  inclined  outwards,  and 
gives  attachment  to  a  few  fibres  of  the  Levator  Anguli  Scapulae  muscle.  The 
inferior  angle,  thick  and  rough,  is  formed  by  the  union  of  the  vertebral  and 
axillary  borders,  its  outer  surface  affording  attachment  to  the  Teres  Major, 
and  occasionally  a  few  fibres  of  the  Latissimus  Dorsi.  The  anterior  angle  is 
the  thickest  part  of  the  bone,  and  forms  what  is  called  the  head  of  the  scapula, 
'i'he  head  presents  a  shallow,  pyriform,  articular  surface,  the  glenoid  cavity  (y?t»ivj;, 
a  socket),  whose  longest  diameter  is  from  above  downwards,  and  its  direction 
outwards  and  forwards.  It  is  broader  below  than  above ;  at  its  apex  is  attached 
the  long  tendon  of  the  Biceps  muscle.  It  is  covered  with  cartilage  in  the  recent 
state;  and  its  margins,  slightly  raised,  give  attachment  to  a  fibro-cartilaginous 
structure,  the  glenoid  ligament,  by  which  its  cavity  is  deepened.  The  neck  of 
the  scapula  is  the  slightly  depressed  surface  which  surrounds  the  head;  it  is 
more  distinct  on  the  posterior  than  on  the  anterior  surface,  and  below  than 
above.  In  the  latter  situation,  it  has,  arising  from  it,  a  thick  prominence,  the 
coracoid  process. 

The  coracoid  process,  so  called  from  its  fancied  resemblance  to  a  crow's  beak 
(xopaf,  a  crow),  is  a  thick  curved  process  of  bone,  which  arises  by  a  broad  base 
from  the  upper  part  of  the  neck  of  the  scapula;  it  ascends  at  first  upwards  and 
inwards;  then,  becoming  smaller,  it  changes  its  direction,  and  passes  forwards 
and  outwards.  The  ascending  portion,  flattened  from  before  backwards,  pre- 
sents in  front  a  smooth  concave  surface,  over  which  passes  the  Subscapularis 
muscle.  The  horizontal  portion  is  flattened  from  above  downwards;  its  upper 
surface  is  convex  and  irregular;  its  under  surface  is  smooth;  its  anterior  border 
is  rough,  and  gives  attachment  to  the  Pectoralis  Minor;  its  posterior  boraer  Vs 
also  rough  for  the  coraco-acromial  ligament,  while  the  apex  is  embraced  by  the 
conjoined  tendon  of  origin  of  the  short  head  of  the  Biceps  and  Coraco-brachialis 
muscles.     At  the  inner  side  of  the  root  of  the  coracoid  process  is  a  rough 


206 


THE    SKELETON. 


depression  for  the  attachment  of  the  conoid  ligament,  and,  running  fr<^  it 
obiiquely  forwards  and  outwards  on  the  upper  surface  of  the  horizontal  portion, 
an  elevated  ridge  for  the  attachment  of  the  trapezoid  ligament. 

Structure.  In  the  head,  processes,  and  all  the  thickened  parts  of  the  bone,  it 
is  cellular  in  structure,  of  a  dense  compact  tissue  in  the  rest  of  its  extent.  The 
centre  and  upper  part  of  the  dorsum,  but  especially  the  former,  is  usually  so 
thin  as  to  be  semi-transparent;  occasionally  the  bone  is  found  wanting  in  this 
situation,  and  the  adjacent  muscles  come  into  contact. 

Development  (Fig.  153).  By  seven  centres;  one  for  the  body,  two  for  the  cora- 
coid  process,  two  for  the  acromion,  one  for  the  posterior  border,  and  one  for 

Fig.  153. — Plan  of  the  Development  of  the  Scapula.    By  Seven  Centres. 


m. 


The  epiphyses  (except  one  for  the  coracoid  process)  appear  from  fifteen  to  seventeen  yean 
and  unite  between  twenty-two  and  twenty-five  years. 

the  inferior  angle.  Ossification  of  the  body  of  the  scapula  commences  abou 
the  second  month  of  foetal  life,  by  the  formation  of  an  irregular  quadrilateral 
plate  of  bone,  immediately  behind  the  glenoid  cavity.  This  plate  extends  itself  J 
so  as  to  form  the  chief  part  of  the  bone,  the  spine  growing  up  from  its  poslH 
terior  surface  about  the  third  month.  At  birth,  the  chief  part  of  the  scapula 
is  osseous,  only  the  coracoid  and  acromion  processes,  the  posterior  border,  and 
inferior  angle  being  cartilaginous.  About  the  first  year  after  birth,  ossification 
takes  place  in  the  middle  of  the  coracoid  process;  which  usually  becomes  joined 
with  the  rest  of  the  bone  at  the  time  when  the  other  centres  make  their  appear- 
ance. Between  the  fifteenth  and  seventeenth  years,  ossification  of  the  remaining 
centres  takes  place  in  quick  succession,  and  in  the  following  order:  first,  near 
the  base  of  the  acromion,  and  in  the  root  of  the  coracoid  process,  the  latter 
appearing  in  the  form  of  a  broad  scale;  secondly,  in  the  inferior  angle  and 
contiguous  part  of  the  posterior  border;  thirdly,  near  the  extremity  of  the 
acromion;  fourthly,  in  the  posterior  border.     The  acromion  process,  besides 


I 


HUMERUS.  207 

being  formed  of  two  se[)arate  nuclei,  has  its  base  formed  by  an  extension  into 
it  of  the  centre  of  ossification  which  belongs  to  the  spine,  the  extent  of  which 
varies  in  different  cases.  The  two  separate  nuclei  unite,  and  then  join  with  the 
extension  carried  in  from  the  spine.  These  various  epiphyses  become  joined 
to  the  bone  between  the  ages  of  twenty-two  and  twenty-five  years.  Sometimes 
failure  of  union  between  the  acromion  process  and  spine  occurs,  the  junction 
being  effected  by  fibrous  tissue,  or  by  an  imperfect  articulation;  in  some  cases 
of  supposed  fracture  of  the  acromion  with  ligamentous  union,  it  is  probable 
that  the  detached  segment  was  never  united  to  the  rest  of  the  bone. 

Articulations.     With  the  humerus  and  clavicle. 

Attachment  of  Muscles.  To  the  anterior  surface,  the  Subscapularis ;  posterior 
surface,  Supraspinatus,  Infraspinatus;  spine.  Trapezius,  Deltoid;  superior  border, 
Omo-hyoid;  vertebral  border,  Serratus  Magnus,  Levator  Anguli  Scapulae, 
Ehomboideus  Minor  and  Ehomboideus  Major;  axillary  border,  Triceps,  Teres 
Minor,  Teres  Major;  glenoid  cavity,  long  head  of  the  Biceps;  coracoid  process, 
short  head  of  the  Biceps,  Coraco-brachialis,  Pectoralis  Minor;  and  to  the  in- 
ferior angle  occasionally  a  few  fibres  of  the  Latissimus  Dorsi. 

The  Humerus.  h 

The  Humerus  is  the  longest  and  largest  bone  of  the  upper  extremity;  it  pre- 
sents for  examination  a  shaft  and  two  extremities.  ,, 

The  Upper  Extremity  is  the  largest  part  of  the  bone ;  it  presents  a  rounded 
head  joined  to  the  shaft  by  a  constricted  part,  called  the  neck,  and  two  other 
eminences,  the  greater  and  lesser  tuberosities  (Fig.  154). 

The  head^  nearly  hemispherical  in  form,  is  directed  upwards,  inwards,  and  a 
little  backwards ;  its  surface  is  smooth,  coated  with  cartilage  in  the  recent  state, 
and  articulates  with  the  glenoid  cavity  of  the  scapula.  The  circumference  of 
its  articular  surface  is  slightly  constricted,  and  is  termed  the  anatomical  neck,  in 
contradistinction  to  the  constriction  which  exists  below  the  tuberosities,  and  is 
called  the  surgical  neck,  from  its  often  being  the  seat  of  fracture.  It  should  be 
remembered,  however,  that  fracture  of  the  anatomical  neck  does  sometimes, 
though  rarely,  occur. 

The  anatomical  neck  is  obliquely  directed,  forming  an  obtuse  angle  with  the 
shaft.  It  is  more  distinctly  marked  in  the  lower  half  of  its  circumference  than 
in  the  upper  half,  where  it  presents  a  narrow  groove,  separating  the  head  from 
the  tuberosities.  Its  circumference  affords  attachment  to  the  capsular  ligament, 
and  is  perforated  by  numerous  vascular  foramina. 

The  greater  tuberosity  is  situated  on  the  outer  side  of  the  head  and  lesser 
tuberosity.  Its  upper  surface  is  rounded  and  marked  by  three  flat  facets,  sepa- 
rated by  two  slight  ridges.  The  anterior  facet  gives  attachment  to  the  tendon 
of  the  Supraspinatus;  the  middle  one  to  the  Infraspinatus;  the  posterior  facet, 
and  the  shaft  of  the  bone  below  it,  to  the  Teres  Minor.  The  outer  surface  of 
the  great  tuberosity  is  convex,  rough,  and  continuous  with  the  outer  side  of  the 
shaft. 

The  lesser  tuberosity  is  more  prominent,  although  smaller  than  the  greater.  It 
is  situated  in  front  of  the  head,  and  is  directed  inwards  and  forwards.  Its 
summit  presents  a  prominent  facet  for  the  insertion  of  the  tendon  of  the  Sub- 
scapularis muscle.  The  tuberosities  are  separated  from  one  another  by  a  deep 
groove,  the  bicipital  groove,  so  called  from  its  lodging  the  long  tendon  of  the 
Biceps  muscle.  It  commences  above  between  the  two  tuberosities,  passes 
obliquely  downwards  and  a  little  inwards,  and  terminates  at  the  junction  of  the 
upper  with  the  middle  third  of  the  bone.  It  is  deep  and  narrow  at  its  com- 
mencement, and  becomes  shallowed  and  a  little  broader  as  it  descends.  In  the 
recent  state  it  is  covered  with  a  thin  layer  of  cartilage,  lined  by  a  prolongation 
of  the  synovial  membrane  of  the  shoulder-joint,  and  receives  part  of  the  ten- 
don of  insertion  of  the  Latissimus  Dorsi  about  its  centre. 


ao8 


THE    SKELETON. 

Fig.  154. — Left  Humerus.    Anterior  View. 


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SUPINATOR    RADII    lONCUI 


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of 


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>  V  CXTENIOR.CARP.IAD.  SRCV 
„    OICITD«UM  COMMUNIS 
.,     MINIMI    OICITI 
„     CARPI  UlNiRIS 
tUPIMATOR  IRCVIt 


HUMERUS.  209 

The  Shaft  of  the  humerus  is  almost  cylindrical  in  the  upper  half  of  its  ex- 
tent, prismatic  and  flattened  below,  and  presents  three  borders  and  three  surfaces 
for  examination. 

The  anterior  border  runs  from  the  front  of  the  great  tuberosity  above  to  the 
coronoid  depression  below,  separating  the  internal  from  the  external  surface. 
Its  upper  part  is  very  prominent  and  rough,  forms  the  outer  lip  of  the  bicipital 
groove,  and  serves  for  the  attachment  of  the  tendon  of  the  Pectoralis  Major. 
About  its  centre  is  seen  the  rough  deltoid  impression ;  below,  it  is  smooth  and 
rounded,  affording  attachment  to  the  Brachialis  Anticus. 

The  external  border  runs  from  the  back  part  of  the  greater  tuberosity  to  the 
external  condyle,  and  separates  the  external  from  the  posterior  surface.  It  is 
rounded  and  indistinctly  marked  in  its  upper  half,  serving  for  the  attachment 
of  the  external  head  of  the  Triceps  muscle ;  its  centre  is  traversed  by  a  broad 
but  shallow  oblique  depression,  the  musculo-spiral  groove ;  its  lower  part  is 
marked  by  a  prominent  rough  margin,  a  little  curved  from  behind  forwards, 
which  presents  an  anterior  lip  for  the  attachment  of  the  Supinator  Longus 
above  and  Extensor  Carpi  Radialis  Longior  below,  a  posterior  lip  for  the 
Triceps,  and  an  interstice  for  the  attachment  of  the  external  intermuscular 
aponeurosis. 

The  internal  border  extends  from  the  lesser  tuberosity  to  the  internal  condyle. 
Its  upper  third  is  marked  by  a  prominent  ridge,  forming  the  inner  lip  of  the 
bicipital  groove,  and  gives  attachment  from  above  downwards  to  the  tendons  of 
the  Latissimus  Dorsi,  Teres  Major,  and  part  of  the  origin  of  the  inner  head  of 
the  Triceps.  About  its  centre  is  a  rough  ridge  for  the  attachment  of  the  Coraco- 
brachialis,  and  just  below  this  is  seen  the  entrance  of  the  nutrient  canal  directed 
downwards.  Sometimes  there  is  a  second  canal  higher  up,  which  takes  a  simi- 
lar direction.  The  inferior  third  of  this  border  is  raised  into  a  slight  ridge, 
which  becomes  very  prominent  below;  it  presents  an  anterior  lip  for  the 
attachment  of  the  Brachialis  Anticus,  a  posterior  lip  for  the  internal  head  of  the 
Triceps,  and  an  intermediate  space  for  the  internal  intermuscular  aponeurosis. 

The  external  surface  is  directed  outwards  above,  where  it  is  smooth,  rounded, 
and  covered  by  the  Deltoid  muscle ;  forwards  below,  where  it  is  slightly  con- 
cave from  above  downwards,  and  gives  origin  to  part  of  the  Brachialis  Anticus 
muscle.  About  the  middle  of  this  surface  is  seen  a  rough  triangular  impres- 
sion for  the  insertion  of  the  Deltoid  muscle,  and  below  it  the  musculo-spiral 
groove,  directed  obliquely  from  behind,  forwards,  and  downwards,  and  trans- 
mitting the  musculo-spiral  nerve  and  superior  profunda  artery. 

The  internal  surface,  less  extensive  than  the  external,  is  directed  forwards 
above,  forwards  and  inwards  below ;  at  its  upper  part  it  is  narrow,  and  forms 
the  bicipitjtl  groove.  The  middle  part  of  this  surface  is  slightly  rough  for  the 
attachment  of  the  Coraco-brachialis ;  its  lower  part  is  smooth,  concave,  and 
gives  attachment  to  the  Brachialis  Anticus  muscle.^ 

The  posterior  surface  (Fig.  155)  appears  somewhat  twisted,  so  that  its  upper 
part  is  directed  a  little  inwards,  its  lower  part  backwards  and  a  little  outwards. 
Nearly  the  whole  of  this  surface  is  covered  by  the  external  and  internal  heads 
of  the  Triceps,  the  former  being  attached  to  its  upper  and  outer  part,  the  latter 

'  A  small  hook-shaped  process  of  bone,  varying  from  j'^  to  |  of  an  inch  in  length,  is  not 
unfrequently  found  projecting  from  the  inner  surface  of  the  shaft  of  the  humerus  two  inches 
above  the  internal  condyle.  It  is  curved  downwards,  forwards,  and  inwards,  and  its  pointed 
extremity  is  connected  to  the  internal  border,  just  above  the  inner  condyle,  by  a  ligament  or 
fibrous  band ;  completing  an  arch,  through  which  the  median  nerve  and  brachial  artery  pass, 
when  these  structures  deviate  from  their  usual  course.  Sometimes  the  nerve  alone  is  transmitted 
through  it,  or  the  nerve  may  be  accompanied  by  the  ulnar-interosseous  artery,  in  cases  of  high 
division  of  the  brachial.  A  well-marked  groove  is  usually  found  behind  the  process,  in  which 
the  nerve  and  artery  are  lodged.  This  space  is  analogous  to  the  supracondyloid  foramen  in 
many  animals,  and  probably  serves  in  them  to  protect  the  nerve  and  artery  from  compression 
during  the  contraction  of  the  muscles  in  this  region.  A  detailed  account  of  this  process  is 
given  by  Dr.  Struthera,  in  his  "  Anatomical  and  Physiological  Observations,"  p.  202. 
14 


210 

Fig.  155. — Left  Humerus. 
Surface. 


THE    SKELETON. 


I 


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^  i 


Mi 


w 


I 


\jro  chi 


Posterior    to  its  inner  and  back  part,  at  either  side  of  the 
musculo-spiral  groove. 

The  Lower  Extremity  is  flattened  from  be- 
fore backwards,  and  curved  slightly  forwards; 
it  terminates  below  in  a  broad  articular  sur- 
face, which  is  divided  into  two  parts  by  a 
slight  ridge.     On  either  side  of  the  articular 
surface  are  the  external  and  internal  condyles.     " 
The  articular  surface  extends  a  little  lower   | 
than  the  condyles,  and  is  curved  slightly  for-   J 
wards,  so  as  to  occupy  the  more  anterior  part  ^ 
of   the  bone;   its  greatest  breadth  is  in  the 
transverse  diameter,  and  it  is  obliquely  di- 
rected, so  that  its  inner  extremity  occupies  a 
lower  level  than  the  outer.    The  outer  portion 
of  the  articular  surface    presents  a   smooth 
rounded  eminence,  which    has   received  the 
name  of   the    hsser   or    radial    head    of   the 
humerus;  it  articulates  with  the  cup-shaped 
depression  on  the  head  of  the  radius,  and  is 
limited  to  the  front  and   lower  part  of  the 
bone,  not  extending  as  far  back  as  the  other 
portion  of  the  articular  surface.    On  the  inner 
side  of  this  eminence  is  a  shallow  groove,  in 
which  is  received  the  inner  margin  of  the 
head  of  the  radius.     The  inner  or  trochlear 
portion  of  the  articular  surface  presents  a  deep 
depression  between  two  well-marked  borders. 
This  surface  is  convex  from  before  backwards, 
concave  from  side  to  side,  and  occupies  the 
anterior   lower   and    posterior   parts   of   the 
bone.     The  external  border,  less   prominent 
than  the  internal,  corresponds  to  the  interval 
between  the  radius  and  ulna.     The  internal 
border  is  thicker,  more  prominent,  and  con- 
sequently of  greater  length  than  the  external. 
The  grooved  portion  of  the  articular  surface 
fits    accurately   within    the   greater  sigmoid    i 
cavity  of  the  ulna;  it  is  broader  and  deepeiM 
on  the  posterior  than  on  the  anterior  aspeoP^ 
of  the  bone,  and  is  directed  obliquely  from 
behind  forwards,  and  from  without  inwards. 
Above  the  back  part  of  the  trochlear  surface 
is  a  deep  triangular  depression,  the  olecranon 
fossa,  in  which  is  received  the  summit  of  thej 
olecranon  process  in  extension  of  the  forearnijH 
Above  the  front  part  of  the  trochlear  surfac^^ 
is   seen  a  smaller  depression,  the   coronoid 
fossa,  which  receives  the  coronoid  process  of 
the  ulna  during  flexion  of  the  forearm.   These 
iossas  are  separated  from  one  another  by  a 
thin  transparent   lamina   of  bone,  which   i 
sometimes  perforated;   their   margins  affor 
attachment  to  the  anterior  and  posterior  liga- 
ments of  the  elbow-joint,  and  they  are  lined 
in  the  recent  state  by  the  synovial  membrane 
of  this  articulation.     Above  the  front  part  of 


N 


HUMERUS. 


211 


the  radial  tuberosity  is  seen  a  slight  depression,  which  receives  the  anterior 
border  of  the  head  of  the  radius  when  the  forearm  is  strongly  flexed.  The 
external  condyle  is  a  small  tubercular  eminence,  less  prominent  than  the  inter- 
nal, curved  a  little  forwards,  and  giving  attachment  to  the  external  lateral 
ligament  of  the  elbow-joint,  and  to  a  tendon  common  to  the  origin  of  some  of 
the  extensor  and  supinator  muscles.  The  internal  condyle,  larger  and  more 
prominent  than  the  external,  is  directed  a  little  backwards ;  it  gives  attachment 
to  the  internal  lateral  ligament,  and  to  a  tendon  common  to  the  origin  of  some 
of  the  flexor  muscles  of  the  forearm.  These  eminences  are  directly  continuous 
above  with  the  external  and  internal  borders.  The  greater  prominence  of  the 
inner  one  renders  it  more  liable  to  fracture. 

Structure.  The  extremities  consist  of  cancellous  tissue,  covered  with  a  thin 
compact  layer;  the  shaft  is  composed  of  a  cylinder  of  compact  tissue,  thicker 
at  the  centre  than  at  the  extremities,  and  hollowed  out  by  a  large  medullary 
canal,  which  extends  along  its  whole  length. 

Development.  By  seven  centres  (Fig.  156) — one  for  the  shaft,  one  for  the 
head,  one  for  the  greater  tuberosity,  one  for  the  radial,  one  for  the  trochlear 
portion  of  the  articular  surface,  and  one  for  each  condyle.  The  centre  for  the 
shaft  appears  very  early,  soon  after  ossification  has  commenced  in  the  clavicle, 
and  soon  extends  towards  the  extremities.  At  birth  the  humerus  is  ossified 
nearly  in  its  whole  length,  the  extremities  remaining  cartilaginous.  Between 
the  first  and  second  years  ossification  commences  in  the  head  of  the  bone,  and 
between  the  second  and  third  years  the  centre  for  the  tuberosities  makes  its 
appearance,  usually  by  a  single  ossific  point,  but  sometimes,  according  to 
Beclard,  by  one  for  each  tuberosity,  that 
for  the  lesser  being  small,  and  not  appear- 
ing until  after  the  fourth  year.  By  the 
fifth  year  the  centres  for  the  head  and 
tuberosities  have  enlarged  and  become 
joined,  so  as  to  form  a  single  large  epi- 
physis. 

The  lower  end  of  the  humerus  is  de- 
veloped in  the  following  manner :  At 
the  end  of  the  second  year  ossification 
commences  in  the  radial  portion  of  the 
articular  surface,  and  from  this  point  ex- 
tends inwards,  so  as  to  form  the  chief  part 
of  the  articular  end  of  the  bone,  the  centre 
for  the  inner  part  of  the  articular  surface 
not  appearing  until  about  the  age  of  twelve. 
Ossification  commences  in  the  internal 
condyle  about  the  fifth  year,  and  in  the 
external  one  not  until  between  the  thir- 
teenth or  fourteenth  year.  About  sixteen 
or  seventeen  years,  the  outer  condyle  and 
both  portions  of  the  articulating  surface 
(having  already  joined)  unite  with  the 
shaft ;  at  eighteen  years  the  inner  condyle 
becomes  joined,  whilst  the  upper  epiphysis, 
although  the  first  formed,  is  not  united 
until  about  the  twentieth  year. 

Articulations.  With  the  glenoid  cavity 
of  the  scapula,  and  with  the  ulna  and 
radius. 

Attachment  of  Muscles.     To  the  greater 
tuberosity,  the  Supraspinatus,  Infraspinatus,  and  Teres  Minor;  to  the  lesser 
tuberosity,  the  Subscapularis ;   to  the  anterior  bicipital  ridge,  the  i'ectoralis 


Fig.  i5(i. — Plan  of  the  Development  of  the 
Humerus.     By  Seven  Centres. 


EpiplysesofHeaJ  ic\    A,' 
'Tuberosities  hie  ml  at  I  ry  / /I*. 
S.yV and  itnifp  j 
with  SAaJYatzo^tfTj 


Xliiites  with 
Shaft  at 


212  THE    SKELETON. 

Major ;  to  the  posterior  bicipital  ridge  and  groove,  the  Latissimus  Dorsi  and 
Teres  Major;  to  the  shaft,  the  Deltoid,  Coraco-brachialis,  Brachialis  Anticus, 
external  and  internal  heads  of  the  Triceps ;  to  the  internal  condyle,  the  Pro- 
nator Kadii  Teres,  and  common  tendon  of  the  Flexor  Carpi  Radialis,  Palmaris 
Longus,  Flexor  Digitorum  Sublimis,  and  Flexor  Carpi  Ulnaris;  to  the  external 
condyloid  ridge,  the  Supinator  Longus,  and  Extensor  Carpi  Radialis  Longior; 
to  the  external  condyle,  the  common  tendon  of  the  Extensor  Carpi  Radialis 
Brevior,  Extensor  Communis  Digitorum,  Extensor  Minimi  Digiti,  and  Extensor 
Carpi  Ulnaris,  the  Anconeus,  and  Supinator  Brevis. 

The  Forearm  is  that  portion  of  the  upper  extremity  which  is  situated  between 
the  elbow  and  wrist.     It  is  composed  of  two  bones,  the  Ulna  and  the  Radius. 

The  Ulna. 

The  Ulna  (Figs.  157,  158),  so  called  from  its  forming  the  elbow  (wxsij;),  is  a 
long  bone,  prismatic  in  form,  placed  at  the  inner  side  of  the  forearm,  parallel 
with  the  radius.  It  is  the  larger  and  longer  of  the  two  bones.  Its  upper 
extremity,  of  great  thickness  and  strength,  forms  a  large  part  of  the  articula- 
tion of  the  elbow-joint;  it  diminishes  in  size  from  above  downwards,  its  lower 
extremity  being  very  small,  and  excluded  from  the  wrist-joint  by  the  interposi- 
tion of  an  interarticular  fibro-cartilage.  It  is  divisible  into  a  shaft,  and  two 
extremities. 

The  Upper  Extremity,  the  strongest  part  of  the  bone,  presents  for  examination 
two  large  curved  processes,  the  olecranon  process  and  the  coronoid  process ;  and 
two  concave  articular  cavities,  the  greater  and  lesser  sigmoid  cavities. 

The  olecranon  process  (uUvtj^  elbow;  xpdvov^  head)  is  a  large  thick  curved  emi- 
nence, situated  at  the  upper  and  back  part  of  the  ulna.  It  rises  somewhat 
higher  than  the  coronoid,  and  is  curved  forward  at  the  summit  so  as  to  present 
a  prominent  tip,  its  base  being  contracted  where  it  joins  the  shaft.  This  is  the 
narrowest  part  of  the  upper  end  of  the  ulna,  and,  consequently,  the  most  usual 
seat  of  fracture.  The  posterior  surface  of  the  olecranon,  directed  backwards,  is 
of  a  triangular  form,  smooth,  subcutaneous,  and  covered  by  a  bursa.  Its  upper 
surface,  directed  upwards,  is  of  a  quadrilateral  form,  marked  behind  by  a  rough, 
impression  for  the  attachment  of  the  Triceps  muscle ;  and  in  front,  near  tho 
margin,  by  a  slight  transverse  groove  for  the  attachment  of  part  of  the  posterior 
ligament  of  the  elbow-joint.  Its  anterior  surface  is  smooth,  concave,  covered 
with  cartilage  in  the  recent  state,  and  forms  the  upper  and  back  part  of  tho 
great  sigmoid  cavity.  The  lateral  borders  present  a  continuation  of  the  same 
groove  that  was  seen  on  the  margin  of  the  superior  surface ;  they  serve  for  the 
attachment  of  ligaments,  viz.,  the  back  part  of  the  internal  lateral  ligament 
internally,  the  posterior  ligament  externally.  The  olecranon  process,  in  its 
structure  as  well  as  in  its  position  and  use,  resembles  the  patella  in  the  lower 
limb ;  and,  like  it,  sometimes  exists  as  a  separate  piece,  not  united  to  the  rest 
of  the  bone.^ 

The  coronoid  process  (xopoi-j;,  a  crowds  beak)  is  a  rough  triangular  eminence  of 
bone  which  projects  horizontally  forwards  from  the  upper  and  front  part  of  tho 
ulna,  forming  the  lower  part  of  the  great  sigmoid  cavity.  Its  base  is  continuous 
with  the  shaft,  and  of  considerable  strength,  so  much  so  that  fracture  of  it  is  an 
accident  of  rare  occurrence.  Its  apex  is  pointed,  slightly  curved  upwards,  and 
received  into  the  coronoid  depression  of  the  humerus  in  flexion  of  the  forearm. 
Its  upper  surface  is  smooth,  concave,  and  forms  the  lower  part  of  the  great 
sigmoid  cavity.  The  under  surface  is  concave,  and  marked  internally  by  a 
rough  impression  for  the  insertion  of  the  Brachialis  Anticus.     At  the  junction 

'  Professor  Owen  regards  the  olecranon  as  homologous  not  with  the  patella,  but  with  an 
extension  of  the  upper  end  of  the  fibula  above  tho  knee-joint,  which  is  met  with  in  the  Orui- 
Iborynchus,  Echidna,  and  some  other  animals.    (Owkn,  "On  (he  Xaiure  of  Limbs.") 


ULNA. 


213 


Fig.  15T.— Bones  of  the  Left  Forearm.    Anterior  Surface. 

ULNA 


e  r  ct 


RADIUS 


PIBKOR    OIOITORUM 
fiUBLIIVIIS 


PRONATOR 
RADII.  TERES 


«/ FLEXOR     lONCUS    FOUICIs|%'/'  ilV'"*      " 


Itcu/uiZ  Orlqiiy 


fFLEXOR   DICITORUM 
•USLlMla 


Styloid  S'rocess 


UPIHATOR  LONCUS 
Groove  ft,r  cxt.ocsii 

MCTACARPl  POLLICrg 
.Crc/>I«'  y?  rJCXT.  PRIMI 
NTEITKOCil  POUICIS 


Stylotd  Mroeess 


2U  THE    SKELETON. 

of  this  surface  with  the  shaft  is  a  rough  eminence,  the  tubercle  of  the  ulna,  for 
the  attachment  of  the  oblique  ligament.  Its  outer  surface  presents  a  narrow, 
oblong,  articular  depression,  the  lesser  sigmoid  cavity.  The  inner  surface,  by 
its  prominent  free  margin,  serves  for  the  attachment  of  part  of  the  internal 
lateral  ligament.  At  the  front  part  of  this  surface  is  a  small  rounded  eminence 
for  the  attachment  of  one  head  of  the  Flexor  Digitorum  Sublimis,  behind  the 
eminence,  a  depression  for  part  of  the  origin  of  the  Flexor  Profundus  Digito- 
rum, and,  descending  from  the  eminence,  a  ridge,  which  gives  attachment  to 
one  head  of  the  Pronator  Eadii  Teres.  Occasionally  the  Flexor  Longus  Pol- 
licis  arises  from  the  lower  part  of  the  coronoid  process  by  a  rounded  bundle 
of  muscular  fibres. 

The  greater  sigmoid  cavity^  so  called  from  its  resemblance  to  the  old  shape  of 
the  Greek  letter  2,  is  a  semilunar  depression  of  large  size,  formed  by  the  ole- 
cranon and  coronoid  processes,  and  serving  for  articulation  with  the  trochlear 
surface  of  the  humerus.  About  the  middle  of  either  lateral  border  of  this 
cavity  is  a  notch,  which  contracts  it  somewhat,  and  serves  to  indicate  the  junc- 
tion of  the  two  processes  of  which  it  is  formed.  The  cavity  is  concave  from 
above  downwards,  and  divided  into  two  lateral  parts  by  a  smooth  elevated 
ridge,  which  runs  from  the  summit  of  the  olecranon  to  the  tip  of  the  coronoid 
process.  Of  these  two  portions,  the  internal  is  the  larger ;  it  is  slightly  concave 
transversely,  the  external  portion  being  nearly  plane  from  side  to  side. 

The  lesser  sigmoid  cavity  is  a  narrow,  oblong,  articular  depression,  placed  on 
the  outer  side  of  the  coronoid  process,  and  serving  for  articulation  with  the 
head  of  the  radius.  It  is  concave  from  before  backwards ;  and  its  extremities, 
which  are  prominent,  serve  for  the  attachment  of  the  orbicular  ligament. 

The  Shaft  is  prismatic  in  form  at  its  upper  part,  and  curved  from  behind 
forwards,  and  from  within  outwards,  so  as  to  be  convex  behind  and  externally; 
its  central  part  is  quite  straight ;  its  lower  part  rounded,  smooth,  and  bent  a 
little  outwards ;  it  tapers  gradually  from  above  downwards,  and  presents  for 
examination  three  borders,  and  three  surfaces. 

The  anterior  border  commences  above  at  the  prominent  inner  angle  of  the 
coronoid  process,  and  terminates  below  in  front  of  the  styloid  process.  It  is 
well  marked  above,  smooth  and  rounded  in  the  middle  of  its  extent,  and  affords 
attachment  to  the  Flexor  Profundus  Digitorum:  sharp  and  prominent  in  its 
lower  fourth  for  the  attachment  of  the  Pronator  Quadratus.  It  separates  the 
anterior  from  the  internal  surface. 

The  posterior  border  commences  above  at  the  apex  of  the  triangular  surface 
at  the  back  part  of  the  olecranon,  and  terminates  below  at  the  back  part  of  the 
styloid  process;  it  is  well  marked  in  the  upper  three-fourths,  and  gives  attach- 
ment to  an  aponeurosis  common  to  the  Flexor  Carpi  Ulnaris,  the  Extensor 
Carpi  Ulnaris,  and  the  Flexor  Profundus  Digitorum  muscles;  its  lower  fourth 
is  smooth  and  rounded.  This  border  separates  the  internal  from  the  posterior 
surface.  \ 

The  external  border  commences  above  by  two  lines,  which  converge  one  from  j 
each  extremity  of  the  lesser  sigmoid  cavity,  inclosing  between  them  a  triangu- 
lar space  for  the  attachment  of  part  of  the  Supinator  Brevis,  and  terminates 
below  at  the  middle  of  the  head  of  the  ulna.  Its  two  middle  fourths  are  very 
prominent,  and  serve  for  the  attachment  of  the  interosseous  membrane;  its 
lower  fourth  is  smooth  and  rounded.  This  border  separates  the  anterior  from 
the  posterior  surface.  ; 

The  anterior  surface,  much  broader  above  than  below,  is  concave  in  the  upper 
three-fourths  of  its  extent,  and  affords  attachment  to  the  Flexor  Profundus  Digi- 
torum ;  its  lower  fourth,  also  concave,  to  the  Pronator  Quadratus.  The  lower 
fourth  is  separated  from  the  remaining  portion  of  the  bone  by  a  prominent 
ridge,  directed  obliquely  from  above  downwards  and  inwards;  this  ridge  marks 
the  extent  of  attachment  of  the  Pronator  above.     At  the  junction  of  the  upper 


ULNA. 


fil5 


Fig.  158. — Bones  of  the  Left  Forearm.    Posterior  Surface. 

VUHA 


^rEXT.CARPI    RAO. LONG. 

&XT.  CARPI    RAO.BREVIOR 
EXT.   CCCUNOl   INTCRNODII  P^ULICItt 


LCXOR    DIQITOBUM 
SUBLIMIS 


_firr    EXT.  CARPI     ULNAB. 

EXT.  INOICIS 
ff'r^    CXT,    OtCITORUM    COMMUNIS 
tXT.    MI.MIV)!     OIOITI 


216 


THE    SKELETON. 


with  the  middle  third  of  the  bone  is  the  nutrient  canal,  directed  obliquely 
upwards  and  inwards. 

The  posterior  surface,  directed  backwards  and  outwards,  is  broad  and  concave 
above,  somewhat  narrower  and  convex  in  the  middle  of  its  course,  narrow, 
smooth,  and  rounded  below.  It  presents  above  an  oblique  ridge,  which  runs 
from  the  posterior  extremity  of  the  lesser  sigmoid  cavity  downwards  to  the 
posterior  border;  the  triangular  surface  above  this  ridge  receives  the  insertion 
of  the  Anconeus  muscle,  whilst  the  ridge  itself  affords  attachment  to  the  Supi- 
nator Brevis.  The  surface  of  bone  below  this  is  subdivided  by  a  longitudinal 
ridge,  sometimes  called  the  perpendicular  line,  into  two  parts:  the  internal  part 
is  smooth,  concave,  and  gives  origin  to  (occasionally  is  merely  covered  by)  the 
Extensor  Carpi  Ulnaris;  the  external  portion,  wider  and  rougher,  gives  attach- 
ment from  above  downwards  to  part  of  the  Supinator  Brevis,  the  Extensor 
Ossis  Metacarpi  Pollicis,  the  Extensor  Secundi  Internodii  Pollicis,  and  the  Ex- 
tensor Indicis  muscles. 

The  internal  surface  is  broad  and  concave  above,  narrow  and  convex  below. 
It  gives  attachment  by  its  upper  three-fourths  to  the  Flexor  Profundus  Digi- 
torum  muscle;  its  lower  fourth  is  subcutaneous. 

The  Lower  Extremity  of  the  ulna  is  of  small  size,  and  excluded  from  the 
articulation  of  the  wrist-joint.  It  presents  for  examination  two  eminences,  the 
outer  and  larger  of  which  is  a  rounded  articular  eminence,  termed  the  head  of 
the  ulna;  the  inner,  narrower  and  more  projecting,  is  a  non-articular  eminence, 
the  styloid  process.  The  head  presents  an  articular  facet,  part  of  which,  of  an 
oval  form,  is  directed  downwards,  and  plays  on  the  surface  of  the  triangular 
fibro-cartilage,  which  separates  this  bone  from  the  wrist-joint ;  the  remaining 
portion,  directed  outwards,  is  narrow,  convex,  and  received  into  the  sigmoid 
cavity  of  the  radius.     The  styloid  process  projects  from  the  inner  and  back  part 

of  the  bone,  and  descends  a  little  lower 
than  the  head,  terminating  in  a  rounded 
summit,  which  affords  attachment  to  the 
internal  lateral  ligament  of  the  wrist. 
The  head  is  separated  from  the  styloid 
process  by  a  depression  for  the  attach- 
ment of  the  triangular  interarticular 
fibro-cartilage;  and  behind  by  a  shallow 
groove  for  the  passage  of  the  tendon  of 
the  Extensor  Carpi  Ulnaris. 

Structure.    Similar  to  that  of  the  other 
long  bones. 

Development.  By  three  centres:  one 
for  the  shaft,  one  for  the  inferior  ex- 
tremity, and  one  for  the  olecranon  (Fig. 
159).  Ossification  commences  near  the 
middle  of  the  shaft  about  the  fifth  week, 
and  soon  extends  through  the  greater 
part  of  the  bone.  At  birth  the  ends  are 
cartilaginous.  About  the  fourth  year, 
a  separate  osseous  nucleus  appears  in  the 
middle  of  the  head,  which  soon  extends 
into  the  styloid  process.  About  the  tenth 
year,  ossific  matter  appears  in  the  ole- 
cranon near  its  extremity,  the  chief  part 
of  this  process  being  formed  from  an 
extension  of  the  shaft  of  the  bone  into 
it.  At  about  the  sixteenth  year,  the  upper  epiphysis  becomes  joined,  and  at 
about  the  twentieth  year  the  lower  one. 

Articulations.    With  the  humerus  and  radius. 


Fig.  159. — Plan  of  the  Development  of  the 
Ulna.    By  Three  Centres. 

Olecran/nt 
Agpea  79  at  fO^y^C^^^-Jouu  Shaft  at  /S^  y* 


A^eart  at  4^  y * 


Iffins  STifiJi  tU  ZO^yf 


RADIUS.  21^ 

Attachment  of  Muscles.  To  tlie  olecranon:  the  Triceps,  Anconeus,  and  one 
Lead  of  the  Flexor  Carpi  Ulnaris.  To  the  coronoid  process :  the  Brachialis 
Anticus,  Pronator  Radii  Teres,  Flexor  Sublimis  Digitorum,  and  Flexor  Pro- 
fundus Digitorum,  occasionally,  also  the  Flexor  Longus  Pollicis.  To  the  shaft: 
the  Flexor  Profundus  Digitorum,  Pronator  Quadratus,  Flexor  Carpi  Ulnaris, 
Extensor  Carpi  Ulnaris,  Anconeus,  Supinator  Brevis,  Extensor  Ossis  Meta- 
carpi  Pollicis,  Extensor  Secundi  Internodii  Pollicis,  and  Extensor  Indicis. 

The  Radius. 

The  Radius  is  situated  on  the  outer  side  of  the  forearm,  lying  parallel  with 
the  ulna,  which  exceeds  it  in  length  and  size.  Its  upper  end  is  small,  and  forms 
only  a  small  part  of  the  elbow-joint;  but  its  lower  end  is  large,  and  forms 
the  chief  part  of  the  wrist.  It  is  one  of  the  long  bones,  prismatic  in  form, 
slightly  curved  longitudinally,  and  like  other  long  bones  has  a  shaft  and  two 
extremities. 

The  Upper  Extremity  presents  a  head,  neck,  and  tuberosity.  The  head  is  of 
a  cylindrical  form,  depressed  on  its  upper  surface  into  a  shallow  cup,  which 
articulates  with  the  radial  or  lesser  head  of  the  humerus  in  flexion  of  the  joint. 
Around  the  circumference  of  the  head  is  a  smooth  articular  surface,  coated  with 
cartilage  in  the  recent  state,  broad  internally  where  it  rotates  within  the  lesser 
sigmoid  cavity  of  the  ulna ;  narrow  in  the  rest  of  its  circumference,  to  play  in 
the  orbicular  ligament.  The  head  is  supported  on  a  round,  smooth,  and  con- 
stricted portion  of  bone,  called  the  neck,  which  presents,  behind,  a  slight  ridge, 
for  the  attachment  of  part  of  the  Supinator  Brevis.  Beneath  the  neck,  at  the 
inner  and  front  aspect  of  the  bone,  is  a  rough  eminence,  the  tuberosity.  Its 
surface  is  divided  into  two  parts  by  a  vertical  line — a  posterior  rough  portion, 
for  the  insertion  of  the  tendon  of  the  Biceps  muscle ;  and  an  anterior  smooth 
portion,  on  which  a  bursa  is  interposed  between  the  tendon  and  the  bone. 

The  Shaft  of  the  bone  is  prismoid  in  form,  narrower  above  than  below,  and 
slightly  curved,  so  as  to  be  convex  outwards.  It  presents  three  surfaces,  sepa- 
rated by  three  borders. 

The  anterior  hojxler  extends  from  the  lower  part  of  the  tuberosity  above,  to 
the  anterior  part  of  the  base  of  the  styloid  process  below.  It  separates  the 
anterior  from  the  external  surface.  Its  upper  third  is  very  prominent ;  and 
from  its  oblique  direction,  downwards  and  outwards,  has  received  the  name  of 
the  ohlique  line  of  the  radius.  It  gives  attachment,  externally,  to  the  Supinator 
Brevis ;  internally,  to  the  Flexor  Longus  Pollicis,  and  between  these  to  the 
Flexor  Digitorum  Sublimis.  The  middle  third  of  the  anterior  border  is  indis- 
tinct and  rounded.  Its  lower  fourth  is  sharp,  prominent,  affords  attachment  to 
the  Pronator  Quadratus,  and  terminates  in  a  small  tubercle,  into  which  is 
inserted  the  tendon  of  the  Supinator  Longus. 

^\\Q  posterior  border  commences  above,  at  the  back  part  of  the  neck  of  the 
radius,  and  terminates -below,  at  the  posterior  part  of  the  base  of  the  styloid 
process ;  it  separates  the  posterior  from  the  external  surface.  It  is  indistinct 
above  and  below,  but  well  marked  in  the  middle  third  of  the  bone. 

The  internal  or  interosseous  border  commences  above,  at  the  back  part  of  the 
tuberosity,  where  it  is  rounded  and  indistinct,  becomes  sharp  and  prominent  as 
it  descends,  and  at  its  lower  part  bifurcates  into  two  ridges,  which  descend  to 
the  anterior  and  posterior  margins  of  the  sigmoid  cavity.  This  border  separates 
the  anterior  from  the  posterior  surface,  and  has  the  interosseous  membrane 
attached  to  it  throughout  the  greater  part  of  its  extent. 

The  anterior  surface  is  narrow  and  concave  for  its  upper  two-thirds,  and  gives 
attachment  to  the  Flexor  Longus  Pollicis  muscle ;  below,  it  is  broad  and  flat, 
and  gives  attachment  to  the  Pronator  Quadratus.  At  thej'unction  of  the  upper 
and  middle  thirds  of  this  surface  is  the  nutrient  foramen,  which  is  directed 
obliquely  upwards. 


218 


THE    SKELETON. 


The  posterior  surface  is  rounded,  convex  and  smooth,  in  the  upper  third  of  its 
extent,  and  covered  by  the  Supinator  Brevis  muscle.  Its  middle  third  is  broad, 
slightly  concave,  and  gives  attachment  to  the  Extensor  Ossis  Metacarpi  Pollicis 
above,  the  Extensor  Primi  Internodii  Pollicis  below.  Its  lower  third  is  broad, 
convex,  and  covered  by  the  tendons  of  the  muscles,  which  subsequently  run  in 
the  grooves  on  the  lower  end  of  the  bone. 

The  external  surface  is  rounded  and  convex  throughout  its  entire  extent.  Its 
upper  third  gives  attachment  to  the  Supinator  Brevis  muscle.  About  its  centre 
is  seen  a  rough  ridge,  for  the  insertion  of  the  Pronator  Radii  Teres  muscle.  Its 
lower  part  is  narrow,  and  covered  by  the  tendons  of  the  Extensor  Ossis  Meta- 
carpi Pollicis  and  Extensor  Primi  Internodii  Pollicis  muscles. 

The  Lower  Extremity  of  the  radius  is  large,  of  quadrilateral  form,  and  pro- 
vided with  two  articular  surfaces,  one  at  the  extremity  for  articulation  with  the 
carpus,  and  one  at  the  inner  side  of  the  bone  for  articulation  with  the  ulna. 
The  carpal  articular  surface  is  of  triangular  form,  concave,  smooth,  and  divided 
by  a  slight  antero-posterior  ridge  into  two  parts.  Of  these,  the  external  is 
large,  of  a  triangular  form,  and  articulates  with  the  scaphoid  bone ;  the  inner, 
smaller  and  quadrilateral,  articulates  with  the  semilunar.  The  articular  surface 
for  the  ulna  is  called  the  sigmoid  cavity  of  the  radius;  it  is  narrow,  concave, 
smooth,  and  articulates  with  the  head  of  the  ulna.  The  circumference  of  this 
end  of  the  bone  presents  threo  surfaces,  an  anterior,  external,  and  posterior. 
The  anterior  surface,  rough  and  irregular,  affords  attachment  to  the  anterior 
ligament  of  the  wrist-joint.  The  external  surface  is  prolonged  obliquely  down- 
wards into  a  strong  conical  projection,  the  styloid  process,  which  gives  attach- 
ment by  its  base  to  the  tendon  of  the  Supinator  Longus,  and  by  its  apex  to  the 
external  lateral  ligament  of  the  wrist-joint.  The  outer  surface  of  this  process 
is  marked  by  two  grooves,  which  run  obliquely  downwards  and  forwards,  and 

are  separated  from  one  another  by  an 
elevated  ridge.  The  anterior  one  gives 
passage  to  the  tendon  of  the  Extensor 
Ossis  Metacarpi  Pollicis,  the  posterior 
one  to  the  tendon  of  the  Extensor 
Primi  Internodii  Pollicis.  The  poste- 
rior surface  is  convex,  affords  attach- 
ment to  the  posterior  ligament  of  the 
wrist,  and  is  marked  by  three  grooves. ' 
Proceeding  from  without  inwards,  the 
first  groove  is  broad,  but  shallow,  and 
subdivided  into  two  by  a  slightly  elevat- 
ed ridge ;  the  outer  of  these  two  trans- 
mits the  tendon  of  the  Extensor  Carpi 
Radialis  Longior,  the  inner  the  tendon 
of  the  Extensor  Carpi  Radialis  Brevior. 
The  second,  which  is  near  the  centre 
of  the   bone,  is   a  deep   but 


Fig.  160.— Plan  of  the  Development  of  the 
Radius.    By  Three  Centres. 


Apjitan  »t  5f*^- 


'ffjeoeg 


oi  the  bone,  is  a  deep  out  narrow  ^ 
groove,  directed  obliquely  from  above,  IH 
downwards  and  outwards;  it  transmits  ^ 


Apptar*  at  2**^?- 


.  inutf4  viitk  Shnft  akt 


the  tendon  of  the  Extensor  Secundi 
Internodii  Pollicis.  The  third,  lying 
most  internally,  is  a  broad  groove,  for 
the  passage  of  the  tendons  of  the  Ex- 
^T^Trtit^  tensor  Communis  Digitorum,  Extensor 

""  Indicis  and  Extensor  Minimi  Digiti; 

the  tendon  of  the  last-named  muscle 
passing  through  the  groove  at  the  point  of  articulation  of  the  radius  with  the 
ulna. 

Structure.     Similar  to  that  of  the  other  long  bones. 


btfll/^ 


CARPUIS.  219 

Development  (Fig.  160).  Ej  three  centres,  one  for  the  shaft,  and  one  for  each 
extremity.  That  for  the  shaft  makes  its  appearance  near  the  centre  of  the 
bone,  soon  after  the  development  of  the  humerus  commences.  At  birth  the 
shaft  is  ossified,  but  the  ends  of  the  bone  are  cartilaginous.  About  the  end  of 
the  second  year,  ossification  commences  in  the  lower  epiphysis ;  and  about  the 
fifth  year,  in  the  upper  one.  At  the  age  of  puberty,  the  upper  epiphysis 
becomes  joined  to  the  shaft ;  the  lower  epiphysis  becoming  united  about  the 
twentieth  year. 

Articulations.     "With  four  bones — the  humerus,  ulna,  scaphoid,  and  semilunar. 

Attachment  of  Muscles.  To  the  tuberosity,  the  Biceps;  to  the  oblique  ridge, 
the  Supinator  Brevis,  Flexor  Digitorum  Sublimis,  and  Flexor  Longus  Pollicis  ; 
to  the  shaft  (its  anterior  surface),  the  Flexor  Longus  Pollicis  and  Pronator 
Quadratus ;  (its  posterior  surface),  the  Extensor  Ossis  Metacarpi  Pollicis  and 
Extensor  Primi  Internodii  Pollicis;  (its  outer  surface),  the  Pronator  Eadii 
Teres  ;  and  to  the  styloid  process,  the  Supinator  Longus. 

The  Hand  is  subdivided  into  three  segments— the  Carpus  or  "Wrist,  the  Meta- 
carpus or  Palm,  and  the  Phalanges  or  Fingers. 

The  Carpus. 

The  bones  of  the  Carpus,  eight  in  number,  are  arranged  in  two  rows.  Those 
of  the  upper  row,  enumerated  from  the  radial  to  the  ulnar  side,  are  the  scaphoid, 
semilunar,  cuneiform,  and  pisiform  ;  those  of  the  lower  row,  enumerated  in  the 
same  order,  are  the  trapezium,  trapezoid,  os  magnum,  and  unciform. 

Common  Characters  of  the  Carpal  Bones.  Each  bone  (excepting  the  pisiform) 
presents  six  surfaces.  Of  these,  the  anterior  or  j^lmar,  and  the  posterior  or 
dorsal,  are  rough,  for  ligamentous  attachment,  the  dorsal  surface  being  generally 
the  broader  of  the  two.  The  superior  and  inferior  are  articular,  the  superior 
generally  convex,  the  inferior  concave ;  and  the  internal  and  external  are  also 
articular  when  in  contact  with  contiguous  bones,  otherwise  rough  and  tuber- 
cular. Their  structure  in  all  is  similar,  consisting  within  of  cancellous  tissue 
inclosed  in  a  layer  of  compact  bone.  Each  bone  is  also  developed  from  a 
single  centre  of  ossification. 

Bones  of  the  Upper  Row.    (Figs.  161, 162.) 

The  Scaphoid  is  the  largest  bone  of  the  first  row.  It  has  received  its  name 
from  its  fancied  resemblance  to  a  boat,  being  broad  at  one  end,  and  narrowed 
like  a  prow  at  the  opposite.  It  is  situated  at  the  upper  and  outer  part  of  the 
carpus,  its  direction  being  from  above  downwards,  outwards,  and  forwards. 
The  sup>erior  surface  is  convex,  smooth,  of  triangular  shape,  and  articulates 
with  the  lower  end  of  the  radius.  The  inferior  surface,  directed  downwards, 
outwards,  and  backwards,  is  smooth,  convex,  also  triangular,  and  divided  by  a 
slight  ridge  into  two  parts,  the  external  of  which  articulates  with  the  trape- 
zium, the  inner  with  the  trapezoid.  The  posterior  or  dorsal  surface  presents  a 
narrow,  rough  groove,  which  runs  the  entire  breadth  of  the  bone,  and  serves 
for  the  attachment  of  ligaments.  The  anterior  or  palmar  surface  is  concave 
above,  and  elevated  at  its  lower  and  outer  part  into  a  prominent  rounded 
tubercle,  which  projects  forwards  from  the  front  of  the  carpus,  and  gives  attach- 
ment to  the  anterior  annular  ligament  of  the  wrist.  The  external  surface  is 
rough  and  narrow,  and  gives  attachment  to  the  external  lateral  ligament  of  the 
wrist.  The  internal  surface  presents  two  articular  facets :  of  these,  the  superior 
or  smaller  one  is  flattened,  of  semilunar  form,  and  articulates  with  the  semi- 
lunar ;  the  inferior  or  larger  is  concave,  forming  with  the  semilunar  bone,  a 
concavity  for  the  head  of  the  os  magnum. 

To  ascertain  to  which  hand  this  bone  belongs,  hold  the  convex  radial  articu- 
lar surface  upwards,  and  the  dorsal  surface  backwards;  the  prominent  tubercle 
will  be  directed  to  the  side  to  which  the  bone  belongs. 


220 


THE    SKELETON". 


Articulations.  With  five  bones :  the  radius  above,  trapezium  and  trapezoid 
below,  OS  magnum  and  semilunar  internally. 

The  Semilunar  bone  may  be  distinguished  by  its  deep  concavity  and  cres- 
centic  outline.    It  is  situated  in  the  centre  of  the  upper  row  of  the  carpus,   _] 

Fig.  161.— Bones  of  the  Left  Hand.    Dorsal  Surfiace. 


*A^A^^, 


Carjpus 


**T 


"inn 


"^"^•"iriOMus 


'RKVlOi 


•NTERWooil 


MetacaTpu& 


FTialanges 


Z^Kow 


CARPUS.  221 

between  the  scaphoid  and  cuneiform.  The  superior  surf  ace,  convex,  smooth,  and 
bounded  by  four  edges,  articulates  with  the  radius.  The  inferior  surface  is 
deeply  concave,  and  of  greater  extent  from  before  backwards  than  transversely  ; 
it  articulates  with  the  head  of  the  os  magnum,  and  by  a  long  narrow  facet 
(separated  by  a  ridge  from  the  general  surface)  with  the  unciform  bone.  The 
anterior  or  palmar  and  posterior  or  dorsal  surfaces  are  rough,  for  the  attachment 
of  ligaments,  the  former  being  the  broader,  and  of  somewhat  rounded  form. 
The  external  surface  presents  a  narrow,  flattened,  semilunar  facet,  for  articula- 
tion with  the  scaphoid.  The  internal  surface  is  marked  by  a  smooth,  quadri- 
lateral facet,  for  articulation  with  the  cuneiform. 

To  ascertain  to  which  hand  this  bone  belongs,  hold  it  with  the  dorsal  surface 
upwards,  and  the  convex  articular  surface  backwards ;  the  quadrilateral  articular 
facet  will  then  point  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  five  bones :  the  radius  above,  os  magnum  and  unciform 
below,  scaphoid  and  cuneiform  on  either  side. 

The  Cuneiform  {VOs  Pyramidal)  may  be  distinguished  by  its  pyramidal  shape, 
and  by  its  having  an  oval,  isolated  facet,  for  articulation  with  the  pisiform  bone. 
It  is  situated  at  the  upper  and  inner  side  of  the  carpus.  The  superior  surface 
presents  an  internal,  rough,  nonarticular  portion;  and  an  external  or  articular 
portion,  which  is  convex,  smooth,  and  separated  from  the  lower  end  of  the  ulna 
by  the  interarticular  fibro-cartilage  of  the  wrist.  The  inferior  surface,  directed 
outwards,  is  concave,  sinuously  curved,  and  smooth  for  articulation  with  the 
unciform.  The  posterior  or  dorsal  surface  is  rough,  for  the  attachments  of  liga- 
ments. The  anterior  or  palmar  surface  presents,  at  its  inner  side,  an  oval  facet, 
for  articulation  with  the  pisiform ;  and  is  rough  externally,  for  ligamentous 
attachment.  The  external  surface,  the  base  of  the  pyramid,  is  marked  by  a  flat, 
quadrilateral,  smooth  facet,  for  articulation  with  the  semilunar.  The  internal 
surface,  the  summit  of  the  pyramid,  is  pointed  and  roughened,  for  the  attach- 
ment of  the  internal  lateral  ligament  of  the  wrist. 

To  ascertain  to  which  hand  this  bone  belongs,  hold  it  so  that  the  base  is 
directed  backwards,  and  the  articular  facet  for  the  pisiform  bone  upwards;  the 
concave  articular  facet  will  point  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  three  bones :  the  semilunar  externally,  the  pisiform  in 
front,  the  unciform  below,  and  with  the  triangular  interarticular  fibro-cartilage 
which  separates  it  from  the  lower  end  of  the  ulna. 

The  Pisiform  bone  may  be  known  by  its  small  size,  and  by  its  presenting  a 
single  articular  facet.  It  is  situated  at  the  anterior  and  inner  side  of  the  carpus, 
is  nearly  circular  in  form,  and  presents  on  its  posterior  surface  a  smooth  oval 
facet,  for  articulation  with  the  cuneiform  bone.  This  facet  approaches  the 
superior,  but  not  the  inferior,  border  of  the  bone.  The  anterior  or  palmar 
surface  is  rounded  and  rough,  and  gives  attachment  to  the  anterior  annular 
ligament.  The  outer  and  inner  surfaces  are  also  rough,  the  former  being  convex, 
the  latter  usually  concave. 

To  ascertain  to  which  hand  it  belongs,  hold  the  bone  with  its  posterior  or 
articular  facet  downwards,  and  the  nonarticular  portion  of  the  same  surface 
backwards ;  the  inner  concave  surface  will  then  point  to  the  side  to  which  the 
bone  belongs. 

Articulations.     With  one  bone,  the  cuneiform. 

Attachment  of  Muscles.  To  two :  the  Flexor  Carpi  Ulnaris,  and  Abductor 
Minimi  Digiti ;  and  to  the  anterior  annular  ligament. 

Bones  of  the  Lower  Row.    (Figs.  161,  162.) 

The  Trapezium  is  of  very  irregular  form.  It  may  be  distinguished  by  a  deep 
groove,  for  the  tendon  of  the  Flexor  Carpi  Radialis  muscle.  It  is  situated  at 
the  external  and  inferior  part  of  the  carpus,  between  the  scaphoid  and  first 
metacarpal  bone.    The  superior  surface,  concave  and  smooth,  is  directed  upwards 


222 


THE    SKELETON. 


and  inwards,  and  articulates  with  the  scaphoid.  Tho  inferior  surface^  directed 
downwards  and  outwards,  is  oval,  concave  from  side  to  side,  convex  from  before 
backwards,  so  as  to  form  a  saddle-shaped  surface,  for  articulation  with  the  base 
of  the  first  metacarpal  bone.  The  anterior  or  palmar  surface  is  narrow  and 
rough.  At  its  upper  part  is  a  deep  groove,  running  from  above  obliquely 
downwards  and  inwards ;  it  transmits  the  tendon  of  the  Flexor  Carpi  Eadialis, 
and  is  bounded  externally  by  a  prominent  ridge,  the  oblique  ridge  of  the  tra- 

Fig.  162.— Bones  of  the  Left  Hand.    Palmar  Surface. 


Cu/rjius 

ri.KXOR.eAI(M    ULKARIS 
PLCyOR    BREV\S  MINIMI     DICITI 


rLEXOR   0SSI5    METACARPI 
MINIMI      DICITI 


MrJttenr/iiui 


rtCX.  BREWIS 

& 

ABDUCTOR 
MINIMI     DICITI 


CARPUS.  223 

pezium.  This  surface  gives  attachment  to  the  Abductor  Pollicis,  Flexor  Ossis 
Metacarpi,  and  Flexor  Brevis  Pollicis  muscles ;  and  the  anterior  annular  liga- 
ment. The  posterior  or  dorsal  surface  is  rough,  and  the  external  surface  also 
broad  and  rough,  for  the  attachment  of  ligaments.  The  internal  surface  presents 
two  articular  facets :  the  upper  one,  large  and  concave,  articulates  with  the 
trapezoid ;  the  lower  one,  narrow  and  flattened,  with  the  base  of  the  second 
metacarpal  bone. 

To  ascertain  to  which  hand  it  belongs,  hold  the  bone  with  the  grooved 
palmar  surface  upwards,  and  the  external  broad,  nonarticular  surface  back- 
wards ;  the  saddle-shaped  surface  will  then  be  directed  to  the  side  to  which  the 
bone  belongs. 

Articulations.  With  four  bones:  the  scaphoid  above,  the  trapezoid  and 
second  metacarpal  bones  internally,  the  first  metacarpal  below. 

Attachment  of  Mmcles.  Abductor  Pollicis,  Flexor  Ossis  Metacarpi,  and  part 
of  the  Flexor  Brevis  Pollicis. 

The  Trapezoid  is  the  smallest  bone  in  the  second  row.  It  may  be  known  by 
its  wedge-shaped  form,  the  broad  end  of  the  wedge  forming  the  dorsal,  the  nar- 
row end  the  palmar  surface ;  and  by  its  having  four  articular  surfaces  touching 
each  other,  and  separated  by  sharp  edges.  The  superior  surface,  quadrilateral 
in  form,  smooth  and  slightly  concave,  articulates  with  the  scaphoid.  The  infe- 
rior surface  articulates  with  the  upper  end  of  the  second  metacarpal  bone;  it  is 
convex  from  side  to  side,  concave  from  before  backwards,  and  subdivided,  by 
an  elevated  ridge,  into  two  unequal  lateral  facets.  The  posterior  or  dorsal  and 
anterior  or  palmar  surfaces  are  rough,  for  the  attachment  of  ligaments,  the 
former  being  the  larger  of  the  two.  The  external  surface,  convex  and  smooth, 
articulates  with  the  trapezium.  The  internal  surface  is  concave  and  smooth 
below,  for  articulation  with  the  os  magnum ;  rough  above,  for  the  attachment 
of  an  interosseous  ligament. 

To  ascertain  to  which  side  this  bone  belongs,  let  the  broad  dorsal  surface  be 
held  upwards,  and  the  inferior  concavo-convex  surface  forwards ;  the  internal 
concave  surface  will  then  point  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  four  bones:  the  scaphoid  above,  second  metacarpal  bone 
below,  trapezium  externally,  os  magnum  internally. 

Attachment  of  Muscles.     Part  of  the  Flexor  Brevis  Pollicis. 

The  Os  Magnum  is  the  largest  bone  of  the  carpus,  and  occupies  the  centre  of 
the  wrist.  It  presents  above  a  rounded  portion  or  head,  which  is  received  into 
the  concavity  formed  by  the  scaphoid  and  semilunar  bones ;  a  constricted  por- 
tion or  neck;  and,  below,  the  body.  The  superior  surface  is  rounded,  smooth, 
and  articulates  with  the  semilunar.  The  inferior  surface  is  divided  by  two 
ridges  into  three  facets,  for  articulation  with  the  second,  third,  and  fourth  meta- 
carpal bones ;  that  for  the  third  (the  middle  facet)  being  the  largest  of  the  three. 
^hQ posterior  or  dorsal  surface  is  broad  and  rough;  the  anterior  or  palmar,  nar- 
row, rounded,  and  also  rough,  for  the  attachment  of  ligaments.  The  external 
surface  articulates  with  the  trapezoid  by  a  small  facet  at  its  anterior  inferior 
angle,  behind  which  is  a  rough  depression  for  the  attachment  of  an  interosseous 
ligament.  Above  this  is  a  deep  and  rough  groove,  which  forms  part  of  the 
neck,  and  serves  for  the  attachment  of  ligaments,  bounded  superiorly  by  a 
smooth  convex  surface,  for  articulation  with  the  scaphoid.  The  internal  sur- 
face articulates  with  the  unciform  by  a  smooth,  concave,  oblong  facet,  which 
occupies  its  posterior  and  superior  parts;  and  is  rough  in  front,  for  the  attach- 
ment of  an  interosseous  ligament. 

To  ascertain  to  which  hand  this  bone  belongs,  the  rounded  head  should  be 
held  upwards,  and  the  broad  dorsal  surface  forwards;  the  internal  concave 
articular  surface  will  point  to  its  appropriate  side. 

Articulations.  With  seven  bones:  the  scaphoid  and  semilunar  above;  the 
second,  third,  and  fourth  metacarpal  below;  the  trapezoid  on  the  radial  side; 
and  the  unciform  on  the  ulnar  side. 


224  THE    SKELETON". 

Attachment  of  Muscles.     Part  of  the  Flexor  Brevis  Pollicis. 

The  Unciform  bone  may  be  readily  distinguished  by  its  wedge-shaped  form, 
and  the  hook-like  process  that  projects  from  its  palmar  surface.  It  is  situated 
at  the  inner  and  lower  angle  of  the  carpus,  with  its  base  downwards,  resting 
on  the  two  inner  metacarpal  bones,  and  its  apex  directed  upwards  and  out- 
wards. The  superior  surface,  the  apex  of  the  wedge,  is  narrow,  convex,  smooth, 
and  articulates  with  the  semilunar.  The  inferior  surface  articulates  with  the 
fourth  and  fifth  metacarpal  bones,  the  concave  surface  for  each  being  separated 
by  a  ridge,  which  runs  from  before  backwards.  The  posterior  or  dorsal  surface 
is  triangular  and  rough,  for  ligamentous  attachment.  The  anterior  or  palmar 
surface  presents,  at  its  lower  and  inner  side,  a  curved  hook-like  process  of  bone, 
the  unciform  process,  directed  from  the  palmar  surface  forwards  and  outwards. 
It  gives  attachment,  by  its  apex,  to  the  annular  ligament;  by  its  inner  surface, 
to  the  Flexor  Brevis  Minimi  Digiti,  and  the  Flexor  Ossis  Metacarpi  Minimi 
Digiti ;  and  is  grooved  on  its  outer  side,  for  the  passage  of  the  flexor  tendons 
into  the  palm  of  the  hand.  This  is  one  of  the  four  eminences  on  the  front  of 
the  carpus,  to  which  the  anterior  annular  ligament  is  attached ;  the  others  being") 
the  pisiform  internally,  the  oblique  ridge  of  the  trapezium  and  the  tuberosity 
of  the  scaphoid  externally.  The  internal  surface  articulates  with  the  cuneiform 
by  an  oblong  surface,  cut  obliquely  from  above,  downwards  and  inwards.  Th( 
external  surface  articulates  with  the  os  magnum  by  its  upper  and  posterior  part,' 
the  remaining  portion  being  rough,  for  the  attachment  of  ligaments. 

To  ascertain  to  which  hand  it  belongs,  hold  the  apex  of  the  bone  upwards, 
and  the  broad  dorsal  surface  backwards:  the  concavity  of  the  unciform  process' 
will  be  directed  to  the  side  to  which  the  bone  belongs. 

Articulations.     With  five  bones :  the  semilunar  above,  the  fourth  and  fifth 
metacarpal  below,  the  cuneiform  internally,  the  os  magnum  externally. 

Attachment  of  Muscles.     To  two:  the  Flexor  Brevis  Minimi  Digiti,  the  Flexor 
Ossis  Metacarpi  Minimi  Digiti ;  and  to  the  anterior  annular  ligament. 

The  Metacarpus. 

The  Metacarpal  "Bones  are  five  in  number ;  they  are  long  cylindrical  bones, 
presenting  for  examination  a  shaft,  and  two  extremities. 

Common  Characters  of  the  Metacarpal  Bones.     The  shaft  is  prismoid  in  form, 
and  curved  longitudinally,  so  as  to  be  convex  in  the  longitudinal  direction 
behind,  concave  in  front.     It  presents  three  surfaces :  two  lateral,  and  one  pos- 
terior.    The  lateral  surfaces  are  concave,  for  the  attachment  of  the  Interossei 
muscles,  and  separated  from  one  another  by  a  prominent  line.     ^\\q  posterior  or^ 
dorsal  surface  is  triangular,  smooth,  and  flattened  below,  and  covered,  in  the] 
recent  state,  by  the  tendons  of  the -extensor  muscles.     In  its  upper  half  it  is! 
divided  by  a  ridge  into  two  narrow  lateral  depressions,  for  the  attachment  of 
the  Dorsal  Interossei  muscles.     This  ridge  bifurcates  a  little  above  the  centre 
of  the  bone,  and  its  branches  run  to  the  small  tubercles  on  each  side  of  the,] 
digital  extremity. 

The  carjjal  extremity,  or  base,  is  of  a  cuboidal  form,  and  broader  behind  than  i 
in  front :  it  articulates  above  with  the  carpus,  and  on  each  side  with  the  adjoin- 
ing metacarpal  bones;  its  dorsal  and  palmar  surf  aces  being  rough,  for  the  attach- 
ment of  tendons  and  ligaments. 

The  digital  extremity,  or  head,  presents  an  oblong  surface,  flattened  at  each 
side,  for  articulation  with  the  first  phalanx ;  it  is  broader,  and  extends  farther 
forwards  in  front  than  behind,  and  is  longer  in  the  antero-posterior  than  in  thoj 
transverse  diameter.  On  either  side  of  the  head  is  a  deep  depression,  sur- 
mounted by  a  tubercle,  for  the  attachment  of  the  lateral  ligament  of  the  meta- 
carpo-phalangeal  joint.  The  posterior  surface,  broad  and  flat,  supports  the  ex- 
tensor tendons;  the  anterior  surface  presents  a  median  groove,  bounded  on  each 
side  by  a  tubercle,  for  the  passage  of  the  flexor  tendons. 


METACARPUS.  225 

Peculiar  Characters  of  the  Metacarpal  Bones.  The  metacarpal  hone  of  the  thumb 
is  shorter  and  wider  than  the  rest,  diverges  to  a  greater  degree  from  the  carpus, 
and  its  palmar  surface  is  directed  inwards  towards  the  palm.  The  shaft  is  flat- 
tened and  broad  on  its  dorsal  aspect,  and  does  not  present  the  bifurcated  ridge 
which  is  found  on  the  other  metacarpal  bones ;  it  is  concave  from  before  back- 
wards on  its  palmar  surface.  The  carpal  extremity^  or  hase,  presents  a  concavo- 
convex  surface,  for  articulation  with  the  trapezium,  and  has  no  lateral  facets. 
The  digital  extremity  is  less  convex  than  that  of  the  other  metacarpal  bones, 
broader  from  side  to  side  than  from  before  backwards,  and  terminates  ante- 
riorly in  a  small  articular  eminence  on  each,  side,  over  which  play  two  sesa- 
moid bones. 

The  metacarpal  lone  of  the  index  finger  is  the  longest,  -and  its  base  the  largest 
of  the  other  four.  Its  carpal  extremity  is  prolonged  upwards  and  inwards.  The 
dorsal  and  palmar  surfaces  of  this  extremity  are  rough,  for  the  attachment  of 
tendons  and  ligaments.  It  presents  four  articular  facets :  the  first,  at  the  end 
of  the  bone,  is  concave  from  side  to  side,  convex  from  before  backwards,  and 
articulates  witli  the  trapezoid ;  the  second,  on  the  radial  side,  is  a  flat  quadri- 
lateral facet,  for  the  trapezium ;  the  third,  which  occupies  the  outer  part  of  the 
ulnar  side  of  the  extremity,  is  a  long  narrow  facet,  for  the  os  magnum;  and  the 
fourth,  which  occupies  the  inner  part  of  the  same  side,  is  a  considerably  broader 
surface,  for  third  metacarpal  bone. 

The  metacarpal  hone  of  the  middle  finger  is  a  little  smaller  than  the  preceding; 
it  presents  a  pyramidal  eminence  on  the  radial  side  of  its  base  (dorsal  aspect), 
which  extends  upwards  behind  the  os  magnum.  The  carpal  articular  facet  is 
concave  behind,  flat  and  horizontal  in  front,  and  corresponds  to  the  os  magnum. 
On  the  radial  side  is  a  smooth  concave  facet,  for  articulation  with  the  second 
metacarpal  bone ;  and  on  the  ulnar  side  two  small  oval  facets,  for  articulation 
with  the  fourth  metacarpal. 

The  metacarpal  hone  of  the  ring-finger  is  shorter  and  smaller  than  the  preced- 
ing, and  its  base  small  and  quadrilateral ;  the  carpal  surface  of  the  base  pre- 
senting two  facets,  for  articulation  with  the  unciform  and  os  magnum.  On  the 
radial  side  are  two  oval  facets,  for  articulation  with  the  third  metacarpal  bone; 
and  on  the  ulnar  side  a  single  concave  facet,  for  the  fifth  metacarpal. 

The  metacarpal  hone  of  the  little  finger  may  be  distinguished  by  the  concavo- 
convex  form  of  its  carpal  surface,  which  articulates  with  the  unciform;  and 
from  having  only  one  lateral  articular  facet,  which  corresponds  with  the  fourth, 
metacarpal  bone.  On  its  ulnar  side  is  a  prominent  tubercle,  for  the  insertion 
of  the  tendon  of  the  Extensor  carpi  ulnaris.  The  dorsal  surface  of  the  shaft 
is  marked  by  an  oblique  ridge,  which  extends  from  near  the  ulnar  side  of  the 
upper  extremity  to  the  radial  side  of  the  lower.  The  outer  division  of  this 
surface  serves  for  the  attachment  of  the  fourth  Dorsal  Interosseous  muscle;  the 
inner  division  is  smooth,  and  covered  by  the  extensor  tendons  of  the  little  finger. 

Articulations.  The  first  metacarpal  bone  articulates  with  the  trapezium;  the 
second  with  the  trapezium,  trapezoides,  os  magnum,  and  third  metacarpal 
bones;  the  third  with  the  os  magnum,  and  second  and  fourth  metacarpal  bones; 
the  fourth  with  the  os  magnum,  unciform,  and  third  and  fifth  metacarpal 
bones ;  and  the  fifth  with  the  unciform  and  fourth  metacarpal. 

Attachment  of  Muscles.  To  the  metacarpal  bone  of  the  thumb,  three:  the 
Flexor  Ossis  Metacarpi  Pollicis,  Extensor  Ossis  Metacarpi  Pollicis,  and  first 
Dorsal  Interosseous.  To  the  second  metacarpal  bone,  five :  the  Flexor  Carpi 
Radialis,  Extensor  Carpi  Radialis  Longior,  first  and  second  Dorsal  Interos- 
seous, and  first  Palmar  Interosseous.  To  the  third,  five :  the  Extensor  Carpi 
Radialis  Brevior,  Flexor  Brevis  Pollicis,  Adductor  Pollicis,  and  second  and 
third  Dorsal  Interosseous.  To  the  fourth,  three :  the  third  and  fourth  Dorsal 
and  second  Palmar  Interosseous.  To  the  fifth,  five:  the  Extensor  Carpi  Ulna- 
ris, Flexor  Ossis  Metacarpi  Minimi  Digiti,  fourth  Dorsal,  and  third  Palmar 
Interosseous. 
15 


226  THE    SKELETON. 

Phalanges. 

The  Phalanges  are  the  bones  of  the  fingers;  they  are  fourteen  in  number,  three 
for  each  finger,  and  two  for  the  thumb.  They  are  long  bones,  and  present  for 
examination  a  shaft,  and  two  extremities.  The  shaft  tapers  from  above  down- 
wards, is  convex  posteriorly,  concave  in  front  from  above  downwards,  flat  from 
side  to  side,  and  marked  laterally  by  rough  ridges,  which  give  attachment  to 
the  fibrous  sheaths  of  the  flexor  tendons.  The  metacarpal  extremity,  or  base, 
in  the  first  row,  presents  an  ovaI  concave  articular  surface,  broader  from  side 
to  side  than  from  before  backwards ;  and  the  same  extremity  in  the  other  two 
rows,  a  double  concavity  separated  by  a  longitudinal  median  ridge,  extending 
from  before  backwards.  The  digital  extremities  are  smaller  than  the  others, 
and  terminate,  in  the  first  and  second  row,  in  two  small  lateral  condyles,  sepa- 
rated by  a  slight  groove;  the  articular  surface  being  prolonged  farther  forwards 
on  the  palmar  than  on  the  dorsal  surface,  especially  in  the  first  row. 

The  ungual  phalanges  are  convex  on  their  dorsal,  flat  on  their  palmar  sur- 
faces ;  they  are  recognized  by  their  small  size,  and  by  a  roughened  elevated 
surface  of  a  horseshoe  form  on  the  palmar  aspect  of  their  ungual  extremity, 
which  serves  to  support  the  sensitive  pulp  of  the  finger. 

Articulations.     The  first  row  with  the  metacarpal  bones,  and  the  second  rowj 
of  phalanges;  the  second  row  with  the  first  and  third;  the  third,  with  th€ 
second  row. 

Attachment  of  Muscles.     To  the  base  of  the  first  phalanx  of  the  thumb,  foui 
muscles:  the  Extensor  Primi  Internodii  Pollicis,  Flexor  Brevis  Pollicis,  Ab-I 
ductor  Pollicis,  Adductor  Pollicis.     To  the  second  phalanx,  two :  the  Flexor! 
Longus  Pollicis,  and  the  Extensor  Secundi  Internodii.     To  the  base  of  the  first! 
phalanx  of  the  index  finger,  the  first  Dorsal  and  the  first  Palmar  Interosseous  a 
to  that  of  the  middle  finger,  the  second  and  third  Dorsal  Interosseous ;  to  that 
of  the  ring-finger,  the  fourth  Dorsal  and  the  second  Palmar  Interosseous;  an( 
to  that  of  the  little  finger,  the  third  Palmar  Interosseous,  the  Flexor  Brevis 
Minimi  Digiti,  and  Abductor  Minimi  Digiti.     To  the  second  phalanges,  the 
Flexor  Sublimis  Digitorura,  Extensor  Communis  Digitorum;  and,  in  addition,^ 
the  Extensor  Indicis  to  the  index  finger,  the  Extensor  Minimi  Digiti  to  the 
little  finger.     To  the  third  phalanges,  the  Flexor  Profundus  Digitorum  am 
Extensor  Communis  Digitorum. 

Development  of  the  Bones  op  the  Hand. 

The  Carpal  Bones  are  each  developed  by  a  single  centre.  At  birth,  they  are] 
all  cartilaginous.  Ossification  proceeds  in  the  following  order  (Fig.  163):  ittj 
the  OS  magnum  and  unciform  an  ossific  point  appears  during  the  first  yearJ 
the  former  preceding  the  latter;  in  the  cuneiform,  at  the  third  year;  in  thd 
trapezium  and  semilunar,  at  the  fifth  year,  the  former  preceding  the  latter;  in! 
the  scaphoid,  at  the  sixth  year ;  in  the  trapezoid,  during  the  eighth  year ;  andj 
in  the  pisiform,  about  the  twelfth  year. 

The  Metacarpal  Bones  are  each  developed  by  two  centres :  one  for  the  shaft,! 
and  one  for  the  digital  extremity,  for  the  four  inner  metacarpal  bones ;  one  fc 
the  shaft,  and  one  for  the  base,  for  the  metacarpal  bone  of  the  thumb,  whicl 
in  this  respect  resembles  the  phalanges.     Ossification  commences  in  the  centrd 
of  the  shaft  about  the  sixth  week,  and  gradually  proceeds  to  either  end  of  th^j 
bone;  about  the  third  year  the  digital  extremities  of  the  four  inner  metacarpa 
bones,  and  the  base  of  the  first  metacarpal,  commence  to  ossify,  and  they  unit 
about  the  twentieth  year. 

The  Phalanges  are  each  developed  by  two  centres:  one  for  the  shaft,  and  on( 
for  the  base.     Ossification  commences  in  the  shaft,  in  all  three  rows,  at  about 
the  sixth  week,  and  gradually  involves  the  wliole  of  the  bone,  excepting  thej 
upper  extremity.     Ossification  of  the  base  commences  in  the  first  row  betweei 


OS    INNOMINATUM. 

Fig.  163.— Plan  of  the  Development  of  the  Hand. 


227 


Carpus 
1.  cenirefo reach  lone 


All  curtilaqinotis  at  iirth 


Metacarpus 

Z  Centres  for  euch  done 
■Ifor  Sh(rft 

ij'or  Digital  Extremity 
except  /-^ 


Phalanges 

2  Cetitres for  each  lone 

t  for  Shaft 

i  forMetacariml  Extv. 


'aft/iears  4.-5^*  y  { 
\    umte  IS  20'^y^ 


}   un'tU  18-Z0*ff  y^ 

-  "PFu 


the  third  and  fourth  years,  and  a  year  later  in  those  of  the  second  and  third 
rows.  The  two  centres  become  united  in  each  row,  between  the  eighteenth  and 
twentieth  years. 


OF  THE  LOWER  EXTREMITY. 

The  Lower  Extremity  consists  of  three  segments,  the  Thigh^  Leg,  and  Foot, 
which  correspond  to  the  arm,  forearm,  and  liand  in  the  upper  extremity.  It  is 
connected  to  the  trunk  through  the  os  innominatum,  or  haunch,  which  is 
homologous  with  the  shoulder. 

The  Os  Innominatum. 

The  Os  Innominatum,  or  nameless  bone,  so  called  from  bearing  no  resem- 
blance to  any  known  object,  is  a  large  irregular-shaped  bone,  which,  with  its 
fellow  of  the  opposite  side,  forms  the  sides  and  anterior  wall  of  the  pelvic 
cavity.  In  young  subjects  it  consists  of  three  separate  parts,  which  meet  and 
form  the  large  cup-like  cavity,  situated  near  the  middle  of  the  outer  side  of 
the  bone ;  and,  although  in  the  adult  these  have  become  united,  it  is  usual  to 
describe  the  bone  as  divisible  into  three  portions — the  ilium,  the  ischium,  and 
the  pubes. 

The  Ilium,  so  called  from  its  supporting  the  flank  (ilia),  is  the  superior  broad 
and  expanded  portion  which  runs  upwards  from  the  upper  and  iDack  part  of 
the  acetabulum,  and  forms  the  prominence  of  the  hip. 

The  Ischium  {^lax^ov,  the  hip)  is  the  inferior  and  strongest  portion  of  the  bone ; 


228 


THE    SKELETON. 


it  proceeds  downwards  from  the  acetabulum,  expands  into  a  largo  tuberosity, 
ana  then,  curving  u])wards,  forms  with  tho  dosceudiug  ramus  of  the  pubes  a 
largo  aperture,  tho  obturator  foramen. 

The  Tubes  is  that  jjortioa  which  runs  horizontally  inwards  from  the  inner 
side  of  tho  acetabulum  for  about  two  inches,  then  makes  a  sudden  bend,  and 
descends  to  the  same  extent;  it  forms  the  front  of  tho  pelvis,  supports  the 
external  organs  of  generation,  and  has  received  its  name  from  being  covered 
with  hair. 

The  Ilium  presents  for  examination  two  surfaces,  an  external  and  an  internal, 
a  crest,  and  two  borders,  an  anterior  and  a  posterior. 

External  surface  or  dorsum  of  the  ilium  (Fig.  164).    The  back  part  of  this 

Pig.  164.— Right  Os  Innomiuatum.    External  Surface. 


f^Prnfuri*  kiQAMU 


'Tut  Aau»MtNI 


■■■KLUII  lUXIU 


flurfiioe  is  directed  backwards,  downwards,  and  outwards;  its  front  part  fo^ 
wards,  downwards,  and  outwards.     It  is  smooth,  convex  in  front,  deeply  con* 


ILIUM.  229 

cave  behind;  bounded  above  by  the  crest,  below  by  the  upper  border  of  the 
acetabulum;  iu  front  and  bcliind,  by  the  anterior  and  posterior  borders.  This 
surface  is  crossed  in  an  arched  direction  by  three  semicircular  lines,  the  supe- 
rior, middle,  and  inferior  curved  lines.  The  superior  curved  line,  the  shortest 
of  the  three,  commences  at  the  crest,  about  two  inches  in  front  of  its  posterior 
extremity ;  it  is  at  first  distinctly  marked,  but  as  it  passes  downwards  and  out- 
wards to  the  upper  part  of  the  great  sacro-sciatic  notch,  where  it  terminates,  it 
becomes  less  marked,  and  is  often  altogether  lost.  The  rough  surface  included 
between  this  line  and  the  crest,  affords  attachment  to  part  of  the  Gluteus 
Maximus  above,  a  few  fibres  of  the  Pyriformis  below.  The  middle  curved 
line,  the  longest  of  the  three,  commences  at  the  crest,  about  an  inch  behind  its 
anterior  extremity,  and,  taking  a  curved  direction  downwards  and  backwards, 
terminates  at  the  upper  part  of  the  great  sacro-sciatic  notch.  The  space  between 
the  middle  and  superior  curved  lines  and  the  crest  is  concave,  and  affords 
attachment  to  the  Gluteus  Medius  muscle.  Near  the  central  part  of  this  line 
may  often  be  observed  the  orifice  of  a  nutrient  foramen.  The  inferior  curved 
line,  the  least  distinct  of  the  three,  commences  in  front  at  the  upper  part  of  the 
anterior  inferior  spinous  process,  and  taking  a  curved  direction  backwards  and 
downwards,  terminates  at  the  anterior  part  of  the  great  sacro-sciatic  notch. 
The  surface  of  bone  included  between  the  middle  and  inferior  curved  lines  is 
concave  from  above  downwards,  convex  from  before  backwards,  and  affords 
attachment  to  the  Gluteus  Minimus  muscle.  Beneath  the  inferior  curved  line, 
and  corresponding  to  the  upper  part  of  the  acetabulum,  is  a  smooth  eminence 
(sometimes  a  depression),  to  which  is  attached  the  reflected  tendon  of  the  Rectus 
Femoris  muscle. 

The  internal  surface  (Fig.  165)  of  the  ilium  is  bounded  above  by  the  crest, 
below  by  a  prominent  line,  the  linea  ilio-pectinea,  and  before  and  behind  by 
the  anterior  and  posterior  borders.  It  presents  anteriorly  a  large  smooth  con- 
cave surface  called  the  internal  iliac  fossa,  or  venter  of  the  ilium,  which  lodges 
the  Iliacus  muscle,  and  presents  at  its  lower  part  the  orifice  of  a  nutrient  canal. 
Behind  the  iliac  fossa  is  a  rough  surface,  divided  into  two  portions,  a  superior 
and  an  inferior.  The  inferior  or  auricular  portion,  so  called  from  its  resem- 
blance in  shape  to  the  ear,  is  coated  with  cartilage  in  the  recent  state,  and 
articulates  with  a  similar  shaped  surface  on  the  side  of  the  sacrum.  The  supe- 
rior portion  is  concave  and  rough,  for  the  attachment  of  the  posterior  sacro-iliac 
ligaments. 

The  crest  of  the  ilium  is  convex  in  its  general  outline  and  sinuously  curved, 
being  bent  inwards  anteriorly,  outwards  posteriorly.  It  is  longer  in  the  female 
than  in  the  male,  very  thick  behind,  and  thinner  at  the  centre  than  at  the 
extremities.  It  terminates  at  either  end  in  a  prominent  eminence,  the  anterior 
superior  and  posterior  superior  spinous  process.  The  surface  of  the  crest  is 
broad,  and  divided  into  an  external  lip,  an  internal  lip,  and  an  intermediate 
space.  To  the  external  lip  is  attached  the  Tensor  Vaginae  Femoris,  Obliquus 
Externus  Abdominis,  and  Latissimus  Dorsi,  and  by  its  whole  length  the  fascia 
lata ;  to  the  interspace  between  the  lips,  the  Internal  Oblique ;  to  the  internal 
lip,  the  Transversalis,  Quadratus  Lumborum,  and  Erector  Spinte. 

The  anterior  border  of  the  ilium  is  concave.  It  presents  two  projections  sepa- 
rated by  a  notch.  Of  these,  the  uppermost,  situated  at  the  junction  of  the  crest 
and  anterior  border,  is  called  the  anterior  superior  spinous  process  of  the  ilium, 
the  outer  border  of  which  gives  attachment  to  the  fascia  lata,  and  the  origin  of 
the  Tensor  Vaginae  Femoris ;  its  inner  border,  to  the  Iliacus  Internus ;  whilst 
its  extremity  affords  attachment  to  Poupart's  ligament,  and  the  origin  of  the 
Sartorius.  Beneath  this  eminence  is  a  notch  which  gives  attachment  to  the 
Sartorius  muscle,  and  across  which  passes  the  external  cutaneous  nerve.  Below 
the  notch  is  the  anterior  inferior  spinous  process,  which  terminates  in  the  upper 
lip  of  the  acetabulum;  it  gives  attachment  to  the  straight  tendon  of  the  Rectus 
Femoris  muscle.     On  the  inner  side  of  the  anterior  inferior  spinous  process  is  a 


230 


THE    SKELETON. 


broad  shallow  groove  over  which  passes  the  Iliacus  muscle.  The  posterior 
border  of  the  ilium,  shorter  than  the  anterior,  also  presents  two  projections  sepa- 
rated by  a  notch,  the  posterior  superior  and  the  posterior  inferior  spinous  pro- 
cesses.    The  former  corresponds  with  that  portion  of  the  posterior  surface  of 

Pig.  165. — Right  Qs  InnomiDatum.     Internal  Surface. 


the  ilium  which  serves  for  the  attachment  of  the  sacro-iliac  ligaments ;  the  lattei 
to  the  auricular  portion  which  articulates  with  the  sacrum.  Below  the  poste- 
rior inferior  spinous  process  is  a  deep  notch,  the  great  sacro-sciatic. 

The  Ischium  forms  the  lower  and  back  part  of  the  os  innominatum.     It 
divisible  into  a  thick  and  solid  portion,  the  body ;  the  tuberosity,  a  large  rougl 
eminence,  on  which  the  body  rests  in  sitting ;  and  a  thin  ascending  part,  the 
ramus. 

The  hody,  somewhat  triangular  in  form,  presents  three  surfaces,  external,  in- 
ternal, and  posterior.  The  external  surface  corresponds  to  that  portion  of  th( 
acetabulum  formed  by  the  ischium ;  it  is  smooth  and  concave  above,  and  forms 
a  little  more  than  two-fifths  of  that  cavity ;  its  outer  margin  is  bounded  by 


ISCHIUM.  .  231 

prominent  rim  or  lip,  to  which  the  cotyloid  fibro-cartilage  is  attached.  Below 
the  acetabulum,  between  it  and  the  tuberosity,  is  a  deep  groove,  along  which 
the  tendon  of  the  Obturator  Externus  muscle  runs,  as  it  passes  outwards,  to  be 
inserted  into  the  digital  fossa  of  the  femur.  The  internal  surface  is  smooth, 
concave,  and  forms  the  lateral  boundary  of  the  true  pelvic  cavity ;  it  is  broad 
above,  and  separated  from  the  venter  of  the  ilium  by  the  linea  ilio-pectinea ; 
narrow  below,  its  posterior  border  is  encroached  upon,  a  little  below  its  centre, 
by  the  spine  of  the  ischium,  above  and  below  which  are  the  greater  and  lesser 
sacro-sciatic  notches ;  in  front  it  presents  a  sharp  margin,  which  forms  the  outer 
boundary  of  the  obturator  foramen.  This  surface  is  perforated  by  two  or  three 
large  vascular  foramina,  and  affords  attachment  to  part  of  the  Obturator  In- 
ternus  muscle.  The  jjosterior  sxirface  is  quadrilateral  in  form,  broad  and  smooth 
above,  narrow  below  where  it  becomes  continuous  with  the  tuberosity ;  it  is 
limited,  in  front,  by  the  margin  of  the  acetabulum;  behind,  by  the  front  part 
of  the  great  sacro-sciatic  notch.  This  surface  supports  the  Pyriformis,  the  two 
Gemelli,  and  the  Obturator  Internus  muscles,  in  their  passage  outwards  to  the 
great  trochanter.  The  body  of  the  ischium  presents  three  borders,  posterior, 
inferior,  and  internal.  The  posterior  border  presents,  a  little  below  the  centre, 
a  thin  and  pointed  triangular  eminence,  the  spine  of  the  ischium,  more  or  less 
elongated  in  different  subjects.  Its  external  surface  gives  attachment  to  the 
Gemellus  Superior,  its  internal  surface  to  the  Coccygeus  and  Levator  Ani ; 
whilst  to  the  pointed  extremity' is  connected  the  lesser  sacro-sciatic  ligament. 
Above  the  spine  is  a  notch  of  large  size,  the  great  sacro-sciatic,  converted  into 
a  foramen  by  the  lesser  sacro-sciatic  ligament ;  it  transmits  the  Pyriformis 
muscle,  the  gluteal  vessels,  and  superior  gluteal  nerve  passing  out  of  the  pelvis 
above  the  muscle ;  the  sciatic  artery,  the  greater  and  lesser  sciatic  nerves,  the 
internal  pudic  vessels  and  nerve,  and  a  small  nerve  to  the  Obturator  Internus 
muscle  below  it.  Below  the  spine  is  a  smaller  notch,  the  lesser  sacro-sciatic ; 
it  is  smooth,  coated  in  the  recent  state  with  cartilage,  the  surface  of  which  pre- 
sents numerous  markings  corresponding  to  the  subdivisions  of  the  tendon  of 
the  Obturator  Internus  which  winds  over  it.  It  is  converted  into  a  foramen  by 
the  sacro-sciatic  ligaments,  and  transmits  the  tendon  of  the  Obturator  Internus, 
the  nerve  which  supplies  that  muscle,  and  the  pudic  vessels  and  nerve.  The 
inferior  border  is  thick  and  broad;  at  its  point  of  junction  with  the  posterior  is 
the  tuberosity  of  the  ischium.  The  internal  border  is  thin,  and  forms  the  outer 
circumference  of  the  obturator  foramen. 

The  tuberosity  presents  for  examination  an  external  lip,  an  internal  lip,  and 
an  intermediate  space.  The  external  lip  gives  attachment  to  the  Quadratus 
Femoris,  and  part  of  the  Adductor  Magnus  muscles.  The  inner  lip  is  bounded 
by  a  sharp  ridge,  for  the  attachment  of  a  falciform  prolongation  of  the  great 
sacro-sciatic  ligament;  it  presents  a  groove  on  the  inner  side  of  this  for  the 
lodgment  of  the  internal  pudic  vessels  and  nerve ;  and,  more  anteriorly,  has 
attached  the  Transversus  Perinei  and  Erector  Penis  muscles.  The  intermediate 
surface  presents  four  distinct  impressions.  Two  of  these,  seen  at  the  front  part 
of  the  tuberosity,  are  rough,  elongated,  and  separated  from  each  other  by  a 
prominent  ridge ;  the  outer  one  gives  attachment  to  the  Adductor  Magnus,  the 
inner  one  to  the  great  sacro-sciatic  ligament.  Two,  situated  at  the  back  part, 
are  smooth,  larger  in  size,  and  separated  by  an  oblique  ridge :  from  the  upper 
and  outer  arises  the  Semi-membranosus ;  from  the  lower  and  inner,  the  Biceps 
and  Semi-tendinosus.  The  uppermost  part  of  the  tuberosity  gives  attachment 
to  the  Gemellus  Inferior. 

The  ramus,  or  ascending  ramus,  is  the  thin  flattened  part  of  the  ischium, 
which  ascends  from  the  tuberosity  upwards  and  inwards,  and  joins  the  ramus 
of  the  pubes — their  point  of  junction  being  indicated  in  the  adult  by  a  rough 
eminence.  The  outer  surface  of  the  ramus  is  rough,  for  the  attachment  of  the 
Obturator  Externus  muscle,  also  some  fibres  of  the  Adductor  Magnus,  and  of 
the  Gracilis ;  its  inner  surface  forms  part  of  the  anterior  wall  of  the  pelvis. 


232  THE    SKELETON. 

Its  inner  border  is  thick,  rough,  slightly  everted,  forms  part  of  the  outlet  of 
the  pelvis,  and  serves  for  the  attachment  of  the  crus  penis.  Its  outer  border 
is  thin  and  sharp,  and  forms  part  of  the  inner  margin  of  the  obturator  foramen. 
The  Pxihes  forms  the  anterior  part  of  the  os  innominatum;  it  is  divisible  into 
a  horizontal  ramus  or  body,  and  a  perpendicular  ramus. 

The  hody^  or  horizontal  ramus,  presents  for  examination  two  extremities,  an 
outer  and  an  inner,  and  four  surfaces.  The  oriter  extremity^  the  thickest  part  of 
the  bone,  forms  one-fifth  of  the  cavity  of  the  acetabulum ;  it  presents,  above, 
a  rough  eminence,  the  ilio-pectineal,  which  serves  to  indicate  the  point  of  junc- 
tion of  the  ilium  and  pubes.  The  inner  extremity  is  the  symphysis;  it  is  oval, 
covered  by  eight  or  nine  transverse  ridges,  or  a  series  of  nipple- like  processes 
arranged  in  rows,  separated  by  grooves ;  they  serve  for  the  attachment  of  the 
interarticular  fibro-cartilage,  placed  between  it  and  the  opposite  bone.  The 
uj)per  surface,  triangular  in  form,  wider  externally  than  internally,  is  bounded 
behind  by  a  sharp  ridge,  the  pectineal  line,  or  linea  ilio-pectinea,  which,  run- 
ning outwards,  marks  the  brim  of  the  true  pelvis.  The  surface  of  bone  in 
front  of  the  pubic  portion  of  the  linea  ilio-pectinea,  serves  for  the  attachment 
of  the  Pectineus  muscle.  This  ridge  terminates  internally  at  a  tubercle,  which 
projects  forwards,  and  is  called  the  spine  of  the  pubes.  The  portion  of  bone 
included  between  the  spine  and  inner  extremity  of  the  pubes  is  called  the  crest; 
it  serves  for  the  attachment  of  the  Rectus,  Pyramidalis,  and  conjoined  tendon 
of  the  Internal  Oblique  and  Transversalis.  The  point  of  junction  of  the  crest 
with  the  symphysis  is  called  the  angle  of  the  puhes.  The  inferior  surface  pre- 
sents, externally,  a  broad  and  deep  oblique  groove,  for  the  passage  of  the  obtu- 
rator vessels  and  nerve ;  and  internally,  a  sharp  margin,  which  forms  part  of 
the  circumference  of  the  obturator  foramen.  Its  external  surface,  flat  and  com- 
pressed, serves  for  the  attachment  of  muscles.  Its  internal  surface,  convex  from 
above  downwards,  concave  from  side  to  side,  is  smooth,  and  forms  part  of  the 
anterior  wall  of  the  pelvis. 

The  descending  ramu^  of  the  pubes  passes  outwards  and  downwards,  becom- 
ing thinner  and  narrower  as  it  descends,  and  joins  with  the  ramus  of  the 
ischium.  Its  extei^nal  surface  is  rough  for  the  attachment  of  muscles ;  the  Ad- 
ductor Longus  above,  the  Adductor  Brevis  below;  the  Gracilis  along  its  inner 
border,  the  Compressor  Urethrse  towards  its  internal  aspect ;  and  a  portion  of 
the  Obturator  Externus  where  it  enters  into  the  formation  of  the  foramen  oi 
that  name.  Its  inner  surface  is  smooth.  Its  inner  border  is  thick,  rough,  and 
everted,  especially  in  females.  In  the  male  it  serves  for  the  attachment  of  the 
crus  penis.  Its  outer  border  forms  part  of  the  circumference  of  the  obturatoi' 
foramen. 

The  cotyloid  cavity,  or  acelabuhim,  is  a  deep,  cup-shaped,  hemispherical  de- 
pression ;  formed,  internally,  by  the  pubes,  above  by  the  ilium,  behind  and 
below  by  the  ischium;  a  little  less  than  two-fifths  being  formed  by  the  ilium,  a 
little  more  than  two-fifths  by  the  ischium,  and  the  remaining  fifth  by  the  pubes- 
It  is  bounded  by  a  prominent  uneven  rim,  which  is  thick  and  strong  above,  and 
serves  for  the  attachment  of  a  fibro-cartilaginous  structure  which  contracts  its 
orifice,  and  deepens  the  surface  for  articulation.  It  presents  on  its  inner  side  a 
deep  notch,  the  cotyloid  notch,  which  transmits  the  nutrient  vessels  into  the 
interior  of  the  joint,  and  is  continuous  with  a  circular  depression  at  the  bottom 
of  the  cavity :  this  depression  is  perforated  by  numerous  apertures,  lodges  a 
mass  of  fat,  and  its  margins  serve  for  the  attachment  of  the  ligamentum  teres. 
The  notch  is  converted,  in  the  natural  state,  into  a  foramen  by  a  dense  liga- 
mentous band  which  passes  across  it.  Through  this  foramen  the  nutrient  ves- 
sels and  nerves  enter  the  joint. 

The  obturator  or  thyroid  foramen  is  a  large  aperture,  situated  between  the 
ischium  and  pubes.  In  the  male  it  is  large,  of  an  oval  form,  its  longest  diameter 
being  obliquely  from  above  downwards;  in  the  female  it  is  smaller,  and  more 
triangular.     It  is  bounded  by  a  thin  uneven  margin,  to  which  a  strong  mem- 


DEVELOPMENT  OF  OS  INNOMINATUM. 


233 


brane  is  attached ;  and  presents,  at  its  upper  and  outer  part,  a  deep  groove, 
which  runs  from  the  pelvis  obliquely  forwards,  inwards,  and  downwards.  This 
groove  is  converted  into  a  foramen  by  the  obturator  membrane,  and  transmits 
the  obturator  vessels  and  nerve. 

Structure  of  the  Os  Innominaium.  This  bone  consists  of  much  cancellous  tis- 
sue, especially  where  it  is  thick,  inclosed  between  two  layers  of  dense  compact 
tissue.  In  the  thinner  parts  of  the  bone,  as  at  the  bottom  of  the  acetabulum 
and  centre  of  the  iliac  fossa,  it  is  usually  semi-transparent,  and  composed 
entirely  of  compact  tissue. 

Development  (Fig.  166).  By  eight  centres:  three  primary — one  for  the  ilium, 
one  for  the  ischium,  and  one  for  the  pubes ;  and  five  secondary — one  for  the 

Fig.  166. — Plan  of  the  Development  of  the  Os  Innominatum. 

I     S.Seconda.'T-u 


The  3  Frlmu/ry  ee/nlret  ^jtUe    throupli.  YMa/it<7 fiieecjalota^uZetfy 

J^^ijfTtyses  ajy^ear  about j^aierty^^    U,nCt&    aboiU:  2.6^  year 

crest  of  the  ilium  its  whole  length,  one  for  the  anterior  inferior  spinous  process 
(said  to  occur  more  frequently  in  the  male  than  the  female),  one  for  the  tuber- 
osity of  the  ischium,  one  for  the  symphysis  pubis  (more  frequent  in  the  female 
than  the  male),  and  one  for  the  Y-shaped  piece  at  the  bottom  of  the  acetabulum. 
These  various  centres  appear  in  the  following  order:  First,  in  the  ilium,  at  the 
lower  part  of  the  bone,  immediately  above  the  sciatic  notch,  at  about  the  same 
period  that  the  development  of  the  vertebras  commences.  Secondly,  in  the 
body  of  the  ischium,  at  about  the  third  month  of  foetal  life.  Thirdly,  in  the 
body  of  the  pubes,  between  the  fourth  and  fifth  months.  At  birth,  the  three 
primary  centres  are  quite  separate,  the  crest,  the  bottom  of  the  acetabulum,  and 
the  rami  of  the  ischium  and  pubes,  being  still  cartilaginous.  At  about  the 
sixth  year,  the  rami  of  the  pubes  and  ischium  are  almost  completely  ossified. 
About  the  thirteenth  or  fourteenth  year,  the  three  divisions  of  the  bone  have 
extended  their  growth  into  the  bottom  of  the  acetabulum,  being  separated  from 
each  other  by  a  Y-shaped  portion  of  cartilage,  which  now  presents  traces  of 
ossification.     The  ilium  and  ischium  then  become  joined,  and  lastly  the  pubes, 


234  THE    SKELETON. 

through  the  intervention  of  this  Y-shaped  portion.  At  about  the  age  of  pu- 
berty, ossification  takes  place  in  each  of  the  remaining  portions,  and  they  be- 
come joined  to  the  rest  of  the  bone  about  the  twenty-fitth  year. 

Articulations.     With  its  fellow  of  the  opposite  side,  the  sacrum  and  femur. 

Attachment  of  Muscles.  Ilium.  To  the  outer  lip  of  the  crest,  the  Tensor 
Vaginae  Feraoris,  Obliquus  Externus  Abdominis,  and  Latissimus  Dorsi ;  to  the 
internal  lip,  the  Transversalis,  Quadratus  Lumborum,  and  Erector  Spinas ;  to 
the  interspace  between  the  lips,  the  Obliquus  Internus.  To  the  outer  surface 
of  the  ilium,  the  Gluteus  Maximus,  Gluteus  Medius,  Gluteus  Minimus,  reflected 
tendon  of  Kectus,  portion  of  Pyriformis ;  to  the  internal  surface,  the  Iliacus ;  to 
the  anterior  border,  the  Sartorius  and  straight  tendon  of  the  Eectus.  Ischium^ 
To  its  outer  surface,  the  Obturator  Externus;  internal  surface,  Obturator  In- 
ternus, and  Levator  Ani.  To  the  spine,  the  Gemellus  Superior,  Levator  Ani, 
and  Coccygeus.  To  the  tuberosity,  the  Biceps,  Semi-tendinosus,  Semi-mem- 
branosus,  Quadratus  Femoris,  Adductor  Magnus,  Gemellus  Inferior,  Transversus 
Perinei,  Erector  Penis.  Puhes.  The  Obliquus  Externus,  Oliquus  Internus, 
Transversalis,  Rectus,  Pyramidalis,  Psoas  Parvus,  Pectineus,  Adductor  Longus, 
Adductor  Brevis,  Gracilis,  Obturator  Externus  and  Internus,  Levator  Ani, 
Compressor  Urethras,  and  occasionally  a  few  fibres  of  the  Accelerator  Urince. 

The  Pelvis  (Figs.  167",  168). 

The  Pelvis,  so  called  from  its  resemblance  to  a  basin,  is  stronger  and  more 
massively  constructed  than  either  the  cranial  or  thoracic  cavity;  it  is  a  bony 
ring,  interposed  between  the  lower  end  of  the  spine,  which  it  supports,  and  the 
lower  extremities,  upon  which  it  rests.  It  is  composed  of  four  bones — the  two 
ossa  innominata,  which  bound  it  on  either  side  and  in  front ;  and  the  sacrum 
and  coccyx,  which  complete  it  behind. 

The  pelvis  is  divided  by  a  prominent  line,  the  linea  ilio-pectinea,  into  the 
false  and  true  pelvis. 

The  False  Pelvis  is  all  that  expanded  portion  of  the  pelvic  cavity  which  is 
situated  above  the  linea  ilio-pectinea.  It  is  bounded  on  each  side  by  the  ossa 
ilii ;  in  front  it  is  incomplete,  presenting  a  wide  interval  between  the  spinous 
processes  of  the  ilia  on  either  side,  which  is  filled  up  in  the  recent  state  by  the 
parietes  of  the  abdomen;  behind,  in  the  middle  line,  is  a  deep  notch.  This 
broad  shallow  cavity  is  fitted  to  support  the  intestines,  and  to  transmit  part  of 
their  weight  to  the  anterior  wall  of  the  abdomen. 

The  True  Pelvis  is  all  that  part  of  the  pelvic  cavity  which  is  situated  beneath 
the  linea  ilio-pectinea.  It  is  smaller  than  the  false  pelvis,  but  its  walls  are 
more  perfect.  For  convenience  of  description,  it  is  divided  into  a  superior 
circumference  or  inlet,  an  inferior  circumference  or  outlet,  and  a  cavity. 

The  superior  circumference  forms  the  margin  or  brim  of  the  pelvis,  the  included 
space  being  called  the  i7ilet.  It  is  formed  by  the  linea  ilio-pectinea,  completed 
in  front  by  the  spine  and  crest  of  the  pubes,  and  behind  by  the  anterior  margin 
of  the  base  of  the  sacrum  and  sacro-vertebral  angle. 

The  inlet  of  the  pelvis  is  somewhat  heart-shaped,  obtusely  pointed  in  front, 
diverging  on  either  side,  and  encroached  upon  behind  by  the  projection  forwards 
of  the  promontory  of  the  sacrum.  It  has  three  principal  diameters :  antero- 
posterior (sacro-pubic),  transverse,  and  oblique.  The  antero-posterior  extends 
from  the  sacro-vertebral  angle  to  the  symphysis  pubis;  its  average  measurement 
is  four  inches.  The  transverse  extends  across  the  greatest  width  of  the  inlet, 
from  the  middle  of  the  brim  on  one  side  to  the  same  point  on  the  opposite;  its 
average  measurement  is  five  inches.  The  oblique  extends  from  the  margin  of 
the  pelvis,  corresponding  to  the  ilio-pectineal  eminence  on  one  side,  to  the  sacro- 
iliac symphysis  on  the  opposite  side;  its  average  measurement  is  also  five  inches. 

The  cavity  of  tlie  true  pelvis  is  bounded  in  front  by  the  symphysis  pubis; 
behind  by  the  concavity  of  the  sacrum  and  coccyx,  which,  curving  forwards 


PELVIS.  235 


above  and  below,  contracts  the  inlet  and  outlet  of  the  canal;  and  laterally  it  is 
bounded  by  a  broad,  smooth,  quadrangular  plate  of  bone,  corresponding  to  the 
inner  surface  of  the  body  of  the  ischium.  The  cavity  is  shallow  in  front,  mea- 
suring at  the  symphysis  an  inch  and  a  half  in  depth,  three  inches  and  a  half  in 

Fig.  167.— Male  Pelvis  (Adult). 


Fig.  168.— Female  Pelvis  (Adult). 


tlie  middle,  and  four  inches  and  a  half  posteriorly.  From  this  description  it 
will  be  seen  that  the  cavity  of  the  pelvis  is  a  short  curved  canal,  considerably 
deeper  on  its  posterior  than  on  its  anterior  wall,  and  broader  in  the  middle  than 
at  either  extremity,  from  the  projection  forwards  of  the  sacro-coccygeal  cjolumn 
above  and  below.  This  cavity  contains,  in  the  recent  subject,  the  rectum,  blad- 
der, and  part  of  the  organs  of  generation.  The  rectum  is  placed  at  the  back 
of  the  pelvis,  and  corresponds  to  the  curve  of  the  sacro-coccygeal  column;  the 


236 


THE    SKELETON. 


Fig,  169.— Yertical  Section  of  the 
Pelvis,  with  lines  indieating  the  Axes 
of  the  Pelvis. 


bladder  in  front,  behind  the  symphysis  pubis.     In  the  female,  the  uterus  and 
vagina  occupy  the  interval  between  these  parts. 

The  lower  circumference  of  the  pelvis  is  very  irregular,  and  forms  what  is 
called  the  outlet.  It  is  bounded  by  three  prominent  eminences:  one  posterior, 
formed  by  the  point  of  the  coccyx;  and  one  on  each  side,  the  tuberosities  of 
the  ischia.  These  eminences  are  separated  by  three  notches:  one  in  front,  the 
puhic  arch,  formed  by  the  convergence  of  the  rami  of  the  ischia  and  pubes  on 
each  side.  The  other  notches,  one  on  each  side,  are  formed  by  the  sacrum  and 
coccyx  behind,  the  ischium  in  front,  and  the  ilium  above:  they  are  called  the 
sacro-sciatic  notches;  in  the  natural  state  they  are  converted  into  foramina  bv 
the  lesser  and  greater  sacro-sciatic  ligaments.  The  diameters  of  the  outlet  of 
the  pelvis  are  two,  antero- posterior  and  transverse.  The  antero-posierior  extends 
from  the  tip  of  the  coccyx  to  the  lower  part  of  the  symphysis  pubis,  and  the 
transverse  from  the  posterior  part  of  one  ischiatic  tuberosity  to  the  same  point 

on  the  opposite  side:  the  average  measurement 
of  both  is  four  inches.  The  antero-posterior 
diameter  varies  with  the  length  of  the  coccyx, 
and  is  capable  of  increase  or  diminution,  on 
account  of  the  mobility  of  that  bone. 

Position  of  the  Pelvis.  In  the  erect  posture, 
the  pelvis  is  placed  obliquely  with  regard  to 
the  trunk  of  the  body;  the  pelvic  surface  of 
the  symphysis  pubis  looking  upwards  and 
backwards,  the  concavity  of  the  sacrum  and 
coccyx  looking  downwards  and  forwards;  the 
base  of  the  sacrum  in  well-formed  female 
bodies  being  nearly  four  inches  above  the  up- 
per border  of  the  symphysis  pubis,  and  the 
apex  of  the  coccyx  a  little  more  than  half  an 
inch  above  its  lower  border.  The  obliquity 
is  much  greater  in  the  foetus,  and  at  an  early 
period  of  life,  than  in  the  adult. 

Axes  of  the  Pelvis  (Fig.  169).  The  plane  of 
the  inlet  of  the  true  pelvis  will  be  represented 
by  a  line  drawn  from  the  base  of  the  sacrum 
to  the  upper  margin  of  the  symphysis  pubis. 
A  line  carried  at  right  angles  with  this  at  its  middle,  would  correspond  at  one 
extremity  with  the  umbilicus,  and  at  the  other  with  the  middle  of  the  coccyx; 
the  axis  of  the  inlet  is  therefore  directed  downwards  and  backwards.  The  axis 
of  the  outlet  produced  upwards  would  touch  the  base  of  the  sacrum,  and  is 
therefore  directed  downwards  and  forwards.  The  axis  of  the  cavity  is  curved 
like  the  cavity  itself:  this  curve  corresponds  to  the  concavity  of  the  sacrum 
and  coccyx,  the  extremities  being  indicated  by  the  central  points  of  the  inlet 
and  outlet.  A  knowledge  of  the  direction  of  these  axes  serves  to  explain  the 
course  of  the  foetus  in  its  passage  through  the  pelvis  during  parturition.  It  is 
also  important  to  the  surgeon,  as  indicating  the  direction  of  the  force  required 
in  the  removal  of  calculi  from  the  bladder,  and  as  determining  the  direction  in 
which  instruments  should  be  used  in  operations  upon  the  pelvic  viscera. 

Differences  between  the  Male  and  Female  Pelvis.  In  the  male  the  bones  are 
thicker  and  stronger,  and  the  muscular  eminences  and  impressions  on  their 
surfaces  more  strongly  marked.  The  male  pelvis  is  altogether  more  massive; 
its  cavity  is  deeper  and  narrower,  and  the  obturator  foramina  of  larger  siz:e. 
In  the  female  the  bones  are  lighter  and  more  expanded,  the  muscular  impres- 
sions on  their  surfaces  are  only  slightly  marked,  and  the  pelvis  generally  is 
less  massive  in  structure.  The  iliac  fossaa  are  broad,  and  the  spines  of  the  ilia 
widely  separated;  hence  the  great  prominence  of  the  hips.  The  inlet  and  the 
outlet  are  larger;  the  cavity  is  more  capacious,  and  the  spines  of  the  ischia 


i 


-ji::^^  O'^'^' 


FEMUR 


237 


project  less  into  it.  The  promontory 
IS  less  projecting,  the  sacrum  wider  and 
less  curved/  and  the  coccyx  more 
movable.  The  arch  of  the  pubes  is 
wider,  and  its  edges  more  everted.  The 
tuberosities  of  the  ischia  and  the  aceta- 
bula  are  wider  apart. 

In  the  foetus,  and  for  several  years 
after  birth,  the  pelvis  is  small  in  pro- 
portion to  that  of  the  adult.  The  cavity 
is  deep,  and  the  projection  of  the  sacro' 
vertebral  angle  less  marked.  The  an- 
tero-posterior  and  transverse  diameters 
are  nearly  equal.  Ahout  puberty,  the 
pelvis  in  both  sexes  presents  the  general 
characters  of  the  adult  male  pelvis,  but 
after  puberty  it  acquires  its  proper  sex 
ual  characters. 

The  Femur  op.  Thigh-Bone. 

The  Femur  is  the  longest,  largest,  and 
strongest  bone  in  the  skeleton,  and  al- 
most perfectly  cylindrical  in  the  greater 
part  of  its  extent.  In  the  erect  posture 
it  is  not  vertical,  being  separated  from 
its  fellow  above  by  a  considerable  in- 
terval, which  corresponds  to  the  entire 
breadth  of  the  pelvis,  but  inclining 
gradually  downwards  and  inwards,  so 
as  to  approach  its  fellow  towards  its 
lower  part,  for  the  purpose  of  bringing 
the  knee-joint  near  the  line  of  gravity 
of  the  body.  The  degree  of  this  in- 
clination varies  in  different  persons, 
and  is  greater  in  the  female  than  in  the 
male,  on  account  of  the  greater  breadth 
of  the  pelvis.  The  femur,  like  other 
long  bones,  is  divisible  into  a  shaft,  and 
two  extremities. 

The  Upper  Extremity  presents  for  exa- 
mination a  head,  a  neck,  and  the  greater 
and  lesser  trochanters. 

The  head,  which  is  globular,  and  forms 
rather  more  than  a  hemisphere,  is  di 
rected  upwards,  inwards,  and  a  little 
forwards,  the  greater  part  of  its  con- 
vexity being  above  and  in  front.  Its 
surface  is  smooth,  coated  with  cartilage 
in  the  recent  state,  and  presents,  a  little 
behind  and  below  its  centre,  an  ovoid 
depression,  for  the  attachment  of  the 
ligamentum  teres.  The  nech  is  a  flat- 
tened pyramidal  process  of  bone,  which 

'  It  is  not  unusual,  however,  to  find  the  sacrum 
in  the  female  presenting  a  considerable  curve 
extending  throughout  its  whole  length. 


Fig.  170.— Right  Femur.    Anterior  Surface. 


MXIUI«TOA     INTCRNUS     &,  acNBLLl 
PVRVtRilia 


UCAMCNTUM   Te 


^''/•t'o/u'j 


'^hL^I, 


238  THE    SKELETON- 

connects  the  head  with  the  shaft.  It  varies  in  length  and  obliquity  at  varioug 
periods  of  life,  and  under  different  circumstances.  Before  puberty  it  is  directed 
obliquely,  so  as  to  form  a  gentle  curve  from  the  axis  of  the  shaft.  In  the  adult 
male  it  forms  an  obtuse  angle  with  the  shaft,  being  directed  upwards,  inwards, 
and  a  little  forwards.  In  the  female  it  approaches  more  nearly  a  right  angle. 
Occasionally,  in  very  old  subjects,  and  more  especially  in  those  greatly  debili- 
tated, its  direction  becomes  horizontal ;  so  that  the  head  sinks  below  the  level 
of  the  trochanter,  and  its  length  diminishes  to  such  a  degree,  that  the  head 
becomes  almost  contiguous  with  the  shaft.  The  neck  is  flattened  from  before 
backwards,  contracted  in  the  middle,  and  broader  at  its  outer  extremity,  where 
it  is  connected  with  the  shaft,  than  at  its  summit,  where  it  is  attached  to  the 
head.  It  is  much  broader  in  the  vertical  than  in  the  antero-posterior  diameter, 
and  much  thicker  below  than  above,  on  account  of  the  greater  amount  of 
resistance  required  in  sustaining  the  weight  of  the  trunk.  The  anterior  surface 
of  the  neck  is  perforated  by  numerous  vascular  foramina.  The  posterior  surface 
is  smooth,  and  is  broader  and  more  concave  than  the  anterior ;  it  receives 
towards  its  outer  side  the  attachment  of  the  capsular  ligament  of  the  hip,  Tbe 
superior  border  is  short  and  thick,  bounded  externally  by  the  great  trochanter, 
and  its  surface  perforated  by  large  foramina.  The  inferior  border,  long  and 
narrow,  curves  a  little  backwards,  to  terminate  at  the  lesser  trochanter. 

The  trochanters  {tp6xaM-,  to  run  or  roll)  are  prominent  processes  of  bone  which 
afford  leverage  to  the  muscles  which  rotate  the  thigh  on  its  axis.  They  are 
two  in  number,  the  greater  and  the  lesser. 

The  Great  Trochanter  is  a  large  irregular  quadrilateral  eminence,  situated  at 
the  outer  side  of  the  neck,  at  its  junction  with  the  upper  part  of  the  shaft.  It 
is  directed  a  little  outwards  and  backwards,  and,  in  the  adult,  is  about  three 
quarters  of  an  inch  lower  than  the  head.  It  presents  for  examination  two 
surfaces,  and  four  borders.  The  external  surface,  quadrilateral  in  form,  is 
broad,  rough,  convex,  and  marked  by  a  prominent  diagonal  line,  which  extends 
from  the  posterior  superior  to  the  anterior  inferior  angle ;  this  line  serves  for 
the  attachment  of  the  tendon  of  the  Gluteus  Medius.  Above  the  line  is  a 
triangular  surface,  sometimes  rough  for  part  of  the  tendon  of  the  same  muscle, 
sometimes  smooth  for  the  interposition  of  a  bursa  between  that  tendon  and 
the  bone.  Below  and  behind  the  diagonal  line  is  a  smooth  triangular  surface, 
over  which  the  tendon  of  the  Gluteus  Maximus  muscle  plays,  a  bursa  bein^ 
interposed.  The  internal  surface  is  of  much  less  extent  than  the  external,  and 
presents  at  its  base  a  deep  depression,  the  digital  or  trochanteric  fossa  for  the ' 
attachment  of  the  tendon  of  the  Obturator  Externus  muscle.  The  superior 
border  is  free;  it  is  thick  and  irregular,  and  marked  by  impressions  for  the 
attachment  of  the  Pyriformis  behind,  the  Obturator  Internus  and  Gemelli  in 
front.  The  inferior  border  corresponds  to  the  point  of  junction  of  the  base  of 
the  trochanter  with  the  outer  surface  of  the  shaft;  it  is  rough,  prominent, 
slightly  curved,  and  gives  attachment  to  the  upper  part  of  the  Vastus  Externua 
muscle.  The  anterior  border  is  prominent,  somewhat  irregular,  as  well  as  th* 
surface  of  bone  immediately  below  it ;  it  affords  attachment  by  its  outer  part" 
to  the  Gluteus  Minimus.  The  iiosterior  border  is  very  prominent,  and  appears' 
as  a  free  rounded  edge,  which  forms  the  back  part  of  the  digital  fossa. 

The  Lesser  Trochanter  is  a  conical  eminence,  which  varies  in  size  in  different 
subjects ;  it  projects  from  the  lower  and  back  part  of  the  base  of  the  neck.  Ita 
base  is  triangular,  and  connected  with  the  adjacent  parts  of  the  bone  by  three 
well-marked  borders;  of  these,  the  superior  is  continuous  with  the  lower  border^ 
of  the  neck;  i\\Q posterior,  with  the  posterior  intertrochanteric  line;  and  the 
inferior,  with  the  middle  division  of  the  linea  aspera.  Its  summit,  which  is 
directed  inwards  and  backwards,  is  rough,  and  gives  insertion  to  the  tendon  of 
the  Psoas  Magnus.  The  Iliacus  is  inserted  into  the  shaft  below  the  lesser 
trochanter,  between  the  Vastus  Internus  in  front,  and  the  Pectincus  behind.  A 
well-marked  prominence,  of  variable  size,  which  projects  from  the  upper  and 


FEMUR. 


239 


front  part  of  the  neck,  at  its  junction    Fig 
with  the  great  trochanter,  is  called  the 
tubercle  of  the  femur ;  it  is  the  point  of 
meeting  of  three  muscles,  the  Gluteus 
Minimus  externally,  the  Vastus  Exter- 
nus  below,  and  the  tendon  of  the  Obtu- 
rator Internus  and  Gemelli  above.  Run- 
ning obliquely  downwards  and  inwards 
from  the  tubercle  is  the  spiral  line  of 
the  femur,  or  anterior  intertrochanteric 
line;  it  winds  round  the  inner  side  of 
the  shaft,  below  the  lesser  trochanter, 
and  terminates  in  the  linea  aspera,  about 
two  inches  below  this  eminence.     Its 
upper  half  is  rough,  and  affords  attach- 
ment to  the  capsular  ligament  of  the 
hip-joint ;  its  lower  half  is  less  promi- 
nent, and  gives  attachment  to  the  upper 
part  of  the  Vastus  Internus.     The  pos- 
terior   intertrochanteric    line    is   very 
prominent,  and  runs  from  the  summit 
of  the  great  trochanter  downwards  and 
inwards  to  the  upper  and  back  part  of 
the  lesser  trochanter.     Its  upper  half 
forms  the  posterior  border  of  the  great 
trochanter.     A   well-marked   eminence 
commences  about  the  middle  of  the  pos- 
terior intertrochanteric  line,  and  passes 
vertically   downwards   for    about    two 
inches  along  the  back  part  of  the  shaft: 
it  is  called  the  lijiea  quadratic  and  gives 
attachment  to  the  Quadratus  Femoris, 
and  a  few  fibres  of  the  Adductor  Mag- 
nus muscles. 

The  Shaft^  almost  perfectly  cylindrical 
in  form,  is  a  little  broader  above  than 
in  the  centre,  and  somewhat  flattened 
from  before  backwards  below.  It  is 
slightly  arched,  so  as  to  be  convex  in 
front ;  concave  behind,  where  it  is 
strengthened  by  a  ])rominent  longitudi- 
nal ridge,  the  linea  aspera.  It  presents 
for  examination  three  borders  separating 
three  surfaces.  Of  the  three  borders, 
one,  the  linea  aspera,  is  posterior;  the 
other  two  are  placed  laterally. 

The  linea  aspera  (Fig.  171)  is  a  promi 
nent  longitudinal  ridge  or  crest,  present- 
ing, on  the  middle  third  of  the  bone,  an 
external  lip,  an  internal  lip,  and  a  rough 
intermediate  space.  A  little  above  the 
centre  of  the  shaft,  this  crest  divides  into 
three  lines  ;^  the  most  external  one  be- 
comes  very   rough,    and   is   continued 

'  Of  these  three  lines,  only  the  outer  and  inner 
are  described  by  many  anatomists :  the  linea 
aspera  is  then  said  to  bifurcate  above  and  below. 


Eight  Femur.     Posterior  Surface. 


240  THE    SKELETON. 

almost  vertically  upwards  to  the  base  of  the  great  trochanter ;  the  middle  one, 
the  least  distinct,  is  continued  to  the  base  of  the  trochanter  minor ;  and  the 
internal  one  is  lost  above  in  the  spiral  line  of  the  femur.  Below,  the  linea 
aspera  divides  into  two  bifurcations,  which  inclose  between  them  a  triangular 
space  (the  popliteal  space),  upon  which  rests  the  popliteal  artery.  Of  these  two 
bifurcations,  the  outer  branch  is  the  most  prominent,  and  descends  to  the 
summit  of  the  outer  condyle.  The  inner  branch  is  less  marked,  presents  a 
broad  and  shallow  groove  for  the  passage  of  the  femoral  artery,  and  terminates 
in  a  small  tubercle  at  the  summit  of  the  internal  condyle. 

To  the  inner  lip  of  the  linea  aspera,  along  its  whole  length,  is  attached  tho 
Vastus  Internus ;  and  to  the  whole  length  of  the  outer  lip,  the  Vastus  Externus. 
The  Adductor  Magnus  is  also  attached  to  the  whole  length  of  the  linea  aspera, 
being  connected  with  the  outer  lip  above,  and  the  inner  lip  below.  Between 
the  Vastus  Externus  and  the  Adductor  Magnus  are  attached  two  muscles,  viz., 
the  Gluteus  Maximus  above,  and  the  short  head  of  the  Biceps  below.  Between 
the  Adductor  Magnus  and  the  Vastus  Internus  four  muscles  are  attached:  the 
Iliacus  and  Pectineus  above  (the  latter  to  the  middle  of  the  upper  divisions) ; 
below  these,  the  Adductor  Brevis  and  Adductor  Longus.  The  linea  aspera  is 
perforated  a  little  below  its  centre  by  the  nutrient  canal,  which  is  directed 
obliquely  upwards. 

The  two  lateral  borders  of  the  femur  are  only  slightly  marked,  the  outer  one 
extending  from  the  anterior  inferior  angle  of  the  great  trochanter  to  the  anterior 
extremity  of  the  external  condyle ;  the  inner  one  from  the  spiral  line,  at  a  point 
opposite  the  trochanter  minor,  to  the  anterior  extremity  of  the  internal  condyle. 
The  internal  border  marks  the  limit  of  attachment  of  the  Crureus  muscle 
internally. 

The  anterior  surface  includes  that  portion  of  the  shaft  which  is  situated 
between  the  two  lateral  borders.  It  is  smooth,  convex,  broader  above  and 
below  than  in  the  centre,  slightly  twisted,  so  that  its  upper  part  is  directed 
forwards  and  a  little  outwards,  its  lower  part  forwards  and  a  little  inwards.  To 
the  upper  three-fourths  of  this  surface  the  Crureus  is  attached ;  the  lower  fourth 
is  separated  from  the  muscle  by  the  intervention  of  the  synovial  membrane  of 
the  knee-joint,  and  affords  attachment  to  the  Subcrureus  to  a  small  extent. 
•The  ea:/erwa?5wr/ace  includes  the  portion  of  bone  between  the  external  border 
and  the  outer  lip  of  the  linea  aspera ;  it  is  continuous  above,  with  the  outer 
surface  of  the  great  trochanter;  below  with  the  outer  surface  of  the  externa] 
condyle :  to  its  upper  three-fourths  is  attached  the  outer  portion  of  the  Crureus 
muscle.  The  internal  surface  includes  the  portion  of  bone  between  the  internal 
border  and  the  inner  lip  of  the  linea  aspera ;  it  is  continuous,  above,  with  tho 
lower  border  of  the  neck ;  below,  with  the  inner  side  of  the  internal  condyle : 
it  is  covered  by  the  Vastus  Internus  muscle. 

The  Lower  Extremity,  larger  than  the  upper,  is  of  a  cuboid  form,  flattened 
from  before  backwards,  and  divided  by  an  interval  presenting  a  smooth  depres- 
sion in  front  and  a  notch  of  considerable  size  behind,  into  two  large  eminences, 
the  condyles  (xdfifXos,  a  knuckle).  The  interval  is  called  the  intercondyloid  notch. 
The  external  condyle  is  the  more  prominent  anteriorly,  and  is  the  broader  both 
in  the  antero-posterior  and  transverse  diameters.  The  internal  condyle  is  the 
narrower,  longer,  and  more  prominent  internally.  This  difference  in  the  length 
of  the  two  condyles  is  only  observed  when  the  bone  is  perpendicular,  and  de 
pends  upon  the  obliquity  of  the  thigh-bones,  in  consequence  of  their  separation 
above  at  the  articulation  with  the  pelvis.  If  the  femur  is  held  obliquely,  tho 
surfaces  of  the  two  condyles  will  be  seen  to  bo  nearly  horizontal.  The  two 
condyles  are  directly  continuous  in  front,  and  form  a  smooth  trochlear  surface, 
the  external  border  of  which  is  more  prominent,  and  ascends  higher  than  tha 
internal  one.  This  surface  articulates  witli  the  patella.  It  presents  a  median 
groove,  which  extends  downwards  and  backwards  to  the  intercondyloid  notch ; 
and   two   lateral   convexities,  of  which  tho   external   is   the   broader,    more 


FEMUR. 


241 


prominent,  and  prolonged  further  upwards  upon  the  front  of  the  outer  condyle. 
The  intercondyloid  notch  lodges  the  crucial  ligaments ;  it  is  bounded  laterally 
by  the  opposed  surfaces  of  the  two  condyles,  and  in  front  by  the  lower  end  of 
the  shaft. 

Outer  Condyle.  The  outer  surface  of  the  external  condyle  presents,  a  little 
behind  its  centre,  an  eminence,  the  outer  tuberosity ;  it  is  less  prominent  than  the 
inner  tuberosity,  and  gives  attachment  to  the  external  lateral  ligament  of  the 
knee.  Immediately  beneath  it  is  a  groove,  which  commences  at  a  depression  a 
little  behind  the  centre  of  the  lower  border  of  this  surface.  The  depression  is 
for  the  tendon  of  origin  of  the  Popliteus  muscle ;  the  groove  in  which  this 
tendon  is  contained  is  smooth,  covered  with  cartilage  in  the  recent  state,  and 
runs  upwards  and  backwards  to  the  posterior  extremity  of  the  condyle.  The 
inner  surface  of  the  outer  condyle  forms  one  of  the  lateral  boundaries  of  the 
intercondyloid  notch,  and  gives  attachment,  by  its  posterior  part,  to  the  ante- 
rior crucial  ligament.  The  inferior  surface  is  convex,  smooth,  and  broader  than 
that  of  the  internal  condyle.  The  posterior  extremity  is  convex  and  smooth ; 
just  above  the  articular  surface  is  a  depression  for  the  tendon  of  the  outer  head 
of  the  Gastrocnemius,  above  which  is  the  origin  of  the  Plantaris. 

Inner  Condyle.  The  iniier  surface  of  the  inner  condyle  presents  a  convex 
eminence,  the  inner  tuberosity,  rough,  for  the  attachment  of  the  internal  lateral 
ligament.  Above  this  tuberosity,  at  the  termination  of  the  inner  bifurcation 
of  the  linea  aspera,  is  a  tubercle,  for  the  insertion  of  the  tendon  of  the  Adductor 
Magnus ;  and  behind  and  beneath  the  tubercle  a  depression,  for  the  tendon 
of  the  inner  head  of  the  Gastrocnemius.  The  outer  side  of  the  inner  condyle 
forms  one  of  the  lateral  boundaries  of  the  intercondyloid  notch,  and  gives 
attachment,  by  its  anterior  part,  to  the  posterior  crucial  ligament.  Its  inferior 
or  articular  surface  is  convex,  and  presents  a  less  extensive  surface  than  the 
external  condyle. 

Structure.  The  shaft  of  the  femur  is  a  cylinder  of  compact  tissue,  hollowed 
by  a  large  medullary  canal.  The  cylinder  is  of  great  thickness  and  density  in 
the  middle  third  of  the  shaft,  where  the  bone  is  narrowest,  and  the  medullary 
canal  well  formed  ;  but  above  and  below  this,  the  cylinder  gradually  becomes 
thinner,  owing  to  a  separation  of  the  layers  of  the  bone  into  cancelli,  which 
project  into  the  medullary  canal  and  finally  obliterate  it,  so  that  the  upper  and 
lower  ends  of  the  shaft,  and  the  articular  ex- 
tremities more  especially,  consist  of  cancel- 
lated tissue  invested  by  a  thin  compact  layer. 

The  arrangement  of  the  cancelli  in  the 
ends  of  the  femur  is  remarkable.  In  the 
upper  end  (Fig.  172),  they  run  in  parallel 
columns  a  a  from  the  summit  of  the  head  to 
the  thick  under  wall  of  the  neck,  while  a 
series  of  transverse  fibres  b  b  cross  the 
parallel  columns,  and  connect  them  to  the 
thin  upper  wall  of  the  neck.  Another  series 
of  plates  G  c  springs  from  the  whole  interior 
of  the  cylinder  above  the  lesser  trochanter ; 
these  pass  upwards  and  converge  to  form  a 
series  of  arches  beneath  the  upper  wall  of  the 
neck,  near  its  junction  with  the  great  tro- 
chanter. This  structure  is  admirably  adapted 
to  sustain,  with  the  greatest  mechanical  ad- 
vantage,   concussion    or    weight    transmitted 

from  above,  and  serves  an  important  office  in  strengthening  a  part  especially 
liable  to  fracture. 

In  the  lower  end,  the  cancelli  spring  on  all  sides  from  the  inner  surface  of 
the  cylinder,  and  descend  in  a  perpendicular  direction  to  the  articular  surface, 
16 


Fig.   172.  -  Diagram   showing  the 
Structure  of  the  Neck  of  the  Femur. 


242 


THE    SKELETON. 


Appears  at  i^gr 


Appears  at  end  ofl'^y^ 
^MnsShaJl  aloat  IS'fy' 


Apptarsa-i4'*  y?- 
Join* Shaft  about  /**  y  f 


the  cancel] i  being  strongest  and  having  a  more  accurately  perpendicular  course, 
above  the  condyles. 

Articulations.     With  three  bones :  the  os  innominatum,  tibia,  and  patella. 
Development  (Fig.  173).     The  femur  is  developed  by  five  centres ;  one  for  the 
shaft,  one  for  each  extremity,  and  one  for  each  trochanter.     Of  all  the  long 
bones,  except  the  clavicle,  it  is  the  first  to  show  traces  of  ossification;  this 

commences  in  the  shaft,  at  about  the 
Fig.  173.— Plan  of  the  Development  of  the    fifth  week  of  foetal  life,  the  centres 
Femur.    By  Five  Centres.  of  ossification  in  the  epiphyses  ap- 

pearing in  the  following  order:  First, 
in  the  lower  end  of  the  bone,  at  the 
ninth  month  of  foetal  life ;  from  this 
the  condyles  and  tuberosities  are 
formed ;  in  the  head,  at  the  end  of 
the  first  year  after  birth ;  in  the 
great  trochanter,  during  the  fourth 
year ;  and  in  the  lesser  trochanter, 
between  the  thirteenth  and  four- 
teenth. The  order  in  which  the  epi- 
physes are  joined  to  the  shaft  is  the 
reverse  of  that  of  their  appearance ; 
their  junction  does  not  commence 
until  after  puberty,  the  lesser  tro- 
chanter being  first  joined,  then  the 
greater,  then  the  head,  and,  lastly,  the 
inferior  extremity  (the  first  in  which 
ossification  commenced),  which  is 
not  united  until  the  twentieth  year. 
Attachment  of  Muscles.  To  the 
great  trochanter :  the  Gluteus  Medius, 
Gluteus  Minimus,  Pyriformis,  Obtu- 
rator Internus,  Obturator  Externus, 
Gemellus  Superior,  Gemellus  Infe- 
rior, and  Quadratus  Femoris.  To  tlie 
lesser  trochanter:  the  Psoas  Magnus, 
and  the  Iliacus  below  it.  To  tlie 
shaft,  its  posterior  surface:  the  Vastus  Externus,  Gluteus  Maximus,  short 
head  of  the  Biceps,  Vastus  Internus,  Adductor  Magnus,  Pectineus,  Adductor 
Brevis,  and  Adductor  Longus ;  to  its  anterior  surface:  the  Crureus  and  Sub- 
crureus.     To  the  condyles :  the  Gastrocnemius,  Plantaris,  and  Popliteus. 


w      -m- 'inrii- Joina  ShiLfttitZO^if, 

avpears  at  Q  'mo.  ^fM^JTyS^^^ 


The  Skeleton  of  the  Leg  consists  of  three  bones :  the  Patella,  a  large  S' 
moid  bone,  placed  in  front  of  the  knee;  and  the  Tibia,  and  Fibula. 


1 


The  .Patella.   (Figs.  174,  175.) 

The  Patella  is  a  flat,  triangular  bone,  situated  at  the  anterior  part  of  the 
knee-joint.  It  resembles  the  sesamoid  bones,  from  being  developed  in  the 
tendon  of  the  Quadriceps  Extensor,  and  in  its  structure,  being  composed 
throughout  of  dense  cancellous  tissue ;  but  it  is  generally  regarded  as  analo- 
gous to  the  olecranon  process  of  the  ulna,  which  occasionally  exists  as  a  sepa- 
rate piece,  connected  to  the  shaft  of  the  bone  by  a  continuation  of  the  tendon 
of  the  Triceps  muscle.^    It  serves  to  protect  the  front  of  the  joint,  and  increases 

'  Professor  Owen  states,  that,  "  in  certain  bats,  there  is  a  development  of  a  sesamoid  bone 
in  the  biceps  brachii,  which  is  tlie  true  homotype  of  the  patella  in  the  leg."  regarding  the  ole- 
cranon to  be  homologous,  not  with  the  patella,  but  with  an  extension  of  the  upper  end  of  the 
fibula  above  the  knee-joint,  which  is  met  with  in  some  animals.  {"  On  the  Nature  of  Limhs" 
pp.  19,  24.) 


TIBIA. 


243 


Fig.  174.— Right  Patella. 
Anterior  yurface. 


Fig. 


17.5. — Posterior 
Surface. 


the  leverage  of  the  Quadriceps  Extensor  by  making  it  act  at  a  greater  angle. 
It  presents  an  anterior  and  posterior  surface,  three  borders,  a  base,  and  an  apex. 

The  anterior  surface  is  convex,  perforated  by  small  apertures,  for  the  passage 
of  nutrient  vessels,  and  marked  by  numerous  rough  longitudinal  striae.  This 
surface  is  covered,  in  the  recent  state  by  an  expansion 
from  the  tendon  of  the  Quadriceps  Extensor,  and  sepa- 
rated from  the  integument  by  a  bursa.  It  gives  attach- 
ment below  to  the  ligamentum  patellae.  Theposferwr 
surface  presents  a  smooth,  oval-shaped,  articular  sur- 
face, covered  with  cartilage  in  the  recent  state,  alid 
divided  into  two  facets  by  a  vertical  ridge,  which  de- 
scends from  the  superior  towards  the  inferior  angle  of 
the  bone.  The  ridge  corresponds  to  the  groove  on  the 
trochlear  surface  of  the  femur,  and  the  two  facets  to 
the  articular  surfaces  of  the  two  condyles ;  the  outer 
facet,  for  articulation  with  the  outer  condyle,  being  the 
broader  and  deeper.  This  character  serves  to  indicate 
the  side  to  which  the  bone  belongs.  Below  the  arti- 
cular surface  is  a  rough,  convex,  non-articular  depres- 
sion, the  lower  half  of  which  gives  attachment  to  the 
ligamentum  patellae ;  the  upper  half  being  separated 
from  the  head  of  the  tibia  by  adipose  tissue. 

The  superior  and  lateral  borders  give  attachment  to 
the  tendon  of  the  Quadriceps  Extensor ;  the  superior 
border,  to  that  portion  of  the  tendon  which  is  derived 
from  the  Eectus  and  Crureus  muscles ;  and  the  lateral 
borders,  to  the  portion  derived  from  the  External  and 
Internal  Vasti  muscles. 

The  base,  or  superior  border,  is  thick,  directed  up- 
ward.s,  and  cut  obliquely  at  the  expense  of  its  outer 

surface ;  it  receives  the  attachment,  as  already  mentioned,  of  part  of  the  Quad- 
riceps Extensor  tendon. 

The  apex  is  pointed,  and  gives  attachment  to  the  ligamentum  patellae. 

Structure.  It  consists  of  dense  cancellous  tissue,  covered  by  a  thin  compact 
lamina. 

Development.  By  a  single  centre,  which  makes  its  appearance,  according  to 
Beclard,  about  the  third  year.  In  two  instances,  I  have  seen  this  bone  cartila- 
ginous throughout,  at  a  much  later  period  (six  years).  More  rarely,  the  bone 
is  developed  by  two  centres,  placed  side  by  side. 

Articulations.    With  the  two  condyles  of  the  femur. 

Attachment  of  Muscles.  The  Eectus,  Crureus,  Vastus  Internus,  and  Vastus 
Externus.  These  muscles  joined  at  their  insertion  constitute  the  Quadriceps 
Extensor  Cruris. 

The  Tibia.    (Figs.  176,  177.) 

The  Tibia  is  situated  at  the  front  and  inner  side  of  the  leg,  and,  excepting 
the  femur,  is  the  longest  and  largest  bone  in  the  skeleton.  It  is  prismoid  in 
form,  expanded  above,  where  it  enters  i^to  the  knee-joint,  more  slightly  en- 
larged below.  In  the  male,  its  direction  is  vertical,  and  parallel  with  the  bone 
of  the  opposite  side ;  but  in  the  female  it  has  a  slight  oblique  direction  down- 
wards and  outwards,  to  compensate  for  the  oblique  direction  of  the  femur  in- 
wards.    It  presents  for  examination  a  shaft  and  two  extremities. 

The  Upper  Extremity,  or  Head,  is  large  and  expanded  on  each  side  into  two 
lateral  eminences,  the  tuberosities.  Superiorly,  the  tuberosities  present  two 
smooth  concave  surfaces,  which  articulate  with  the  condyles  of  the  femur ;  the 
internal  articular  surface  is  longer  than  the  external,  and  oval  from  before 
backwards,  to  articulate  with  the  internal  condyle;  the  external  one  being 


244 


THE    SKELETON. 


Fig.  176.— Bones  of  the  Right  Leg.  Anterior  Surface. 


tfhf7«!if  frraeet. 


Jntmrit^  MaU4cim0 


XrtfW^-1  hTntlrrtu^ 


broader,  flatter,  and  more  circular, 
to  articulate  -with  the  external 
condyle.  Between  the  two  arti- 
cular surfaces,  and  nearer  the 
posterior  than  the  anterior  aspect 
of  the  bone,  is  an  eminence,  the 
spinous  process  of  the  tibia,  sur- 
mounted by  a  prominent  tubercle 
on  each  side,  which  gives  attach- 
ment to  the  extremities  of  the 
semilunar  fibro-cartilages ;  in  front 
and  behind  the  spinous  process 
is  a  rough  depression  for  the  at- 
tachment of  the  anterior  and  pos- 
terior crucial  ligaments  and  the 
semilunar  cartilages.  The  ante- 
rior surfaces  of  the  tuberosities 
are  continuous  with  one  another, 
forming  a  single  large  surface, 
which  is  somewhat  flattened:  it 
is  triangular,  broad  above,  and 
perforated  by  large  vascular  fora- 
mina, narrow  below,  where  it  ter- 
minates in  a  prominent  oblong 
elevation  of  large  size,  the  tuber- 
cle of  the  tibia;  the  lower  half 
of  this  tubercle  is  rough,  for  the 
attachment  of  the  ligamentum  pa- 
tellae ;  the  upper  half  is  a  smooth 
facet  corresponding,  in  the  recent 
state,  with  a  bursa  which  sepa- 
rates the  ligament  from  the  bone. 
Posteriorly,  the  tuberosities  are 
separated  from  each  other  b}"^  a 
shallow  depression,  the  popliteal 
notch,  which  gives  attachment  to 
the  posterior  crucial  ligament. 
The  posterior  surface  of  the  inner 
tuberosity  presents  a  deep  trans- 
verse groove,  for  the  insertion  of 
the  tendon  of  the  Semi-membra- 
nosus ;  and  the  posterior  surface 
of  the  outer  one,  a  flat  articular 
facet,  nearly  circular  in  form,  di- 
rected downwards,  backwards,  and 
outwards,  for  articulation  with  the 
fibula.  The  lateral  surfaces  are 
convex  and  rough :  the  internal 
one,  the  most  prominent,  gives 
attachment  to  the  internal  lateral 
ligament. 

The  Shaft  of  the  tibia  is  of  a 
triangular  prismoid  form,  broad 
above,  gradually  decreasing  in 
size  to  the  commencement  of 
its  lower  fourth,  its  most  slender 


TIBIA. 


245 


Fig.  177. — Bones  of  the  Right  Leg.    Posterior  Surface. 


SttfloiJj)  foeesi 


part,  where  fracture  most  fre- 
quently occurs;  it  then  enlarges 
.•iiiaiu  towards  its  lower  ex- 
tremity. It  presents  for  exami- 
nation three  surfaces  and  three 
borders. 

The  anterior  border^  the  most 
prominent  of  the  three,  is  called 
the  crest  of  the  tibia,  or,  in  popu- 
lar language,  the  shin ;  it  com- 
mences above  at  the  tubercle, 
and  terminates  below  at  the 
anterior  margin  of  the  inner 
malleolus.  This  border  is  very 
prominent  in  the  upper  two- 
thirds  of  its  extent,  smooth  and 
rounded  below.  It  presents  a 
very  flexuous  course,  being 
curved  outwards  above,  and 
inwards  below;  it  gives  attach- 
ment to  the  deep  fascia  of  the 
leg. 

The  internal  border  is  smooth 
and  rounded  above  and  below, 
but  more  prominent  in  the  cen- 
tre ;  it  commences  at  the  back 
part  of  the  inner  tuberosity,  and 
terminates  at  the  posterior  bor- 
der of  the  internal  malleolus; 
its  upper  third  gives  attachment 
to  the  internal  lateral  ligament 
of  the  knee,  and  to  some  fibres 
of  the  Popliteus  muscle;  its 
middle  third,  to  some  fibres  of 
the  Soleus  and  Flexor  Longus 
Digitorum  muscles. 

The  external  border  is  thin 
and  prominent,  especially  its 
central  part,  and  gives  attach- 
ment to  the  interosseous  mem- 
brane ;  it  commences  above  in 
front  of  the  fibular  articular 
facet,  and  bifurcates  below,  to 
form  the  boundaries  of  a  tri- 
angular rough  surface,  for  the 
attachment  of  the  interosseous 
ligament,  connecting  the  tibia 
and  fibula. 

The  internal  surface  is  smooth, 
convex,  and  broader  above  than 
below;  its  upper  third,  directed 
forwards  and  inwards,  is  cover- 
ed by  the  aponeurosis  derived 
from  the  tendon  of  the  Sarto- 
rius,  and  by  the  tendons  of  the 

Gracilis  and  Semi-tendinosus,  all  of  which  are  inserted  nearly  as  far  forwards  as 
the  anterior  border ;  in  the  rest  of  its  extent  it  is  subcutaneous. 


246  THE    SKELETOX. 


le  external  surface  is  narrower  than  the  internal ;  its  upper  two-thirds  pre- 
a  shallow  groove  for  the  attachment  of  the  Tibialis  Auticus  muscle;  its 


Th( 
sent 

lower  third  is  smooth,  convex,  curves  gradually  forwards  to  the  anterior  part 
of  the  bone,  and  is  covered  from  within  outwards  by  the  tendons  of  the  follow- 
ing muscles :  Tibialis  Anticus,  Extensor  Proprius  Pollicis,  Extensor  Longus 
Bigitorum,  Peroneus  Tertius. 

The  posterior  surface  (Fig.  177)  presents,  at  its  upper  part,  a  prominent  ridge, 
the  oblique  line  of  the  tibia,  which  extends  from  the  back  part  of  the  articular 
facet  for  the  fibula,  obliquely  downwards,  to  the  internal  border,  at  the  junction 
of  its  upper  and  middle  thirds.  It  marks  the  limit  for  the  insertion  of  the 
Popliteus  muscle,  and  serves  for  the  attachment  of  the  popliteal  fascia,  and  part 
of  the  Soleus,  Flexor  Longus  Digitorum,  and  Tibialis  Posticus  muscles; 'the 
triangular  concave  surface,  above  and  to  the  inner  side  of  this  line,  gives  attach- 
ment to  the  Popliteus  muscle.  The  middle  third  of  the  posterior  surface  is 
divided  by  a  vertical  ridge  into  two  lateral  halves :  the  ridge  is  well  marked  at 
its  commencement  at  the  oblique  line,  but  becomes  gradually  indistinct  below: 
the  inner  and  broader  half  gives  attachment  to  the  Flexor  Longus  Digitorum, 
the  outer  and  narrower  to  part  of  the  Tibialis  Posticus.  The  remaining  part 
of  the  bone  is  covered  by  the  Tibialis  Posticus,  Flexor  Longus  Digitorum,  and 
Flexor  Longus  Pollicis  muscles.  Immediately  below  the  oblique  line  is  the 
medullary  foramen,  which  is  directed  obliquely  downwards. 

The  Lower  Extremity^  much  smaller  than  the  upper,  presents  five  surfaces ;  it 
is  prolonged  downwards,  on  its  inner  side,  into  a  strong  process,  the  internal 
malleolus.  The  inferior  surface  of  the  bone  is  quadrilateral,  and  smooth,  for 
articulation  with  the  astragalus.  This  surface  is  narrow  internally,  where  it 
becomes  continuous  with  the  articular  surface  of  the  inner  malleolus,  broader 
externally,  and  traversed  from  before  backwards  by  a  slight  elevation,  sepa- 
rating two  lateral  depressions.  The  anterior  surface  of  the  lower  extremity  is 
smooth  and  rounded  above,  and  covered  by  the  tendons  of  the  extensor  mus- 
cles of  the  toes ;  its  lower  margin  presents  a  rough  transverse  depression,  for 
the  attachment  of  the  anterior  ligament  of  the  ankle-joint :  the  postei'ior  surface 
presents  a  superficial  groove  directed  obliquely  downwards  and  inwards,  con- 
tinuous with  a  similar  groove  on  the  posterior  extremity  of  the  astragalus,  and 
serving  for  the  passage  of  the  tendon  of  the  Flexor  Longus  Pollicis :  the  exter- 
nal surface  presents  a  triangular  rough  depression  for  the  attachment  of  th'3 
inferior  interosseous  ligament  connecting  it  with  the  fibula ;  the  lower  part  of 
this  depression  is  smooth  in  some  bones,  covered  with  cartilage  in  the  recent 
state,  and  articulating  with  the  fibula.  This  surface  is  bounded  by  two  promi- 
nent ridges,  continuous  above  with  the  interosseous  ridge ;  they  afford  attach- 
ment to  the  anterior  and  posterior  tibio-fibular  ligaments.  The  internal  surface 
of  the  lower  extremity  is  prolonged  downwards  to  form  a  strong  pyramidal 
process,  flattened  from  without  inwards,  the  inner  malleolus.  The  inner  surface 
of  this  process  is  convex  and  subcutaneous;  its  outer  surface,  smooth  and  slightly 
concave,  deepens  the  articular  surface  for  the  astragalus  ;  its  anterior  horcler  is 
rough,  for  the  attachment  of  ligamentous  fibres ;  its  jwsterior  border  presents  a 
broad  and  deep  groove,  directed  obliquely  downwards  and  inwards,  which  is 
occasionally  double:  this  groove  transmits  the  tendons  of  the  Tibialis  Posticus 
and  Flexor  Longus  Digitorum  muscles.  The  summit  of  the  internal  malleolus 
is  marked  by  a  rough  depression  behind,  for  the  attachment  of  the  internal 
lateral  ligament  of  the  ankle-joint. 

Structure.     Like  that  of  the  other  long  bones. 

Development.  By  three  centres  (Fig.  178):  one  for  the  shaft,  and  one  for  each 
extremity.  Ossification  commences  in  the  centre  of  the  shaft  about  tlie  same 
time  as  in  the  femur,  the  fifth  week,  and  gradually  extends  towards  either 
extremity.  The  centre  for  the  upper  epiphysis  appears  at  birth;  it  is  flat- 
tened in  form,  and  has  a  thin  tongue- shaped  process  in  front,  which  forms 
the  tubercle.     That  for  the  lower  epiphysis  appears  in  the  second  year.     The 


FIBULA. 


241 


Fig.  178. — Plan  of  the  Development  of  the 
Tibia.    By  Three  Centres. 


^^pper  eoctrcm/fz, 


Ajijieccrt  ad,  b  ink 


Appears  at  ZTfyZ-j^ 


^oCns  Shaft  about 
Z6  f>  2/' 


Jairia  Sh  n  ft  a  lent 


''u^cr  cxtre 


.vdt]l 


lower  epiphysis  joins  the  shaft  at  about  the  twentieth  year,  and  the  upper 
one  about  the  twenty-fifth  year.  Two  additional  centres  occasionally  exist, 
one  for  the  tongue-shaped  process  of 
the  upper  epiphysis,  the  tubercle,  and 
one  for  the  inner  malleolus. 

Articulations.  With  three  bones; 
the  femur,  fibula,  and  astragalus. 

Attachment  of  Muscles.  To  the  inner 
tuberosity,  the  Semi-membranosus;  to 
the  outer  tuberosity,  the  Tibialis  An- 
ticus  and  Extensor  Longus  Digitorum ; 
to  the  shaft,  its  internal  surface,  the 
Sartorius,  Gracilis,  and  Semi-tendino- 
sus;  to  its  external  surface,  the  Tibia- 
lis Anticus;  to  its  posterior  surface, 
the  Popliteus,  Soleus,  Flexor  Longus 
Digitorum,  and  Tibialis  Posticus;  to 
the  tubercle,  the  ligamentum  patellae. 

The  Fibula.    (Figs.  176,  177.) 

The  Fibula  is  situated  at  the  outer 
side  of  the  leg.  It  is  the  smaller  of 
the  two  bones,  and,  in  proportion  to 
its  length,  the  most  slender  of  all  the 
long  bones ;  it  is  placed  nearly  parallel 
with  the  tibia.  Its  upper  extremity  is 
small,  placed  below  the  level  of  the 
knee-joint,  and  excluded  from  its  for- 
mation; the  lower  extremity  inclines  a  little  forwards,  so  as  to  be  on  a  plane 
anterior  to  that  of  the  upper  end,  projects  below  the  tibia,  and  forms  the  outer 
ankle.     It  presents  for  examination  a  shaft  and  two  extremities. 

The  Up2:ier  Extremity^  or  Head^  is  of  an  irregular  rounded  form,  presenting 
above  a  flattened  articular  facet,  directed  upwards  and  inwards,  for  articulation 
with  a  corresponding  facet  on  the  external  tuberosity  of  the  tibia.  On  the 
outer  side  is  a  thick  and  rough  prominence,  continued  behind  into  a  pointed 
eminence,  the  styloid  process,  which  projects  upwards  from  the  posterior  part 
of  the  head.  The  prominence  gives  attachment  to  the  tendon  of  the  Biceps 
muscle,  and  to  the  long  external  lateral  ligament  of  the  knee,  the  ligament 
dividing  the  tendon  into  two  parts.  The  summit  of  the  styloid  process  gives 
attachment  to  the  short  external  lateral  ligament.  The  remaining  part  of  the 
circumference  of  the  head  is  rough,  for  the  attachment,  in  front,  of  the  anterior 
superior  tibio-fibular  ligament,  and  the  upper  and  anterior  part  of  the  Peroneus 
Longus;  and  behind,  to  the  posterior  superior  tibio-fibular  ligament,  and  the 
upper  fibres  of  the  outer  head  of  the  Soleus  muscle. 

The  Lower  Extremity^  or  External  Malleolus^  is  of  a  pyramidal  form,  somewhat 
flattened  from  without  inwards,  and  is  longer,  and  descends  lower,  than  the  in- 
ternal malleolus.  Its  external  surface  is  convex,  subcutaneous,  and  continuous 
with  a  triangular  (also  subcutaneous)  surface  on  the  outer  side  of  the  shaft. 
The  internal  surface  presents  in  front  a  smooth  triangular  facet,  broader  above 
than  below,  and  convex  from  above  downwards,  which  articulates  with  a  corre- 
sponding surface  on  the  outer  side  of  the  astragalus.  Behind  and  beneath  the 
articular  surface  is  a  rough  depression,  which  gives  fittachment  to  the  posterior 
fasciculus  of  the  external  lateral  ligament  of  the  ankle.  The  anterior  border  is 
thick  and  rough,  and  marked  below  by  a  depression  for  the  attachment  of  the 
anterior  fasciculus  of  the  external  lateral  ligament.  The  posterior  border  is  broad 
and  marked  by  a  shallow  groove,  for  the  passage  of  the  tendons  of  the  Pero- 


248  THE    SKELETON. 

neus  Longus  and  Peroneus  Brevis  muscles.     The  summit  is  rounded,  and  gives 
attachment  to  the  middle  fasciculus  of  the  external  lateral  ligament. 

The  Shaft  presents  three  surfaces  and  three  borders.  The  anterior  border  com- 
mences above  in  front  of  the  head,  runs  vertically  downwards  to  a  little  below 
the  middle  of  the  bone,  and  then,  curving  a  little  outwards,  bifurcates  below. 
The  two  lines  so  formed  bound  the  triangular  subcutaneous  surface  immediately 
above  the  outer  side  of  the  external  malleolus.  This  border  gives  attachment 
to  an  intermuscular  septum,  which  separates  the  muscles  on  the  anterior  surface 
from  those  on  the  external. 

The  internal  border,  or  interosseous  ridge,  is  situated  close  to  the  inner  side  of 
the  preceding,  and  runs  nearly  parallel  with  it  in  the  upper  third  of  its  extent, 
but  diverges  from  it  so  as  to  include  a  broader  space  in  the  lower  two-thirds. 
It  commences  above  just  beneath  the  head  of  the  bone  (sometimes  it  is  quite 
indistinct  for  about  an  inch  below  the  head),  and  terminates  below  at  the  apex 
of  a  rough  triangular  surface  immediately  above  the  articular  facet  of  the  ex- 
ternal malleolus.  It  serves  for  the  attachment  of  the  interosseous  membrane, 
and  separates  the  extensor  muscles  in  front  from  the  flexor  muscles  behind. 
The  portion  of  bone  included  between  the  anterior  and  interosseous  lines  forms 
the  anterior  surface. 

The  posterior  border  is  sharp  and  prominent;  it  commences  above  at  the  base 
of  the  styloid  process,  and  terminates  below  in  the  posterior  border  of  the  outer 
malleolus.  It  is  directed  outwards  above,  backwards  in  the  middle  of  its  course, 
backwards  and  a  little  inwards  below,  and  gives  attachment  to  an  aponeurosis 
which  separates  the  muscles  on  the  outer  from  those  on  the  inner  surface  of 
the  shaft.  The  portion  of  bone  included  between  this  line  and  the  interosseous 
ridge,  and  which  includes  more  than  half  of  the  whole  circumference  of  the 
fibula,  is  known  as  the  internal  surface.  Its  upper  three-fourths  are  subdivided 
into  two  parts,  an  anterior  and  a  posterior,  by  a  very  prominent  ridge,  the 
oblique  line  of  the  fibula,  which  commences  above  at  the  inner  side  of  the  head, 
and  terminates  by  becoming  continuous  with  the  interosseous  ridge  at  the 
lower  fourth  of  the  bone.  The  oblique  line  attaches  an  aponeurosis  which 
separates  the  Tibialis  Posticus  from  the  Soleus  above,  and  the  Flexor  Longus 
Pollicis  below.  This  line  sometimes  ceases  just  before  approaching  the  inter- 
osseous ridge. 

The  anterior  surface  is  the  interval  between  the  anterior  and  interosseous 
lines.    It  is  extremely  narrow  and  flat  in  the  upper  third  of  its  extent;  broade: 
and  grooved  longitudinally  in  its  lower  third;  it  serves  for  the  attachment  o: 
three  muscles,  the  Extensor  Longus  Digitorum,  Peroneus  Tertius,  and  Extenso: 
Longus  Pollicis. 

The  external  surface,  much  broader  than  the  preceding,  and  often  deeply 
grooved,  is  directed  outwards  in  the  upper  two-thirds  of  its  course,  backwards 
in  the  lower  third,  where  it  is  continuous  with  the  posterior  border  of  the  e 
ternal  malleolus.  This  surface  is  completely  occupied  by  the  Peroneus  Long 
and  Peroneus  Brevis  muscles. 

The  internal  surface  is  the  interval  between  the  interosseous  ridge  and  th 
posterior  border,  and  occupies  nearly  two-thirds  of  the  circumference  of  th« 
bone.    Its  upper  three-fourths  are  divided  into  an  anterior  and  a  posterior  portiont 
by  a  very  prominent  ridge  already  mentioned,  the  oblique  line  of  the  fibula* 
.  The  anterior  portion  is  directed  inwards,  and  is  grooved  for  the  attachment  o" 
the  Tibialis  Posticus  muscle.     The  posterior  portion  is  continuous  below  wit 
the  rough  triangular  surface  above  the  articular  facet  of  the  outer  malleolus 
it  is  directed  backwards  above,  backwards  and  inwards  at  its  middle,  direct! 
inwards  below.     Its  upper  fourth  is  rough,  for  the  attachment  of  the  Soleui 
muscle ;  its  lower  part  presents  a  triangular  rough  surface,  connected  to  the 
tibia  by  a  strong  interosseous  ligament,  and  between  these  two  points  the  entire 
surface  is  covered  by  the  fibres  of  origin  of  the  Flexor  Longus  Pollicis  muscle* 


TARSUS. 


249 


Fig.  179. — Plan  of  the  Development 
of  the  Fibula.    By  Three  Centres. 


fifj/t'4  about Ifl'j'ij&i 


ViuUi  aboat25(^  (Jf, 


*"> 


ctr<5 


UntUa  about  20^  ff* 


Af  about  the  middle  of  this  surface  is  the  nutrient  foramen,  which  is  directed 
downwards. 

In  order  to  distinguish  the  side  to  which 
the  bone  belongs,  hold  it  with  the  lower  ex- 
tremity downwards,  and  the  broad  groove  for 
the  Peronei  tendons  backwards,  towards  the 
holder;  the  triangular  subcutaneous  surface 
will  then  be  directed  to  the  side  to  which  the 
bone  belongs. 

Articulations.  With  two  bones;  the  tibia 
and  astragalus. 

Development.  By  three  centres  (Fig.  179); 
one  for  the  shaft,  and  one  for  each  extremity. 
Ossification  commences  in  the  shaft  about  the 
sixth  week  of  foetal  life,  a  little  later  than  in 
the  tibia,  and  extends  gradually  towards  the 
extremities.  At  birth  both  ends  are  cartila- 
ginous. Ossification  commences  in  the  lower 
end  in  the  second  year,  and  in  the  upper  one 
about  the  fourth  year.  The  lower  epiphysis, 
the  first  in  which  ossification  commences,  be- 
comes united  to  the  shaft  first,  contrary  to  the 
law  which  appears  to  prevail  with  regard  to 
the  junction  of  the  epiphyses  with  the  shaft; 
this  takes  place  about  the  twentieth  year ;  the 
upper  epiphysis  is  joined  about  the  twenty-fifth 
year.^ 

Attachment  of  Muscles.  To  the  head,  the  Bi- 
ceps, Soleus,  and   Peroneus  Longus;   to  the 

shaft,  its  anterior  surface,  the  Extensor  Longus  Digitorum,  Peroneus  Tertius, 
and  Extensor  Longus  Pollicis;  to  the  internal  surface,  the  Soleus,  Tibialis 
Posticus,  and  Flexor  Lopgus  Pollicis;  to  the  external  surface,  the  Peroneus 
Longus  and  Peroneus  Brevis. 

The  Skeleton  of  the  Foot  (Figs.  180,  181)  consists  of  three  divisions :  the 
Tarsus,  Metatarsus,  and  Phalanges. 

The  Taesus. 

The  bones  of  the  Tarsus  are  seven  in  number,  viz.,  the  calcaneum,  or  os 
calcis,  astragalus,  cuboid,  scaphoid,  internal,  middle,  and  external  cuneiform 
bones. 

The  Os  Calcis. 

The  Calcaneum,  or  Os  Calcis,  is  the  largest  and  strongest  of  the  tarsal  bones. 
It  is  irregularly  cuboidal  in  form,  and  situated  at  the  lower  and  back  part  of  the 
foot,  serving  to  transmit  the  weight  of  the  body  to  the  ground,  and  forming  a 
strong  lever  for  the  muscles  of  the  calf.  It  presents  for  examination  six  sur- 
faces :  superior,  inferior,  external,  internal,  anterior,  and  posterior. 

The  superior  surface  is  formed  behind,  of  the  upper  aspect  of  that  part  of  the 
OS  calcis  which  projects  backwards  to  form  the  heel.  It  varies  in  length  in 
diJSferent  individuals ;  is  convex  from  side  to  side,  concave  from  before  back- 
wards, and  corresponds  above  to  a  mass  of  adipose  substance  placed  in  front  of 
the  tendo  Achillis.  In  the  middle  of  the  superior  surface  are  two  (sometimes 
three)  articular  facets,  separated  by  a  broad  shallow  groove,  which  is  directed 

'  It  will  be  observed  that  in  the  fibula,  as  in  other  long  bones,  the  epiphysis,  towards  which 
the  nutrient  artery  is  directed,  is  the  one  first  joined  to  the  shaft. 


250 


THE    SKELETON. 

Fig.  180.— Bones  of  the  Right  Foot.    Dorsal  Surface. 


Groom  Jot  moMrus  loncvs 


Groove  fur   pcRONtus  brevis 


rsRONEus  entvis 


Crtwue  for  Trncle^  nf 

rLUOR   LSNCOS     POU..CIS 


Tarsut 


MetatttTsiM 


InntrvuJst  tciuLfn  if 

EXT.SREVIS  OICITORUW 


TliAjlancjea 


CXT.  lONCUS   PeiLlbIt 


OS    CALCIS.  251 

obliquely  forwards  and  outwards,  and  is  rough  for  the  attachment  of  the  inter- 
osseous ligament  connecting  the  astragalus  and  os  calcis.  Of  the  two  articular 
surfaces,  the  external  is  the  larger,  and  situated  on  the  body  of  the  bone :  it  is 
of  an  oblong  form,  wider  behind  than  in  front,  and  convex  from  before  back- 
wards. The  internal  articidar  surface  is  supported  on  a  projecting  process  of 
bone,  called  the  lesser  process  of  the  calcaneum  (sustentaculum  tali);  it  is  also 
oblong,  concave  longitudinally,  and  sometimes  subdivided  into  two  parts,  which 
differ  in  size  and  shape.  More  anteriorly  is  seen  the  upper  surface  of  the 
greater  process^  marked  by  a  rough  depression  for  the  attachment  of  numerous 
ligaments,  and  the  origin  of  the  Extensor  Brevis  Digitorum  muscle. 

The  inferior  surface  is  narrow,  rough,  uneven,  wider  behind  than  in  front,  and 
convex  from  side  to  side ;  it  is  bounded  posteriorly  by  two  tubercles,  separated 
by  a  rough  depression;  the  external^  small,  prominent,  and  rounded,  gives 
attachment  to  part  of  the  Abductor  Minimi  Digiti ;  the  internal^  broader  and 
larger,  for  the  support  of  the  heel,  gives  attachment,  by  its  prominent  inner 
margin,  to  the  Abductor  PoUicis,  and  in  front  to  the  Flexor  Brevis  Digitorum 
muscles ;  the  depression  between  the  tubercles  attaches  the  Abductor  Minimi 
Digiti  and  plantar  fascia.  The  rough  surface  in  front  of  the  tubercles  gives 
attachment  to  the  long  plantar  ligament,  and  to  the  outer  head  of  the  Flexor 
Accessorius  muscle ;  and  to  a  prominent  tubercle  nearer  the  anterior  part  of 
the  bone,  as  well  as  to  a  transverse  groove  in  front  of  it,  is  attached  the  short 
plantar  ligament. 

The  external  surface  is  broad,  flat,  and  almost  subcutaneous ;  it  presents  near 
its  centre  a  tubercle,  for  the  attachment  of  the  middle  fasciculus  of  the  external 
lateral  ligament.  Above  the  tubercle  is  a  broad  smooth  surface,  giving  attach- 
ment, at  its  upper  and  anterior  part,  to  the  external  astragalo-calcanean  liga- 
ment ;  and  in  front  of  the  tubercle  a  narrow  surface  marked  by  two  oblique 
grooves,  separated  by  an  elevated  ridge :  the  superior  groove  transmits  the  ten- 
don of  the  Peroneus  Brevis;  the  inferior^  the  tendon  of  the  Peroneus  Longus; 
the  intervening  ridge  gives  attachment  to  a  prolongation  from  the  external 
annular  ligament. 

The  internal  surface  presents  a  deep  concavity,  directed  obliquely  downwards 
and  forwards,  for  the  transmission  of  the  plantar  vessels  and  nerves  and  flexor 
tendons  into  the  sole  of  the  foot ;  it  affords  attachment  to  part  of  the  Flexor 
Accessorius  muscle.  This  surface  presents  an  eminence  of  bone,  the  lesser  pro- 
cess^ which  projects  horizontally  inwards  from  its  upper  and  fore  part,  and  to 
which  a  slip  of  the  tendon  of  the  Tibialis  Posticus  is  attached.  This  process  is 
concave  above,  and  supports  the  anterior  articular  surface  of  the  astragalus; 
below,  it  is  convex,  and  grooved  for  the  tendon  of  the  Flexor  Longus  Pollicis. 
Its  free  margin  is  rough,  for  the  attachment  of  ligaments. 

The  anterior  surface^  of  a  somewhat  triangular  form,  is  smooth,  concavo-con- 
vex, and  articulates  with  the  cuboid.  It  is  surmounted,  on  its  outer  side,  by  a 
rough  prominence,  which  forms  an  important  guide  to  the  surgeon  in  the  per- 
formance of  Chopart's  amputation. 

The  posterior  surface  is  rough,  prominent,  convex,  and  wider  below  than 
above.  Its  lower  part  is  rough,  for  the  attachment  of  the  tendo  Achillis,  and 
of  the  Plantaris  muscle ;  its  upper  part  is  smooth,  coated  with  cartilage,  and 
corresponds  to  a  bursa  which  separates  that  tendon  from  the  bone. 

Articulations.     With  two  bones :  the  astragalus  and  cuboid. 

Aitacliment  of  Muscles.  Part  of  the  Tibialis  Posticus,  the  tendo  Achillis, 
Plantaris,  Abductor  Pollicis,  Abductor  Minimi  Digiti,  Flexor  Brevis  Digito- 
rum, Flexor  Accessorius,  and  Extensor  Brevis  Digitorum. 

The  Cuboid. 

The  Cuboid  Bone  is  placed  on  the  outer  side  of  the  foot,  in  front  of  the  os 
calcis,  and  behind  the  fourth  and  fifth  metatarsal  bones.  It  is  of  a  pyramidal 
Bhape,  its  base  being  directed  upwards  and  inwards,  its  apex  downwards  and 


252 


THE    SKELETON. 
Figr.  181. — Bones  of  the  Right  Foot.    Plantar  Surface. 


3(JTERrtEA»0F««SSK 


LCXOR  BRCVia  POLLIOI* 


FLoa*  aiicvi* 

AIDUCTOR 
IMI    OICITI 


rLCXOR    LSNCUi 
OICITORUM 


ASTRAGALUS.  253 

outwards.  It  may  be  distinguished  from  the  other  tarsal  bones  by  the  exist- 
ence of  a  deep  groove  on  its  under  surface,  for  the  tendon  of  the  Peroneus 
Lono^us  muscle.  It  presents  for  examination  six  surfaces :  three  articular,  and 
three  non-articular. 

The  non-articular  surfaces  are  the  superior,  inferior,  and  external.  The 
superior  or  dorsal  surface^  directed  upwards  and  outwards,  is  rough,  for  the 
attachment  of  numerous  ligaments.  The  inferior  ov  plantar  surface  presents  in 
front  a  deep  groove,  which  runs  obliquely  from  without,  forwards  and  inwards; 
it  lodges  the  tendon  of  the  Peroneus  Longus,  and  is  bounded  behind  by  a 
prominent  ridge,  terminating  externally  in  an  eminence,  the  tuberosity  of  the 
cuboid,  the  surface  of  which  presents  a  convex  facet,  for  articulation  with  the 
sesamoid  bone  of  the  tendon  contained  in  the  groove.  The  ridge  and  surface 
of  bone  behind  it  are  rough,  for  the  attachment  of  the  long  and  short  plantar 
ligaments.  A  few  fibres  of  the  Flexor  Brevis  Pollicis  may  be  traced  to  this 
surface.  The  external  surface^  the  smallest  and  narrowest  of  the  three,  presents 
a  deep  notch  formed  by  the  commencement  of  the  peroneal  groove. 

The  articular  surfaces  are  the  posterior,  anterior,  and  internal.  The  posterior 
surface  is  smooth,  triangular,  concavo-convex,  for  articulation  with  the  anterior 
surfoce  of  the  os  calcis.  The  anterior^  of  smaller  size,  but  also  irregularly 
triangular,  is  divided  by  a  vertical  ridge  into  two  facets:  the  inner  facet, 
quadrilateral  in  form,  articulates  with  the  fourth  metatarsal  bone;  the  outer 
one,  larger  and  more  triangular,  articulates  with  the  fifth  metatarsal.  Tne 
internal  surface  is  broad,  rough,  irregularly  quadrilateral,  presenting  at  its  mid- 
dle and  upper  part  a  small  oval  facet,  for  articulation  with  the  external  cunei- 
form bone ;  and  behind  this  (occasionally)  a  smaller  facet,  for  articulation  with 
the  scaphoid ;  it  is  rough  in  the  rest  of  its  extent,  for  the  attachment  of  strong 
interosseous  ligaments. 

To  ascertain  to  which  foot  it  belongs,  hold  the  bone  so  that  its  under  surface, 
marked  by  the  peroneal  groove,  looks  downwards,  and  the  large  concavo- 
convex  articular  surface  backwards,  towards  the  holder:  the  narrow,  non- 
articular  surface,  marked  by  the  commencement  of  the  peroneal  groove,  will 
point  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  four  bones :  the  os  calcis,  external  cuneiform,  and  the 
fourth  and  fifth  metatarsal  bones,  occasionally  with  the  scaphoid. 

Attachment  of  Muscles.     Part  of  the  Flexor  Brevis  Pollicis. 

The  Astragalus. 

The  Astragalus  (Fig.  180)  is  the  largest  of  the  tarsal  bones,  next  to  the  os 
calcis.  It  occupies  the  middle  and  upper  part  of  the  tarsus,  supporting  the 
tibia  above,  articulating  with  the  malleoli  on  either  side,  resting  below  upon 
the  OS  calcis,  and  joined  in  front  to  the  scaphoid.  This  bone  may  easily  be 
recognized  by  its  large  rounded  head,  by  the  broad  articular  facet  on  its  upper 
convex  surface,  or  by  the  two  articular  facets  separated  by  a  deep  groove  on  its 
under  concave  surface.     It  presents  six  surfaces  for  examination. 

The  superior  surface  presents,  behind,  a  broad  smooth  trochlear  surface,  for 
articulation  with  the  tibia.  The  trochlea  is  broader  in  front  than  behind,  con- 
vex from  before  backwards,  slightly  concave  from  side  to  side ;  in  front  of  it  is 
the  upper  surface  of  the  neck  of  the  astragalus,  rough  for  the  attachment  of 
ligaments.  The  inferior  surface  presents  two  articular  facets  separated  by  a 
deep  groove.  The  groove  runs  obliquely  forwards  and  outwards,  becoming 
gradually  broader  and  deeper  in  front :  it  corresponds  with  a  similar  groove 
upon  the  upper  surface  of  the  os  calcis,  and  forms,  when  articulated  with  that 
bone,  a  canal,  filled  up  in  the  recent  state  by  the  calcaneo-«astragaloid  inter- 
osseous ligament.  Of  the  two  articular  facets,  the  posterior  is  the  larger,  of  an 
oblong  form,  and  deeply  concave  from  side  to  side;  the  anterior,  although 
nearly  of  equal  length,  is  narrower,  of  an  elongated  oval  form,  convex  longi- 


254  THE    SKELETON. 

tudinally,  and  often  subdivided  into  two  by  an  elevated  ridge;  of  tbese  tte 
posterior  articulates  with  the  lesser  process  of  the  os  calcis ;  the  anterior,  with 
the  upper  surface  of  the  calcaneo-scaphoid  ligament.  The  internal  surface  pre- 
sents  at  its  upper  part  a  pear-shaped  articular  facet  for  the  inner  malleolus, 
continuous  above  with  the  trochlear  surface ;  below  the  articular  surface  is  a 
rough  depression,  for  the  attachment  of  the  deep  portion  of  the  internal  lateral 
ligament.  The  external  surface  presents  a  large  triangular  facet,  concave  from 
above  downwards,  for  articulation  with  the  external  malleolus ;  it  is  continuous! 
above  with  the  trochlear  surface ;  and  in  front  of  it  is  a  rough  depression  for 
the  attachment  of  the  anterior  fasciculus  of  the  external  lateral  ligament.  The 
anterior  surface^  convex  and  rounded,  forms  the  head  of  the  astragalus ;  it  is 
smooth,  of  an  oval  form,  and  directed  obliquely  inwards  and  downwards;  it  is 
continuous  below  with  that  part  of  the  anterior  facet  on  the  under  surface  which 
rests  upon  the  calcaneo-scaphoid  ligament.  The  head  is  surrounded  by  a  con- 
stricted portion,  the  neck  of  the  astragalus.  The  posterior  surface  is  narrow, 
and  traversed  by  a  groove,  which  runs  obliquely  downwards  and  inwards,  and 
transmits  the  tendon  of  the  Flexor  Longus  Pollicis. 

To  ascertain  to  which  foot  it  belongs,  hold  the  bone  with  the  broad  articular 
surface  upwards,  and  the  rounded  head  forwards ;  the  lateral  triangular  articu- 
lar surface  for  the  external  malleolus  will  then  point  to  the  side  to  which  the 
bone  belongs. 

Articulations.    With  four  bones :  tibia,  fibula,  os  calcis,  and  scaphoid. 

The  Scaphoid. 

The  Scaphoid  or  Navicular  Bone,  so  called  from  its  fancied  resemblance  to 
a  boat,  is  situated  at  the  inner  side  of  the  tarsus,  between  the  astragalus  behind 
and  the  three  cuneiform  bones  in  front.  This  bone  may  be  distinguished  by 
its  form,  being  concave  behind,  convex  and  subdivided  into  three  facets  in  front. 

The  anterior  surface,  of  an  oblong  form,  is  convex  from  side  to  side,  and  sub- 
divided by  two  ridges  into  three  facets,  for  articulation  with  the  three  cunei- 
form bones.  The  posterior  surface  is  oval,  concave,  broader  externally  than 
internally,  and  articulates  with  the  rounded  head  of  the  astragalus.  The  supe- 
rior surface  is  convex  from  side  to  side,  and  rough  for  the  attachment  of  liga- 
ments. The  inferior  is  somewhat  concave,  irregular,  and  also  rough  for  the 
attachment  of  ligaments.  The  internal  surf  ace  presents  a  rounded  tubercular 
eminence,  the  tuberosity  of  the  scaphoid,  which  gives  attachment  to  part  of 
the  tendon  of  the  Tibialis  Posticus.  The  external  surface  is  broad,  rough,  and 
irregular,  for  the  attachment  of  ligamentous  fibres,  and  occasionally  presents  a 
small  facet  for  articulation  with  the  cuboid  bone. 

To  ascertain  to  which  foot  it  belongs,  hold  the  bone  with  the  concave  arti- 
cular surface  backwards,  and  the  convex  dorsal  surface  upwards ;  the  broad 
external  surface 'will  point  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  four  bones :  astragalus  and  three  cuneiform ;  occasion- 
ally also  with  the  cuboid. 

Attachment  of  Mmcles.    Part  of  the  Tibialis  Posticus. 

The  Cuneiform  Bones. 

The  Cuneiform  Bones  have  received  their  name  from  their  wedge-like  shape.  ^ 
They  form  with  the  cuboid  the  most  anterior  row  of  the  tarsus,  being  placed 
between  the  scaphoid  behind,  the  three  innermost  metatarsal  bones  in  front, 
and  the  cuboid  externally.  They  are  called  i\\Q  first,  second,  and  third,  counting 
from  the  inner  to  the  outer  side  of  the  foot,  and,  from  their  position,  internal^ 
middle,  and  external. 

The  Internal  Cuneiform  is  the  largest  of  the  three.  It  is  situated  at  the 
inner  side  of  the  foot,  between  the  scaphoid  behind  and  the  base  of  the  first 
metatarsal  in  front.     It  may  be  distinguished  from  the  other  two  by  its  large 


CUNEIFORM    BONES.  255 

size,  and  its  more  irregular  wedge-like  form.  "Without  the  others,  it  may  be 
kuowu  by  the  large  kidney-shaped  anterior  articulating  surface,  and  by  the 
prominence  on  the  non-articular  surface  (or  base  of  the  wedge),  for  the  attach- 
ment of  a  large  tendon.     It  presents  for  examination  six  surfaces. 

The  internal  surf  ace  is  subcutaneous,  and  forms  part  of  the  inner  border  of  the 
foot;  it  is  broad,  quadrilateral,  and  presents  at  its  anterior  inferior  angle  a 
smooth  oval  facet,  over  which  the  tendon  of  the  Tibialis  Anticus  muscle  glides; 
in  the  rest  of  its  extent  it  is  rough,  for  the  attachment  of  ligaments.  The  ex- 
ternal surface  is  concave,  presenting,  along  its  superior  and  posterior  borders,  a 
narrow  surface  for  articulation  with  the  middle  cuneiform  behind,  and  second 
metatarsal  bone  in  front.  In  the  rest  of  its  extent,  it  is  rough  for  the  attach- 
ment of  ligaments,  and  prominent  below,  where  it  forms  part  of  the  tuberosity. 
The  anterior  surface^  kidney-shaped,  articulates  with  the  metatarsal  bone  of  the 
great  toe.  The  posterior  surface  is  triangular,  concave,  and  articulates  with  the 
innermost  and  largest  of  the  three  facets  on  the  anterior  surface  of  the  sca- 
phoid. The  inferior  or  plantar  surface  is  rough,  and  presents  a  prominent 
tuberosity  at  its  back  part  for  the  attachment  of  part  of  the  tendon  of  the 
Tibialis  Posticus.  It  also  gives  attachment  in  front  to  part  of  the  tendon  of 
the  Tibialis  Anticus.  The  superior  surface  is  the  narrow  pointed  end  of  the 
wedge,  which  is  directed  upwards  and  outwards ;  it  is  rough  for  the  attachment 
of  ligaments. 

To  ascertain  to  which  side  it  belongs,  hold  the  bone  so  that  its  superior  nar- 
row edge  looks  upwards,  and  the  long  articular  surface  forwards ;  the  external 
surface,  marked  by  its  vertical  and  horizontal  articular  facets,  will  point  to  the 
side  to  which  it  belongs. 

Articulations.  With  four  bones:  scaphoid,  middle  cuneiform,  first  and  second 
metatarsal  bones. 

Attachment  of  Muscles.     The  Tibialis  Anticus  and  Tibialis  Posticus. 

The  Middle  Cuneiform^  the  smallest  of  the  three,  is  of  very  regular  wedge- 
like form,  the  broad  extremity  being  placed  upwards,  the  narrow  end  down- 
wards. It  is  situated  between  the  other  two  bones  of  the  same  name,  and  cor- 
responds to  the  scaphoid  behind,  and  the  second  metatarsal  in  front.  It  may  be 
distinguished  from  the  external  cuneiform  bone,  which  it  much  resembles  in 
general  appearance,  by  the  articular  facet,  of  angular  form,  which  runs  round 
the  upper  and  back  part  of  its  inner  surface. 

The  anterior  surface^  triangular  in  form,  and  narrower  than  the  posterior, 
articulates  with  the  base  of  the  second  metatarsal  bone.  The  posterior  surface, 
also  triangular,  articulates  with  the  scaphoid.  The  internal  surface  presents  an 
articular  facet,  running  along  the  superior  and  posterior  borders  for  articulation 
with  the  internal  cuneiform,  and  is  rough  below  for  the  attachment  of  liga- 
ments. The  external  surface  presents  posteriorly  a  smooth  facet  for  articulation 
with  the  external  cuneiform  bone.  The  superior  surface  forms  the  base  of  the 
wedge :  it  is  quadrilateral,  broader  behind  than  in  front,  and  rough  for  the 
attachment  of  ligaments.  The  inferior  surface,  pointed  and  tubercular,  is  also 
rough  for  ligamentous  attachment. 

To  ascertain  to  which  foot  the  bone  belongs,  hold  its  superior  or  dorsal  sur- 
faceupwards,  the  broadest  edge  being  towards  the  holder:  the  smooth  facet 
(limited  to  the  posterior  border)  will  then  point  to  the  side  to  which  it  belongs. 

Articulations.  With  four  bones :  scaphoid,  internal  and  external  cuneiform, 
and  second  metatarsal  bone. 

The  External  Cuneiform,  intermediate  in  size  between  the  two  preceding,  is 
of  a  very  regular  wedge-like  form,  the  broad  extremity  being  placed  upwards, 
the  narrow  end  downwards.  It  occupies  the  centre  of  the  front  row  of  the 
tarsus  between  the  middle  cuneiform  internally,  the  cuboid  externally,  the  sca- 
phoid behind,  and  the  third  metatarsal  in  front.     It  is  distinguished"  from  the 


256  THE    SKELETON. 

internal  cuneiform  bone  by  its  more  regular  wedge-like  shape,  and  by  the 
absence  of  the  kidney-shaped  articular  surface :  from  the  middle  cuneiform,  by 
the  absence  of  the  bent,  or  angular,  facet,  and  by  the  two  articular  facets  which 
mark  both  its  inner  and  outer  surfaces.     It  has  six  surfaces  for  examination. 

The  anterior  surface,  triangular  in  form,  articulates  with  the  third  metatarsal 
bone.  The  posterior  surface  articulates  with  the  most  external  facet  of  the 
scaphoid,  and  is  rough  below  for  the  attachment  of  ligamentous  fibres.  The 
internal  surface  presents  two  articular  facets  separated  by  a  rough  depression ; 
the  anterior  one,  situated  at  the  superior  angle  of  the  bone,  articulates  with  the 
outer  side  of  the  base  of  the  second  metatarsal  bone ;  the  posterior  one  skirts 
the  posterior  border,  and  articulates  with  the  middle  cuneiform ;  the  rough  de- 
pression between  the  two  gives  attachment  to  an  interosseous  ligament.  The 
external  surface  also  presents  two  articular  facets,  separated  by  a  rough  non- 
articular  surface ;  the  anterior  facet,  situated  at  the  superior  angle  of  the  bone, 
is  small,  and  articulates  with  the  inner  side  of  the  base  of  the  fourth  meta- 
tarsal ;  the  posterior,  and  larger  one,  articulates  with  the  cuboid ;  the  rough 
non-articular  surface  serves  for  the  attachment  of  an  interosseous  ligament. 
The  three  facets  for  articulation  with  the  three  metatarsal  bones  are  continuous 
with  one  another,  and  covered  by  a  prolongation  of  the  same  cartilage ;  the 
facets  for  articulation  with  the  middle  cuneiform  and  scaphoid  are  also  continu- 
ous, but  that  for  articulation  with  the  cuboid  is  usually  separate.  The  superior 
or  dorsal  surface,  of  an  oblong  form,  is  rough  for  the  attachment  of  ligaments. 
The  inferior  or  plantar  surface  is  an  obtuse  rounded  margin,  and  serves  for  the 
attachment  of  part  of  the  tendon  of  the  Tibialis  Posticus,  part  of  the  Flexor 
Brevis  Pollicis,  and  ligaments. 

To  ascertain  to  which  side  it  belongs,  hold  the  bone  with  the  broad  dorsal, 
surface  upwards,  the  prolonged  edge  backwards ;  the  separate  articular  facet] 
for  the  cuboid  will  point  to  the  proper  side. 

Articulations.     With  six  bones:  the  scaphoid,  middle  cuneiform,  cuboid,  anc 
second,  third,  and  fourth  metatarsal  bones. 

Attachment  of  Muscles.    Part  of  Tibialis  Posticus,  and  Flexor  Brevis  PoUicisj 


f 


The  Metatarsus. 


The  Metatarsal  Bones  are  five  in  number ;  they  are  long  bones,  and  sub- 
divided into  a  shaft  and  two  extremities. 

Common  Characters.    The  Shaft  is  prismoid  in  form,  tapers  gradually  from  th«| 
tarsal  to  the  phalangeal  extremity,  and  is  slightly  curved  longitudinally,  so  aaj 
to  be  concave  b^elow,  slightly  convex  above.     The  Posterior  Extremity,  or  ^owe,! 
is  wedge-shaped,  articulating  by  its  terminal  surface  with  the  tarsal  bones,  andj 
by  its  lateral  surfaces  with  the  contiguous  bones ;  its  dorsal  and  plantar  sur- 
faces being  rough  for  the  attachment  of  ligaments.     The  Anterior  Extremity,  or 
Head,  presents  a  terminal  rounded  articular  surface,  oblong  from  above  down^ 
wards,  and  extending  further  backward^  below  than  above.     Its  sides  are  flat- 
tened, and  present  a  depression,  surmounted  by  a  tubercle,  for  ligamentouaj 
attachment.     Its  under  surface  is  grooved  in  the  middle  line,  for  the  passage  of 
the  flexor  tendon,  and  marked  on  each  side  by  an  articular  eminence  continu- 
ous with  the  terminal  articular  surface. 

Pectiliar  Characters.  The  First  is  remarkable  for  its  great  size,  but  is  thuj 
shortest  of  all  the  metatarsal  bones.  The  shaft  is  strong,  and  of  well-markedj 
prismoid  form.  l}hQ posterior  extremity  presents  no  lateral  articular  facets;  itaj 
terminal  articular  surface  is  of  large  size,  of  semilunar  form,  and  its  circum- 
ference grooved  for  the  tarso-metatarsal  ligaments  ;  its  inferior  angle  presents] 
a  rough  oval  prominence  for  the  insertion  of  the  tendon  of  the  Peroneusj 
Longus.  The  head  is  of  large  size;  on  its  plantar  surface  are  two  groovedj 
facets,  over  which  glide  sesamoid  bones ;  the  facets  are  separated  by  a  smoothj 
elevated  ridge. 


PHALANGES.  257 

The  Second  is  the  longest  and  largest  of  the  remaining  metatarsal  bones, 
being  prolonged  backwards  into  the  recess  formed  between  the  three  cuneiform 
bones.  Its  tarsal  extremity  is  broad  above,  narrow  and  rough  below.  It 
presents  four  articular  surfaces :  one  behind,  of  a  triangular  form,  for  articula- 
tion with  the  middle  cuneiform ;  one  at  the  upper  part  of  its  internal  lateral 
surface,  for  articulation  with  the  internal  cuneiform ;  and  two  on  its  external 
lateral  surface,  a  superior  and  an  inferior,  separated  by  a  rough  depression. 
Each  of  the  latter  articular  surfaces  is  divided  by  a  vertical  ridge  into  two 
parts ;  the  anterior  segment  of  each  facet  articulates  with  the  third  metatarsal ; 
the  two  posterior  (sometimes  continuous)  with  the  external  cuneiform. 

The  Third  articulates  behind,  by  means  of  a  triangular  smooth  surface,  with 
the  external  cuneiform;  on  its  inner  side,  by  two  facets,  with  the  second 
metatarsal ;  and  on  its  outer  side,  by  a  single  facet,  with  the  fourth  metatarsal. 
The  latter  facet  is  of  circular  form,  and  situated  at  the  upper  angle  of  the  base. 

The  Fourth  is  smaller  in  size  than  the  preceding ;  its  tarsal  extremity  presents 
a  terminal  quadrilateral  surface,  for  articulation  with  the  cuboid ;  a  smooth 
facet  on  the  inner  side,  divided  by  a  ridge  into  an  anterior  portion  for  articula- 
tion with  the  third  metatarsal,  and  a  posterior  portion  for  articulation  with  the 
external  cuneiform ;  on  the  outer  side  a  single  facet,  for  articulation  with  the 
fifth  metatarsal. 

The  Fifth  is  recognized  by  the  tubercular  eminence  on  the  outer  side  of  its 
base.  It  articulates  behind,  by  a  triangular  surface  cut  obliquely  from  without 
inwards,  with  the  cuboid ;  and  internally,  with  the  fourth  metatarsal. 

Articulations.  Each  bone  articulates  with  the  tarsal  bones  by  one  extremity, 
and  by  the  other  with  the  first  row  of  phalanges.  The  number  of  tarsal  bones 
with  which  each  metatarsal  articulates,  is  one  for  the  first,  three  for  the  second, 
one  for  the  third,  two  for  the  fourth,  and  one  for  the  fifth. 

Attachment  of  Muscles.  To  the  first  metatarsal  bone,  three:  part  of  the 
Tibialis  Anticus,  the  Peroneus  Longus,  and  First  Dorsal  Interosseous.  To  the 
second,  three:  the  Adductor  Pollicis,  and  First  and  Second  Dorsal  Interosseous. 
To  the  third,  four:  the  Adductor  Pollicis,  Second  and  Third  Dorsal,  and  First 
Plantar  Interosseous.  To  the  fourth,  four :  the  Adductor  Pollicis,  Third  and 
Fourth  Dorsal,  and  Second  Plantar  Interosseous.  To  the  fifth,  five:  the 
Peroneus  Brevis,  Peroneus  Tertius,  Flexor  Brevis  Minimi  Digiti,  Fourth 
Dorsal,  and  Third  Plantar  Interosseous. 

Phalanges. 

The  Phalanges  of  the  foot,  both  in  number  and  general  arrangement,  resem- 
ble those  in  the  hand;  there  being  two  in  the  great  toe,  and  three  in  each  of 
the  other  toes. 

The  phalanges  of  ihe  first  row  resemble  closely  those  of  the  hand.  The  shaft 
is  compressed  from  side  to  side,  convex  above,  concave  below.  The  ^^osterior 
extremity  is  concave ;  and  the  anterior  extremity  presents  a  trochlear  surface,  for 
articulation  with  the  second  phalanges. 

The  phalanges  of  the  second  row  are  remarkably  small  and  short,  but  rather 
broader  than  those  of  the  first  row. 

The  ungual  phalanges,  in  form,  resemble  those  of  the  fingers ;  but  they  are 
smaller,  flattened  from  above  downwards,  presenting  a  broad  base  for  articula- 
tion with  the  second  row,  and  an  expanded  extremity  for  the  support  of  the 
nail  and  end  of  the  toe. 

Articulations.  The  first  row,  with  the  metatarsal  bones,  and  second  phalanges; 
the  second  of  the  great  toe,  with  the  first  phalanx,  and  of  the  other  toes,  with, 
the  first  and  third  phalanges ;  the  third  with  the  second  row. 

Attachment  of  Muscles.  To  the  first  phalanges,  great  toe  :  innermost  tendon 
of  Extensor  Brevis  Digitorum,  Abductor  Pollicis,  Adductor  Pollicis,  Flexor 
Brevis  Pollicis,  Transversus  Pedis.  Second  toe:  First  and  Second  Dorsal 
17 


258 


THE    SKELETON. 


Interosseous.  Third  toe:  Third  Dorsal  and  First  Plantar  Interosseous.  Fourth 
toe:  Fourth  Dorsal  and  Second  Plantar  Interosseous.  Fifth  toe:  Flexor  Brevis 
Minimi  Digiti,  Abductor  Minimi  Digiti,  and  Third  Plantar  Interosseous.  Second 
phalanges,  great  toe:  Extensor  Longus  Pollicis,  Flexor  Longus  Pollicis.  Other 
toes :  Flexor  Brevis  Digitorum,  one  slip  from  the  Extensor  Brevis  Digitorura 
(except  in  the  little  toe),  and  Extensor  Longus  Digitorum.  Third  phalanges . 
two  slips  from  the  common  tendon  of  the  Extensor  Longus  and  Extensor 
Brevis  Digitorum,  and  the  Flexor  Longus  Digitorum. 

Development  of  the  Foot.    (Fig.  182.) 

The  Tarsal  Bones  are  each  developed  by  a  single  centre,  excepting  the  08 
calcis,  which  has  an  epiphysis  for  its  posterior  extremity.  The  centres  make 
their  appearance  in  the  following  order :  in  the  os  calcis,  at  the  sixth  montl 

Fig.  182.— Plan  of  the  Development  of  the  Foot 
-—Jjrp.'  fO^  y-^ 

uititet  afttr puierty 

Tartu* 

/  Centre  for  eaoA  iorio 
teceevt  0»  CaZcif 


Metatarsus 

g  Centres  far  each  bone 
/  fm-  Shaft 

1  far  Di^itallxtremity 
mren/t  iff 


\ 


Appear*  S^yT 
Unitt.  /SX.0^  tj* 

1-   App.  7^wi 


VnU*  18-20  yA 

App.&^Vr-^^ 
Vnae/J-^«f\ 


%\ 


1ESS3 


FAaZange* 

SCentreefm"  eaak  bona 

IforSlkaft 

f forMtUttantdJEiUS        Aj^.C-Tl^yr^ 
U'.itt  q-ia  y.r[ 

AjfpAffy.^^, 
App7-'^'^J>\ 

of  foetal  life ;  in  the  astragalus,  about  the  seventh  month  \  in  the  cuboid,  at  the 
ninth  month;  external  cuneiform,  during  the  first  year;  internal  cuneiform  in 
the  third  year;  middle  cuneiform  and  scaphoid  in  the  fourth  year.  The 
epiphysis  for  the  posterior  tuberosity  of  the  os  calcis  appears  at  the  tenth  yearj 
and  unites  with  the  rest  of  the  bone  soon  after  puberty. 

The  Metatarsal  Bones  are  each  developed  by  two  centres ;  one  for  the  shai 
and  one  for  the  digital  extremity,  in  the  four  outer  metatarsal ;  one  for  the  shai 


SESAMOID    BOXES.  259 

and  one  for  the  base,  in  the  metatarsal  bone  of  the  great  toe.  Ossification  com- 
mences in  the  centre  of  the  shaft  about  the  seventh  week,  and  extends  towards 
either  extremity,  and  in  the  digital  epiphyses  about  the  third  year ;  they  become 
joined  between  the  eighteenth  and  twentieth  years. 

The  Phalanges  are  developed  by  two  centres  for  each  bone ;  one  for  the  shaft, 
and  one  for  the  metatarsal  extremity. 

Sesamoid  Bones. 

These  are  small  rounded  masses,  cartilaginous  in  early  life,  osseous  in  the 
adult,  which  are  developed  in  those  tendons  which  exert  a  great  amount  of  pres- 
sure upon  the  parts  over  which  they  glide.  It  is  said  that  they  are  more  com- 
monly found  in  the  male  than  in  the  female,  and  in  persons  of  an  active  muscular 
habit  than  in  those  who  are  weak  and  debilitated.  They  are  invested  throughout 
their  whole  surface  by  the  fibrous  tissue  of  the  tendon  in  which  they  are  found, 
excepting  upon  that  side  which  lies  in  contact  with  the  part  over  which  they 
play,  where  they  present  a  free  articular  facet.  They  may  be  divided  into  two 
kinds :  those  which  glide  over  the  articular  surfaces  of  joints,  and  those  which 
play  over  the  cartilaginous  facets  found  on  the  surfaces  of  certain  bones. 

The  sesamoid  bones  of  the  joints  are,  in  the  lower  extremity,  the  patella, 
which  is  developed  in  the  tendon  of  the  Quadriceps  Extensor ;  two  small  sesa- 
moid bones,  found  in  the  tendons  of  the  Flexor  Brevis  Pollicis,  opposite  the 
metatarso-phalangeal  joint  of  the  great  toe,  and  occasionally  one  in  the  meta- 
tarso-phalangeal  joint  of  the  second  toe,  the  little  toe,  and,  still  more  rarely,  the 
third  and  fourth  toes. 

In  the  upper  extremity,  there  are  two  on  the  palmar  surface  of  the  metacarpo- 
phalangeal joint  in  the  thumb,  developed  in  the  tendons  of  the  Flexor  Brevis 
Pollicis,  occasionally  one  or  two  opposite  the  metacarpo-phalangeal  articulations 
of  the  fore  and  little  fingers,  and,  still  more  rarely,  one  opposite  the  same  joints 
,of  the  third  and  fourth  fingers. 

Those  found  in  the  tendons  which  glide  over  certain  bones,  occupy  the  follow- 
ing situations:  one  in  the  tendon  of  the  Peroneus  Longus,  where  it  glides  through 
the  groove  in  the  cuboid  bone ;  one  appears  late  in  life  in  the  tendon  of  the 
Tibialis  Anticus,  opposite  the  smooth  facet  on  the  internal  cuneiform  bone;  one 
is  found  in  the  tendon  of  the  Tibialis  Posticus,  opposite  the  inner  side  of  the 
astragalus ;  one  in  the  outer  head  of  the  Gastrocnemius,  behind  the  outer  con- 
dyle of  the  femur ;  and  one  in  the  Psoas  and  Iliacus,  where  they  glide  over  the 
body  of  the  pubes.  Sesamoid  bones  are  found  occasionally  in  the  tendon  of 
the  Biceps,  opposite  the  tuberosity  of  the  radius;  in  the  tendon  of  the  Gluteus 
Maximus,  as  it  passes  over  the  great  trochanter ;  and  in  the  tendons  which  wind 
round  the  inner  and  outer  malleoli. 


The  author  has  to  acknowledge  valuable  aid  derived  from  the  perusal  of  the  worlcs  of  Cloquet, 
Cruveilhier,  Bourgery,  and  Boyer,  especially  of  the  latter.  Reference  has  also  been  made  to  the 
following:  "Outlines  of  Human  Osteology."  bv  F.  0.  Ward.  "A  Treatise  on  the  Human 
Skeleton,  and  Observations  on  the  Limbs  of  Vertebrate  Animals,"  by  G.  M.  Humphry.  Hold- 
en's  "Human  Osteology."  Henle's  "Handbuchder  systematischen  Anatomic  des  Menschen. 
Erster  Band.  Erste  Abtheilung.  Knochenlehre."  "  Os^eological  Memoirs  (The  Clavicle),"  by 
Struthers.  "On  the  Archetype  and  Homologies  of  the  Vertebrate  Skeleton,"  and  "On  the 
Nature  of  Limbs,"  by  Owen.— Todd  and  Bowman's  "  Physiological  Anatomy,"  and  Kolliker's 
'•  Manual  of  Human  Microscopic  Anatomy,"  contain  the  most  complete  account  of  the  structure 
and  development  of  bone.  The  development  of  the  bones  is  minutely  described  in  "  Quain's 
Anatomy,"  edited  by  Sharpey  and  Ellis.— On  the  chemical  analysis  of  bone,  refer  to  "  Lehmann's 
Physiological  Chemistry,"  translated  by  Day;  vol.  iii.  p.  12.  "Simon's  Chemistry."  translated 
by  Day ;  vol.  ii.  p.  396.  A  paper  by  Dr.  Stark,  "  On  the  Chemical  Constitution  of  the  Bones  of 
the  Vertebrated  Animals"  (Edinburgh  Medical  and  Surgical  Journal;  vol.  liii.  p.  308) ;  and  Dr. 
Owen  Eees'  paper  in  the  21st  vol.  of  the  Medico-Chirurgical  Transactions. 


The  Articulations. 

f 

The  various  bones  of  whicli  the  Skeleton  consists  are  connected  together  at 
different  parts  of  their  surfaces,  and  such  a  connection  is  designated  by  the 
name  of  Joint  or  Articulation.  If  the  joint  is  immovable^  as  between  the  cranial 
and  most  of  the  facial  bones,  their  adjacent  margins  are  applied  in  almost  close 
contact,  a  thin  layer  of  fibrous  membrane,  the  sutural  ligament,  and,  at  the  base 
of  the  skull,  in  certain  situations,  a  thin  layer  of  cartilage  being  interposed. 
"Where  slight  movement  is  required,  combined  with  great  strength,  the  osseous 
surfaces  are  united  by  tough  and  elastic  fibro-cartilages,  as  in  the  joints  of  the 
spine,  the  sacro-iliac,  and  interpubic  articulations ;  but  in  the  movahle  joints,  the 
bones  forming  the  articulation  are  generally  expanded  for  greater  convenience 
of  mutual  connection,  covered  by  cartilage,  held  together  by  strong  bands  or 
capsules  of  fibrous  tissue,  called  ligaments,  and  lined  by  a  membrane,  the  synovial 
membrane,  which  secretes  a  fluid  to  lubricate  the  various  parts  of  which  the  joint 
is  formed :  so  that  the  structures  which  enter  into  the  formation  of  a  joint  are 
bone,  cartilage,  fibro-cartilage,  ligament,  and  synovial  membrane. 

Bone  constitutes  the  fundamental  element  of  all  the  joints.  In  the  long  bones, 
the  extremities  are  the  parts  which  form  the  articulations ;  they  are  generally 
somewhat  enlarged,  consisting  of  spongy  cancellous  tissue,  with  a  thin  coating 
of  compact  substance.  In  the  flat  bones,  the  articulations  usually  take  place 
at  the  edges ;  and,  in  the  short  bones,  at  various  parts  of  their  surface.  The 
layer  of  compact  bone  which  forms  the  articular-  surface,  and  to  which  the 
cartilage  is  attached,  is  called  the  articular  lamella.  It  is  of  a  white  color, 
extremely  dense,  and  varies  in  thickness.  Its  structure  differs  from  ordinary 
bone  tissue  in  this  respect,  that  it  contains  no  Haversian  canals,  and  its  lacunae 
are  much  larger  than  in  ordinary  bone,  and  have  no  canaliculi.  The  vessels  of 
the  cancellous  tissue,  as  they  approach  the  articular  lamella,  turn  back  in  loops, 
and  do  not  perforate  it ;  this  layer  is  consequently  more  dense  and  firmer  than 
ordinary  bone,  and  is  evidently  designed  to  form  a  firm  and  unyielding  support 
for  the  articular  cartilage. 

The  articular  will  be  found  described  along  with  the  other  kinds  of  cartilage 
in  the  Introduction. 

Ligaments  are  found  in  nearly  all  the  movable  articulations ;  they  consist  of 
bands  of  various  forms,  serving  to  connect  together  the  articular  extremities  of 
bones,  and  composed  mainly  of  bundles  of  tvhite  fibrous  tissue  placed  parallel 
with,  or  closely  interlaced  with,  one  another,  and  presenting  a  white,  shining 
silvery  aspect.  Ligament  is  pliant  and  flexible,  so  as  to  allow  of  the  most 
perfect  freedom  of  movement,  but  strong,  tough,  and  inextensile,  so  as  not 
readily  to  yield  under  the  most  severely  applied  force ;  it  is  consequently  well 
adapted  to  serve  as  the  connecting  medium  between  the  bones.  Some  ligaments 
consist  entirely  o{  yellow  elastic  tissue,  as  the  ligamenta  subflava,  which  connect  || 
together  the  adjacent  arches  of  the  vertebrae,  and  the  ligamentum  nucha3.  In 
these  cases,  it  will  be  observed  that  the  elasticity  of  the  ligament  is  intended  to 
act  as  a  substitute  for  muscular  power. 

Synovial  Membraiie  is  a  thin,  delicate  membrane,  arranged  in  the  form  of  a 
short  wide  tube,  attached  by  its  open  ends  to  the  margins  of  the  articular 
extremities  of  the  bones,  and  covering  the  inner  surface  of  the  various  liga- 
ments which  connect  the  articulating  surfaces.  It  resembles  the  serous  mem- 
branes in  structure,  but  differs  in  the  nature  of  its  secretion,  which  is  thick, 
viscid,   and  glairy,  like  the  white  of  egg;  and  hence  termed  synovia.     The 

260 


I 


STRUCTURE    OF    JOINTS.  261 

synovial  membranes  found  in  the  body  admit  of  subdivision  into  three  kinds, 
articular,  bursal,  and  vaginal. 

The  articular  synovial  membranes  are  found  in  all  the  freely  movable  joints. 
In  the  foetus,  this  membrane  is  said,  by  Toynbee,  to  be  continued  over  the 
surface  of  the  cartilages;  but  in  the  adult  it  is  wanting,  excepting  at  their 
circumference,  upon  which  it  encroaches  for  a  short  distance ;  it  then  invests 
the  inner  surface  of  the  capsular  or  other  ligaments  inclosing  the  joint,  and  is 
reflected  over  the  surface  of  any  tendons  passing  through  its  cavity,  as  the 
tendon  of  the  Popliteus  in  the  knee,  and  the  tendon  of  the  Biceps  in  the  shoulder. 
In  most  of  the  joints,  the  synovial  membrane  is  thrown  into  folds,  which  project 
into  the  cavity.  Some  of  these  folds  contain  large  masses  of  fat.  These  are 
especially  distinct  in  the  hip  and  the  knee.  Others  are  flattened  folds,  subdi- 
vided at  their  margins  into  fringe-like  processes,  the  vessels  of  which  have  a 
convoluted  arrangement.  The  latter  generally  project  from  the  synovial  mem- 
brane near  the  margin  of  the  cartilage,  and  lie  flat  upon  its  surface.  They 
consist  of  connective  tissue,  covered  with  epithelium,  and  contain  fat  cells  in 
variable  quantity,  and,  more  rarely,  isolated  cartilage  cells.  They  are  found  in 
most  of  the  bursal  and  vaginal,  as  well  as  in  the  articular  synovial  membranes, 
and  were  described,  by  Olopton  Havers,  as  mucilaginous  glands,  and  as  the 
source  of  the  synovial  secretion.  Under  certain  diseased  conditions,  similar 
processes  are  found  covering  the  entire  surface  of  the  synovial  membrane, 
forming  a  mass  of  pedunculated  fibro-fatty  growths,  which  project  into  the 
joint. 

The  hursss  are  found  interposed  between  surfaces  which  move  upon  each 
other,  producing  friction,  as  in  the  gliding  of  a  tendon,  or  of  the  integument, 
over  projecting  bony  surfaces.  They  admit  of  subdivision  into  two  kinds,  the 
Imrsse  mucosde,  and  the  synovial  hursse.  The  former  are  large,  simple,  or  irregu- 
lar cavities  in  the  subcutaneous  areolar  tissue,  inclosing  a  clear  viscid  fluid. 
They  are  found  in  various  situations,  as  between  the  integument  and  front  of 
the  patella,  over  the  olecranon,  the  malleoli,  and  other  prominent  parts.  The 
synovial  hursse  are  found  interposed  between  muscles  or  tendons  as  they  play 
over  projecting  bony  surfaces,  as  between  the  Glutei  muscles  and  surface  of  the 
great  trochanter.  They  consist  of  a  thin  wall  of  connective  tissue,  partially 
covered  by  epithelium,  and  contain  a  viscid  fluid.  Where  one  of  these  exists 
in  the  neighborhood  of  a  joint,  it  usually  communicates  with  its  cavity,  as  is 
generally  the  case  with  the  bursa  between  the  tendon  of  the  Psoas  and  Iliacus, 
and  the  capsular  ligament  of  the  hip,  or  the  one  interposed  between  the  under 
surface  of  the  Subscapularis  and  the  neck  of  the  scapula. 

The  vaginal  synovial  membranes  (synovial  sheaths)  serve  to  facilitate  the 
gliding  of  tendons  in  the  osseo-fibrous  canals  through  which  they  pass.  The 
membrane  is  here  arranged  in  the  form  of  a  sheath,  one  layer  of  which  adheres 
to  the  wall  of  the  canal,  and  the  other  is  reflected  upon  the  outer  surface  of  the 
contained  tendon;  the  space  between  the  two  free  surfaces  of  the  membrane 
being  partially  filled  with  synovia.  These  sheaths  are  chiefly  found  surrounding 
the  tendons  of  the  flexor  and  extensor  muscles  of  the  fingers  and  toes,  as  they 
pass  through  the  osseo-fibrous  canals  in  the  hand  or  foot. 

Synovia  is  a  transparent,  yellowish-white,  or  slightly  reddish  fluid,  viscid  like 
the  white  of  egg,  having  an  alkaline  reaction,  and  slightly  saline  taste.  It  con- 
sists, according  to  Frerichs,  in  the  ox,  of  94.85  water,  0.56  mucus  and  epithelium, 
0.07  fat,  3.51  albumen  and  extractive  matter,  and  0.99  salts. 

The  Articulations  are  divided  into  three  classes:  Synarthrosis,  or  immovable; 
Amphiarthrosis,  or  mixed;  and  Uiarthrosis,  or  movable  joints. 


262 


ARTICULATIOXS. 


1.  Synarthrosis.    Immovable  Articulations. 

Synarthrosis  includes  all  those  articulations  in  which  the  surfaces  of  the  bones 
are  in  almost  direct  contact,  not  separated  by  an  intervening  synovial  cavity, 
and  immovably  connected  with  each  other,  as  the  joints  between  the  bones  of 
the  cranium  and  face,  excepting  those  of  the  lower  jaw.  The  varieties  of  synar- 
throsis are  three  in  number :  Sutura,  Schindylesis,  and  Gomphosis. 

Sutura  (a  seam).  Where  the  articulating  surfaces  are  connected  by  a  series 
of  processes  and  indentations  interlocked  together,  it  is  termed  sutura  vera] 
of  which  there  are  three  varieties:  sutura  dentata,  serrata,  and  limbosa.  The 
surfaces  of  the  bones  are  not  in  direct  contact,  being  separated  by  a  layer  of 
membrane  continuous  externally  with  the  pericranium,  internally  with  the  dura 
mater.  The  sutura  dentata  {dens,  a  tooth)  is  so  called  from  the  tooth-like  form 
of  the  projecting  articular  processes,  as  in  the  suture  between  the  parietal 
bones.  In  the  sutura  serrata  {serra,  a  saw),  the  edges  of  the  two  bones  forming 
the  articulation  are  serrated  like  the  teeth  of  a  fine  saw,  as  between  the  two 
portions  of  the  frontal  bone.  In  the  sutura  limbosa  {limlus,  a  selvage),  besides 
the  dentated  processes,  there  is  a  certain  degree  of  bevelling  of  the  articular 
surfaces,  so  that  the  bones  overlap  one  another,  as  in  the  suture  between  the 
parietal  and  frontal  bones.  When  the  articulation  is  formed  by  roughened  sur- 
faces placed  in  apposition  with  one  another,  it  is  termed  the  false  suture,  sutura 
notha,  of  which  there  are  two  kinds .  the  sutura  squamosa  {squama,  a  scale), 
formed  by  the  overlapping  of  two  contiguous  bones  by  broad  bevelled  margins, 
as  in  the  temporo-parietal  (squamous)  suture;  and  the  sutura  harmonia  (ap/iona, 
a  joining  together),  where  there  is  simple  apposition  of  two  contiguous  rough 
bony  surfaces,  as  in  the  articulation  between  the  two  superior  maxillary  bones, 
or  of  the  horizontal  plates  of  the  palate. 

Schindylesis  {azi^vbv-KTiaii,  a  fissure)  is  that  form  of  articulation  in  which  a  thin 
plate  of  bone  is  received  into  a  cleft  or  fissure  formed  by  the  separation  of  two 
laminae  of  another,  as  in  the  articulation  of  the  rostrum  of  the  sphenoid,  and 

{)erpendicular  plate  of  the  ethmoid  with  the  vomer,  or  in  the  reception  of  the 
atter  in  the  fissure  between  the  superior  maxillary  and  palate  bones. 

Gomphosis  (y6ju4)oj,  a  nail)  is  an  articulation  formed  by  the  insertion  of  a  conical 
process  into  a  socket,  as  a  nail  is  driven  into  a  board;  this  is  not  illustrated  by 
any  articulations  between  bones,  properly  so  called,  but  is  seen  in  the  articula- 
tion of  the  teeth  with  the  alveoli  of  the  maxillary  bones. 


2.   A MPHI ARTHROSIS.      MiXED  ARTICULATIONS. 


«il 


In  this  form  of  articulation,  the  contiguous  osseous  surfaces  are  connected 
together  by  broad  flattened  disks  of  fibro-cartilage,  which  adhere  to  the  ends 
of  both  bones,  as  in  the  articulation  between  the  bodies  of  the  vertebrae,  and 
first  two  pieces  of  the  sternum;  or  the  articulating  surfaces  are  covered  with 
fibro-cartilage,  partially  lined  by  synovial  membrane,  and  connected  together 
by  external  ligaments,  as  in  the  sacro-iliac  and  pubic  symphyses;  both  these 
forms  being  capable  of  limited  motion  in  every  direction.  The  former  resemble 
the  synarthrodial  joints  in  the  continuity  of  their  surfaces,  and  absence  of 
synovial  sac;  the  latter,  the  diarthrodial.  These  joints  occasionally  become 
obliterated  in  old  age;  as  is  frequently  the  case  in  the  pubic  articulation,  and 
occasionally  in  the  intervertebral  and  sacroiliac. 


■8.  DiARTHRosis.    Movable  Articulations. 


* 


This  form  of  articulation  includes  the  greater  number  of  joints  in  the  bod 
mobility  being  their  distinguishing  character.    They  are  formed  by  the  approxi 
mation  of  two  contiguous  bony  surfaces,  covered  with  cartilage,  connected  by 
ligaments,  and  lined  by  synovial  membrane.     The  varieties  of  joints  in  this 


STRUCTURE    OF    JOINTS.  263 

class  have  been  determined  by  the  kind  of  motion  permitted  in  each;  they  are 
four  in  number:  Arthrodia,  Enarthrosis,  Ginglymus,  Diarthrosis  rotatorius. 

Arthrodia  is  that  form  of  joint  which  admits  of  a  gliding  movement;  it  is 
formed  by  the  approximation  of  plane  surfaces,  or  one  slightly  concave,  the 
other  slightly  convex;  the  amount  of  motion  between  them  being  limited  by  the 
ligaments,  or  osseous  processes,  surrounding  the  articulation;  as  in  the  articular 
processes  of  the  vertebrae,  temporo-maxillary,  sterno-  and  acromio-clavicular, 
inferior  radio-ulnar,  carpal,  carpo-metacarpal,  superior  tibio-fibular,  tarsal,  and 
tarso-metatarsal  articulations. 

Enarthrosis  is  that  form  of  joint  which  is  capable  of  motion  in  all  directions. 
It  is  formed  by  the  reception  of  a  globular  head  into  a  deep  cup-like  cavity 
(hence  the  name  "ball  and  socket"),  the  parts  being  kept  in  apposition  by  a 
capsular  ligament,  strengthened  by  accessory  ligamentous  bands.  Examples  of 
this  form  of  articulation  are  found  in  the  hip  and  shoulder. 

Ginglymus^  Hinge-joint  (ytyyxv^oj,  a  hinge).  In  this  form  of  joint,  the  articular 
surfaces  are  moulded  to  each  other  in  such  a  manner,  as  to  permit  motion  only 
in  two  directions,  forwards  and  backwards,  the  extent  of  motion  at  the  same 
time  being  considerable.  The  articular  surfaces  are  connected  together  by 
strong  lateral  ligaments,  which  form  their  chief  bond  of  union.  The  most 
perfect  forms  of  ginglymus  are  the  elbow  and  ankle ;  the  knee  is  less  perfect, 
as  it  allows  a  slight  degree  of  rotation  in  certain  positions  of  the  limb :  there 
are  also  the  metatarso- phalangeal  and  phalangeal  joints  in  the  lower  extremity, 
and  the  metacarpo-phalangeal  and  phalangeal  joints  in  the  upper  extremity. 

Diarthrosis  rotatorius  (Lateral  Ginglymus).  "Where  the  movement  is  limited 
to  rotation,  the  joint  is  formed  by  a  pivot-like  process  turning  within  a  ring, 
or  the  ring  on  the  pivot,  the  ring  being  formed  partly  of  bone,  partly  of  liga- 
ment. In  the  articulation  of  the  odontoid  process  of  the  axis  with  the  atlas, 
the  ring  is  formed  in  front  by  the  anterior  arch  of  the  atlas ;  behind,  by  the 
transverse  ligament ;  here  the  ring  rotates  round  the  odontoid  process.  In  the 
superior  radio-ulnar  articulation,  the  ring  is  formed  partly  by  the  lesser  sig- 
moid cavity  of  the  ulna ;  in  the  rest  of  its  extent,  by  the  orbicular  ligament , 
here,  the  head  of  the  radius  rotates  within  the  ring. 

Subjoined,  in  a  tabular  form,  are  the  names,  distinctive  characters,  and  ex- 
amples of  the  different  kinds  of  articulations. 


264 


ARTICULATIONS. 


Sutura  vera  (true) 
'articulate  by  in- 
dented borders. 


Synarthrosis,  or  im- 
movable joint.  Sur- 
faces separated  by 
fibrous  membrane, 
without  any  inter- 
vening synovial  ca- 
vity, and  immova- 
bly connected  with 
each  other. 

As  in  joints  of  cra- 
nium and  face  (ex- 
cept lower  jaw). 


iSutura.  Arti- 
[culation  by  pro- 
cesses and  inden- 
tations interlock- 
ed together. 


Sutura  notha 
I  (false)  articulate  by 
rough  surfaces. 


A  mphiarthrosis, 
Mixed  Articulation. 


Diarihrosis, 
Movable  Joint. 


Dentata,  having 
'tooth-like  processes. 

As  in  interparie- 
tal suture. 

Serrata,  having 
Iserrated  edges,  like 
jthe  teeth  of  a  saw. 

As  in  interfrontal 
\suture. 

Limbosa,  having 
[bevelled  margins, 
and  dentated  pro- 
cesses. 

As  in  fronto-pa- 
^rietal  suture. 

Squamosa,  formed 
Ihy  thin  bevelled 
margins  overlap- 
ping each  other. 

As  in  Squamo- 
/parietal  suture. 

Harmonia,  formed 
iby  the  apposition  of 
contiguous  rough 
surfaces. 

As  in  intermaxil- 
lary suture. 

Schindylesis.  Articulation  formed  by  the  reception  of  a 
thin  plate  of  bone  into  a  fissure  of  another. 

As  in  articulation  of  rostrum  of  sphenoid  with  vomer. 

Gomphosis.     Articulation  formed  by  the  insertion  of 
conical  process  into  a  socket. 
^    The  teeth. 

1.  Surfaces  connected  by  fibro-cartilage,  not  separated 
by  synovial  membrane,  and  having  limited  motion.  As 
in  joints  between  bodies  of  vertebrae. 

2.  Surfaces  covered  by  fibro-cartilage ;  lined  by  a  partial 
synovial  membrane.  As  in  sacro-iliac  and  pubic  sym- 
physes. 

Arthrodia.  Gliding  joint;  articulations  by  plane  sur- 
faces, which  glide  upon  each  other.  As  in  sterno-  and 
acromio-clavicular  articulations. 

Enarthrosis.  Ball-and-socket  joint;  capable  of  motion 
in  all  directions.  Articulations  by  a  globular  head  received 
into  a  cup-like  cavity.     As  in  hip  and  shoulder-joints. 

Oinglymus.  Hinge-joint;  motion  limited  to  two  direc- 
tions, forwards  and  backwards.  Articular  surfaces  fitted 
together  so  as  to  permit  of  movement  in  one  plane.  As  in 
the  elbow,  ankle,  and  knee. 

Diarihrosis  rotatorius  or  Lateral  Oinglymus.  Articulation 
by  a  pivot  process  turning  within  a  ring,  or  ring  around 
a  pivot.  As  in  superior  radio-ulnar  articulation,  and  atlo- 
axoid  joint. 


H 


OF    THE    VERTEBRAL    COLUMN.  265 

The  Kinds  of  Movement  Admitted  in  Joints. 

The  movements  admissible  in  joints  may  be  divided  into  four  kinds,  gliding, 
angular  movement,  circumduction,  and  rotation. 

Gliding  movement  is  the  most  simple  kind  of  motion  that  can  take  place  in 
a  joint,  one  surface  gliding  over  another.  It  is  common  to  all  movable  joints; 
but  in  some,  as  in  the  articulations  of  the  carpus  and  tarsus,  it  is  the  only 
motion  permitted.  This  movement  is  not  confined  to  plane  surfaces,  but  may 
exist  between  any  two  contiguous  surfaces,  of  whatever  form,  limited  by  the 
ligaments  which  inclose  the  articulation. 

Angular  movement  occurs  only  between  the  long  bones,  and  may  take  place 
in  four  directions,  forwards  and  backwards,  constituting  flexion  and  extension, 
or  inwards  and  outwards,  constituting  adduction  and  abduction.  The  strictly 
ginglymoid  or  hinge-joints  admit  of  flexion  and  extension  only.  Abduction 
and  adduction,  combined  with  flexion  and  extension,  are  met  with  in  the  more 
movable  joints ;  as  in  the  hip,  shoulder,  and  metacarpal  joint  of  the  thumb, 
and  partially  in  the  wrist  and  ankle. 

Circumduction  is  that  limited  degree  of  motion  which  takes  place  between 
the  head  of  a  bone  and  its  articular  cavity,  whilst  the  extremity  and  sides  of 
the  limb  are  made  to  circumscribe  a  conical  space,  the  base  of  which  corres- 
ponds with  the  inferior  extremity  of  the  limb,  the  apex  with  the  articular 
cavity;  this  kind  of  motion  is  best  seen  in  the  shoulder  and  hip-joints. 

Rotation  is  the  movement  of  a  bone  upon  its  own  axis,  the  bone  retaining 
the  same  relative  situation  with  respect  to  the  adjacent  parts ;  as  in  the  articu- 
lation between  the  atlas  and  axis,  where  the  odontoid  process  serves  as  a  pivot 
around  which  the  atlas  turns ;  or  in  the  rotation  of  the  radius  upon  the  hume- 
rus, and  also  in  the  hip  and  shoulder. 

The  articulations  may  be  arranged  into  those  of  the  trunk,  those  of  the  upper 
extremity,  and  those  of  the  lower  extremity. 

ARTICULATIONS  OF  THE  TRUNK. 

These  may  be  divided  into  the  following  groups,  viz : — 

I.  Of  the  vertebral  column.  YII.  Of  the  cartilages  of  the  ribs  with 

II.  Of  the  atlas  with  the  axis.  the  sternum,  and  with  each 

III.  Of  the   atlas  with  the   occipital  other. 

bone.  VIII.  Of  the  sternum. 

IV.  Of  the  axis  with  the  occipital  bone.        IX.  Of  the  vertebral  column  with  the 
V.  Of  the  lower  jaw.  pelvis. 

VI.  Of  the  ribs  with  the  vertebrae.  X.  Of  the  pelvis. 

I.  ARTICULATIONS  OF  THE  VERTEBRAL  COLUMN. 

The  different  segments  of  the  spine  are  connected  together  by  ligaments, 
which  admit  of  the  same  arrangement  as  the  vertebrae.  They  may  be  divided 
into  five  sets.  1.  Those  connecting  the  bodies  of  the  vertebrae.  2.  Those  con- 
necting the  laminse.  3.  Those  connecting  the  articular  processes.  4.  Those 
connecting  the  spinous  processes.     5.  Those  of  the  transverse  processps. 

The  articulations  of  the  bodies  of  the  vertebrse  with  each  other  form  a  series 
of  amphiarthrodial  joints :  those  between  the  articular  processes  form  a  series  of 
I  arthrodial  joints. 


2G6 


ARTICULATIONS. 


1.  The  Ligaments  of  the  Bodies. 

Anterior  Common  Ligament.  Posterior  Common  Ligament. 

Intervertebral  Substance. 

The  Anterior  Common  Ligament  (Figs.  183,  184,  191,  194")  is  a  broad  and 
strong  band  of  ligamentous  fibres,  which  extends  along  the  front  surface  of  the 
bodies  of  the  vertebrae,  from  the  axis  to  the  sacrum.  It  is  broader  below  than 
above,  thicker  in  the  dorsal  than  in  the  cervical  or  lumbar  regions,  and  some- 
what thicker  opposite  the  front  of  the  body  of  each  vertebra,  than  opposite  the 
intervertebral  substance.  It  is  attached,  above,  to  the  body  of  the  axis  by  a 
pointed  process,  which  is  connected  with  the  tendon  of  insertion  of  the  Longus 
Colli  muscle ;  and  extends  down  as  far  as  the  upper  bone  of  the  sacrum.  It 
consists  of  dense  longitudinal  fibres,  which  are  intimately  adherent  to  the  inter- 
vertebral substance,  and  the  prominent  margins  of  the  vertebrae ;  but  less 
closely  to  the  middle  of  the  bodies.  In  the  latter  situation  the  fibres  are  ex- 
ceedingly thick,  and  serve  to  fill  up  the  concavities  on  their  front  surface,  and 
to  make  the  anterior  surface  of  the  spine  more  even.  This  ligament  is  com- 
posed of  several  layers  of  fibres,  which  vary  in  length,  but  are  closely  inter- 
laced with  each  other.  The  most  superficial  or  longest  fibres  extend  between 
four  or  five  vertebrae.  A  second  subjacent  set  extend  between  two  or  three 
vertebrae ;  whilst  a  third  set,  the  shortest  and  deepest,  extend  from  one  vertebra 
to  the  next.  At  the  side  of  the  bodies,  the  ligament  consists  of  a  few  short 
fibres,  which  pass  from  one  vertebra  to  the  next,  separated  from  the  median 
portion  by  large  oval  apertures,  for  the  passage  of  vessels. 

The  Posterior  Common  Ligament  (Figs.  183,  187)  is  situated  within  the  spinal 
canal,  and  extends  along  the  posterior  surface  of  the  bodies  of  the  vertebrae, 

Fig.  183. — ^Vertical  Section  of  two  Vertebrae  and  their  Ligaments,  from  the  Lumbar  Kegion. 


POSTEaiOR 

COMMON 

LICT 


3*'.*Q  <5 


from  the  body  of  the  axis  above,  where  it  is  continuous  with  the  occipito-axoic 
ligament,  to  the  sacrum  below.     It  is  broader  at  the  upper  than  at  the  lo\ver^| 
part  of  the  spine,  and  thicker  in  the  dorsal  than  in  the  cervical  or  lumbar 
region.     In  the  situation  of  the  intervertebral  substance  and  contiguous  mar- 


OF    THE    VERTEBRAL    COLUMN.  267 

gins  of  the  vertebrae,  where  the  ligament  is  more  intimately  adherent,  it  is 
broad,  and  presents  a  series  of  dentations  with  intervening  concave  margins; 
but  it  is  narrow  and  thick  over  the  centre  of  the  bodies,  from  which  it  is  sepa- 
rated by  the  ve7ise  basis  vertebrse.  This  ligament  is  composed  of  smooth,  shining, 
longitudinal  fibres,  denser  and  more  compact  than  those  of  the  anterior  liga- 
ment, and  composed  of  a  superficial  layer  occupying  the  interval  between 
.three  or  four  vertebrse,  and  of  a  deeper  layer  which  extends  between  one 
vertebra  and  the  next  adjacent  to  it.  It  is  separated  from  the  dura  mater  of 
the  spinal  cord  by  some  loose  filamentous  tissue,  very  liable  to  serous  in- 
filtration. 

The  Intervertebral  Substance  (Fig.  183)  is  a  lenticular  disk  of  fibro-cartilage, 
interposed  between  the  adjacent  surfaces  of  the  bodies  of  the  vertebrae,  from 
the  axis  to  the  sacrum,  and  forming  the  chief  bond  of  connection  between 
those  bones.  These  disks  vary  in  shape,  size,  and  thickness,  in  different  parts 
of  the  spine.  In  shape  they  accurately  correspond  with  the  surfaces  of  the 
bodies  between  which  they  are  placed,  being  oval  in  the  cervical  and  lumbar 
regions,  and  circular  in  the  dorsal.  Their  size  is  greatest  in  the  lumbar  region. 
In  thickness  they  vary  not  only  in  the  different  regions  of  the  spine,  but  in 
different  parts  of  the  same  region  :  thus,  they  are  uniformly  thick  in  the  lumbar 
region ;  thickest,  in  front,  in  the  cervical  and  lumbar  regions  which  are  convex 
forwards ;  and  behind,  to  a  slight  extent,  in  the  dorsal  region.  They  thus  con- 
tribute, in  a  great  measure,  to  the  curvatures  of  the  spine  in  the  neck  and 
loins ;  whilst  the  concavity  of  the  dorsal  region  is  chiefly  due  to  the  shape  of 
the  bodies  of  the  vertebrae.  The  intervertebral  disks  form  about  one-fourth  of 
the  spinal  column,  exclusive  of  the  first  two  vertebrae ;  they  are  not  equally 
distributed,  however,  between  the  various  bones;  the  dorsal  portion  of  the 
spine  having,  in  proportion  to  its  length,  a  much  smaller  quantity  than  in  the 
cervical  and  lumbar  regions,  which  necessarily  gives  to  the  latter  parts  greater 
pliancy  and  freedom  of  movement.  The  intervertebral  disks  are  adherent, 
by  their  surfaces,  to  the  adjacent  parts  of  the  bodies  of  the  vertebrae ;  and 
by  their  circumference  are  closely  connected  in  front  to  the  anterior,  and  behind 
to  the  posterior  common  ligament ;  whilst,  in  the  dorsal  region,  they  are  con- 
nected laterally,  by  means  of  the  interarticular  ligament,  to  the  heads  of  those 
ribs  which  articulate  with  two  vertebrae ;  they,  consequently,  form  part  of  the 
articular  cavities  in  which  the  heads  of  these  bones  are  received. 

The  intervertebral  substance  is  composed,  at  its  circumference,  of  laminae  of 
fibrous  tissue  and  fibro-cartilage ;  and,  at  its  centre,  of  a  soft,  elastic,  pulpy 
matter.  The  laminae  are  arranged  concentrically  one  within  the  other,  with 
their  edges  turned  towards  the  corresponding  surfaces  of  the  vertebrae,  and 
consist  of  alternate  plates  of  fibrous  tissue  and  fibro-cartilage.  These  plates 
are  not  quite  vertical  in  their  direction,  those  near  the  circumference  being 
curved  outwards  and  closely  approximated;  whilst  those  nearest  the  centre  curve 
in  the  opposite  direction,  and  are  somewhat  more  widely  separated.  The  fibres 
of  which  each  plate  is  composed,  are  directed,  for  the  most  part,  obliquely  from 
above  downwards;  the  fibres  of  an  adjacent  plate  have  an  exactly  opposite 
arrangement,  varying  in  their  direction  in  every  layer;  whilst  in  some  few  they 
are  horizontal.  This  laminar  arrangement  belongs  to  about  the  outer  half  of 
each  disk,  the  central  part  being  occupied  by  a  soft,  pulpy,  highly  elastic  sub- 
stance, of  a  yellowish  color,  which  rises  up  considerably  above  the  surrounding 
level,  when  the  disk  is  divided  horizontally.  This  substance  presents  no  con- 
centric arrangement,  and  consists  of  white  fibrous  tissue,  with  cells  of  variable 
shape  and  size  interspersed.  The  pulpy  matter,  which  is  especially  well  de- 
veloped in  the  lumbar  region,  is  separated  from  immediate  contact  with  the 
vertebrae  by  the  interposition  of  thin  plates  of  cartilage. 


268  ARTICULATIONS. 

2.  Ligaments  connecting  the  Lamina. 

Ligamenta  Subflava. 

The  Ligamenta  Subflava  (Fig.  183)  are  interposed  between  the  laminse  of  the 
vertebrae,  from  the  axis  to  the  sacrum.  They  are  most  distinct  when  seen  from 
the  interior  of  the  spinal  canal;  when  viewed  from  the  outer  surface,  they 
appear  short,  being  overlapped  by  the  laminas.  Each  ligament  consists  of  two 
lateral  portions,  which  commence  on  each  side  at  the  root  of  either  articular 
process,  and  pass  backwards  to  the  point  where  the  laminae  converge  to  form 
the  spinous  process,  where  their  margins  are  thickest,  and  separated  by  a  slic^ht 
interval,  filled  up  with  areolar  tissue.  These  ligaments  consist  of  yellow  elastic 
tissue,  the  fibres  of  which,  almost  perpendicular  in  direction,  are  attached  to 
the  anterior  surface  of  the  margin  of  the  lamina  above,  and  to  the  posterior 
surface,  as  well  as  to  the  margin  of  the  lamina  below.  In  the  cervical  region, 
they  are  thin  in  texture,  but  very  broad  and  long ;  they  become  thicker  in  the 
dorsal  region:  and  in  the  lumbar  acquire  very  considerable  thickness.  Their 
highly  elastic  property  serves  to  preserve  the  upright  posture,  and  to  assist  in 
resuming  it,  after  the  spine  has  been  flexed.  These  ligaments  do  not  exist 
between  the  occiput  and  atlas,  or  between  the  atlas  and  axis. 

8.  Ligaments  connecting  the  Articulab  Processes. 

Capsular. 

The  Capsular  Ligaments  (Fig.  185)  are  thin  and  loose  ligamentous  sacs, 
attached  to  the  contiguous  margins  of  the  articulating  processes  of  each  verte- 
bra, through  the  greater  part  of  their  circumference,  and  completed  internally 
by  the  ligamenta  subflava.  They  are  longer  and  more  loose  in  the  cervical 
than  in  the  dorsal  or  lumbar  regions.  The  capsular  ligaments  are  lined  on 
their  inner  surface  by  synovial  membrane. 

4.  Ligaments  connecting  the  Spinous  Processes. 
Inter-spinoug.  Supra-spinous. 

The  Int&r-spinous  Ligaments  (Fig.  183),  thin  and  membranous,  are  interposed 
between  the  spinous  processes  in  the  dorsal  and  lumbar  regions.   Each  ligamenl^] 
extends  from  the  root  to  near  the  summit  of  each  spinous  process,  and  connectaj 
together  their  adjacent  margins.     They  are  narrow  and  elongated  in  the  dorsa 
region,  broader,  quadrilateral  in  form,  and  thicker  in  the  lumbar  region. 

The  Snpra-spinoiis  Ligament  is  a  strong  fibrous  cord,  which  connects  togethei 
the  apices  of  the  spinous  processes  from  the  seventh  cervical  to  the  spine  of  th< 
sacrum.  It  is  thicker  and  broader  in  the  lumbar  than  in  the  dorsal  region,  anc 
intimately  blended,  in  both  situations,  with  the  neighboring  aponeuroses.  Th( 
most  superficial  fibres  of  this  ligament  connect  three  or  four  vertebrae ;  thos< 
deeper  seated  pass  between  two  or  three  v^rtebroB ;  whilst  the  deepest  conneo 
the  contiguous  extremities  of  neighboring  vertebrae. 

5.  Ligaments  connecting  the  Transverse  Processes. 

(JP        Inter-transverse. 

The  Inter-transverse  Ligaments  consist  of  a  few  thin  scattered  fibres,  interposed 
between  the  transverse  processes.  They  afe  generally  wanting  in  the  cervical 
region;  in  the  dorsal,  they  are  rounded  cords;  in  the  lumbar  region  they  are 
thin  and  membranous. 

Actions.  The  movements  permitted  in  the  spinal  column  are,  Flexion,  Ex 
tension,  Lateral  Movement,  Circumduction,  and  Rotation. 

In  Flexion,  or  movement  of  the  spine  forwards,  the  anterior  common  liga- 
ment is  relaxed,  and  the  intervertebral  substances  are  compressed  in  front ; 


OF    THE    ATLAS    WITH    THE    AXIS.  269 

while  tlie  posterior  common  ligament,  the  ligamenta  subflava,  and  the  inter- 
aud  supra-spinous  ligaments,  are  stretched,  as  well  as  the  posterior  fibres  of  the 
intervertebral  disk^.  The  interspaces  between  the  laminae  are  widened,  and 
the  inferior  articuiar  processes  of  the  vertebras  above  glide  upwards,  upon  the 
articular  processes  of  the  vertebrae  below.  Flexion  is  the  most  extensive  of  all 
the  movements  of  the  spine. 

In  Extension,  or  movement  of  the  spine  backwards,  an  exactly  opposite  dis- 
position of  the  parts  takes  place.  This  movement  is  not  extensive,  being 
limited  by  the  anterior  common  ligament,  and  by  the  approximation  of  the 
spinous  processes. 

Flexion  and  extension  are  most  free  in  the  lower  part  of  the  lumbar,  and  in 
the  cervical  regions;  extension  in  the  latter  region  being  greater  than  flexion, 
the  reverse  of  which  is  the  case  in  the  lumbar  region.  These  movements  are 
least  free  in  the  middle  and  upper  part  of  the  back. 

In  Lateral  Movement,  the  sides  of  the  intervertebral  disks  are  compressed,  the 
extent  of  motion  being  limited  by  the  resistance  offered  by  the  surrounding  liga- 
ments, and  by  the  approximation  of  the  transverse  processes.  This  movement 
may  take  place  in  any  part  of  the  spine,  but  is  most  free  in  the  neck  and  loins. 

Circumduction  is  very  limited,  and  is  produced  merely  by  a  succession  of  the 
preceding  movements. 

Eotation  is  produced  by  the  twisting  of  the  interverteb'ral  substances ;  this, 
although  only  slight  between  any  two  vertebrae,  produces  a  great  extent  of 
movement,  when  it  takes  place  in  the  whole  length  of  the  spine,  the  front  of  the 
column  being  turned  to  one  or  the  other  side.  This  movement  takes  place 
only  to  a  slight  extent  in  the  neck,  but  is  more  free  in  the  lower  part  of  the 
dorsal  and  lumbar  regions. 

It  is  thus  seen,  that  the  cervical  region  enjoys  the  greatest  extent  of  each 
I  variety  of  movement,  flexion  and  extension  especially  being  very  free.  In  the 
;  dorsal  region^  especially  at  its  upper  part,  the  movements  are  most  limited ; 
I  flexion,  extension,  and  lateral  motion  taking  place  only  to  a  slight  extent. 

II.  AETICULATION  OF  THE  ATLAS  WITH  THE  AXIS. 

The  articulation  of  the  anterior  arch  of  the  atlas  with  the  odontoid  process 
forms  a  lateral  ginglymoid  joint,  whilst  that  between  the  articulating  processes 
of  the  two  bones  forms  a  double  arthrodia.  The  ligaments  which  connect  these 
bones  are,  the 

Two  Anterior  Atlo-axoid.  Transverse. 

Posterior  Atlo-axoid.  Two  Capsular. 

Of  the  two  Anterior  Atlo-axoid  Ligaments  (Fig.  184),  the  more  superficial  is 
a  rounded  cord,  situated  in  the  middle  line;  it  is  attached,  above,  to  the 
tubercle  on  the  anterior  arch  of  the  atlas ;  below,  to  the  base  of  the  odontoid 
process  and  body  of  the  axis.  The  deeper  ligament  is  a  membranous  layer, 
attached,  above,  to  the  lower  border^of  the  anterior  arch  of  the  atlas ;  below, 
to  the  base  of  the  odontoid  process,  and  body  of  the  axis.     These  ligaments 

;  are  in  relation,  in  front,  with  the  Eecti  Antici  Majores. 

The  Posterior  Atlo-axoid  Ligament  (Fig.  185)  is  a  broad  and  thin  membranous 

1  layer,  attached,  above,  to  the  lower  border  of  the  posterior  arch  of  the  atlas ; 

!  below,  to  the  upper  edge  of  the  laminae  of  the  axis.     This  ligament  supplies 

,  the  place  of  the  ligamenta  subflava,  and  is,  in  relation,  behind,  with  the  Inferior 

I  Oblique  muscles. 

j      The  Transverse  Ligament^  (Figs.  186,  187)  is  a  thick  and  strong  ligamentous 

I  band,  which  arches  across  the  ring  of  the  atlas,  and  serves  to  retain  the  odon- 

'  It  has  been  found  necessary  to  describe  the  transverse  ligament  with  those  of  the  atlas  and 
I  axis ;  but  the  student  must  remember  that  it  is  really  a  portion  of  the  mechanism  by  which  the 
I  movements  of  the  head  on  the  spine  are  regulated ;  so  that  the  connections  between  the  atlas 
'  and  axis  ought  always  to  be  studied  together  with  those  between  the  latter  bones  and  the  skull. 


270 


ARTICULATIONS. 


toid  process  in  firm  connection  with  its  anterior  arch.     This  ligament  is  flat 
tened  from  before  backwards,  broader  and  thicker  in  the  middle  than  at  eithei^ 

Fig,  184 — Occipito-atloid  and  Atlo-axoid  Ligaments.    Anterior  View. 


r       CAPSULAR     LICT     h 
I         CVNOVIAL.    M  CMBRANC 


CAPILLAR     Lie''    le 
•  YNOVIAk  MBMRRANB 


Fig.  185. — Occipito-atloid  and  Atlo-axoid  Ligaments.    Posterior  View. 


Arck  farjoitttaar  efVerttiralAu 


extremity,  and  firmly  attached  on  each  side  of  the  atlas  to  a  small  tubercle  on 
the  inner  surface  of  its  lateral  mass.     As  it  crosses  the  odontoid  process,  a 


OF    THE    ATLAS    WITH    THE    OCCIPITAL    BONE.        271 

small  fasciculus  is  derived  from  its  upper  and  lower  borders ;  the  former  passing 
upwards,  to  be  inserted  into  the  basilar  process  of  the  occipital  bone ;  the  latter, 
downwards,  to  be  attached  to  the  root  of  the  odontoid  process;  hence,  the  whole 
ligament  has  received  the  name  of  cruciform.    The  transverse  ligament  divides 

Fig.  186. — Articulation  between  Odontoid  Process  and  Atlas. 


the  ring  of  the  atlas  into  two  unequal  parts :  of  these,  the  posterior  and  larger 
serves  for  the  transmission  of  the  cord  and  its  membranes ;  the  anterior  and 
smaller  contains  the  odontoid  process.  Since  the  lower  border  of  the  space 
between  the  anterior  arch  of  the  atlas  and  the  transverse  ligament  is  smaller 
than  the  upper  (because  the  transverse  ligament  embraces  firmly  the  narrow 
neck  of  the  odontoid  process),  this  process  is  retained  in  firm  connection  with 
the  atlas,  when  all  the  other  ligaments  have  been  divided. 

The  Capsular  Ligaments  are  two  thin  and  loose  capsules,  connecting  the 
articular  surfaces  of  the  atlas  and  axis,  the  fibres  being  strongest  on  the  an- 
terior and  external  part  of  the  articulation. 

There  are/owr  Synovial  Membranes  in  this  articulation.  One  lining  the  inner 
surface  of  each  of  the  capsular  ligaments ;  one  between  the  anterior  surface  of 
the  odontoid  process  and  the  anterior  arch  of  the  atlas ;  and  one  between  the 
posterior  surface  of  the  odontoid  process  and  the  transverse  ligament.  The 
latter  often  communicates  with  those  between  the  condyles  of  the  occipital 
bone  and  the  articular  surfaces  of  the  atlas. 

Actions.  This  joint  is  capable  of  great  mobility,  and  allows  the  rotation  of 
the  atlas,  and,  with  it,  of  the  cranium  upon  the  axis,  the  extent  of  rotation 
being  limited  by  the  odontoid  ligaments. 

The  ligaments  connecting  the  spine  with  the  cranium  may  be  divided  into 
two  sets,  those  connecting  the  occipital  bone  with  the  atlas,  and  those  connect- 
ing the  occipital  bone  with  the  axis. 

III.  ARTICULATION  OF  THE  ATLAS  WITH  THE  OCCIPITAL  BONE. 

This  articulation  is  a  double  arthrodia.     Its  ligaments  are  the 

Two  Anterior  Occipito-atloid. 
Posterior  Occipito-atloid. 
Two  Lateral  Occipito-atloid. 
Two  Capsular. 

Of  the  two  Anterior  Occipito-atloid  Ligaments  (Fig,  184),  the  superficial  is  a 
strong,  narrow,  rounded  cord,  attached,  above,  to  the  basilar  process  of  the 
occiput ;  below,  to  the  tubercle  on  the  anterior  arch  of  the  atlas ;  the  deeper 
ligament  is  a  broad  and  thin  membranous  layer,  which  passes  t)etween  the 
anterior  margin  of  the  foramen  magnum  above,  and  the  whole  length  of  the 
upper  border  of  the  anterior  arch  of  the  atlas  below.  This  ligament  is  in  rela- 
tion, in  front,  with  the  Eecti  Antici  Minores;  behind,  with  the  odontoid  ligaments. 


272 


ARTICULATIONS. 


The  Posterior  Occipito-atloid  Ligament  (Fig.  185)  is  a  very  broad  but  thin 
membranous  lamina,  intimately  blended  with  the  dura  mater.  It  is  connected, 
above,  to  the  posterior  margin  of  the  foramen  magnum ;  below,  to  the  upper 
border  of  the  posterior  arch  of  the  atlas.  This  ligament  is  incomplete  at  each 
side,  and  forms,  with  the  superior  intervertebral  notch,  an  opening  for  the 
passage  of  the  vertebral  artery  and  sub-occipital  nerve.  It  is  in  relation, 
behind,  with  the  Eecti  Postici  Minores  and  Obliqui  Superiores ;  in  front,  with 
the  dura  mater  of  the  spinal  canal,  to  which  it  is  intimately  adherent. 

The  Lateral  Occipito-atloid  Ligaments  are  strong  fibrous  bands,  directed  ob- 
liquely upwards  and  inwards,  attached  above  to  the  jugular  process  of  the 
occipital  bone;  below,  to  the  base  of  the  transverse  process  of  the  atlas. 

The  Capsular  Ligaments  surround  the  condyles  of  the  occipital  bone,  and 
connect  them  with  the  articular  surfaces  of  the  atlas ;  they  consist  of  thin  and 
loose  capsules,  which  inclose  the  synovial  membrane  of  the  articulation.  The 
synovial  membranes  between  the  occipital  bone  and  atlas  communicate  occa- 
sionally with  that  between  the  posterior  surface  of  the  odontoid  process  and 
transverse  ligament. 

Actions.  The  movements  permitted  in  this  joint  are  flexion  and  extension, 
which  give  rise  to  the  ordinary  forward  or  backward  nodding  of  the  head, 
besides  slight  lateral  motion  to  one  or  the  other  side.  When  either  of  these 
actions  is  carried  beyond  a  slight  extent,  the  whole  of  the  cervical  portion  of 
the  spine  assists  in  its  production.  According  to  Cruveilhier,  there  is  a  slight 
motion  of  rotation  in  this  joint. 

IV.  ARTICULATION  OF  THE  AXIS  WITH  THE  OCCIPITAL  BONE. 

Occipito-axoid.  Three  Odontoid. 

To  expose  these  ligaments,  the  spinal  canal  should  be  laid  open  by  removing 
the  posterior  ^rch  of  the  atlas,  the  laminaa  and  spinous  process  of  the  axis, 

Fig.  187. — Occipito-axoid  and  Atlo-axoid  Ligaments.     Posterior  View,  obtained  by  removing 
the  arches  of  the  Vertebrae  and  the  posterior  part  of  the  Skull. 


lAf  Vertical  fioi^iam 

O/OOONTOJO    LICll 


CA^suuR  Lie?  a. 
Synovial  memtraM 


APiuLAR   Licr    a 
'jajvial  laemiranr 


i 


and  the  portion  of  the  occipital  bone  behind  the  foramen  magnum,  as  seen  in 
Fig.  187. 


TEMPO  RO-M  AXILLARY 


273 


The  Occipito-axoid  Ligament  (apparatus  ligamentosus  colli)  is  situated  at 
the  upper  part  of  the  front  surface  of  the  spinal  canal.  It  is  a  broad  and 
strong  ligamentous  band,  which  covers  the  odontoid  process  and  its  ligaments, 
and  appears  to  be  a  prolongation  upwards  of  the  posterior  common  ligament 
of  the  spine.  It  is  attached,  below,  to  the  posterior  surface  of  the  body  of  the 
axis,  and  becoming  expanded  as  it  ascends,  is  inserted  into  the  basilar  groove 
of  the  occipital  bone,  in  front  of  the  foramen  magnum. 

Relations.  By  its  anterior  surface,  it  is  intimately  connected  with  the  trans- 
verse ligament,  by  its  posterior  surface  with  the  dura  mater.  By  cutting  this 
ligament  across,  and  turning  its  ends  aside,  the  transverse  and  odontoid  liga- 
ments are  exposed. 

The  Odontoid  or  Check  Ligaments  are  strong,  rounded,  fibrous  cords,  which 
arise  one  on  either  side  of  the  apex  of  the  odontoid  process,  and  passing  ob- 
liquely upwards  and  outwards,  are  inserted  into  the  rough  depressions  on  the 
inner  side  of  the  condyles  of  the  occipital  bone.  In  the  triangular  interval 
left  between  these  ligaments  and  the  margin  of  the  foramen  magnum,  a  third 
strong  ligamentous  band  (ligamentum  suspensorium)  maybe  seen,  which  passes 
almost  perpendicularly  from  the  apex  of  the  odontoid  process  to  the  anterior 
margin  of  the  foramen,  being  intimately  blended  with  the  anterior  occipito- 
atloid  ligament,  and  upper  fasciculus  of  the  transverse  ligament  of  the  atlas. 

Actions.  The  odontoid  ligaments  serve  to  limit  the  extent  to  which  rotation 
of  the  cranium  may  be  carried ;  hence  they  have  received  the  name  of  check 
ligaments. 

Y.  TEMPORO-MAXILLARY  ARTICULATION. 

This  is  an  arthrodial  joint ;  the  parts  entering  into  its  formation  are,  on  each 
side,  the  anterior  part  of  the  glenoid  cavity  of  the  temporal  bone  and  the. 

Fig.  188. — Temporo-maxillary  Articulation.     Exterual  View. 


j  eminentia  articularis  above;  with  the  condyle  of  the  lower  jaw  below. 
I  ligaments  are  the  following : — 

External  Lateral.  Stylo-maxillary. 

Internal  Lateral.  Capsular. 

Interarticular  Fibro-cartilage. 
18 


The 


} 


274 


ARTICULATIONS. 


The  External  Lateral  Ligament  (Fig.  188)  is  a  short,  thin,  and  narrow  fasci- 
culus attached  above  to  the  outer  surface  of  the  zygoma  and  to  the  rough 
tubercle  on  its  lower  border ;  below,  to  the  outer  surface  and  posterior  border 
of  the  neck  of  the  lower  jaw.  This  ligament  is  broader  ^bove  than  below ; 
its  fibres  are  placed  parallel  with  one  another,  and  directed  obliquely  down- 
wards and  backwards.  Externally,  it  is  covered  by  the  parotid  gland,  and  bv 
the  integument.  Internally,  it  is  in  relation  with  the  interarticular  fibro- 
cartilage  and  the  synovial  membranes. 

The  Internal  Lateral  Ligament  (Fig.  189)  is  a  long,  thin,  and  loose  band, 
which  is  attached  above  to  the  spinous  process  of  the  sphenoid  bone,  and  be- 
coming broader  as  it  descends,  is 


Fig.  189.- 


-Temporo-maxillary  Articulation. 

Internal  View. 


s«\^^Ii:^^, 


inserted  into  the  inner  margin  of 
the  dental  foramen.  Its  outer  sur- 
face is  in  relation  above  with  the 
External  Pterygoid  muscle ;  lower 
down  it  is  separated  from  the  neck 
of  the  condyle  by  the  internal 
maxillary  artery;  and  still  more 
inferiorly  the  inferior  dental  ves- 
sels and  nerve  separate  it  from  the 
ramus  of  the  jaw.  Internally  it  i~ 
in  relation  with  the  Internal  Ptery 
goid.^ 

The  Stylo-maxillary  Ligament  is 
a  thin  aponeurotic  cord,  which  ex- 
tends from  near  the  apex  of  the 
styloid  process  of  the  temporal 
bone,  to  the  angle  and  posterior 
border  of  the  ramus  of  the  lower 
jaw,  between  the  Masseter  and  In- 
ternal Pterygoid  muscles.  This 
ligament  separates  the  parotid  from 
the  submaxillary  gland,  and  has 
attached  to  its  inner  side  part  df 
the  fibres  of  origin  of  the  Stylo- 
glossus muscle.  Although  usually  classed  among  the  ligaments  of  the  jaw,  it 
can  only  be  considered  as  an  accessory  in  the  articulation. 

Along  with  the  stylo-maxillary  ligament,  although  in  no  way  connected  witli 
the  functions  of  the  lower  jaw,  may  be  described  the  slylo-hyoid  ligament.  This 
is  a  fibrous  cord,  which  continues  the  styloid  process  down  to  the  hyoid  bone, 
being  attached  to  the  tip  of  the  former  and  the  small  cornu  of  the  latter.  It  is 
often  more  or  less  ossified. 

The  Capsular  Ligament  consists  of  a  thin  and  loose  ligamentous  capsule, 
attached  above  to  the  circumference  of  the  glenoid  cavity  and  the  articular 
surface  immediately  in  front:  below,  to  the  neck  of  the  condyle  of  the  lower 
jaw.  It  consists  of  a  few  thin  scattered  fibres,  and  can  hardly  be  considered  as 
a  distinct  ligament ;  it  is  thickest  at  the  back  part  of  the  articulation. 

The  Interarticular  Fihro-cartilage  (Fig.  190)  is  a  thin  plate  of  an  oval  form, 
placed  horizontally  between  the  condyle  of  the  jaw  and  the  glenoid  cavity. 
Its  upper  surface  is  concave  from  before  backwards,  and  a  little  convex 
transversely,  to  accommodate  itself  to  the  form  of  the  glenoid  cavity.  Its 
under  surface,  where  it  is  in  contact  with  the  condyle,  is  concave.  ^  Its  circum- 
ference is  connected  externally  to  the  external  lateral  ligament;  internally,  to 
the  capsular  ligament;  and  in  front  to  the  tendon  of  the  External  Pterygoid 

'  Dr.  Humphry  describes  the  internal  portion  of  the  capsular  lipament  separately,  as  the 
short  internal  lateral  litramont;  and  it  certainly  seems  as  deserving  of  a  separate  descriptiou  as 
the  external  lateral  llgameut  is. 


OF    THE    RIBS    WITH    THE    VERTEBRA. 


275 


muscle.  It  is  thicker  at  its  circumference,  especially  behind,  than  at  its  centre, 
where  it  is  sometimes  perforated.  The  fibres  of  which  it  is  composed  have  a 
concentric  arrangement,  more  apparent  at  the  circumference  than  at  the  centre. 
Its  surfaces  are  smooth,  and  divide 

the  joint  into  two  cavities,  each  of  Fig.  190.— Vertical  Section  of  Temporo-maxillary 
which  is  furnished  with  a  separate  Articulation, 

synovial  membrane.  When  the 
fibro-cartilage  is  perforated,  the  sy- 
novial membranes  are  continuous 
with  one  another. 

The  Synovial  Membranes^  two  in 
number,  are  placed  one  above,  and 
the  other  below  the  fibro-cartilage. 
The  upper  one,  the  larger  and  looser 
of  the  two,  is  continued  from  the 
margin  of  the  cartilage  covering  the 
glenoid  cavity  and  eminentia  articu- 
laris,  over  the  upper  surface  of  the 
fibro-cartilage.  The  lower  one  is 
interposed  between  the  under  sur- 
face of  the  fibro-cartilage  and  the  condyle  of  the  jaw,  being  prolonged  down- 
wards a  little  further  behind  than  in  front. 

The  nerves  of  this  joint  are  derived  from  the  auriculo-temporal  and  masse- 
teric branches  of  the  inferior  maxillary. 

Actions.  The  movements  permitted  in  this  articulation  are  very  extensive. 
Thus,  the  jaw  may  be  depressed  or  elevated,  or  it  may  be  carried  forwards  or 
backwards,  or  from  side  to  side.  It  is  by  the  alternation  of  these  movements 
performed  in  succession,  that  a  kind  of  rotary  movement  of  the  lower  jaw  upon 
the  upper  takes  place,  which  materially  assists  in  the  mastication  of  the  food. 

If  the  movement  of  depression  is  carried  only  to  a  slight  extent,  the  condyles 
remain  in  the  glenoid  cavities,  their  anterior  part  descending  only  slightly  ;  but 
if  depression  is  considerable,  the  condyles  glide  from  the  glenoid  foss£e  on  to 
the  articular  eminences,  carrying  with  them  the  interarticular  fibro-cartilages. 
When  this  movement  is  carried  to  too  great  an  extent,  as,  for  instance,  during  a 
convulsive  yawn,  dislocation  of  the  condyle  into  the  zygomatic  fossa  may  occur; 
the  interarticular  cartilage  being  carried  forwards,  and  the  capsular  ligament 
raptured.  When  the  jaw  is  elevated,  after  forced  depression,  the  condyles  and 
fibro-cartilages  are  carried  backwards  into  their  original  position.  When  the 
jaw  is  carried  horizontally  forwards  and  backwards,  or  from  side  to  side,  a 
horizontal  gliding  movement  of  the  fibro-cartilages  and  condyles  upon  the 
glenoid  cavities  takes  place  in  the  corresponding  direction. 


YI.  ARTICULATION  OF  THE  RIBS  WITH  THE  YERTEBR^. 

The  articulation  of  the  ribs  with  the  vertebral  column  may  be  divided  into 
two  sets:  1.  Those  which  connect  the  heads  of  the  ribs  with  the  bodies  of  the 
vertebrse;  2.  Those  which  connect  the  neck  and  tubercle  of  the  ribs  with  the 
transverse  processes, 

1.  Articulation  between  the  Heads  of  the  Ribs  and  the  Bodies  of  the 

Vertebra.    (Fig.  191.) 

These  constitute  a  series  of  ginglymoid  joints,  formed  by  the  articulation  of 
the  h.eads  of  the  ribs  with  the  cavities  on  the  contiguous  margins  of  the  bodies 
of  the  dorsal  vertebra?,  connected  together  by  the  following  ligaments : — 

Anterior  Costo- vertebral  or  Stellate. 

Capsular. 

Interarticular. 


276 


ARTICULATIONS. 


The  Anterior  Costo-vertebral  or  Stellate  Ligament  connects  the  anterior  part  ot 
the  head  of  each  rib  with  the  sides  of  the  bodies  of  two  vertebrae,  and  the  in. 
tervertebral  disk  between  them.     It  consists  of  three  flat  bundles  of  ligamen- 

.    .    ,    .  tons  fibres,  which  radiate 

Fig.  191.— Costo-vertebral  and  Costo-trans verse  Articulations,      from  the    anterior   r)art 

ot  the  head  of  the  nb. 
The  superior  fasciculus 
passes  upwards  to  be 
connected  with  the  body 
of  the  vertebra  above  : 
the  inferior  one  descends 
to  the  body  of  the  ver- 
tebra below ;  and  the 
middle  one,  the  smallest 
and  least  distinct,  passes 
horizontally  inwards  to 
be  attached  to  the  inter- 
vertebral substance. 

Relations.  In  front, 
with  the  thoracic  gan- 
glia of  the  sympathetic, 
the  pleura,  and,  on  the 
right  side,  with  the  vena 
azygos  major;  behind, 
with  the  interarticular 
ligament  and  synovial 
membranes. 

In  the  first  rib,  which 
articulates  with  a  single  vertebra  only,  this  ligament  does  not  present  a  distinct 
division  into  three  fasciculi ;  its  superior  fibres,  however,  pass  to  be  attached 
to  the  body  of  the  last  cervical  vertebra,  as  well  as  to  the  body  of  the  vertebra 
with  which  the  rib  articulates.  In  the  eleventh  and  twelfth  ribs  also,  which 
likewise  articulate  with  a  single  vertebra,  the  division  does  not  exist ;  but  the 
upper  fibres  of  the  ligament,  in  each  case,  are  connected  with  the  vertebra 
above,  as  well  as  that  with  which  the  ribs  articulate. 

The  Capsular  Ligament  is  a  thin  and  loose  ligamentous  bag,  which  surrount  I 
the  joint  between  the  head  of  the  rib  and  the  articular  cavity  formed  by  tl  | 
junction  of  the  vertebrge.     It  is  very  thin,  firmly  connected  with  the  anteri< 
ligament,  and  most  distinct  at  the  upper  and  lower  parts  of  the  articulation. 

The  Interarticular  Ligament  is  situated  in  the  interior  of  the  joint.  It  col 
sists  of  a  short  band  of  fibres,  flattened  from  above  downwards,  attached  by  oi  I 
extremity  to  the  sharp  crest  on  the  head  of  the  rib,  and  by  the  other  to  tl  I 
intervertebral  disk.  It  divides  the  joint  into  two  cavities,  which  have  no  coi 
mnnication  with  one  another,  but  are  each  lined  by  a  separate  synovial  mei 
brane.  In  the  first,  eleventh,  and  twelfth  ribs,  the  interarticular  ligament  dodj 
not  exist ;  consequently,  there  is  but  one  synovial  membrane. 

Actions.  The  movements  permitted  in  these  articulations  are  limited  tcT 
elevation,  depression,  and  a  slight  amount  of  movement  forwards  and  back- 
wards. The  mobility,  however,  of  the  different  ribs  varies  very  much.  The 
first  rib  is  almost  immovable,  excepting  in  deep  inspiration.  The  movement 
of  the  second  rib  is  also  not  very  extensive.  In  the  other  ribs,  their  mobility 
increases  successively  to  the  last  two,  which  are  very  movable.  The  ribs  ai 
generally  more  movable  in  the  female  than  in  the  male. 


Synovial  eavitu 


OF    THE    RIBS    WITH    TRANSVERSE    PROCESSES.       27T 

2.  Articulation  of  the  Neck  axd  Tubercle  of  the  Ribs  with  the 
Transverse  Processes.    (Fig.  192.) 

The  ligaments  connecting  these  parts  are — 

Anterior  Costo-transverse. 

Middle  Costo-transverse  (Interosseous). 

Posterior  Costo-transverse. 

Capsular. 

The  Anterior  Costo-transverse  Ligament  is  a  broad  and  strong  band  of  fibres, 
attached  below  to  the  sharp  crest  on  the  upper  border  of  the  neck  of  each  rib, 
and  passing  obliquely  upwards  and  outwards,  to  the  lower  border  of  the  trans- 
verse process  immediately  above.     It  is  broader  below  than  above,  broader  and 

Fig,  192, — Costo-transverse  Articulation.    Seen  from  above. 


ANTERIOR  COSTO-TRANSVERSE  LI  0 


MIDDLE  COSTO-TRANSVERSE  or. 
INTEROSSEOUS 


SYNOVIAL    CAVITY 


POSTERIOR  COSTO-TRANSVERSE  LIQT 


CAPSULAR    MEMBRANK 


thinner  between  the  lower  ribs  than  between  the  upper,  and  more  distinct  in 
front  than  behind.  This  ligament  is  in  relation,  in  front,  with  the  intercostal 
vessels  and  nerves;  behind,  with  the  Longissimus  Dorsi.  Its  internal  border 
completes  an  aperture  formed  between  it  and  the  articular  processes,  through 
which  pass  the  posterior  branches  of  the  intercostal  vessels  and  nerves.  Its 
external  border  is  continuous  with  a  thin  aponeurosis,  which  covers  the  External 
Intercostal  muscle. 

^\\Q  first  and  last  ribs  have  no  anterior  costo-transverse  ligament. 

The  Middle  Costo-transverse  or  Interosseous  Ligament  consists  of  short,  but 
strong,  fibres,  which  pass  between  the  rough  surface  on  the  posterior  part  of 
the  neck  of  each  rib,  and  the  anterior  surface  of  the  adjacent  transverse  process. 
In  order  fully  to  expose  this  ligament,  a  horizontal  section  should  be  made 
across  the  transverse  process  and  corresponding  part  of  the  rib;  or  the  rib  may 
be  forcibly  separated  from  the  transverse  process,  and  its  fibres  put  on  the 
stretch. 

In  the  eleventh  and  tivelfth  ribs,  this  ligament  is  quite  rudimentary. 

The  Posterior  Costo-transverse  Ligament  is  a  short,  but  thick  and  strong, 
fasciculus,  which  passes  obliquely  from  the  summit  of  the  transverse  process 
to  the  rough  non-articular  portion  of  the  tubercle  of  the  rib.  This  ligament 
is  shorter  and  more  oblique  in  the  upper  than  in  the  lower  ribs.     Those  cor- 


278  ARTICULATIONS. 

responding  to  the  superior  ribs  ascend,  and  those  of  the  inferior  one  slightlj 
descend. 

In  the  eleventh  and  twelfth  ribs,  this  ligament  is  wanting. 

The  articular  portion  of  the  tubercle  of  the  rib,  and  adjacent  transverse 
process,  form  an  arthrodial  joint,  provided  with  a  thin  Capsular  Ligament. 
attached  to  the  circumference  of  the  articulating  surfaces,  and  inclosing  a  small 
synovial  membrane. 

In  the  eleventh  and  twelfth  ribs,  this  articulation  is  wanting. 

Actions.  The  movement  permitted  in  these  joints  is  limited  to  a  slight  glid- 
ing motion  of  the  articular  surfaces  one  upon  the  other. 

VII.  ARTICULATION  OF  THE  CARTILAGES  OF  THE  RIBS  WITH  THE 
STERNUM,  ETC.     (Fig.  193.) 

The  articulation  of  the  cartilages  of  the  true  ribs  with  the  sternum  are 
arthrodial  joints.     The  ligaments  connecting  them  are : — 

Anterior  Costo-sternal. 
Posterior  Costo-sternal. 
Capsular. 

The  Anterior  Costo-sternal  Ligament  is  a  broad  and  thin  membranous  ban( 
that  radiates  from  the  inner  extremity  of  the  cartilages  of  the  true  ribs  to  th|| 
anterior  surface  of  the  sternum.  It  is  composed  of  fasciculi,  which  pass  ii 
different  directions.  The  superior  fasciculi  ascend  obliquely,  the  inferior  pass 
obliquely  downwards,  and  the  middle  fasciculi  horizontally.  The  superficial 
fibres  of  this  ligament  are  the  longest ;  they  intermingle  with  the  fibres  of  the 
ligaments  above  and  below  them,  with  those  of  the  opposite  side,  and  with 
the  tendinous  fibres  of  origin  of  the  Pectoralis  Major ;  forming  a  thick  fibrous 
membrane,  which  covers  the  surface  of  the  sternum.  This  is  more  distinct  at 
the  lower  than  at  the  upper  part. 

The  Posterior  Costo-sternal  Ligament,  less  thick  and  distinct  than  the  anterior, 
is  composed  of  fibres  which  radiate  from  the  posterior  surface  of  the  sternal 
end  of  the  cartilages  of  the  true  ribs,  to  the  posterior  surface  of  the  sternum, 
becoming  blended  with  the  periosteum. 

The  Capsular  Ligament  surrounds  the  joints  formed  between  the  cartilages 
of  the  true  ribs  and  the  sternum.  It  is  very  thin,  intimately  blended  with  ths 
anterior  and  posterior  ligaments,  and  strengthened  at  the  upper  and  lower  part 
of  the  articulation  by  a  few  fibres,  which  pass  from  the  cartilage  to  the  side  of 
the  sternum.     These  ligaments  protect  the  synovial  membranes. 

Synovial  Membranes.  The  cartilage  of  the  first  rib  is  directly  continuous 
with  the  sternum,  without  any  synovial  membrane.  The  cartilage  of  the  second 
rib  is  connected  with  the  sternum  by  means  of  an  interarticular  ligament, 
attached  by  one  extremity  to  the  cartilage  of  the  second  rib,  and  by  the  other 
extremity  to  the  cartilage  which  unites  the  first  and  second  pieces  of  the  ster- 
num. This  articulation  is  provided  with  two  synovial  membranes.  That  of 
the  third  rib  has  also  two  synovial  membranes ;  and  that  of  the  fourth,  fifth, 
sixth,  and  seventh,  each  a  single  synovial  membrane.  Thus  there  are  eigJd 
synovial  cavities  in  the  articulations  between  the  costal  cartilages  of  the  true 
ribs  and  the  sternum.  They  may  be  demonstrated  by  removing  a  thin  sectio  i 
from  the  anterior  surface  of  the  sternum  and  cartilages,  as  seen  in  the  figure. 
After  middle  life,  the  articular  surfaces  lose  their  polish,  become  roughened, 
and  the  synovial  membranes  appear  to  be  wanting.  In  old  age,  the  articula- 
tions do  not  exist,  the  cartilages  of  most  of  the  ribs  becoming  continuous  with 
the  sternum.  The  cartilage  of  the  seventh  rib,  and  occasionally  also  that  of 
the  sixth,  is  connected  to  the  anterior  surface  of  the  ensiform  appendix,  by  a 
band  of  ligamentous  fibres,  which  varies  in  length  and  breadth  in  different 
subjects.     It  is  called  the  costo-xiphoid  ligament. 


OF    THE    RIBS    WITH    THE    STERNUM. 


279 


Fig.  193. — Costo-sternal,  Costo-xiphoid,  and  Intercostal  Articulations.    Anterior  View. 

The  tynovidl  cetidties    exposed 
by  a  vertical  aeetion  aftA^  Steriw,m  k  CartiUgel 


oontiruooiLS  vfith  StcrTlMVU 


INTEII-ARTICUI.AII    lief 
8c 


Senate  S'lftioiitl 
Memhra-iie 


Actions.  The  movements  wlilch  are  permitted  in  tlie  costo-sternal  articula- 
tions, are  limited  to  elevation  and  depression ;  and  these  only  to  a  slight  extent. 

Articulation  of  the  Cartilages  op  the  Ribs  with  each  other.  (Fig.  193.) 

The  cartilages  of  the  sixth,  seventh,  and  eighth  ribs  articulate,  by  their  lower 
borders  with  the  corresponding  margin  of  the  adjoining  cartilages,  by  means  of 
a  small,  smooth,  oblong-shaped  facet.  Each  articulation  is  inclosed  in  a  thin 
capsular  ligament,  lined  by  synovial  memhrane,  and  strengthened  externally  and 
internally  by  ligamentous  fibres  (intercostal  ligaments),  which  pass  from  one 
cartilage  to  the  other.  Sometimes  the  cartilage  of  the  fifth  rib,  more  rarely 
that  of  the  ninth,  articulates,  by  its  lower  border,  with  the  adjoining  cartilage 
by  a  small  oval  facet;  more  frequently  they  are  connected  together  by  a  few 
ligamentous  fibres.  Occasionally,  the  articular  surfaces  above  mentioned  are 
wanting. 


280 


ARTICULATIONS. 


Articulation  op  the  Ribs  with  their  Cartilages.  (Fig.  193.) 

The  outer  extremity  of  each  costal  cartilage  is  received  into  a  depression  in 
the  sternal  end  of  the  ribs,  and  held  together  by  the  periosteum. 

Till.  LIGAMENTS  OF  THE  STERNUM. 

The  first  and  second  pieces  of  the  Sternum  are  united  by  a  layer  of  cartilage 
which  rarely  ossifies,  except  at  an  advanced  period  of  life.  These  two  segments 
are  connected  by  an  anterior  and  posterior  ligament. 

The  Anterior  Sternal  Ligament  consists  of  a  layer  of  fibres,  having  a  longi- 
tudinal direction;  it  blends  with  the  fibres  of  the  anterior  costo-sternal  ligaments 
on  both  sides,  and  with  the  aponeurosis  of  origin  of  the  Pectoralis  Major.  This 
ligament  is  rough,  irregular,  and  much  thicker  at  the  lower  than  at  the  upper 
part  of  the  bone. 

The  Posterior  Sternal  Ligament  is  disposed  in  a  somewhat  similar  manner  on 
the  posterior  surface  of  the  articulation. 


IX.  ARTICULATION  OF  THE  PELVIS  WITH  THE  SPINE. 

The  ligaments  connecting  the  last  lumbar  vertebra  with  the  sacrum  are  similar 
to  those  which  connect  the  segments  of  the  spine  with  each  other,  viz:  1.  The 
continuation  downwards  of  the  anterior  and  posterior  common  ligaments.  2. 
The  intervertebral  substance  connecting  the  flattened  oval  surfaces  of  the  two 

Fig.  194. — Articulations  of  Pelvis  and  Hip.    Anterior  Yiew. 


^fttrfure  of  ramTnunieakon 
BuTMU  of  PSOAS    k.  ILIACUS 


bones,  and  forming  an  amphiarthrodial  joint.     3.  Lig^menta  subflava,  connect- 
ing the  arch  of  the  last  lumbar  vertebra  with  the  posterior  border  of  the  sacrall 
canal.    4.  Capsular  ligaments  connecting  the  articulating  processes  and  forming' 
a  double  artlirodia.     5.  Inter-spinous  and  supra-spinous  ligaments. 


OF    THE    PELVIS. 


281 


The  two  proper  ligaments  connecting  the  pelvis  with  the  spine  are  the  lumbo- 
sacral and  lumbo-iliac. 

The  Lumbosacral  Ligament  (Fig.  194)  is  a  short,  thick,  triangular  fasciculus, 
which  is  connected  above  to  the  lower  and  front  part  of  the  transverse  process 
of  the  last  lumbar  vertebra,  passes  obliquely  outwards,  and  is  attached  below 
to  the  lateral  surface  of  the  base  of  the  sacrum,  becoming  blended  with  the 
anterior  sacro-iliac  ligament.  This  ligament  is  in  relation  in  front  with  the 
Psoas  muscle. 

The  Lumho-iliac  Ligament  {Fig.  194)  passes  horizontally  outwards  from  the 
apex  of  the  transverse  process  of  the  last  lumbar  vertebra,  to  the  crest  of  the 
ilium  immediately  in  front  of  the  sacro-iliac  articulation.  It  is  of  a  triangular 
form,  thick  and  narrow  internally,  broad  and  thinner  externally.  It  is  in  rela- 
tion, in  front,  with  the  Psoas  muscle;  behind,  with  the  muscles  occupying  the 
vertebral  groove;  above,  with  the  Quadratus  Lumborum. 


X.  ARTICULATIONS  OF  THE  PELYIS. 


The  ligaments  connecting  the  bones  of  the  pelvis  with  each   >ther  may  be 
divided  into  four  groups.    1.  Those  connecting  the  sacrum  and  ilium.    2.  Those 

Fig.  195. — Articulations  of  Pelvis  and  Hip.     Posterior  Yiew. 


passing  between  the  sacrum  and  ischium.    3.  Those  connecting  the  sacrum  and 
coccyx.     4.  Those  between  the  two  pubic  bones. 

1.  Articulation  of  the  Sacrum  and  Ilium. 

The  sacro-iliac  articulation  is  an  amphiarthrodial  joint,  formed  between  the 
lateral  surfaces  of  the  sacrum  and  ilium.  The  anterior  or  auricular  portion  of 
each  articular  surface  is  covered  with  a  thin  plate  of  cartilage,  thicker  on  the 
sacrum  than  on  the  ilium.  The  surfaces  of  these  cart!lages  in  the  adult  are 
rough  and  irregular,  and  separated  from  one  another  by  a  soft  yellow  pulpy 


282  ARTICULATIOXS. 

substance.  At  an  early  period  of  life,  occasionally  in  the  adult,  and  in  the 
lemale  during  pregnancy,  they  are  smooth,  and  lined  by  a  delicate  synovial 
membrane.  The  ligaments  connecting  these  surfaces  are  the  anterior  and  pos- 
terior sacro-iliac. 

The  Anterior  Sacro-iliac  Ligament  (Fig.  194)  consists  of  numerous  thin  liga- 
mentous bands,  which  connect  the  anterior  surfaces  of  the  sacrum  and  ilium. 

The  Posterior  Sacro-iliac  (Fig.  195)  is  a  strong  interosseous  ligament,  situated 
in  the  deep  depression  between  the  sacrum  and  ilium  behind,  and  forming  the 
chief  bond  of  connection  between  those  bones.  It  consists  of  numerous  strong 
fasciculi,  which  pass  between  the  bones  in  various  directions.  Three  of  these 
are  of  large  size ;  the  iwo^superior,  nearly  horizontal  in  direction,  arise  from 
the  first  Jind  second  transverse  tubercles  on  the  posterior  surface  of  the  sacrum, 
and  are  inserted  into  the  rough  uneven  surface  at  the  posterior  part  of  the  inner 
surface  of  the  ilium.  The  third  fasciculus,  oblique  in  direction,  is  attached  by 
one  extremity  to  the  third  or  fourth  transverse  tubercle  on  the  posterior  surface 
of  the  sacrum,  and  by  the  other  to  the  posterior  superior  spine  of  the  ilium ;  it 
is  sometimes  called  the  oblique  sacro-iliac  ligament. 

2.  Ligaments  passing  between  the  Sacrum  and  Ischium.    (Fig.  195.) 

The  Great  Sacro-sciatic  (Posterior). 
The  Lesser  Sacro-sciatic  (Anterior). 

The  Great  or  Posterior  Sacro-sciatic  Ligament  is  situated  at  the  lower  and 
back  part  of  the  pelvis.     It  is  thin,  flat,  and  triangular  in  form ;  narrower  in 
the  middle  than  at  the  extremities ;  attached  by  its  broad  base  to  the  posteriori 
inferior  spine  of  the  ilium,  to  the  third  and  fourth  transverse  tubercles  on  the 
sacrum,  and  to  the  lower  part  of  the  lateral  margin  of  that  bone  and  the  coccyx; 
passing  obliquely  downwards,  outwards,  and  forwards,  it  becomes  narrow  and' 
thick;  and  at  its  insertion  into  the  inner  margin  of  the  tuberosity  of  the  ischium, 
it  increases  in  breadth,  and  is  prolonged  forwards  along  the  inner  margin  of  the 
ramus,  forming  what  is  known  as  the  falciform  ligament.     The  free  concave 
edge  of  this  ligament  has  attached  to  it  the  obturator  fascia,  with  which  it 
forms  a   kind  of  groove,  protecting   the   internal   pudic   vessels  and  nerve. 
One  of  its  surfaces  is  turned  towards  the  perina3um,  the  other  towards  tho] 
Obturator  Internus  muscle. 

The  posterior  surface  of  this  ligament  gives  origin,  by  its  whole  extent,  tO' 
fibres  of  the  Gluteus  Maximus,    Its  anterior  surface  is  united  to  the  lesser  sacro- 
sciatic  ligament.     Its  superior  border  forms  the  lower  boundary  of  the  lesser! 
sacro-sciatic  foramen.     Its  lower  border  forms  part  of  the  boundary  of  the  peri* 
naeum.     It  is  pierced  by  the  coccygeal  branch  of  the  sciatic  artery. 

The  Lesser  or  Anterior  Sacro-sciatic  Ligament^  much  shorter  and  smaller  thai 
the  preceding,  is  thin,  triangular  in  form,  attached  by  its  apex  to  the  spine  of] 
the  ischium,  and  internally,  by  its  broad  base,  to  the  lateral  margin  of  the! 
sacrum  and  coccyx,  anterior  to  the  attachment  of  the  great  sacro-sciatic  liga- 
ment, with  which  its  fibres  are  intermingled. 

It  is  in  relation,  anteriorly,  with  the  Coccygeus  muscle ;  posteriorly,  it  is  cov- 
ered by  the  posterior  ligament,  and  crossed   by  the  pudic  vessels  and  nerve.! 
Its  superior  border  forms  the  lower  boundary  of  the  great  sacro-sciatic  foramen;] 
its  inferior  border,  part  of  the  lesser  sacro-sciatic  foramen. 

These  two  ligaments  convert  the  sacro-sciatic  notches  into  foramina.  Th»j 
superior  or  great  sacro-sciatic  foramen  is  bounded,  in  front  and  above,  by  thej 
posterior  border  of  the  os  innominatum ;  behind,  by  the  great  sacro-sciatic] 
ligament;  and  below,  by  the  lesser  ligament.  It  is  partially  filled  up,  in  the! 
recent  state,  by  the  I'yriformis  muscle.  Above  this  muscle,  the  gluteal  vessels 
and  superior  gluteal  nerve  emerge  from  the  pelvis;  and  below  it,  the  ischiatic 
vessels  and  nerves,  the. internal  pudic  vessels  and  nerve,  and  the  nerve  to  the! 
Obturator  internus.     The  inferior  or  lesser  sacro-sciatic  foramen  is  bounded,  m 


SYMPHYSIS    PUBIS.  283 

front,  by  the  tuber  ischii ;  above,  by  the  spine  and  lesser  ligament ;  behind, 
by  the  greater  ligament.  It  transmits  the  tendon  of  the  Obturator  Internus 
muscle,  its  nerve,  and  the  pudio  vessels  and  nerve. 

3.  Articulation  of  the  Sacrum  and  Coccyx. 

This  articulation  is  an  amphiarthrodial  joint,  formed  between  the  oval  sur- 
face, on  the  summit  of  the  sacrum,  and  the  base  of  the  coccyx.  It  is  analogous 
to  the  joints  between  the  bodies  of  the  vertebrae,  and  is  connected  by  similar 
ligaments.     They  are  the — 

Anterior  Sacro-coccygeal. 

Posterior  Sacro-coccygeal. 

Interarticular  Fibro-cartilage. 

The  Anterior  Sacro-coccygeal  Ligament  consists  of  a  few  irregular  fibres,  which 
descend  from  the  anterior  surface  of  the  sacrum  to  the  front  of  the  coccyx,  be- 
coming blended  with  the  periosteum. 

The  Posterior  Sacro-coccygeal  Ligament  is  a  flat  band  of  ligamentous  fibres, 
of  a  pearly  tint,  which  arises  from  the  margin  of  the  lower  orifice  of  the  sacral 
canal,  and  descends  to  be  inserted  into  the  posterior  surface  of  the  coccyx.  This 
ligament  completes  the  lower  and  back  part  of  the  sacral  canal.  Its  superficial 
fibres  are  much  longer  than  the  deep-seated ;  the  latter  extend  from  the  apex 
of  the  sacrum  to  the  upper  cornua  of  the  coccyx.  This  ligament  is  in  relation 
in  front  with  the  arachnoid  membrane  of  the  sacral  canal,  a  portion  of  the 
sacrum  and  almost  the  whole  of  the  posterior  surface  of  the  coccyx ;  behind, 
with  the  Gluteus  Maximus. 

An  Interarticular  Fihro- cartilage  is  interposed  between  the  contiguous  sur- 
faces of  the  sacrum  and  coccyx ;  it  differs  from  that  interposed  between  the 
bodies  of  the  vertebrae  in  being  thinner,  and  its  central  part  more  firm  in  tex- 
ture. It  is  somewhat  thicker  in  front  and  behind  than  at  the  sides.  Occasion- 
ally a  synovial  membrane  is  found  where  the  coccyx  is  freely  movable,  which 
is  more  especially  the  case  during  pregnancy. 

The  dift'erent  segments  of  the  coccyx  are  connected  together  by  an  extension 
downwards  of  the  anterior  and  posterior  sacro-coccygeal  ligaments,  a  thin  an- 
nular disk  of  fibro-cartilage  being  interposed  between  each  of  the  bones.  In 
the  adult  male,  all  the  pieces  become  ossified ;  but  in  the  female,  this  does  not 
commonly  occur  until  a  later  period  of  life.  The  separate  segments  of  the 
coccyx  are  first  united,  and  at  a  more  advanced  age  the  joint  between  the 
sacrum  and  the  coccyx  is  obliterated. 

Actions.  The  movements  which  take  place  between  the  sacrum  and  coccyx, 
and  between  the  different  pieces  of  the  latter  bone,  are  slightly  forwards  and 
backwards ;  they  are  very  limited.     Their  extent  increases  during  pregnancy. 

4.  Articulation  of  the  Pubes.    (Fig.  196.) 

The  articulation  between  the  pubic  bones  is  an  amphiarthrodial  joint,  formed 
by  the  junction  of  the  two  oval  articular  surfaces  of  the  ossa  pubis.  The  arti- 
cular surface  has  been  described  above  under  the  name  of  symjjhysis,  and  the 
same  name  is  given  to  the  joint.     The  ligaments  of  this  articulation  are  the 

Anterior  Pubic.  Posterior  Pubic. 

Superior  Pubic.  Sub-Pubic. 

Interarticular  Fibro-cartilage. 
The  Anterior  Puhic  Ligament  consists  of  several  superimposed  layers,  which 
pass  across  the  front  of  the  articulation.  The  superficial  fibres  pass  obliquely 
from  one  bone  to  the  other,  decussating  and  forming  an  interlacement  with  the 
fibres  of  the  aponeurosis  of  the  External  Oblique  muscle.  The  deep  fibres 
pass  transversely  across  the  symphysis,  and  are  blended  with  the  interarticular 
fibro-cartilage. 


284 


ARTICULATIONS. 


The  Posterior  Pubic  Ligament  consists  of  a  few  thin,  scattered  fibres,  which 
unite  the  two  pubic  bones  posteriorly. 

The  Superior  Pubic  Ligament  is  a  band  of  fibres,  which  connects  together 
the  two  pubic  bones  superiorly. 

The  Sub-pubic  Ligament  is  a  thick,  triangular  arch  of  ligamentous  fibres, 
connecting  together  the  two  pubic  bones  below,  and  forming  the  upper  boun- 
dary of  the  pubic  arch.  Above,  it  is  blended  with  the  interarticular  fibro- 
cartilage ;  laterally,  with  the  rami  of  the  pubes.  Its  fibres  are  of  a  yellowish 
color,  closely  connected,  and  have  an  arched  direction. 

Fig.  196.— Vertical  Section  of  the  Symphysis  Pubis. 
Made  near  its  Posterior  Surface. 

Xaw  Fihro-Cartildginoiie pl/ite* 
Inttrmtdiatt  clfnUe  fUtu^ 
Sy  run-in  I  cavit'j    at  uji^r  ic  hack  ^ri 


The  Interarticular  Fibro-cartilage  consists  of  two  oval-shaped  plates,  one 
covering  the  surface  of  each  symphysis  pubis.  They  vary  in  thickness  in 
different  subjects,  and  project  somewhat  beyond  the  level  of  the  bones,  espe- 
cially behind.  The  outer  surface  of  each  plate,  is  firmly  connected  to  the  bone 
by  a  series  of  nipple-like  processes,  which  accurately  fit  within  corresponding 
depressions  on  the  osseous  surface.  Their  opposed  surfaces  are  connected  in 
the  greater  part  of  their  extent,  by  an  intermediate  elastic  fibrous  tissue ;  and 
by  their  circumference  to  the  various  ligaments  surrounding  the  joint.  An 
interspace  is  left  between  the  plates  at  the  upper  and  back  part  of  the  articula- 
tion, where  the  fibrous  tissue  is  deficient,  and  the  surface  of  the  fibro-cartilage 
is  lined  by  epithelium.  This  space  is  found  at  all  periods  of  life,  both  in  the 
male  and  female ;  but  it  is  larger  in  the  latter,  especially  during  pregnancy, 
and  after  parturition.  It  is  most  frequently  limited  to  the  upper  and  back  part 
of  the  joint ;  but  it  occasionally  reaches  to  the  front,  and  may  extend  the  entire 
length  of  the  cartilages.  This  structure  may  be  easily  demonstrated,  by 
making  a  vertical  section  of  the  symphysis  pubis  near  its  posterior  surface. 

The  Obturator  Ligament  is  more  properly  regarded  as  analogous  to  the  mus- 
cular fasciae,  with  which  it  will  therefore  be  described. 

ARTICULATIONS   OF   THE   UPPER  EXTREMITY. 

The  Articulations  of  the  Upper  Extremity  may  be  arranged  in  the  following 
groups : — 


ne    ^\ 

1  m 


I.  Sterno-clavicular  articulation. 
II.  Scapulo-clavicular  articulation. 

III.  Proper  Ligaments  of  the  Scapula. 

IV.  Shoulder-joint. 
V.  Elbow-joint. 

VI.  Radio-ulnar  articulations. 


VIT.  Wrist-joint. 
VIII.  Articulations  of  the  Carpal  bones. 
IX.  Carpo-metacarpal  articulations. 
X.  Metacarpo- phalangeal     articula- 
tions. 
XI.  Articulations  of  the  Phalanges. 


STERNO-CLAVICULAR. 


285 


I.  STERNO-CLAVICULAR  ARTICULATION.    (Fig.  197.) 

The  Sterno-clavicular  is  an  arthrodial  joint.     The  parts  entering  into  it3 
formation  are  the  sternal  end  of  the  clavicle,  the  upper  and  lateral  part  of  the 

Fiff.  197. — Sterno-clavicular  Articulation.    Anterior  View. 


first  piece  of  the  sternum,  and  the  cartilage  of  the  first  rib.  The  articular 
surface  of  the  clavicle  is  much  longer  than  that  of  the  sternum,  and  invested 
with  a  layer  of  the  cartilage,^  which  is  considerably  thicker  than  that  on  the 
latter  bone.     The  ligaments  of  this  joint  are  the 

Anterior  Sterno-clavicular.  Interclavicular. 

Posterior  Sterno-clavicular.  Costo-clavicular  (rhomboid). 

Interarticular  Fibro-cartilage. 

The  Anterior  Sterno-clavicular  Ligament  is  a  broad  band  of  fibres,  which 
covers  the  anterior  surface  of  the  articulation,  being  attached,  above,  to  the 
upper  and  front  part  of  the  inner  extremity  of  the  clavicle;  and,  passing 
obliquely  downwards  and  inwards,  is  attached,  below,  to  the  front  and  upper 
part  of  the  first  piece  of  the  sternum.  This  ligament  is  covered  in  front  by 
the  sternal  portion  of  the  Sterno-cleido-mastoid  and  the  integument;  behind, 
it  is  in  relation  with  the  interarticular  fibro-cartilage  and  the  two  synovial 
membranes. 

The  Posterior  Sterno-clavicular  Ligament  is  a  similar  band  of  fibres,  which 
covers  the  posterior  surface  of  the  articulation,  being  attached,  above,  to  the 
posterior  part  of  the  inner  extremity  of  the  clavicle;  and  which,  passing 
obliquely  downwards  and  inwards,  is  connected,  below,  to  the  posterior  and 
upper  part  of  the  sternum.  It  is  in  relation,  in  front,  with  the  interarticular 
fibro-cartilage  and  synovial  membranes;  behind,  with  the  Sterno-hyoid  and 
Sterno-thyroid  muscles. 

The  Interclavicular  lAgament  is  a  flattened  band,  which  varies  considerably 
in  form  and  size  in  diflerent  individuals;  it  passes  from  the  upper  part  of  the 
inner  extremity  of  one  clavicle  to  the  other,  and  is  closely  attached  to  the  upper 
margin  of  the  sternum.  It  is  in  relation,  in  front,  with  the  integument ;  behind, 
with  the  Sterno-thyroid  muscles. 

The  Gosto- clavicular  Ligament  {rhomhoid)  is  short,  flat,  and  strong :  it  is  of  a 
rhomboid  form,  attached,  below,  to  the  upper  and  inner  part  of  the  cartilage 
of  the  first  rib:  it  ascends  obliquely  backwards  and  outwards,  and  is  attached, 

'  According  to  Bruch,  the  sternal  end  of  the  clavicle  is  covered  by  a  tissue,  which  is  rather 
fibrous  than  cartilaginous  in  structure. 


286  ARTICULATIONS. 

above,  to  the  rhomboid  depression  on  the  under  surface  of  the  clavicle.  It  ia 
in  relation,  in  front,  with  the  tendon  of  origin  of  the  Subclavius;  behind,  with 
the  subclavian  vein. 

The  Interariicular  Fibro-cartilage  is  a  flat  and  nearly  circular  disk,  interposed 
between  the  articulating  surfaces  of  the  sternum  and  clavicle.  It  is  attached, 
above,  to  the  upper  and  posterior  border  of  the  clavicle;  below,  to  the  cartilage 
of  the  first  rib,  at  its  junction  with  the  sternum :  and  by  its  circumference  to 
the  anterior  and  posterior  sterno-clavicular  ligaments.  It  is  thicker  at  the  cir- 
cumference, especially  its  upper  and  back  part,  than  at  its  centre  or  below.  It 
divides  the  joint  into  two  cavities,  each  of  which  is  furnished  with  a  separate 
synovial  membrane ;  when  the  fibro-cartilage  is  perforated,  which  not  unfre- 
quently  occurs,  the  synovial  membranes  communicate. 

Of  the  two  Synovial  Membranes  found  in  this  articulation,  one  is  reflected  from 
the  sternal  end  of  the  clavicle,  over  the  adjacent  surface  of  the  fibro-cartilage, 
and  cartilage  of  the  first  rib;  the  other  is  placed  between  the  articular  surface 
of  the  sternum  and  adjacent  surface  of  the  fibro-cartilage;  the  latter  is  the  more 
loose  of  the  two.     They  seldom  contain  much  synovia. 

Actions.  This  articulation  is  the  centre  of  the  movements  of  the  shoulder, 
and  admits  of  motion  in  nearly  every  direction — upwards,  downwards,  back- 
wards, forwards,  as  well  as  circumduction;  the  sternal  end  of  the  clavicle  and 
the  interarticular  cartilage  gliding  on  the  articular  surface  of  the  sternum. 

XL  SCAPULO-CLAVICULAR  ARTICULATION.     (Fig.  198.) 

The  Scapulo-clavicular  is  an  arthrodial  joint,  formed  between  the  outer 
extremity  of  the  clavicle,  and  the  upper  edge  of  the  acromion  process  of  the 
scapula.     Its  ligaments  are  the 

Superior  Acromio-clavicular. 
Inferior  Acromio-clavicular. 

{Trapezoid 
and 
Conoid. 
Interarticular  Fibro-cartilage. 

The  Superior  Acromio-clavicular  Ligament  is  a  broad  band,  of  a  quadrilateral 
form,  which  covers  the  superior  part  of  the  articulation,  extending  between  the 
upper  part  of  the  outer  end  of  the  clavicle,  and  the  adjoining  part  of  the  acro- 
mion. It  is  composed  of  parallel  fibres,  which  interlace  with  the  aponeurosis 
of  the  Trapezius  and  Deltoid  muscles;  below,  it  is  in  contact  with  the  inter- 
articular fibro-cartilage  and  synovial  membranes. 

The  Inferior  Acromio-clavicular  Ligament^  somewhat  thinner  than  the  pre- 
ceding, covers  the  under  part  of  the  articulation,  and  is  attached  to  the  adjoin- 
ing surfaces  of  the  two  bones.  It  is  in  relation,  above,  with  the  interarticular 
fibro-cartilage  (when  it  exists)  and  the  synovial  membranes ;  below,  with  the 
tendon  of  the  Supraspinatus.  These  two  ligaments  are  continuous  with  each 
other  in  front  and  behind,  and  form  a  complete  capsule  around  the  joint. 

The  Coraco-clavicular  Ligament  serves  to  connect  the  clavicle  with  the  cora- 
coid  process  of  the  scapula.  It  consists  of  two  fasciculi,  called  the  trapezoid 
and  conoid  ligaments. 

The  trapezoid  ligament,  the  anterior  and  external  fasciculus,  is  broad,  thin, 
and  quadrilateral :  it  is  placed  obliquely  between  the  coracoid  process  and  the 
clavicle.  It  is  attached,  below,  to  the  upper  surface  of  the  coracoid  process; 
above,  to  the  oblique  line  on  the  under  surface  of  the  clavicle.  Its  anterior 
border  is  free ;  its  posterior  border  is  joined  with  the  conoid  ligament,  the  two 
forming  by  their  junction  a  projecting  angle. 

The  conoid  ligament,  the  posterior  and  internal  fasciculus,  is  a  dense  band  of 
fibres,  conical  in  form,  the  base  being  turned  upwards,  the  summit  downwards. 
It  is  attached  by  its  apex  to  a  rough  depression  at  the  base  of  the  coracoid  pro- 


LIGAMENTS  OF  THE  SCAPULA. 


287 


cess,  internal  to  the  preceding;  above,  by  its  expanded  base,  to  tbe  conoid 
tubercle  on  the  under  surface  of  the  clavicle,  and  to  a  line  proceeding  inter- 

Fig.  198. — The  Left  Shoulder-Joint,  Scapulo-clavicular  Articulations  and  Proper  Ligaments 

of  Scapula. 


nally  from  it  for  half  an  inch.  These  ligaments  are  m  relation,  in  front,  with 
the  Subclavius ;  behind,  with  the  Trapezius :  they  serve  to  limit  rotation  of  the 
scapula  forwards  and  backwards. 

The  Interarticular  Fihro-cartilage  is  most  frequently  absent  in  this  articula- 
tion. When  it  exists,  it  generally  only  partially  separates  the  articular  sur- 
faces, and  occupies  the  upper  part  of  the  articulation.  More  rarely,  it  com- 
pletely separates  the  joint  into  two  cavities. 

There  are  two  Synovial  Membranes  when  a  complete  interarticular  cartilage 
exists ;  more  frequently  there  is  only  one  synovial  membrane. 

Actions.  The  movements  of  this  articulation  are  of  two  kinds.  1.  A  gliding 
motion  of  the  articular  end  of  the  clavicle  on  the  acromion.  2.  Eotation  of 
the  scapula  forwards  and  backwards  upon  the  clavicle,  the  extent  of  this  rota- 
tion being  limited  by  the  two  portions  of  the  coraco-clavicular  ligament. 


III.  PROPER  LIGAMENTS  OF  THE  SCAPULA.  (Fig.  198.) 

The  proper  ligaments  of  the  scapula  are,  the 

Coraco-acromial.  Transverse. 

The  Coraco-acromial  Ligament  is  a  broad,  thin,. flat  band,  of  a  triangular  shape, 
extended  transversely  above  the  upper  part  of  -the  shoulder-joint,  between  the 
coracoid  and  acromion  processes.  It  is  attached,  by  its  apex,  to  the  summit  of 
the  acromion  just  in  front  of  the  articular  surface  for  the  clavicle ;  and  by  its 
broad  base,  to  the  whole  length  of  the  outer  border  of  the  .coracoid  process. 


2S8  ARTICULATIONS. 

Its  posterior  fibres  are  directed  obliquely  backwards  and  outwards,  its  anterior 
fibres  transversely.  This  ligament  completes  the  vault  formed  by  the  coraooid 
and  acromion  processes  for  the  protection  of  the  head  of  the  humerus.  It  is  in 
relation,  above,  with  the  clavicle  and  under  surface  of  the  Deltoid ;  below,  with 
the  tendon  of  the  Supraspinatus  muscle,  a  bursa  being  interposed.  Its  anterior 
border  is  continuous  with  a  dense  cellular  lamina  that  passes  beneath  the 
Deltoid  upon  the  tendons  of  the  Supraspinatus  and  Infraspinatus  muscles. 

The  Transverse  or  Coracoid  Ligament  converts  the  suprascapular  notch  into  a 
foramen.  It  is  a  thin  and  flat  fasciculus,  narrower  at  the  middle  than  at  the 
extremities,  attached,  by  one  end,  to  the  base  of  the  coracoid  process,  and,  by 
the  other,  to  the  inner  extremity  of  the  scapular  notch.  The  suprascapular 
nerve  passes  through  the  foramen ;  the  suprascapular  vessels  above  it. 

IV.  SHOULDER-JOINT.    (Fia.  198.) 

The  shoulder  is  an  enarthrodial  or  ball-and-socket  joint.  The  bones  entering 
into  its  formation  are  the  large  globular  head  of  the  hujnerus,  received  into 
the  shallow  glenoid  cavity  of  the  scapula,  an  arrangement  which  permits  of 
very  considerable  movement,  whilst  the  joint  itself  is  protected  against  dis- 
placement by  the  strong  ligaments  and  tendons  which  surround  it,  and  above 
by  an  archea  vault,  formed  by  the  under  surface  of  the  coracoid  and  acromion 
processes,  and  the  coraco-acromial  ligament.  The  articular  surfaces  are  covered 
by  a  layer  of  cartilage ;  that  on  the  head  of  the  humerus  is  thicker  at  the  centre 
than  at  the  circumference,  the  reverse  being  the  case  in  the  glenoid  cavity.  The 
ligaments  of  the  shoulder  are,  the 

Capsular.  Coraco-humeral. 

Glenoid.' 

The  Capsular  Ligament  completely  encircles  the  articulation ;  being  attached, 
above,  to  the  circumference  of  the  glenoid  cavity  beyond  the  glenoid  ligament; 
below,  to  the  anatomical  neck  of  the  humerus,  approaching  nearer  to  the  articular 
cartilage  above  than  in  the  rest  of  its  extent.  It  is  thicker  above  than  below, 
remarkably  loose  and  lax,  and  much  larger  and  longer  than  is  necessary  to 
keep  the  bones  in  contact,  allowing  them  to  be  separated  from  each  other  more 
than  an  inch,  an  evident  provision  for  that  extreme  freedom  of  movement  which 
is  peculiar  to  this  articulation.  Its  external  surface  is  strengthened,  above,  by  the 
Supraspinatus;  above  and  internally,  by  the  coraco-humeral  ligament;  below, 
by  the  long  head  of  the  Triceps ;  externally,  by  the  tendons  of  the  Infraspinatus 
and  Teres  minor;  and  internally,  by  the  tendon  of  the  Subscapularis.  The 
capsular  ligament  usually  presents  three  openings:  one  at  its  inner  side,  below 
the  coracoid  process,  partially  filled  up  by  the  tendon  of  the  Subscapularis ;  it 
establishes  a  communication  between  the  synovial  membrane  of  the  joint  and 
a  bursa  beneath  the  tendon  of  that  muscle.  The  second,  which  is  not  constant, 
is  at  the  outer  part,  where  a  communication  sometimes  exists  between  the  joint 
and  a  bursal  sac  belonging  to  the  Infraspinatus  muscle.  The  third  is  seen  in 
the  lower  border  of  the  ligament,  between  the  two  tuberosities,  for  the  passage 
of  the  long  tendon  of  the  Biceps  muscle. 

The  Coraco-humeral  or  Accessory  Ligament  is  a  broad  band  which  strengthens 
the  upper  and  inner  part  of  the  capsular  ligament.  It  arises  from  the  outer 
border  of  the  coracoid  process,  and  passes  obliquely  downwards  and  outwards 
to  the  front  of  the  great  tuberosity  of  the  humerus,  being  blended  with  the 
tendon  of  the  Supraspinatus  muscle.  This  ligament  is  intimately  united  to  the 
capsular  in  the  greater  part  of  its  extent. 

The  Olenoid  Ligament  is  a  firm  fibrous  band  attached  round  the  margin  of  the 
glenoid  cavity.     It  is  triangular  on  section,  the  thickest  portion  being  fixed  to 

'  The  long  tendon  of  origin  of  the  Biceps  muscle  also  acts  as  one  of  the  ligaments  of  this  joint. 


II 


ELBOW-JOINT.  289 

the  circumference  of  the  cavity,  the  free  edge  being  thin  and  sharp.  It  is  con- 
tinuous above  with  the  long  tendon  of  the  Biceps  muscle,  which  bifurcates  at 
the  upper  part  of  the  cavity  into  two  fasciculi,  encircling  the  margin  of  the 
glenoid  cavity  and  uniting  at  its  lower  part.  This  ligament  deepens  the  cavity 
for  articulation,  and  protects  the  edges  of  the  bone.  It  is  lined  by  the  synovial 
membrane. 

The  Synovial  Membrane  lines  the  margin  of  the  glenoid  cavity  and  the  fibro- 
cartilaginous rim  surrounding  it ;  it  is  then  reflected  over  the  internal  surface 
of  the  capsular  ligament,  covers  the  lower  part  and  sides  of  the  neck  of  the 
humerus,  and  is  continued  a  short  distance  over  the  cartilage  covering  the  head 
of  the  bone.  The  long  tendon  of  the  Biceps  muscle  which  passes  through  the 
joint,  is  inclosed  in  a  tubular  sheath  of  synovial  membrane,  which  is  reflected 
upon  it  at  the  point  where  it  perforates  the  capsule,  and  is  continued  around  it 
as  far  as  the  summit  of  the  glenoid  cavity.  The  tendon  of  the  Biceps  is  thus 
enabled  to  traverse  the  articulation,  but  is  not  contained  in  the  interior  of  the 
synovial  cavity.  The  synovial  membrane  communicates  with  a  large  bursal 
sac  beneath  the  tendon  of  the  Subscapularis,  by  an  opening  at  the  inner  side 
of  the  capsular  ligament ;  it  also  occasionally  communicates  with  another  bursal 
sac,  beneath  the  tendon  of  the  Infraspinatus,  through  an  orifice  at  its  outer  part. 
A  third  bursal  sac,  which  does  not  communicate  with  the  joiat,  is  placed  be- 
tween the  under  surface  of  the  deltoid  and  the  outer  surface  of  the  capsule. 

The  Muscles  in  relation  with  the  joint  are,  above,  the  Supraspinatus ;  below, 
the  long  head  of  the  Triceps;  internally,  the  Subscapularis;  externally,  the 
Infraspinatus,  and  Teres  minor ;  within,  the  long  tendon  of  the  Biceps.  The 
Deltoid  is  placed  most  externally,  and  covers  the  articulation  on  its  outer  side,, 
as  well  as  in  front  and  behind. 

The  Arteries  supplying  the  joint,  are  articular  branches  of  the  anterior  and 
posterior  circumflex,  and  suprascapular. 

The  Nerves  are  derived  from  the  circumflex  aud  suprascapular. 

Actions.  The  shoulder-joint  is  capable  of  movement  in  every  direction,  for- 
wards, backwards,  abduction,  adduction,  circumduction,  and  rotation. 

Y.  ELBOW-JOINT. 

The  Elbow  is  a  ginglymus  or  hinge-joint.  The  bones  entering  into  its  forma- 
tion are  the  trochlear  surface  of  the  humerus,  which  is  received  in  the  greater 
sigmoid  cavity  of  the  ulna,  and  admits  of  the  movements  peculiar  to  this  joint, 
those  of  flexion  and  extension,  whilst  the  cup-shaped  depression  on  the  head  of 
the  radius  articulates  with  the  radial  tuberosity  of  the  humerus,  and  the  cir- 
cumference of  the  head  of  the  radius,  with  the  lesser  sigmoid  cavity  of  the  ulna, 
allowing  of  the  movement  of  rotation  of  the  radius  on  the  ulna,  the  chief  action 
of  the  superior  radio-ulnar  articulation.  The  articular  surfaces  are  covered  with 
a  thin  layer  of  cartilage,  and  connected  together  by  the  following  ligaments : — 

Anterior.  Internal  Lateral. 

Posterior.  External  Lateral. 

The  Anterior  Ligament  (Fig.  199)  is  a  broad  and  thin  fibrous  layer,  which, 
covers  the  anterior  surface  of  the  joint.  It  is  attached  to  the  front  of  the  hu- 
merus immediately  above  the  coronoid  fossa ;  below,  to  the  anterior  surface  of 
the  coronoid  process  of  the  ulna  and  orbicular  ligament,  being  continuous  on 
each  side  with  the  lateral  ligaments.  Its  superficial  or  oblique  fibres  pass  from, 
the  inner  condyle  of  the  humerus  outwards  to  the  orbicular  ligament.  The 
middle  fibres,  vertical  in  direction,  pass  from  the  upper  part  of  the  coronoid 
depression,  and  become  blended  with  the  preceding.  A  third,  or  transverse 
set,  intersect  these  at  right  angles.  This  ligament  is  in  relation,  in  front,  with 
the  Brachialis  Anticus ;  behind,  with  the  synovial  membrane. 

The  Posterior  Ligament  (Fig.  200)  is  a  thin  and  loose  membranous  fold,  at- 
tached,  above,  to  the  lower  end  of  the  humerus,  immediately  above  the  olecra- 
19 


290 


ARTICULATIONS. 


non  depression ;  below,  to  the  margin  of  the  olecranon.  The  superficial  or 
transverse  fibres  pass  between  the  adjacent  margins  of  the  olecranon  fossa. 
The  deeper  portion  consists  of  vertical  fibres,  which  pass  from  the  upper  part 
of  the  olecranon  fossa  to  the  margin  of  the  olecranon.  This  ligament  is  in  rela- 
tion, behind,  with  the  tendon  of  the  Triceps  and  the  Anconeus ;  in  front,  with 
the  synovial  membrane. 


Fig.  199. — Left  Elbow-joint,  showing  Anterior 
and  Internal  Ligaments. 


Fig.  200. — Left  Elbow-joint,  showing  Posterior 
and  External  Ligaments. 


The  Internal  Lateral  Ligament  (Fig.  199)  is  a  thick  triangular  band,  consistuig 
of  two  distinct  portions,  an  anterior  and  posterior.  The  anterior  ^portion,  di- 
rected obliquely  forwards,  is  attached,  above,  by  its  apex,  to  the  front  part  of 
the  internal  condyle  of  the  humerus;  and,  below,  by  its  broad  base,  to  the 
inner  margin  of  the  coronoid  process.  The  posterior  portion^  also  of  triangular 
form,  is  attached,  above,  by  its  apex,  to  the  lower  and  back  part  of  the  internal 
condyle ,  below,  to  the  inner  margin  of  the  olecranon.  This  ligament  is  in 
relation,  internally,  with  the  Triceps  and  Flexor  Carpi  Ulnaris  muscles,  and 
the  ulnar  nerve. 

The  External  Lateral  Ligament  (Fig.  200)  is  a  short  and  narrow  fibrous  fasci- 
culus, less  distinct  than  the  internal,  attached,  above,  to  the  external  condyle 
of  the  humerus ;  below,  to  the  orbicular  ligament,  some  of  its  most  posterior 
fibres  passing  over  that  ligament,  to  bo  inserted  into  the  outer  margin  of  the 
ulna.  This  ligament  is  intimately  blended  with  the  tendon  of  origin  of  the 
Supinator  Brevis  muscle. 

The  Synovial  Membrane  is  very  extensive.  It  covers  the  margin  of  the  arti- 
cular surface  of  the  humerus,  and  lines  the  coronoid  and  olecranon  depressions 


RADIO-ULNAR.  291 

on  that  bone ;  from  these  points  it  is  reflected  over  the  anterior,  posterior,  and 
lateral  ligaments ;  and  forms  a  pouch  between  the  lesser  sigmoid  cavity,  the 
internal  surface  of  the  annular  ligament,  and  the  circumference  of  the  head  of 
the  radius. 

The  Muscles  in  relation  with  the  joint  are,  in  front,  the  Brachialis  Anticus ; 
behind,  the  Triceps  and  Anconeus;  externally,  the  Supinator  Brevis,  and  the 
common  tendon  of  origin  of  the  extensor  muscles;  internally,  the  common 
tendon  of  origin  of  the  flexor  muscles,  and  the  Flexor  Carpi  Ulnaris,  with  the 
ulnar  nerve. 

The  Arteries  supplying  the  joint  are  derived  from  the  communicating 
branches  between  the  superior  profunda,  inferior  profunda,  and  anastomotic 
branches  of  the  brachial,  with  the  anterior,  posterior,  and  interosseous  recur- 
rent branches  of  the  ulnar,  and  the  recurrent  branch  of  the  radial.  These 
vessels  form  a  complete  chain  of  inosculation  around  the  joint. 

The  Nerves  are  derived  from  the  ulnar,  as  it  passes  between  the  internal 
condyle  and  the  olecranon ;  and  a  few  filaments  from  the  musculo-cutaneous. 

Actions.  The  elbow  is  a  perfect  hinge-joint;  its  movements  are,  consequently, 
limited  to  flexion  and  extension,  the  exact  apposition  of  the  articular  surfaces 
preventing  the  least  lateral  motion. 

VI.   EADIO-ULNAR  ARTICULATIONS. 

The  articulation  of  the  radius  with  the  ulna  is  effected  by  ligaments,  which 
connect  together  both  extremities  as  well  as  the  shafts  of  these  bones.  They 
may,  consequently,  be  subdivided  into  three  sets:  1.  The  superior  radio-ulnar; 
2.  The  middle  radio-ulnar ;  and,  3.  The  inferior  radio-ulnar  articulations. 

1.  Superior  Eadio-Ulnar  Articulation. 

This  articulation  is  a  lateral  ginglymus.  The  bones  entering  into  its  forma- 
tion are  the  inner  side  of  the  circumference  of  the  head  of  the  radius,  which 
rotates  within  the  lesser  sigmoid  cavity  of  the  ulna.  These  surfaces  are  covered 
with  cartilage,  and  invested  with  a  duplicature  of  synovial  membrane,  continu- 
ous with  that  which  lines  the  elbow-joint.  Its  only  ligament  is  the  annular  or 
orbicular. 

The  Orbicular  Ligament  (Fig.  200)  is  a  strong  flat  band  of  ligamentous  fibres, 
which  surrounds  the  head  of  the  radius,  and  retains  it  in  firm  connection  with 
the  lesser  sigmoid  cavity  of  the  ulna.  It  forms  about  three-fourths  of  a  fibrous 
ring,  attached  by  each  end  to  the  extremities  of  the  sigmoid  cavity,  and  is 
broader  at  the  upper  part  of  its  circumference  than  below,  by  which  means  the 
head  of  the  radius  is  more  securely  held  in  its  position.  Its  otiter  surface  is 
strengthened  by  the  external  lateral  ligament  of  the  elbow,  and  affords  origin 
to  part  of  the  Supinator  Brevis  muscle.  Its  inner  surface  is  smooth,  and  lined 
by  synovial  membrane. 

Actions.  The  movement  which  takes  place  in  this  articulation  is  limited  to 
rotation  of  the  head  of  the  radius  within  the  orbicular  ligament,  and  upon  the 
lesser  sigmoid  cavity  of  the  ulna;  rotation  forwards  being  called  pronation; 
rotation  backwards,  supination. 

2.  Middle  Radio-ulnar  Articulation. 

The  interval  between  the  shafts  of  the  radius  and  ulna  is  occupied  by  two 
ligaments. 

Oblique.  Interosseous. 

The  Oblique  or  Round  Ligament  (Fig.  199)  is  a  small  round  fibrous  cord, 
which  extends  obliquely  downwards  and  outwards,  from  the  tubercle  of  the 
ulna  at  the  base  of  the  coronoid  process,  to  the  radius  a  little  below  the  bicipital 
tuberosity.     Its  fibres  run  in  the  opposite  direction  to  those  of  the  interosseous 


292  ARTICULATIONS. 

ligament ;  and  it  appears  to  be  placed  as  a  substitute  for  it  in  the  upper  part 
of  the  interosseous  interval.     This  ligament  is  sometimes  wanting. 

The  Interosseoiis  Membrane  is  a  broad  and  thin  plane  of  aponeurotic  fibres, 
descending  obliquely  downwards  and  inwards,  from  the  interosseous  ridge  on 
the  radius  to  that  on  the  ulna.  It  is  deficient  above,  commencing  about  an 
inch  beneath  the  tubercle  of  the  radius;  is  broader  in  the  middle  than  at 
either  extremity ;  and  presents  an  oval  aperture  just  above  its  lower  margin 
for  the  passage  of  the  anterior  interosseous  vessels  to  the  back  of  the  forearm. 
This  ligament  serves  to  connect  the  bones,  and  to  increase  the  extent  of  surface 
for  the  attachment  of  the  deep  muscles.  Between  its  upper  border  and  the 
oblique  ligament  an  interval  exists,  through  which  the  posterior  interosseous 
vessels  pass.  Two  or  three  fibrous  bands  are  occasionally  found  on  the 
posterior  surface  of  this  membrane,  which  descends  obliquely  from  the  ulna 
towards  the  radius,  and  which  have  consequently  a  direction  contrary  to  that 
of  the  other  fibres.  It  is  in  relation,  in  front,  by  its  upper  three-fourths  with 
the  Flexor  Longus  Pollicis  on  the  outer  side,  and  with  the  Flexor  Profundus 
Digitorum  on  the  inner,  lying  upon  the  interval  between  which  are  the  anterior 
interosseous  vessels  and  nerve,  by  its  lower  fourth  with  the  Pronator  Quad- 
ratus ;  behind,  with  the  Supinator  Brevis,  Extensor  Ossis  Metacarpi  Pollicis, 
Extensor  Primi  Internodii  Pollicis,  Extensor  Secundi  Internodii  Pollicis,  Ex- 
tensor Indicis ;  and,  near  the  wrist,  with  the  anterior  interosseous  artery  and 
posterior  interosseous  nerve. 

8.  Inferior  Radio-Ulnar  Articulation. 

This  is  a  lateral  ginglymus,  formed  by  the  head  of  the  ulna  received  into  the 
sigmoid  cavity  at  the  inner  side  of  the  lower  end  of  the  radius.  The  articular 
surfaces  are  covered  by  a  thin  layer  of  cartilage,  and  connected  together  by  the 
following  ligaments : — 

Anterior  Radio-ulnar. 
Posterior  Radio-ulnar. 
Triangular  Interarticular  Fibro-cartilage. 

The  Anterior  Radio-ulnar  Ligament  (Fig.  201)  is  a  narrow  band  of  fibres, 
extending  from  the  anterior  margin  of  the  sigmoid  cavity  of  the  radius  to  the 
anterior  surface  of  the  head  of  the  ulna. 

The  Posterior  Radio-ulnar  Ligament  (Fig.  202)  extends  between  similar  points 
on  the  posterior  surface  of  the  articulation.  -mi-^d 

The  Triangular  Interarticular  Fibro-cartilage  (Fig.  203)  is  placed  transversel^MJ^H 
beneath  the  head  of  the  ulna,  binding  the  lower  end  of  this  bone  and  the  radius 
firmly  together.     Its  circumference  is  thicker  than  its  centre,  which  is  thin  and 
occasionally  perforated.     It  is  attached  by  its  apex  to  a  depression  which  sepa- 
rates the  styloid  process  of  the  ulna  from  the  head  of  that  bone;  and,  by  its-w, 
base,  which  is  thin,  to  the  prominent  edge  of  the  radius,  which  separates  theHJ 
sigmoid  cavity  from  the  carpal  articulating  surface.     Its  margins  are  united  to 
the  ligaments  of  the  wrist-joint.     Its  upper  surface,  smooth  and  concave,  is 
contiguous  with  the  head  of  the  ulna;  its  U7ider  surface,  also  concave  and 
smooth,  with  the  cuneiform  bone.     Both  surfaces  are  lined  by  a  synovial  mem- 
brane: the  upper  surface,  by  one  peculiar  to  the  radio-ulnar  articulation;  the 
under  surface,  by  the  synovial  membrane  of  the  wrist. 

The  Synovial  Membrane  (Fig.  203)  of  this  articulation  has  been  called,  from 
its  extreme  looseness,  the  memhrana  sacciformis;  it  covers  the  margin  of  the 
articular  surface  of  the  head  of  the  ulna,  and  where  reflected  from  this  bone  on 
to  the  radius,  forms  a  very  loose  cid-de-sac ;  from  the  radius,  it  is  continued 
over  the  upper  surface  of  the  fibro-cartilage.  The  quantity  of  synovia  which 
it  contains  is  usually  considerable.  When  the  fibro-cartilage  is  perforated,  the 
synovial  membrane  is  continuous  with  that  which  lines  the  wrist. 


i4l 


RADIO-ULNAR. 


293 


Actions.     The  movement  which  occurs  in  the  inferior  radio-ulnar  articulation 
is  just  the  reverse  of  that  which  takes  place  between  the  two  bones  above ;  it  is 

Fig.  201.— Ligaments  of  Wrist  and  Hand.     Anterior  Yiew. 


NFEKIOR  RADIO-ULNAS  ARTIC* 


WRIST-JOINT 


CARPAL    ARTIC  ?f 


CARPO-METACABPAL  ARTIC  ?! 


limited  to  rotation  of  the  radius  round  the  head  of  the  ulna ;  rotation  forwards 
being  termed  pronation,  rotation  backwards  supination.     In  pronation,  the  sig- 

Fig.  202. — Ligaments  of  Wrist  and  Hand.    Posterior  View. 


Inferior 
3ladio  -uinaT  Arti 

"M^riat- Joint 


Carpal   .Aytit 


Carpe-Mf^aearpnT 
ArtieVf 


moid  cavity  glides  forward  on  the  articular  edge  of  the  ulna ;  in  supination,  it 
rolls  in  the  opposite  direction,  the  extent  of  these  movements  being  limited  by 
the  anterior  and  posterior  ligaments. 


294  ARTICULATIONS. 


VII.  WRIST-JOINT. 

The  Wrist  presents  some  of  the  characters  of  an  enarthrodial  joint,  but  is 
more  correctly  regarded  as  an  arthrodia.  The  parts  entering  into  its  formation 
are,  the  lower  end  of  the  radius,  and  under  surface  of  the  triangular  interar- 
ticular  fibro-cartilage  above ;  and  the  scaphoid,  semilunar,  and  cuneiform  bones 
below.  The  articular  surfaces  of  the  radius  and  interarticular  fibro-cartilage 
form  a  transversely  elliptical  concave  surface.  The  radius  is  subdivided  into 
two  parts  by  a  line  extending  from  before  backwards ;  and  these,  together  with 
the  interarticular  cartilage,  form  three  facets,  one  for  each  carpal  bone.  The 
three  carpal  bones  are  connected  together,  and  form  a  convex  surface,  which  is 
received  into  the  concavity  above  mentioned.  All  the  bony  surfaces  of  the 
articulation  are  covered  with  cartilage,  and  connected  together  by  the  following 
ligaments : — 

External  Lateral.  Anterior. 

Internal  .Lateral.  Posterior. 

The  External  Lateral  Ligament  {radio-carpal)  (Fig.  201)  extends  from  the 
summit  of  the  styloid  process  of  the  radius  to  the  outer  side  of  the  scaphoid, 
some  of  its  fibres  being  prolonged  to  the  trapezium  and  annular  ligament. 

The  Internal  Lateral  Lir/ament  (ulno-carpal)  is  a  rounded  cord,  attached,  above, 
to  the  extremity  of  the  styloid  process  of  the  ulna;  and  dividing  below  into  two 
fasciculi,  which  are  attached,  one  to  the  inner  side  of  the  cuneiform  bone,  the 
other  to  the  pisiform  bone  and  annular  ligament. 

The  Anterior  Ligament  is  a  broad  membranous  band,  consisting  of  three  fas- 
ciculi, attached,  above,  to  the  anterior  margin  of  the  lower  end  of  the  radius,  its 
styloid  process,  and  the  ulna;  its  fibres  pass  downwards  and  inwards,  to  be 
inserted  into  the  palmar  surftice  of  the  scaphoid,  semilunar  and  cuneiform  bones. 
This  ligament  is  perforated  by  numerous  apertures  for  the  passage  of  vessels, 
and  is  in  relation,  in  front,  with  the  tendons  of  the  Flexor  Profundus  Digito- 
rum  and  Flexor  Longus  Pollicis ;  behind,  with  the  synovial  membrane  of  the 
wrist-joint. 

The  Posterior  Ligament  (Fig.  202),  less  thick  and  strong  than  the  anterior,  is 
attached,  above,  to  the  posterior  border  of  the  lower  end  of  the  radius;  its  fibres 
pass  obliquely  downwards  and  inwards  to  be  attached  to  the  dorsal  surface  of 
the  scaphoid,  semilunar,  and  cuneiform  bones,  being  continuous  with  those  of 
the  dorsal  carpal  ligaments.  This  ligament  is  in  relation,  behind,  with  the  ex- 
tensor tendons  of  the  fingers ;  in  front,  with  the  synovial  membrane  of  the  wrist. 

The  Synovial  Membrane  (Fig.  203)  lines  the  under  surface  of  the  triangular 
interarticular  fibro-cartilage  above ;  and  is  reflected  on  the  inner  surface  of  the 
ligaments  just  described. 

Relations.  The  wrist-joint  is  covered  in  front  by  the  flexor,  and  behind  by 
the  extensor  tendons ;  it  is  also  in  relation  with  the  radial  and  ulnar  arteries. 

The  arteries  supplying  the  joint  are  the  anterior  and  posterior  carpal 
branches  of  the  radial  and  ulnar,  the  anterior  and  posterior  interosseous,  and 
some  ascending  branches  from  the  deep  palmar  arch. 

The  nerves  are  derived  from  the  ulnar. 

Actions.  The  movements  permitted  in  this  joint  are  flexion,  extension,  ab- 
duction, adduction,  and  circumduction.  It  is  totally  incapable  of  rotation,  one 
of  the  characteristic  movements  in  true  enarthrodial  joints. 

VIII.   ARTICULATIONS  OF  THE  CARPAL  BONES. 
These  articulations  may  be  subdivided  into  three  sets : — 

1.  The  Articulations  of  the  First  Row  of  Carpal  Bones. 

2.  The  Articulations  of  the  Second  Row  of  Carpal  Bones. 
8.  The  Articulations  of  the  Two  Rows  with  each  other. 


^ 


CARPAL    BONES.  295 

1.  Akticulations  of  the  First  Row  of  Carpal  Bones. 

These  are  arthrodial  joints.  The  articular  surfaces  are  covered  with  cartilage, 
and  connected  together  by  the  following  ligaments : — 

Two  Dorsal.  Two  Palmar. 

Two  Interosseous. 

The  two  Dorsal  Ligaments  are  placed  transversely  behind  the  bones  of  the 
first  row;  they  connect  the  scaphoid  and  semilunar,  and  the  semilunar  and 
cuneiform. 

The  two  Palmar  Ligaments  connect  the  scaphoid  and  semilunar,  and  the  semi- 
lunar and  cuneiform  bones;  they  are  less  strong  than  the  dorsal,  and  placed 
very  deep  under  the  anterior  ligament  of  the  wrist. 

The  two  Interosseous  Ligaments  (Fig.  203)  are  two  narrow  bundles  of  fibrous 
tissue,  connecting  the  semilunar  bone,  on  one  side  with  the  scaphoid,  on  the 
other  with  the  cuneiform.  They  close  the  upper  part  of  the  interspaces  between 
the  scaphoid,  semilunar,  and  cuneiform  bones,  their  upper  surfaces  being 
smooth,  and  lined  by  the  synovial  membrane  of  the  wrist-joint. 

The  articulation  of  the  pisiform  with  the  cuneiform  is  provided  with  a  sepa- 
rate synovial  membrane,  protected  by  a  thin  capsular  ligament.  There  are  also 
two  strong  fibrous  fasciculi,  which  connect  this  bone  to  the  unciform,  and  base 
of  the  fifth  metacarpal  bone  (Fig.  201). 

2.  Articulations  of  the  Second  Row  of  Carpal  Bones. 

These  are  also  arthrodial  joints.  The  articular  surfaces  are  covered  with 
cartilage,  and  connected  by  the  following  ligaments : — 

Three  Dorsal.  Three  Palmar. 

Two  Interosseous. 

The  three  Dorsal  Ligaments  extend  transversely  from  one  bone  to  another  on 
the  dorsal  surface,  connecting  the  trapezium  with  the  trapezoid,  the  trapezoid 
with  the  OS  magnum,  and  the  os  magnum  with  the  unciform. 

The  three  Palmar  Ligaments  have  a  similar  arrangement  on  the  palmar  surface. 

The  two  Interosseous  Ligaments^  much  thicker  than  those  of  the  first  row,  are 
placed  one  on  each  side  of  the  os  magnum,  connecting  it  with  the  trapezoid 
externally,  and  the  unciform  internally.  The  former  is  less  distinct  than  the 
latter. 

8.  Articulations  of  the  Two  Rows  of  Carpal  Bones  with  each  other. 

The  articulations  between  the  two  rows  of  the  carpus  consist  of  a  joint  in  the 
middle,  formed  by  the  reception  of  the  head  of  the  os  magnum  into  a  cavity 
formed  by  the  scaphoid  and  semilunar  bones,  and  of  an  arthrodial  joint  on  each 
side,  the  outer  one  formed  by  the  articulation  of  the  scaphoid  with  the  trape- 
zium and  trapezoid,  the  internal  one  by  the  articulation  of  the  cuneiform  and 
unciform.  The  articular  surfaces  are  covered  by  a  thin  layer  of  cartilage,  and 
connected  by  the  following  ligaments : — 

Anterior  or  Palmar.  External  Lateral. 

Posterior  or  Dorsal.  Internal  Lateral. 

The  Anterior  or  Palmar  Ligaments  consist  of  short  fibres,  which  pass  ob- 
liquely between  the  bones  of  the  first  and  second  row  on  the  palmar  surface. 

The  Posterior  or  Dorsal  Ligaments  have  a  similar  arrangement  on  the  dorsal 
surface  of  the  carpus. 

The  Lateral  Ligaments  are  very  short ;  they  are  placed,  one  on  the  radial, 
the  other  on  the  ulnar  side  of  the  carpus;  the  former,  the  stronger  and  more 
distinct,  connecting  the  scaphoid  and  trapezium  bones,  the  latter  the  cunei- 


296  ARTICULATIONS. 

form  and  unciform  ;  they  are  continuous  with  the  lateral  ligaments  of  the  wrist- 
joint. 

The  common  Synovial  Membrane  of  the  Carpus  is  very  extensive ;  it  lines  tlie 
under  surface  of  the  scaphoid,  semilunar,  and  cuneiform  bones,  sending  up- 
wards two  prolongations  between  their  contiguous  surfaces ;  it  is  then  reflected 
over  the  bones  of  the  second  row,  and  sends  down  three  prolongations  between 
them,  which  line  their  contiguous  surfaces,  and  invest  the  carpal  extremities 
of  the  four  inner  metacarpal  bones.  There  is  a  separate  synovial  membrane 
between  the  pisiform  and  cuneiform  bones. 

Actions.  The  partial  movement  which  takes  place  between  the  bones  of  each 
row  is  very  inconsiderable ;  the  movement  between  the  two  rows  is  more 
Tnarked,  but  limited  chiefly  to  flexion  and  extension. 

IX.  OARPO-METACARPAL  ARTICULATIONS. 

1.  Abticulation  of  the   Metacarpal   Bone  of  the  Thumb  with  the 

Trapezium. 

This  is  ^an  arthrodial  joint,  which  enjoys  great  freedom  of  movement,  on 
account  of  the  shape  of  its  articular  surfaces,  which  are  saddle-shaped,  so  that, 
on  section,  each  bone  appears  to  be  received  into  a  cavity  in  the  other,  accord- 
ing to  the  direction  in  which  they  are  cut.  Hence  this  joint  is  sometimes 
described  as  one  "  by  reciprocal  reception."  Its  ligaments  are  a  capsular  and 
synovial  membrane. 

The  capsular  ligament  is  a  thick  but  loose  capsule,  which  passes  from  the 
circumference  of  the  upper  extremity  of  the  metacarpal  bone  to  the  rough 
edge  bounding  the  articular  surface  of  the  trapezium ;  it  is  thickest  externally 
and  behind,  and  lined  by  a  separate  synovial  membrane. 

2.  Articulation  of  the  Metacarpal  Bones  of  the  Fingers  with  the 

Carpus. 

The  joints  formed  between  the  carpus  and  four  inner  metacarpal  bones  are 
connected  together  by  dorsal,  palmar,  and  interosseous  ligaments. 

The  Dorsal  Ligaments,  the  strongest  and  most  distinct,  connect  the  carpal  and 
metacarpal  bones  on  their  dorsal  surface.  The  second  metacarpal  bone  receives 
two  fasciculi,  one  from  the  trapezium,  the  other  from  the  trapezoid;  the  third 
metacarpal  receives  one  from  the  os  magnum  ;  the  fourth  two,  one  from  the  os 
magnum,  and  one  from  the  unciform  ;  the  fifth  receives  a  single  fasciculus  from 
the  unciform  bone. 

The  Palmar  Ligaments  have  a  somewhat  similar  arrangement  on  the  palmar 
surface,  with  the  exception  of  the  third  metacarpal,  which  has  three  ligaments, 
an  external  one  from  the  trapezium,  situated  above  the  sheath  of  the  tendon 
of  the  Flexor  Carpi  Radialis ;  a  middle  one,  from  the  os  magnum ;  and  an  in- 
ternal one,  from  the  unciform. 

The  Interosmnis  Ligaments  consist  of  short  thick  fibres,  which  are  limited  to 
one  part  of  the  carpo-metacarpal  articulation ;  they  connect  the  contiguous 
inferior  angles  of  the  os  magnum  and  unciform  with  the  adjacent  surfaces  of 
the  third  and  fourth  metacarpal  bones. 

The  Synovial  Membrane  is  a  continuation  of  that  between  the  two  rows  of 
carpal  bones.  Occasionally,  the  articulation  of  the  unciform  with  the  fourth 
and  fifth  metacarpal  bones  has  a  separate  synovial  membrane. 

Tlie  Synovial  Membranes  of  the  Wrist  (Fig.  203)  are  thus  seen  to  be  five  in 
number.  T\\e  first,  the  membrana  sacciformis,  lines  the  lower  end  of  the  ulna, 
the  sigmoid  cavity  of  the  radius,  and  upper  surface  of  the  triangular  inter- 
articular  fibro-cartilage.  The  Seconal  lines  the  lower  end  of  the  radius  and 
interarticular  fibro-cartilage  above,  and  the  scaphoid,  semilunar,  and  cuneiform 
bones  below.  The  third,  the  most  extensive,  covers  the  contiguous  surfaces  of 
the  two  rows  of  carpal  bones,  and,  passing  between  the  bones  of  the  second 


CARPO-MET  A  CARPAL. 


297 


row,  lines  the  carpal  extremities  of  the  four  inner  metacarpal  bones.  The 
fourth  lines  the  adjacent  surfaces  of  the  trapezium  and  metacarpal  bone  of  the 
thumb.  The  ^fth  lines  the  adjacent  surfaces  of  the  cuneiform  and  pisiform 
bones. 

Actions.     The  movement  permitted  in  the  carpo-metacarpal  articulations  is 
limited  to  a  slight  gliding  of  the  articular  surfaces  upon  each  other,  the  extent 

Fig.  203. — Vertical  Section  through  the  Articulations  at  the  Wrist,  showing  the  Five  Synovial 

Membranes. 


of  which  varies  in  the  different  joints.  Thus  the  articulation  of  the  metacarpal 
bone  of  the  thumb  with  the  trapezium  is  most  movable,  then  the  fifth  meta- 
carpal, and  then  the  fourth.  The  second  and  third  are  almost  immovable. 
In  the  articulation  of  the  metacarpal  bone  of  the  thumb  with  the  trapezium, 
the  movements  permitted  are  flexion,  extension,  adduction,  abduction,  and 
circumduction. 


3.  Articulations  of  the  Metacarpal  Bones  with  each  other. 

The  carpal  extremities  of  the  metacarpal  bones  articulate  with  one  another 
at  each  side  by  small  surfaces  covered  with  cartilage,  and  connected  together 
by  dorsal,  palmar,  and  interosseous  ligaments. 

The  Dorsal  and  Palmar  Ligaments  pass  transversely  from  one  bone  to  an- 
other on  the  dorsal  and  palmar  surfaces.  The  Interosseous  Ligaments  pass  be- 
tween their  contiguous  surfaces,  just  beneath  their  lateral  articular  facets. 

The  Synovial  Membrane  lining  the  lateral  facets  is  a  reflection  from  that 
between  the  two  rows  of  carpal  bones. 

The  digital  extremities  of  the  metacarpal  bones  are  connected  together  by  a 
narrow  fibrous  band,  the  transverse  ligament  (Fig.  204)  which  passes  trans- 
versely across  their  anterior  surfaces,  and  is  blended  with  the  ligaments  of  the 
metacarpo-phalangeal  articulations.  Its  anterior  surface  presents  four  grooves 
for  the  passage  of  the  flexor  tendons.  Its  posterior  surface  blends  with  the  liga- 
ments of  the  metacarpo-phalangeal  articulation. 


2y8 


ARTICULATIONS. 


LATCKAL     Lie 


Metacarpff  -  phula.  ngtal 


X.  METACARPO-PHALANGEAL  ARTICULATIONS.    (Fio.  204.) 

These  articulations  are  of  the  ginglyraus  kind,  formed  by  the  reception  of 
the  rounded  head  of  the  metacarpal  bone,  into  a  superficial  cavity  in  the  extre- 
mity of  the  first  phalanx.     They  are  connected  by  the  following  ligaments  : — 

Anterior.  Two  Lateral. 

The  Anterior  Ligaments  {Glenoid  ligaments  of  Cruveilhier)  are   thick,  dense, 

and  fibro-cartilaginous  in  tex- 
Fig.204.-Articulations  of  the  Phalanges.  ^ure.     Each  is  placed  on  the 

palmar  surface  of  the  joint,  in 
the  interval  between  the  late- 
ral ligaments,  to  which  they 
are  connected ;  they  are  loose- 
ly united  to  the  metacarpal 
bone,  but  very  firmly  to  the 
base  of  the  first  phalanges. 
Their  palmar  surface  is  in- 
timately blended  with  the 
transverse  ligament,  forming 
a  groove  for  the  passage  of 
the  flexor  tendons,  the  sheath 
surrounding  which  is  con- 
nected to  each  side  of  the 
groove.  By  their  internal 
surface,  they  form  part  of  the 
articular  surface  for  the  head 
of  the  metacarpal  bone,  and 
are  lined  by  a  synovial  mem- 
brane. 

The  tioo  Lateral  Ligaments 
are  strong  rounded  cords, 
placed  one  on  each  side  of  the 
joint,  each  being  attached  by 
one  extremity  to  the  tubercle 
on  the  side  of  the  head  of  the 
metacarpal  bone,  and  by  the 
other  to  the  contiguous  extre- 
mity of  the  phalanx. 

The  2)oslerior  ligament  is 
supplied  by  the  extensor  ten- 
don placed  over  the  back  of 
each  joint. 

Actions.  The  movements 
which  occur  in  these  joints  are  flexion,  extension,  adduction,  abduction,  and 
circumduction ;  the  lateral  movements  are  very  limited. 


JPhalnngeal 

Artie  ?f 


XI.  ARTICULATIONS  OF  THE  PHALANGES. 
■     These  are  ginglymus  joints,  connected  by  the  following  ligaments : — 
Anterior.  Two  Lateral. 

The  arrangement  of  these  ligaments  is  similar  to  those  in  the  metacarpo 
phalangeal  articulations  ;  the  extensor  tendon  supplies  the  place  of  a  posterior 
ligament. 

Actio7is.     The  only  movements  permitted  in  the  phalangeal  joints  are  flexion 
and  extension ;  these  movements  are  more  extensive  between  the  first  and 


HIP-JOINT. 


299 


second  phalanges  tlian  between  the  second  and  third.  The  movement  of  flexion 
is  very  considerable,  but  the  extension  is  limited  by  the  anterior  and  lateral 
ligaments. 

AETIGULATIOKS  OF  THE  LOWER  EXTREMITY. 

The  Articulations  of  the  Lower  Extremity  comprise  the  following  groups : — 

I.  Hip-joint.  V.  Articulations  of  the  Tarsus. 

II.  Knee-joint,  VI.  Tarso-metatarsal  Articulations. 

III.  Articulations  between  the  Tibia     YIL  Metatarso- phalangeal     Articula- 

and  Fibula.  tions. 

lY.  Ankle-joint.  VIII.  Articulations  of  the  Phalanges. 

I.  HIP-JOINT.     (Fig.  205.) 

This  articulation  is  an  enarthrodial,  or  ball-and-socket  joint,  formed  by  the 
reception  of  the  head  of  the  femur  into  the  cup-shaped  cavity  of  the  acetabulum. 
The  articulating  surfaces  are  covered  with  cartilage,  that  on  the  head  of  the 
femur  being  thicker  at  the  centre  than  at  the  circumference,  and  covering  the 

Fig.  205. — Left  Hip-joint  laid  open, 


entire  surface  with  the  exception  of  a  depression  just  below  its  centre  for  the 
ligamentum  teres ;  that  covering  the  acetabulum  is  much  thinner  at  the  centre 
than  at  the  circumference,  being  deficient  in  the  situation  of  the  circular  de- 
pression at  the  bottom  of  the  cavity.     The  ligaments  of  the  joint  are  the 


Capsular. 
Ilio-femoral. 


Transverse. 


Teres. 
Cotyloid. 


The  Capsular  Ligament  is  a  strong,  dense,  ligamentous  capsule,  embracing 
the  margin  of  the  acetabulum  above,  and  surrounding  the  neck  of  the  femur 
below.     Its  up'per  circumference  is  attached  to  the  acetabulum  two  or  three 


300  ARTICULATIONS. 

lines  external  to  tlie  cotyloid  ligament;  but  opposite  the  notch  where  the 
margin  of  this  cavity  is  deficient,  it  is  connected  with  the  transverse  ligament, 
and  by  a  few  fibres  to  the  edge  of  the  obturator  foramen.  Its  lower  circumference 
surrounds  the  neck  of  the  femur,  being  attached,  in  front,  to  the  spiral  or  an- 
terior intertrochanteric  line ;  above,  to  the  base  of  the  neck ;  behind,  to  the 
middle  of  the  neck  of  the  bone,  about  half  an  inch  above  the  posterior  inter- 
trochanteric line.  It  is  much  thicker  at  the  upper  and  fore  part  of  the  joint 
where  the  greatest  amount  of  resistance  is  required,  than  below,  where  it  is 
thin,  loose,  and  longer  than  in  any  other  part.  Its  external  surface  (Fig.  194) 
is  rough,  covered  by  numerous  muscles,  and  separated  in  front  from  the  Psoas 
and  Iliacus  by  a  synovial  bursa,  which  not  unfrequently  communicates  by  a 
circular  aperture  with  the  cavity  of  the  joint.  It  differs  from  the  capsular 
ligament  of  the  shoulder,  in  being  much  less  loose  and  lax,  and  in  not  being 
perforated  for  the  passage  of  a  tendon. 

The  Ilio-femoral  Ligament  (Fig.  194)  is  an  accessory  band  of  fibres,  extending 
obliquely  across  the  front  of  the  joint ;  it  is  intimately  connected  with  the 
capsular  ligament,  and  serves  to  strengthen  it  in  this  situation.  It  is  attached, 
above,  to  the  anterior  inferior  spine  of  the  ilium ;  below,  to  the  anterior  inter- 
trochanteric line. 

The  Ligamentum  Teres  is  a  triangular  band  of  fibres,  implanted,  by  its  apex, 
into  the  depression  a  little  behind  and  below  the  centre  of  the  head  of  the 
femur,  and  by  its  broad  base,  which  consists  of  two  bundles  of  fibres,  into  the 
margins  of  the  notch  at  the  bottom  of  the  acetabulum,  becoming  blended  with 
transverse  ligament.  It  is  formed  of  a  bundle  of  fibres,  the  thickness  and 
strength  of  which  are  very  variable,  surrounded  by  a  tubular  sheath  of  synovial 
membrane.  Sometimes,  only  the  synovial  fold  exists,  or  the  ligament  may  be 
altogether  absent.  The  use  of  the  round  ligament  is  to  check  rotation  out- 
wards, as  well  as  adduction  in  the  flexed  position :  it  thus  assists  in  preventing 
dislocation  of  the  head  of  the  femur  forwards  and  outwards,  an  accident  likely 
to  occur  from  the  necessary  mechanism  of  the  joint,  if  not  provided  against 
by  this  ligament  and  the  thick  anterior  part  of  the  capsule.^ 

The  Cotyloid  Ligament  is  a  fibro-cartilaginous  rim  attached  to  the  margin  of 
the  acetabulum,  the  -cavity  of  which  it  deepens ;  at  the  same  time  it  protects 
the  edges  of  the  bone,  and  fills  up  the  inequalities  on  its  surface.  It  is  pris- 
moid  in  form,  its  base  being  attached  to  the  margin  of  the  acetabulum,  and  its 
opposite  edge  being  free  and  sharp ;  whilst  its  two  surfaces  are  invested  by 
synovial  membrane,  the  external  one  being  in  contact  with  the  capsular  liga- 
ment, the  internal  one  being  inclined  inwards  so  as  to  narrow  the  acetabulum 
and  embrace  the  cartilaginous  surface  of  the  head  of  the  femur.  It  is  much 
thicker  above  and  behind  than  below  and  in  front,  and  consists  of  close  compact 
fibres,  which  arise  from  different  points  of  the  circumference  of  the  acetabulum, 
and  interlace  with  each  other  at  very  acute  angles. 

The  Transverse  Ligament  is  a  strong  flattened  band  of  fibres,  which  crosses 
the  notch  at  the  lower  part  of  the  acetabulum,  and  converts  it  into  a  foramen. 
It  is  continuous  at  each  side  with  the  cotyloid  ligament.  An  interval  is  left 
beneath  the  ligament  for  the  passage  of  nutrient  vessels  to  the  joint. 

The  Synovial  Membrane  is  very  extensive.  Commencing  at  the  margin  of 
the  cartilaginous  surface  of  the  head  of  the  femur,  it  covers  all  that  portion  of 
the  neck  which  is  contained  within  the  joint ;  from  the  head  it  is  reflected  on 
the  internal  surface  of  the  capsular  ligament,  covers  both  surfaces  of  the 
cotyloid  ligament,  and  the  mass  of  fat  contained  in  the  fossa  at  the  bottom  of 
the  acetabulum,  and  is  prolonged  in  the  form  of  a  tubular  sheath  around  the 
ligamentum  teres,  as  far  as  the  head  of  the  femur. 

The  Muscles  in  relation  with  the  joint  are,  in  front,  the  Psoas  and  Iliacus, 

•  See  an  intercatinp  nancr.  "  On  the  Use  of  the  Round  Ligament  of  the  Hip-Joint,"  by  Dr.  J. 
Struthers.     Edinburgh  Medical  Journal,  IS.oS. 


KNEE-JOINT.  301 

separated  from  tlie  capsular  ligament  by  a  synovial  bursa ;  above,  the  short 
head  of  the  Rectus  and  Gluteus  Minimus,  the  latter  being  closely  adherent  to 
the  capsule;  internally,  the  Obturator  Externus  and  Pectineus;  behind,  the 
Pyriformis,  Gemellus  Superior,  Obturator  Internus,  Gemellus  Inferior,  Obtu 
rator  Externus,  and  Quadratus  Femoris. 

The  Arteries  supplying  the  joint  are  derived  from  the  obturator,  sciatic,  in- 
ternal circumflex,  and  gluteal. 

The  Nerves  are  articular  branches  from  the  sacral  plexus,  great  sciatic,  obtu- 
rator, and  accessory  obturator  nerves. 

Actions.  The  movements  of  the  hips,  like  all  enarthrodial  joints,  are  very 
extensive;  they  are,  flexion,  extension,  adduction,  abduction,  circumduction, 
and  rotation. 

II.  KNEE-JOINT. 

The  Knee  is  a  ginglymus,  or  hinge-joint ;  the  bones  entering  into  its  forma- 
tion are,  the  condyles  of  the  femur  above,  the  head  of  the  tibia  below,  and  the 
patella  in  front.  The  articular  surfaces  are  covered  with  cartilage,  and  con- 
nected together  by  ligaments,  some  of  which  are  placed  on  the  exterior  of  the 
joint,  whilst  others  occupy  its  interior. 

External  Ligaments.  Internal  Ligaments. 

Anterior,  or  Ligamentum  Patellae.  Anterior,  or  External  Crucial. 

Posterior,  or  Ligamentum  Posticum  Posterior,  or  Internal  Crucial. 

Winslowii.  Two  Semilunar  Fibro-cartilages. 

Internal  Lateral.  Transverse. 

Two  External  Lateral.  Coronary. 

Capsular.  Ligamentum  Mucosum. 

Ligamenta  Alaria. 

The  Anterior  Ligament,  or  Ligamentum  Patellse  (Fig.  206),  is  that  portion  of 
the  common  tendon  of  the  extensor  muscles  of  the  thigh  which  is  continued 
from  the  patella  to  the  tubercle  of  the  tibia,  supplying  the  place  of  an  anterior 
ligament.  It  is  a  strong,  flat,  ligamentous  band,  about  three  inches  in  length, 
attached,  above,  to  the  apex  of  the  patella  and  the  rough  depression  on  its 
posterior  surface;  below,  to  the  lower  part  of  the  tuberosity  of  the  tibia;  its 
superficial  fibres  being  continuous  across  the  front  of  the  patella  with  those  of 
the  tendon  of  the  Quadriceps  Extensor.  Two  synovial  bursas  are  connected 
with  this  ligament  and  the  patella  ;  one  is  interposed  between  the  patella  and 
the  skin  covering  its  anterior  surface ;  the  other  of  small  size,  between  the 
ligamentum  patellae  and  the  upper  part  of  the  tuberosity  of  the  tibia.  The 
posterior  surface  of  this  ligament  is  separated  above  from  the  knee-joint  by  a 
large  mass  of  adipose  tissue ;  its  lateral  margins  are  continuous  with  the  apo- 
neuroses derived  from  the  Vasti  muscles. 

The  Posterior  Ligament^  Ligamentum  Posticum  Winslowii  (Fig.  207),  is  a  broad, 
flat,  fibrous  band,  which  covers  over  the  whole  of  the  back  part  of  the  joint. 
It  consists  of  two  lateral  portions,  formed  chiefly  of  vertical  fibres,  which  arise 
above  from  the  condyles  of  the  femur,  and  are  connected  below  with  the  back 
part  of  the  head  of  the  tibia,  being  closely  united  with  the  tendons  of  the  Gas- 
trocnemius, Plantaris,  and  Popliteus  muscles;  the  central  portion  is  formed  of 
fasciculi,  obliquely  directed  and  separated  from  one  another  by  apertures  for 
the  passage  of  vessels.  The  strongest  of  these  fasciculi  is  derived  from  the 
tendon  of  the  Semi-membranosus,  and  passes  from  the  back  part  of  the  inner 
tuberosity  of  the  tibia,  obliquely  upwards  and  outwards  to  the  back  part  of  the 
outer  condyle  of  the  femur.  The  posterior  ligament  forms  part  of  the  floor  of 
the  popliteal  space,  and  the  popliteal  artery  rests  upon  it. 

The  Internal  Lateral  Ligament  is  a  broad,  flat,  membranous  band  thicker 
behind  than  in  front,  and  situated  nearer  to  the  bacl^  than  the  front  of  the  joint. 


302 


ARTICULATIONS. 


It  is  attached,  above,  to  the  inner  tuberosity  of  the  femur:  below,  to  the  inner 
tuberosity  and  inner  surface  of  the  shaft  of  the  tibia,  to  the  extent  of  about 
two  inches.  It  is  crossed,  at  its  lower  part,  by  the  aponeurosis  of  the  Sartorius, 
and  the  tendons  of  the  Gracilis  and  Semi-tendinosus  muscles,  a  synovial  bursa 

Fig.  206. — Right  Knee-joint.  Anterior  View.     Fig.  207. — Right  Knee-joint.    Posterior  View. 


being  interposed.  Its  deep  surface  covers  the  anterior  portion  of  the  tendon  of 
the  Semi-membranosus,  the  synovial  membrane  of  the  joint,  and  the  inferior 
internal  articular  artery;  it  is  intimately  adherent  to  the  internal  semilunar 
fibro-cartilage. 

The  Long  External  Lateral  Ligament  is  a  strong,  rounded,  fibrous  cord,  situ- 
ated nearer  to  the  back  than  the  front  of  the  joint.  It  is  attached,  above,  to 
the  outer  condyle  of  the  femur ;  below,  to  the  outer  part  of  the  head  of  tlie 
fibula.  Its  outer  surface  is  covered  by  the  tendon  of  the  Biceps,  which  divides 
at  its  insertion  into  two  parts,  separated  by  the  ligament.  The  ligament  has, 
pa.ssing  beneath  it,  the  tendon  of  the  Popliteus  muscle,  and  the  inferior  exter- 
nal articular  vessels  and  nerve. 

The  Short  External  Lateral  Ligament  is  an  accessory  bundle  of  fibres,  placed 
behind  and  parallel  with  the  preceding;  attached,  above,  to  the  lower  part  of 
the  outer  condyle  of  the  femur ;  below,  to  the  summit  of  the  styloid  process 
of  the  fibula.  This  ligament  is  intimately  connected  with  the  capsular  liga- 
ment, and  has,  passing  beneath  it,  the  tendon  of  the  Popliteus  muscle. 

The  Gapsidar  Ligament  consists  of  an  exceedingly  thin,  but  strong,  fibrous 
membrane,  which  fills  in  the  intervals  left  by  the  preceding  ligaments.  It  is 
attached  to  the  femur  immediately  above  its  articular  surface ;  below,  to  the 
upper  border  and  sides  of  the  patella  and  the  margins  of  the  head  of  the  tibia 
and  interarticular  cartilages,  and  is  continuous  behind  with  the  posterior  liga- 
ment.    This  membrane  iS  strengthened  by  fibrous  expansions,  derived  from 


KNEE-JOINT. 


303 


Fig.  208. 


-Right  "Knee-joint.       Showing 
ternal  Ligaments. 


In- 


the  fascia  lata,  from  the  Vasti  and  Crureus  muscles,  and  from  the  Biceps,  Sar- 
torius,  and  tendon  of  the  Semi-membranosus. 

The  Crucial  Ligaments  are  two  interosseous  ligaments  of  considerable  strength, 
situated  in  the  interior  of  the  joint, 
nearer  its  posterior  than  its  anterior 
part.  They  are  called  crucial,  because 
they  cross  each  other,  somewhat  like 
the  lines  of  the  letter  X ;  and  have  re- 
ceived the  names  anterior  and  posterior, 
from  the  position  of  their  attachment 
to  the  tibia. 

The  anterior  or  external  crucial  liga- 
ment (Fig.  208),  smaller  than  the  pos- 
terior, is  attached  to  the  inner  side  of 
the  depression  in  front  of  the  spine  of 
the  tibia,  being  blended  with  the  an- 
terior extremity  of  the  external  semi- 
lunar fibro-cartilage,  and  passing  ob- 
liquely upwards,  backwards,  and  out- 
wards, is  inserted  into  the  inner  and 
back  part  of  the  outer  condyle  of  the 
femur. 

The  posterior  or  internal  crucial  liga- 
ment is  larger  in  size,  but  less  oblique 
in  its  direction  than  the  anterior.  It  is 
attached  to  the  back  part  of  the  depres- 
sion behind  the  spine  of  the  tibia,  and 
to  the  posterior  extremity  of  the  exter- 
nal semilunar  fibro-cartilage;  and  passes 
upwards,  forwards,  and  inwards,  to  be 
inserted  into  the  outer  and  fore-part  of 
the  inner  condyle  of  the  femur.  As  it 
crosses  the  anterior  crucial  ligament,  a 
fasciculus  is  given  off  from  it,  which 
blends  with  the  posterior  part  of  that  ligament.  It  is  in  relation,  in  front,  with 
the  anterior  crucial  ligament;  behind,  with  the  ligamentum  posticum  Winslowii. 

The  Semilunar  Fihro-car- 
tilaqes    (Fio-    209)    are    two     Fig.  209.— Head  of  Tibia,  with  Semilunar  Cartilages,  etc. 
crescentic  °iamell«,    which  Seen  from  above.    Right  Side, 

are  attached  to  the  margins 
of  the  head  of  the  tibia,  and 
serve  to  deepen  its  surface 
for  articulation  with  the 
condyles  of  the  femur.  The 
circumference  of  each  car- 
tilage is  thick  and  convex ; 
the  inner  free  border,  thin, 
and  concave.  Their  upper 
surfaces  are  concave,  and  in 
relation  with  the  condyles 
of  the  femur ;  their  lower 
surfaces  are  flat,  and  rest 
upon  the  head  of  the  tibia. 

Each  cartilage  covers  nearly  the  outer  two-thirds  of  the  corresponding  articular 
surface  of  the  tibia,  leaving  the  inner  third  uncovered ;  both  surfaces  are 
smooth,  and  invested  by  synovial  membrane. 

The  Internal  Semilunar  Fihro-cartilage  is  nearly  semicircular  in  form,  a  little 


304  ARTICULATIONS. 

elongated  from  before  backwards,  and  broader  behind  than  in  front ;  its  convex 
border  is  united  to  the  internal  lateral  ligament,  and  to  the  head  of  the  tibia, 
by  means  of  the  coronary  ligaments;  its  anterior  extremity,  thin  and  pointed, 
is  firmly  implanted  into  a  depression  in  front  of  the  inner  articular  surface  of 
the  tibia ;  its  posterior  extremity  into  the  depression  behind  the  spine,  between 
the  attachment  of  the  external  cartilage  and  posterior  crucial  ligament. 

The  External  Semilunar  Fihro-cartilage  forms  nearly  an  entire  circle,  covering 
a  larger  portion  of  the  articular  surface  than  the  internal  one.  It  is  grooved 
on  its  outer  side,  for  the  tendon  of  the  Popliteus  muscle.  Its  circumference  is 
held  in  connection  with  the  head  of  the  tibia,  by  means  of  the  coronary  liga- 
ments ;  and  its  two  extremities  are  firmly  implanted  in  the  depressions  in  front 
and  behind  the  spine  of  the  tibia.  These  extremities,  at  their  insertion,  are 
interposed  between  the  attachments  of  the  internal  cartilage.  The  external 
semilunar  fibro-cartilage  gives  off  from  its  anterior  border  a  fasciculus,  which 
forms  the  transverse  ligament.  By  its  anterior  extremity,  it  is  continuous  with 
the  anterior  crucial  ligament.  Its  posterior  extremity  divides  into  three  slips ; 
two  of  these  pass  upwards  and  forwards,  and  are  inserted  into  the  outer  side  of 
the  inner  tuberosity  of  the  tibia,  one  in  front,  the  other  behind  the  posterior 
crucial  ligament;  the  third  fasciculus  is  inserted  into  the  back  part  of  the 
anterior  crucial  ligament. 

The  Transverse  Ligament  is  a  band  of  fibres,  which  passes  transversely  from 
the  anterior  convex  margin  of  the  external  semilunar  cartilage  to  the  anterior 
extremity  of  the  internal  cartilage ;  its  thickness  varies  considerably  in  different 
subjects. 

The  Coronary  Ligaments  consist  of  numerous  short  fibrous  bands,  which  con- 
nect the  convex  border  of  the  semilunar  cartilages  with  the  circumference  of 
the  head  of  the  tibia,  and  with  the  other  ligaments  surrounding  the  joint. 

The  Synovial  Membrane  of  the  knee-joint  is  the  largest  and  most  extensive  in 
the  body.  Commencing  at  the  upper  border  of  the  patella,  it  forms  a  large  cul- 
de-sac  beneath  the  Extensor  tendon  of  the  thigh  :  this  is  sometimes  replaced  by 
a  synovial  bursa  interposed  between  the  tendon  and  the  front  of  the  femur, 
which  in  some  subjects  communicates  with  the  synovial  membrane  of  the  knee- 
joint,  by  an  orifice  of  variable  size.  On  each  side  of  the  patella,  the  synovial 
membrane  extends  beneath  the  aponeurosis  of  the  Vasti  muscles,  and  more 
especially  beneath  that  of  the  Vastus  Internus;  and,  below  the  patella,  it  is 
separated  from  the  anterior  ligament  by  a  considerable  quantity  of  adipose 
tissue.  In  this  situation  it  sends  oft'  a  triangular  prolongation,  containing  a  few 
ligamentous  fibres,  which  extends  from  the  anterior  part  of  the  joint  below  the 
patella,  to  the  front  of  the  inter-condyloid  notch.  This  fold  has  been  termed 
the  Ugamentum  mucosum.  The  Ugamenta  alaria  consist  of  two  fringe-like  folds, 
which  extend  from  the  sides  of  the  ligamentum  mucosum,  upwards  and  outwards, 
to  the  sides  of  the  patella.  The  synovial  membrane  invests  the  semilunar  fibro- 
cartilages,  and  on  the  back  part  of  the  external  one  forms  a  cul-de-sac  between 
the  groove  on  its  surface,  and  the  tendon  of  the  Popliteus ;  it  is  continued  to 
the  articular  surface  of  the  tibia:  surrounds  the  crucial  ligaments,  and  the  inner 
surface  of  the  ligaments  which  inclose  the  joint ;  lastly,  it  approaches  the  con- 
dyles of  the  femur,  and  from  them  is  continued  on  to  the  lower  part  of  the  front 
of  the  shaft.  The  pouch  of  synovial  membrane  between  the  extensor  tendon 
and  front  of  the  femur  is  supported,  during  the  movements  of  the  knee,  by  a 
small  muscle,  the  Subcrureus,  which  is  inserted  into  it. 

The  arteries  supplying  the  joint  are  derived  from  the  anastomotic  branch  of 
the  femoral,  articular  branches  of  the  popliteal,  and  recurrent  branch  of  the 
anterior  tibial. 

The  Nerves  are  derived  from  the  obturator,  anterior  crural,  and  external  and 
internal  popliteal. 

Actions. — The  knee-joint  allows  of  movements  of  flexion  and  extension,  and 
of  slight  rotation  inwards  and  outwards.     The  complicated  mechanism  of  this 


KNEj:-JOINT.  305 

joint  renders  it  necessary  to  study  eacli  of  these  movements  separately,  pointing 
out  incidentally  the  functions  of  each  of  the  principal  components  of  the  joint. 
The  tibia  executes  a  rotatory  movement  during  flexion  around  an  imaginary 
axis  drawn  transversely  through  its  upper  end.  This  causes  a  change  in  the 
apposition  of  the  tibia  and  femur.  Thus,  in  extreme  extension,  it  is  the  anterior 
portion  of  the  tibia  which  is  in  contact  with  the  femur ;  in  the  semiflexed  posi- 
tion, its  middle;  in  complete  flexion,  its  posterior  edge.^  Also,  dm'mg flexion 
the  articular  surface  of  the  tibia,  covered  by  the  interarticular  cartilages,  glides 
backwards  on  the  femur.  The  patella  is  attached  by  the  inextensible  ligamentum 
patellee  to  the  tubercle  of  the  tibia,  and  as  the  tibia  glides  backwards,  the  patella 
falls  more  and  more  into  the  intercondyloid  notch  of  the  femur.  The  ligamentum 
patellae  is  put  on  the  stretch  during  flexion,  as  is  also  the  posterior  crucial  liga- 
ment in  extreme  flexion.  The  other  ligaments  are  all  relaxed  by  flexion  of  the 
joint,  though  the  relaxation  of  the  anterior  crucial  ligament  is  very  trifling.  In 
partial  flexion  of  the  knee  before  the  ligamentum  patella3  comes  upon  the 
stretch,  and  while  both  crucial  ligaments  are  somewhat  relaxed,  some  rotation 
of  the  joint  is.  permitted.  Flexion  is  only  checked  during  life  by  the  contact 
of  the  leg  with  the  thigh.  In  extension^  the  ligamentum  patellae  becomes  relaxed, 
and,  in  extreme  extension,  completely  so,  so  as  to  allow  free  lateral  movement 
to  the  patella,  which  then  rests  on  the  front  of  the  condyles  of  the  femur.  The 
other  ligaments  are  all  on  the  stretch.  When  the  limb  has  been  brought  into  a 
straight  line  extension  is  checked,  mainly  by  the  tension  of  the  posterior  crucial 
ligament.  The  movements  of  rotation  of  which  the  knee  is  susceptible  are  per- 
mitted in  the  semiflexed  condition  by  the  partial  relaxation  of  both  crucial 
ligaments,  as  well  as  the  lateral  ligaments.  Eotation  inwards  (or  pronation  of 
the  leg)  is  checked  by  the  anterior  crucial  ligament.  The  chief  agent  in  effecting 
this  movement  is  the  Popliteus  muscle.  Eotation  outwards  (or  supination)  is 
checked  by  the  posterior  crucial  ligament.  It  is  effected  mainly  by  the  Biceps. 
The  main  function  of  the  crucial  ligaments  is  to  act  as  a  direct  bond  of  union 
between  the  tibia  and  femur,  preventing  the  former  bone  from  being  carried  too 
far  backwards  or  forwards.  They  also  assist  the  lateral  ligaments  in  resisting 
any  lateral  bending  of  the  joint.  The  interarticular  cartilages  are  intended,  as 
it  seems,  to  adapt  the  surface  of  the  tibia  to  the  shape  of  the  femur  to  a  certain 
extent,  so  as  to  fill  up  the  intervals  which  would  otherwise  be  left  in  the  varying 
positions  of  the  joint,  and  to  interrupt  the  jars  which  would  be  so  frequently 
transmitted  up  the  limb  in  jumping  or  falls  on  the  feet.  The  patella  is  a  great 
defence  to  the  knee-joint  from  any  injury  inflicted  in  front,  and  it  distributes 
upon  a  large  and  tolerably  even  surface  during  kneeling  the  pressure  which 
would  otherwise  fall  upon  the  prominent  ridges  of  the  condyles :  it  also  affords 
leverage  to  the  Qaadriceps  Extensor  muscle  to  act  upon  the  tibia,  and  Mr.  Ward^ 
has  pointed  out  how  this  leverage  varies  in  the  various  positions  of  the  joint, 
80  that  the  action  of  the  muscle  produces  velocity  at  the  expense  of  force  in  the 
commencement  of  extension,  and,  on  the  contrary,  at  the  close  of  extension 
tends  to  diminish  the  velocity,  and  therefore  the  shock  to  the  ligaments ;  whilst 
in  the  standing  position  it  draws  the  tibia  powerfully  forwards,  and  thus  main- 
tains it  in  its  place. 

The  folds  of  synovial  membrane  and  the  fatty  processes  contained  in  them 
act,  as  it  seems,  mainly  as  padding  to  fill  up  interspaces  and  obviate  concussions. 

The  bursse  in  connection  with  the  synovial  membrane  will  be  found  described 
in  connection  with  the  regional  anatomy  of  the  popliteal  space. 

III.  ARTICULATIONS  BETWEEN  THE  TIBIA  AND  FIBULA. 

The  articulations  between  the  tibia  and  fibula  are  effected  by  ligaments  which 
connect  both  extremities,  as  well  as  the  shafts  of  the  bone.     They  may,  conse- 

'  Sec  Plate  XLYII.  in  Humphry,  on  the  "Skeleton."  *  "Human  Osteology,"  p.  405. 

20 


306  ARTICULATIONS 

quently,  be  subdivided  into  three  sets.     1.  Superior  Tibio-fibular  articulation, 
2.  Middle  Tibio-fibular  articulation.     3.  Inferior  Tibio-fibular  articulation. 

1.  Superior  Tibio-fibular  Articulation. 

This  articulation  is  an  arthrodial  joint.  The  contiguous  surfaces  of  the  bones 
present  two  flat  oval  surfaces  covered  with  cartilage,  and  connected  together  by 
the  following  ligaments: — 

Anterior  Superior  Tibio-fibular. 
Posterior  Superior  Tibio-fibular. 

The  Anterior  Superior  Ligament  (Fig.  208)  consists  of  two  or  three  broad  and 
flat  bands,  which  pass  obliquely  upwards  and  inwards  from  the  head  of  the 
fibula  to  the  outer  tuberosity  of  the  tibia. 

The  Posterior  Superior  Ligament  is  a  single  thick  and  broad  band,  which 
passes  from  the  back  part  of  the  head  of  the  fibula  to  the  back  part  of  the  outer 
tuberosity  of  the  tibia.     It  is  covered  by  the  tendon  of  the  Popliteus  muscle. 

A  Synovial  Membrane  lines  this  articulation.  It  is  occasionally  continuous 
with  that. of  the  knee-joint  at  its  upper  and  back  part. 

2.  Middle  Tibio-fibular  Articulation. 

An  interosseous  membrane  extends  between  the  contiguous  margins  of  the 
tibia  and  fibula,  and  separates  the  muscles  on  the  front  from  those  on  the  back 
of  the  leg.  It  consists  of  a  thin  aponeurotic  lamina  composed  of  oblique  fibres, 
which  pass  between  the  interosseous  ridges  on  the  two  bones.  It  is  broader 
above  than  below,  and  presents  at  its  upper  part  a  large  oval  aperture  for  the 
passage  of  the  anterior  tibial  artery  forwards  to  the  anterior  aspect  of  the  \Qg\ 
and  at  its  lower  part  an  opening  for  the  passage  of  the  anterior  peroneal  vessels. 
It  is  continuous  below  with  the  inferior  interosseous  ligament ;  and  is  perforated 
in  numerous  parts  for  the  passage  of  small  vessels.  It  is  in  relation  in  front 
with  the  Tibialis  Anticus,  Extensor  Longus  Digitorum,  Extensor  Proprius 
Pollicis,  Peroneus  Tertius,  and  the  anterior  tibial  vessels  and  nerve ;  behind, 
with  the  Tibialis  Posticus  and  Flexor  Longus  Pollicis. 

3.  Inferior  Tibio-fibular  Articulation. 

This  articulation  is  formed  by  the  rough  convex  surface  of  the  inner  side 
of  the  lower  end  of  the  fibula,  connected  with  a  similar  rough  surface  on  the 
outer  side  of  the  tibia.  Below,  to  the  extent  of  about  two  lines,  these  surfaces 
are  smooth  and  covered  with  cartilage,  which  is  continuous  with  that  of  the 
ankle-joint.    The  ligaments  of  this  joint  are — 

Inferior  Interosseous.  Posterior  Inferior  Tibio-fibular. 

Anterior  Inferior  Tibio-fibular.        Transverse. 

The  Inferior  Interosseous  Ligament  consists  of  numerous  short,  strong  fibrous 
bands,  which  pass  between  the  contiguous  rough  surfaces  of  the  tibia  and 
fibula,  and  constitute  the  chief  bond  of  union  between  the  bones.  This  liga- 
ment is  continuous,  above,  with  the  interosseous  membrane. 

The  Anterior  Inferior  Ligament  (Fig.  211)  is  a  flat  triangular  band  of  fibres, 
broader  below  than  above,  which  extends  obliquely  downwards  and  outwards 
between  the  adjacent  margins  of  the  tibia  and  fibula  on  the  front  aspect  of  the 
articulation.  It  is  in  relation,  in  front,  with  the  Peroneus  Tertius,  the  aponeu- 
rosis of  the  leg,  and  the  integument;  behind,  with  the  inferior  interosseous 
ligament;  and  lies  in  contact  with  the  cartilage  covering  the  astragalus. 

Tiie  Posterior  Inferior  Ligament^  smaller  than  the  preceding,  is  disposed  in  a 
similar  manner  on  the  posterior  surface  of  the  articulation. 

The  Transverse  Ligament  is  a  long  narrow  band,  continuous  with  the  pre- 


ANKLE-JOINT 


30t 


ceding,  passing  transversely  across  tlie  back  of  the  joint,  from  the  external 
malleolus  to  the  tibia,  a  short  distance  from  its  malleolar  process.  This  liga- 
ment projects  below  the  margin  of  the  bones,  and  forms  part  of  the  articulating 
surface  for  the  astragalus. 

The  Synovial  Membrane  lining  the  articular  surfaces  is  derived  from  that  of 
the  ankle-joint. 

Actions.  The  movement  permitted  in  these  articulations  is  limited  to  a  very 
slight  gliding  of  the  articular  surfaces  one  upon  another. 


IV.  ANKLEJOINT. 

The  Ankle  is  a  ginglymus  or  hinge  joint.  The  bones  entering  into  its  forma- 
tion are  the  lower  extremity  of  the  tibia  and  its  malleolus,  and  the  malleolus 
of  the  fibula.  These  bones  are  united  above,  and  form  an  arch,  to  receive  the 
upper  convex  surface  of  the  astragalus  and  its  two  lateral  facets.  The  bony 
surfaces  are  covered  with  cartilage,  and  connected  together  by  the  following 
ligaments : — 

Anterior.  Internal  Lateral. 

External  Lateral. 

The  Anterior  or  Tihio-tarsal  Ligament  (Fig.  210)  is  a  broad,  thin,  membranous 
layer,  attached,  above,  to  the  margin  of  the  articular  surface  of  the  tibia ;  below, 


Fig.  210. — Ankle-joint :  Tarsal  and  Tarso-metatarsal  Articulations. 

Bight  Side. 


Internal  View. 


TARSO-MrTATARBAI. 


TARSAL    ARTIC" 


to  the  margin  of  the  astragalus,  in  front  of  its  articular  surface.  It  is  in  rela- 
tion, in  front,  with  the  extensor  tendons  of  the  toes,  with  the  tendons  of  the 
Tibialis  Anticus  and  Peroneus  Tertius,  and  the  anterior  tibial  vessels  and  nerve; 
behind,  it  lies  in  contact  with  the  synovial  membrane. 

The  Internal  Lateral  or  Deltoid  Ligament  consists  of  two  layers,  superficial 
and  deep.  The  superficial  layer  is  a  strong,  flat,  triangular  band,  attached, 
above,  to  the  apex  and  anterior  and  posterior  borders  of  the  inner  malleolus. 
The  most  anterior  fibres  pass  forwards  to  be  inserted  into  the  scaphoid ;  the 
middle  descend  almost  perpendicularly  to  be  inserted  into  the  os  calcis ;  and 
the  posterior  fibres  pass  backwards  and  outwards  to  be  attached  to  the  inner 


308 


ARTICULATIONS. 


side  of  the  astragalus.  The  ckeper  layer  consists  of  a  short,  thick,  and  strong 
fasciculus,  which  passes  from  the  apex  of  the  malleolus  to  the  inner  surface  of 
the  astragalus,  below  the  articular  surface.  This  ligament  is  covered  by  the 
tendons  of  the  Tibialis  Posticus  and  Flexor  Longus  Digitorura  muscles. 

The  External  Lateral  Ligament  (Fig.  211)  consists  of  three  fasciculi,  taking 


Fig.  211. 


-Ankle-joint:  Tarsal  and  Tarsometatarsal  Articulations. 
Right  Side. 


External  View. 


NFUIOR  TIBIO-FIBOLM 
ARTICn 

ANKLE-JOINT 

TARSAL  ARTie>« 

TARSO-MCTATARSAU  ARTICIt 


different  directions,  and  separated  by  distinct  intervals ;  for  which  reason  it  is 
(^scribed  by  some  anatomists  as  three  distinct  ligaments.^  This  would  seem 
the  preferable  description,  were  it  not  that  the  old  nomenclature  has  passed 
into  general  use. 

The  anterior  fasciculus,  the  shortest  of  the  three,  passes  from  the  anterior 
margin  of  the  summit  of  the  external  malleolus,  downwards  and  forwards,  to 
the  astragalus,  in  front  of  its  external  articular  facet. 

The  posterior  fasciculus,  the  most  deeply  seated,  passes  from  the  depression 
at  the  inner  and  back  part  of  the  external  malleolus  to  the  astragalus,  behind 
its  external  malleolar  facet.     Its  fibres  are  almost  horizontal  in  direction. 

The  middle  fasciculus,  the  longest  of  the  three,  is  a  narrow  rounded  cord, 
passing  from  the  apex  of  the  external  malleolus  downwards  and  slightly  back- 
wards to  the  middle  of  the  outer  side  of  the  os  calcis.  It  is  covered  by  the 
tendons  of  the  Peroneus  Longus  and  Peroneus  Brevis. 

There  is  no  posterior  ligament,  its  place  being  supplied  by  the  transverse 
ligament  of  the  inferior  tibio-fibular  articulation. 

The  Synovial  Membrane  invests  the  inner  surface  of  the  ligaments,  and  sends 
a  duplicature  upwards  between  the  lower  extremities  of  the  tibia  and  fibula 
for  a  short  distance. 

Relations.  The  tendons,  vessels,  and  nerves  in  connection  with  the  joint  are, 
in  front,  from  within  outwards,  the  Tibialis  Anticus,  Extensor  Proprius  PoUicis, 
anterior  tibial  vessels,  anterior  tibial  nerve.  Extensor  Communis  Digitorum, 
and  Peroneus  Tertius;  behind,  from  within  outwards.  Tibialis  Posticus,  Flexor 
Longus  Digitorum,  posterior  tibial  vessels,  posterior  tibial  nerve,  Flexor  Longus 


•  Humphry,  on  the  "  Skeleton,"  p.  559. 


OF    THE    TARSUS.  309 

Pollicis,  and,  in  the  groove  behind  the  external  malleolus,  the  tendons  of  the 
Peroneus  Longus  and  Peroneas  Brevis. 

The  Arteries  supplying  the  joint  are  derived  from  the  malleolar  branches  of 
the  anterior  tibial  and  peroneal. 

The  Nerves  are  derived  from  the  anterior  tibial. 

ActioTis.  The  movements  of  the  joint  are  limited  to  flexion  and  extension 
There  is  no  lateral  motion. 

V.  ARTICULATIONS  OF  THE  TARSUS. 

These  articulations  may  be  subdivided  into  three  sets :  1.  Articulation  of  the 
first  row  of  tarsal  bones.  2.  Articulation  of  the  second  row  of  tarsal  bones. 
3.  Articulations  of  the  two  rows  with  each  other. 

1.  Articulation  qp  the  First  Eow  of  Tarsal  Bones. 

The  articulations  between  the  astragalus  and  os  calcis  are  two  in  number — 
anterior  and  posterior.  They  are  arthrodial  joints.  The  bones  are  connected 
together  by  three  ligaments : — 

External  Calcaneo-astragaloid.  Posterior  Calcaneo-astragaloid. 

Interosseous. 

The  External  Calcaneo-astragaloid  Ligament  (Fig.  211)  is  a  short  strong  fasci- 
culus, passing  from  the  outer  surface  of  the  astragalus,  immediately  beneath 
its  external  malleolar  facet,  to  the  outer  edge  of  the  os  calcis.  It  is  placed  in 
front  of  the  middle  fasciculus  of  the  external  lateral  ligament  of  the  ankle- 
joint,  with  the  fibres  of  which  it  is  parallel. 

The  Posterior  Calcaneo-astragaloid  Ligament  (Fig.  210)  connects  the  posterior 
extremity  of  the  astragalus  with  the  upper  contiguous  surface  of  the  os  calcis ; 
it  is  a  short  narrow  band,  the  fibres  of  which  are  directed  obliquely  backwards 
and  inwards. 

The  Interosseous  Ligament  forms  the  chief  bond  of  union  between  the  bones. 
It  consists  of  numerous  vertical  and  oblique  fibres,  attached,  by  one  extremity, 
to  the  groove  between  the  articulating  surfaces  of  the  astragalus ;  by  the  otheii 
to  a  corresponding  depression  on  the  upper  surface  of  the  os  calcis.  It  is  very 
thick  and  strong,  being  at  least  an  inch  in  breadth  from  side  to  side,  and  serves 
to  unite  the  os  calcis  and  astragalus  solidly  together. 

The  Synovial  Membranes  (Fig.  213)  are  two  in  number:  one  for  the  posterior 
calcaneo-astragaloid  articulation;  a  second  for  the  anterior  calcaneo-astragaloid 
joint.  The  latter  synovial  membrane  is  continued  forwards  between  the  con- 
tiguous surfaces  of  the  astragalus  and  scaphoid  bones. 

2.  Articulations  of  the  Second  Eow  op  Tarsal  Bones, 

The  articulations  between  the  scaphoid,  cuboid,  and  three  cuneiform  are 
effected  by  the  following  ligaments : — 

Dorsal.  Plantar.  Interosseous. 

The  Dorsal  Ligaments  are  small  bands  of  parallel  fibres,  which  pass  from 
each  bone  to  the  neighboring  bones  with  which  it  articulates. 

The  Plantar  Ligaments  have  the  same  arrangement  on  the  plantar  surface. 

The  Interosseous  Ligaments  are  four  in  number.  They  consist  of  strong  trans- 
verse fibres,  which  pass  between  the  rough  non-articular  surfaces  of  adjoining 
bones.  There  is  one  between  the  sides  of  the  scaphoid  and  cuboid ;  a  second 
between  the  internal  and  middle  cuneiform  bones;  a  third  between  the  middle 
and  external  cuneiform ;  and  a  fourth  between  the  external  cuneiform  and 
cuboid.  The  scaphoid  and  cuboid,  when  in  contact,  present  each  a  small 
articulating  facet,  covered  with  cartilage,  and  lined  either  by  a  separate  synovial 
membrane,  or  by  an  offset  from  the  common  tarsal  synovial  membrane. 


310 


ARTICULATIONS. 


3.  Articulations  op  the  Two  Rows  of  the  Tarsus  with  each  other. 

These  may  be  conveniently  divided  into  three  sets :  The  joint  between  the 
OS  calcis  and  the  cuboid.  The  ligaments  connecting  the  os  calcis  with  the  sca- 
phoid.    The  joint  between  the  astragalus  and  the  scaphoid. 

The  ligaments  connecting  the  os  calcis  with  the  cuboid  are  four  in  number : — 

Superior  Calcaneo-cuboid. 

Internal  Calcaneo-cuboid  (Interosseous). 


Dorsal. 


Plantar. 


Long  Calcaneo-cuboid. 
Short  Calcaneo-cuboid. 


Fig.  212. — Ligaments  of  Plantar  Surface  of 
the  Foot. 


The  Superior  Calcaneo-cuboid  Ligament  (Fig.  211)  is  a  thin  and  narrow  fasci- 
culus which  passes  between  the  contigu- 
ous surfaces  of  the  os  calcis  and  cuboid, 
on  the  dorsal  surface  of  the  joint. 

The  Internal  Calcaneo-cuboid  {Interos- 
seous) Ligament  {Fig,  211)  is  a  short,  but 
thick  and  strong,  band  of  fibres,  arising 
from  the  Os  calcis,  in  the  deep  groove 
which  intervenes  between  it  and  the 
astragalus;  and  closely  blended,  at  its 
origin,  with  the  superior  caleaneo-sca- 
phoid  ligament.  It  is  inserted  into  the 
inner  side  of  the  cuboid  bone.  This  liga- 
ment forms  one  of  the  chief  bonds  of  union 
between  the  first  and  second  row  of  the 
tarsus. 

The  Long  Calcaneo-cuboid  (Fig.  212), 
the  more  superficial  of  the  two  plantar 
ligaments,  is  the  longest  of  all  the  liga- 
ments of  the  tarsus ;  it  is  attached  to  the 
under  surface  of  the  os  calcis,  from  near 
the  tuberosities,  as  far  forwards  as  the 
anterior  tubercle;  its  fibres  pass  forAvards 
to.be  attached  to  the  ridge  on  the  under 
surface  of  the  cuboid  bone,  the  more  su- 
perficial fibres  being  continued  onwards 
to  the  bases  of  the  second,  third,  and 
fourth  metatarsal  bones.  This  ligament 
crosses  the  groove  on  the  under  surface 
of  the  cuboid  bone,  converting  it  into  a 
/  .^M||K-|  '  f}-'i   l#r  an    %    '^        canal  for  the  passage  of  the  tendon  of  the 

tz-ir     •'>" twtkLm^^m  l^^l»  reroneus  Longus. 

W^^fa^yroM  pil  •  The  Short  Calcaneo-cuboid  Ligament  lies 

i        ;M   V|w  t  ™  nearer  to  the  bones  than  the  preceding, 

i.'.lli      I    «   f    •  from  which    it  is  separated  by  a  little 

areolar  adipose  tissue.  It  is  exceedingly 
broad,  about  an  inch  in  length,  and  extends  from  the  tubercle  and  the  depres- 
sion in  front  of  it  on  the  fore  part  of  the  under  surface  of  the  os  calcis,  to  the 
inferior  surface  of  the  cuboid  bone  behind  the  peroneal  groove.  A  separate 
synovial  membrane  is  found  in  the  calcaneo-cuboid  articulation. 

The  ligaments  connecting  the  os  calcis  with  the  scaphoid  are  two  in  number: — 

Superior  Calcaneo-scaphoid.  Inferior  Calcaneo-scaphoid. 

The  Superior  Calcaneo-scapboid  (Fig.  211)  arises,  as  already  mentioned,  with 
the  internal  calcaneo-cuboid  in  the  deep  groove  between  the  astragalus  and  os 
calcis  ;  it  passes  forward  from  the  inner  side  of  the  anterior  extremity  of  the  os 


OF    THE    TARSUS.  311 

calcis  to  the  outer  side  of  the  scaphoid  bone.  These  two  ligaments  resemble 
the  letter  Y,  being  blended  together  behind,  but  separated  in  front. 

The  Inferior  Gahaneo-scaiithoid  (Fig.  212)  is  by  far  the  larger  and  stronger  of 
the  two  ligaments  of  this  articulation;  it  is  a  broad  and  thick  band  of  fibres, 
which  passes  forwards  and  inwards  from  the  anterior  and  inner  extremity  of 
the  OS  calcis  to  the  under  surface  of  the  scaphoid  bone.  This  ligament  not  only 
serves  to  connect  the  os  calcis  and  scaphoid,  but  supports  the  head  of  the  astra- 
galus, forming  part  of  the  articular  cavity  in  which  it  is  received.  Its  upper 
surface  is  lined  by  the  synovial  membrane  continued  from  the  anterior  calcaneo- 
astragaloid  articulation.  Its  under  surface  is  in  contact  with  the  tendon  of  the 
Tibialis  Posticus  muscle.^ 

The  articulation  between  the  astragalus  and  scaphoid  is  an  arthrodial  joint ; 
the  rounded  head  of  the  astragalus  being  received  into  the  concavity  formed 
by  the  posterior  surface  of  the  scaphoid,  the  anterior  articulating  surface  of  the 
calcaneum,  and  the  upper  surface  of  the  calcaneo-scaphoid  ligament,  which  fills 
up  the  triangular  interval  between  those  bones.  The  only  ligament  of  this 
joint  is  the  superior  astragalo-scaphoid,  a  broad  band,  which  passes  obliquely 
forwards  from  the  neck  of  the  astragalus  to  the  superior  surface  of  the  scaphoid 
bone.  It  is^  thin  and  weak  in  texture,  and  covered  by  the  extensor  tendons. 
The  inferior  calcaneo-scaphoid  supplies  the  place  of  an  inferior  ligament. 

The  Synovial  Membrane  which  lines  the  joint  is  continued  forwards  from  the 
anterior  calcaneo-astragaloid  articulation.  This  articulation  permits  of  conside- 
rable mobility ;  but  its  feebleness  is  such  as  to  allow  occasionally  of  dislocation 
of  the  astragalus. 

The  Synovial  Membranes  (Fig.  213)  found  in  the  articulations  of  the  tarsus 
are  four  in  number ;  one  for  the  posterior  calcaneo-astragaloid  articulation ;  a 

Fig.  213. — Oblique  Section  of  the  Articulations  of  the  Tarsus  and  Metatarsus. 
Showing  the  Six  Synovial  Membranes. 


second  for  the  anterior  calcaneo-astragaloid  and  astragalo-scaphoid  articulations; 
2k  third  for  the  calcaneo-cuboid  articulation;  and  a /o?/r</i  for  the  articulations 
of  the  scaphoid  with  the  three  cuneiform,  the  three  cuneiform  with  each  other, 
the  external  cuneiform  with  the  cuboid,  and  the  middle  and  external  cuneiform 
with  the  bases  of  the  second  and  third  metatarsal  bones.  The  prolongation 
which  lines  the  metatarsal  bones  passes  forwards  between  the  external  and 
middle  cuneiform  bones.  A  small  synovial  membrane  is  sometimes  found  be- 
tween the  contiguous  surfaces  of  the  scaphoid  and  cuboid  bones. 

Actions.     The  movements  permitted  between  the  bones  of  the  first  row,  the 
astragalus  and  os  calcis,  are  limited  to  a  gliding  upon  each  other  from  before 

'  Mr.  Hancock  describes  an  extension  of  this  lijrament  upwards  on  the  inner  side  of  the  foot, 
which  completes  the  socket  of  the  joint  in  that  direction.     Lancet,  1866,  vol.  i.  p.  618. 


312  ARTICULATIONS. 

backwards,  and  from  side  to  side.  The  gliding  movement  which  takes  place 
between  the  bones  of  the  second  row  is  very  slight,  the  articulation  between  the 
scaphoid  and  cuneiform  bones  being  more  movable  than  those  of  the  cuneiform 
with  each  other  and  with  the  cuboid.  The  movement  which  takes  place  between 
the  two  rows  is  more  extensive,  and  consists  in  a  sort  of  rotation,  by  means  of 
which  the  sole  of  the  foot  may  be  slightly  flexed,  and  extended,  or  carried  in- 
wards and  outwards. 

VI.  TARSO-METATARSAL  ARTICULATIONS. 

These  are  arthrodial  joints.  The  bones  entering  into  their  formation  are 
the  internal,  middle,  and  external  cuneiform,  and  the  cuboid,  which  articulate 
with  the  metatarsal  bones  of  the  five  toes.  The  metatarsal  bone  of  the  great 
toe  articulates  with  the  internal  cuneiform;  that  of  the  second  is  deeply 
wedged  in  between  the  internal  and  external  cuneiform,  resting  against  the 
middle  cuneiform,  and  being  the  most  strongly  articulated  of  all  the  meta- 
tarsal bones ;  the  third  metatarsal  articulates  with  the  extremity  of  the  ex- 
ternal cuneiform ;  the  fourth  with  the  cuboid  and  external  cuneiform ;  and 
the  fifth  with  the  cuboid.  The  articular  surfaces  are  covered  with  cartilage, 
lined  by  synovial  membrane,  and  connected  together  by  the  following 
ligaments : — 

Dorsal.  Plantar. 

Interosseous. 

The  Dorsal  Ligaments  consist  of  strong,  flat,  fibrous  bands,  which  connect  the 
tarsal  with  the  metatarsal  bones.  The  first  metatarsal  is  connected  to  the 
internal  cuneiform  by  a  single  broad,  thin,  fibrous  band ;  the  second  has  three 
dorsal  ligaments,  one  from  each  cuneiform  bone ;  the  third  has  one  from  the 
external  cuneiform  ;  and  the  fourth  and  fifth  have  one  each  from  the  cuboid. 

The  Plantar  Ligaments  consist  of  longitudinal  and  oblique  fibrous  bands 
connecting  the  tarsal  and  metatarsal  bones,  but  disposed  with  less  regularity 
than  on  the  dorsal  surface.  Those  for  the  first  and  second  metatarsal  are  the 
most  strongly  marked ;  the  second  and  third  metatarsal  receive  strong  fibrous 
bands,  which  pass  obliquely  across  from  the  internal  cuneiform ;  the  plantar 
li§|iments  of  the  fourth  and  fifth  metatarsal  consist  of  a  few  scanty  fibres 
derived  from  the  cuboid. 

The  Interosseous  Ligaments  are  three  in  number :  internal,  middle,  and  ex- 
ternal. The  internal  one  passes  from  the  outer  extremity  of  the  internal 
cuneiform  to  the  adjacent  angle  of  the  second  metatarsal.  The  middle  one,  less 
strong  than  the  preceding,  connects  the  external  cuneiform  with  the  adjacent 
angle  of  the  second  metatarsal.  The  external  interosseous  ligament  connects 
the  outer  angle  of  the  external  cuneiform  with  the  adjacent  side  of  the  third 
metatarsal. 

The  Synovial  Membranes  of  these  articulations  are  three  in  number :  one  for 
the  metatarsal  bone  of  the  great  toe,  with  the  internal  cuneiform ;  one  for  the 
second  and  third  metatarsal  bones,  with  the  middle  and  external  cuneiform ; 
this  is  a  part  of  the  great  tarsal  synovial  membrane ;  and  one  for  the  fourth 
and  fifth  metatarsal  bones  with  the  cuboid.  The  synovial  membranes  of  the 
tarsus  and  metatarsus  are  thus  seen  to  be  six  in  number  (Fig.  213). 

Articulations  of  the  Metatarsal  Bones  with  each  other. 

The  bases  of  the  metatarsal  bones,  except  the  first,  are  connected  together  by 
dorsal,  plantar,  and  interosseous  ligaments.  The  dorsal  and  jylantar  ligaments 
pass  from  one  metatarsal  bone  to  another.  The  interosseotis  ligaments  lie  deeply 
between  the  rough  non -articular  portions  of  their  lateral  surfaces.  The  articular 
surfaces  are  covered  with  cartilage,  and  provided  with  synovial  membrane, 
continued  forwards  from  the  tarso- metatarsal  joints.     The  digital  extremities 


METATARSO-PHALANGEAL— OF  THE  PHALANGES.   313 

of  the  metatarsal  bones  are  united  by  the  transverse  metatarsal  ligament.  It 
connects  the  great  toe  with  the  rest  of  the  metatarsal  bones ;  in  this  respect  it 
differs  from  the  transverse  ligament  in  the  hand. 

Actions.  The  movement  permitted  in  the  tarsal  ends  of  the  metatarsal  bones 
is  limited  to  a  slight  gliding  of  the  articular  surfaces  upon  one  another ;  con- 
siderable motion,  however,  takes  place  in  the  digital  extremities. 

VIL  METATARSO-PHALANGEAL  ARTICULATIONS. 

The  heads  of  the  metatarsal  bones  are  connected  with  the  concave  articular 
surfaces  of  the  first  phalanges  by  the  following  ligaments — 

Plantar.  Two  Lateral. 

They  are  arranged  precisely  similar  to  the  corresponding  parts  in  the  hand. 
The  expansion  of  the  extensor  tendon  supplies  the  place  of  a  dorsal  ligament. 

Actions.  The  movements  permitted  in  the  metatarso-phalangeal  articulations 
are  flexion,  extension,  abduction,  and  adduction. 

VIII.  ARTICULATIONS  OF  THE  PHALANGES. 

The  ligaments  of  these  articulations  are  similar  to  those  found  in  the  hand  ; 
each  pair  of  phalanges  being  connected  by  an  anterior  or  plantar  and  two  lateral 
ligaments,  and  their  articular  surfaces  lined  by  synovial  membrane.  Their 
actions  are  also  similar. 


For  further  information  on  this  subject,  the  student  is  referred  to  Cruveilhier's  "  Anatomie 
Descriptive ;"  to  Dr.  Humphry's  work  on  the  "  Human  Skeleton,  including  the  Joints  ;"  and 
to  Arnold's  "  Tabulae  AnatomicEe,"  Fascic.  4.  Pars  2.     Icones  Articulorura  et  Ligamentorum. 


The  Muscles  and  Fasciae.' 

The  Muscles  are  connected  with  the  bones,  cartilages,  ligaments,  and  skin, 
either  directly  or  through  the  intervention  of  fibrous  structures,  called  tendons 
or  aponeuroses.  Where  a  muscle  is  attached  to  bone  or  cartilage,  the  fibres 
terminate  in  blunt  extremities  upon  the  periosteum  or  perichondrium,  and  do 
not  come  into  direct  relation  with  the  osseous  or  cartilaginous  tissue.  Where 
muscles  are  connected  with  the  skin,  they  either  lie  as  a  flattened  layer  beneath 
it,  or  are  connected  with  its  areolar  tissue  by  larger  or  smaller  bundles  of  fibres, 
as  in  the  muscles  of  the  face. 

The  muscles  vary  extremely  in  their  form.  In  the  limbs,  they  are  of  con- 
siderable length,  especially  the  more  superficial  ones,  the  deep  ones  being  gene- 
rally broad ;  they  surround  the  bones,  and  form  an  important  protection  to  the 
various  joints.  In  the  trunk,  they  are  broad,  flattened,  and  expanded,  forming 
the  parietes  of  the  cavities  which  they  inclose ;  hence,  the  reason  of  the  terms, 
long^  broad,  short,  etc.,  used  in  the  description  of  a  muscle. 

There  is  considerable  variation  in  the  arrangement  of  the  fibres  of  certain 
muscles  with  reference  to  the  tendons  to  which  they  are  attached.  In  some, 
the  fibres  are  arranged  longitudinally,  and  terminate  at  either  end  in  a  narrow 
tendon.  If  the  fibres  converge,  like  the  plumes  of  a  pen,  to  one  side  of  a  tendon, 
which  runs  the  entire  length  of  a  muscle,  the  muscle  is  said  to  be  'penniform,  as 
the  Peronei ;  if  they  converge  to  both  sides  of  the  tendon,  the  muscle  is  called 
hipenniform,  as  the  Eectus  Femoris ;  if  they  converge  from  a  broad  surface  to  a 
narrow  tendinous  point,  the  muscle  is  said  to  be  radiated,  as  the  Temporal  and 
Glutei  muscles. 

They  differ  no  less  in  size ;  the  Gastrocnemius  forms  the  chief  bulk  of  the 
back  of  the  leg,  and  the  fibres  of  the  Sartorius  are  nearly  two  feet  in  length, 
whilst  the  Stapedius,  a  small  muscle  of  the  internal  ear,  weighs  about  a  grain, 
and  its  fibres  are  not  more  than  two  lines  in  length. 

The  names  applied  to  the  various  muscles  have  been  derived:  1,  from  their 
situation,  as  the  Tibialis,  Radialis,  Ulnaris,  Peroneus ;  2,  from  their  direction, 
as  tlie  Rectus  Abdominis,  Obliqui  Capitis,  Transversalis ;  3,  from  their  uses,  as 
Flexors,  Extensors,  Abductors,  etc. ;  4,  from  their  shape,  as  the  Deltoid,  Trape- 
zius, Rhomboideus ;  5,  from  the  number  of  their  divisions,  as  the  Biceps,  the 
Triceps;  6,  from  their  points  of  attachment,  as  the  Steroo-cleido-mastoid, 
Sterno-hyoid,  Sterno-thyroid. 

In  the  description  of  a  muscle,  the  tern>  origin  is  meant  to  imply  its  more 
fixed  or  central  attachment;  and  the  term  insertion  the  movable  point  upon 
which  the  force  of  the  muscle  is  directed;  but  the  origin  is  absolutely  fixed  in 
only  a  very  small  number  of  muscles,  such  as  those  of  the  face,  which  are 
attached  by  one  extremity  to  the  bone,  and  by  the  other  to  the  movable 
integument ;  in  the  great  number,  the  muscle  can  be  made  to  act  from  either 
extremity. 

In  the  dissection  of  the  muscles,  the  student  should  pay  especial  attention  to 
the  exact  origin,  insertion,  and  actions  of  each,  and  its  more  important  relations 

'  The  Muscles  jind  Fascia;  are  described  conjointly,  in  order  that  the  student  may  consider 
the  arranfrement  of  the  latter  in  his  dissection  of  the  former.  It  is  rare  for  the  student  of  anatomy 
in  this  country  to  have  the  opportunity  of  dissecting  the  fasciaj  separately;  and  it  is  for  this  rea- 
son, as  well  as  from  the  dose  connection  that  exists  between  the  muscles  and  their  investing 
n|)ont'urose8,  that  they  are  considered  together.  Some  general  observations  are  first  made  on 
the  anatomy  of  the  muscles  and  fasciae,  the  special  description  being  given  in  connection  with 
the  ditl'erent  regions. 

8U 


MUSCLES    AND    FASCIA.  315 

with  surrounding  parts.  An  accurate  knowledge  of  the  points  of  attachment 
of  the  muscles  is  of  great  importance  in  the  determination  of  their  action.  By 
a  knowledge  of  the  action  of  the  muscles,  the  surgeon  is  able  to  explain  the 
causes  of  displacement  in  various  forms  of  fracture,  and  the  causes  which  pro- 
duce distortion  in  various  deformities,  and  consequently,  to  adopt  appropriate 
treatment  in  each  case.  The  relations,  also,  of  some  of  the  muscles,  especially 
those  in  immediate  apposition  with  the  larger  bloodvessels,  and  the  surface- 
markings  they  produce,  should  be  especially  remembered,  as  they  form  useful 
guides  in  the  application  of  a  ligature  to  those  vessels. 

Tendons  are  white,  glistening,  fibrous  cords,  varying  in  length  and  thickness, 
sometimes  round,  sometimes  flattened,  of  considerable  strength,  and  only  slightly 
elastic.  They  consist  almost  entirely  of  white  fibrous  tissue,  the  fibrils  of  which 
have  an  undulating  course  parallel  with  each  other,  and  are  firmly  united 
together.  They  are  very  sparingly  supplied  with  bloodvessels,  the  smaller 
tendons  presenting  in  their  interior  not  a  trace  of  them.  Nerves  also  are  not 
present  in  the  smaller  tendons ;  but  the  larger  ones,  as  the  tendo  Achillis, 
receive  nerves  which  accompany  the  nutrient  vessels.  The  tendons  consist 
principally  of  a  substance  which  yields  gelatine. 

Aponeuroses  are  fibrous  membranes,  of  a  pearly-white  color,  iridescent,  glisten- 
ing, and  similar  in  structure  to  the  tendons.  They  are  destitute  of  nerves,  and 
the  thicker  ones  only  sparingly  supplied  with  bloodvessels. 

The  tendons  and  aponeuroses  are  connected,  on  the  one  hand,  with  the  mus- 
cles ;  and,  on  the  other  hand,  with  the  movable  structures,  as  the  bones,  carti- 
lages, ligaments,  fibrous  membranes  (for  instance,  the  sclerotic),  and  the  syno- 
vial membranes  (Subcrureus,  Subanconeus).  Where  the  muscular  fibres  are  in 
a  direct  line  with  those  of  the  tendon  or  aponeurosis,  the  two  are  directly  con- 
tinuous, the  muscular  fibre  being  distinguishable  from  that  of  the  tendon  only 
by  its  striation.  But  where  the  muscular  fibre  joins  the  tendon  or  aponeurosis 
at  an  oblique  angle,  the  former  terminates,  according  to  'Kolliker,  in  rounded 
extremities,  which  are  received  into  corresponding  depressions  on  the  surface 
of  the  latter,  the  connective  tissue  between  the  fibres  being  continuous  with 
that  of  the  tendon.  The  latter  mode  of  attachment  occurs  in  all  the  penniform 
and  bipenniform  muscles,  and  in  those  muscles  the  tendons  of  which  commence 
in  a  membranous  form,  as  the  Gastrocnemius  and  Soleus. 

The  Fascise  {fascia,  a  bandage)  are  fibro-areolar  or  aponeurotic  laminae,  of 
variable  thickness  and  strength,  found  in  all  regions  of  the  body,  investing  the 
softer  and  more  delicate  organs.  The  fasciae  have  been  subdivided,  from  the 
structure  which  they  present,  into  two  groups,  fibro-areolar  or  superficial  fasciae, 
and  aponeurotic  or  deep  fascia). 

The  Jibro-areola7' fascia  is  found  immediately  beneath  the  integument  over 
almost  the  entire  surface  of  the  body,  and  is  generally  known  as  the  stqyerfcial 
fascia.  It  connects  the  skin  with  the  deep  or  aponeurotic  fascia,  and  consists 
of  fibro-areolar  tissue,  containing  in  its  meshes  pellicles  of  fat  in  varying 
quantity.  In  the  eyelids  and  scrotum,  where  adipose  tissue  is  rarely  deposited, 
this  tissue  is  very  liable  to  serous  infiltration.  The  superficial  fascia  varies  in 
thickness  in  different  parts  of  the  body:  in  the  groin  it  is  so  thick  as  to  be 
capable  of  being  subdivided  into  several  laminae,  but  in  the  palm  of  the  hand 
it  is  of  extreme  thinness,  and  intimately  adherent  to  the  integument.  The 
superficial  fascia  is  capable  of  separation  into  two  or  more  layers,  between 
which  are  found  the  superficial  vessels  and  nerves,  and  superficial  lymphatic 
glands ;  as  the  superficial  epigastric  vessels  in  the  abdominal  region,  the  radial 
and  ulnar  veins  in  the  forearm,  the  saphenous  veins  in  the  leg  and  thigh ;  cer- 
tain cutaneous  muscles  are  also  situated  in  the  superficial  fascia,  as  the  Platysma 
Myoides  in  the  neck,  and  the  Orbicularis  Palpebrarum  around  the  eyelids. 
This  fascia  is  most  distinct  at  the  lower  part  of  the  abdomen,  the  scrotum,  peri- 
nasum,  and  extremities ;  is  very  thin  in  those  regions  where  muscular  fibres  are 
inserted  into  the  integument,  as  on  the  side  of  the  neck,  the  face,  and  around 


316  MUSCLES    AND    FASCIA. 

the  margin  of  the  anus ;  and  is  almost  entirely  wanting  in  the  palms  of  the 
hands  and  soles  of  the  feet,  where  the  integument  is  adherent  to  the  subjacent 
aponeurosis.  The  superficial  fascia  connects  the  skin  to  the  subjacent  parts, 
facilitates  the  movement  of  the  skin,  serves  as  a  soft  nidus  for  the  passage  of 
vessels  and  nerves  to  the  integument,  and  retains  the  warmth  of  the  body,  since 
the  adipose  tissue  contained  in  its  areolae  is  a  bad  conductor  of  caloric. 

The  aponeurotic  or  deep  fascia  is  a  dense  inelastic  and  unyielding  fibrous 
membrane,  forming  sheaths  for  the  muscles,  and  affording  them  broad  surfaces 
for  attachment.  It  consists  of  shining  tendinous  fibres,  placed  parallel  with 
one  another,  and  connected  together  by  other  fibres  disposed  in  a  reticular 
manner.  It  is  usually  exposed  on  the  removal  of  the  superficial  fascia,  form- 
ing a  strong  investment,  which  not  only  binds  down  collectively  the  muscles 
in  each  region,  but  gives  a  separate  sheath  to  each,  as  well  as  to  the  vessels 
and  nerves.  The  fasciae  are  thick  in  unprotected  situations,  as  on  the  outer 
side  of  a  limb,  and  thinner  on  the  inner  side.  Aponeurotic  fasciae  are 
divided  into  two  classes,  aponeuroses  of  insertion,  and  aponeuroses  of  in- 
vestment. 

The  aponeuroses  of  insertion  serve  for  the  insertion  of  muscles.  Some  of  these 
are  formed  by  the  expansion  of  a  tendon  into  an  aponeurosis,  as,  for  instance, 
the  tendon  of  the  Sartorius ;  others  are  connected  directly  to  the  muscle,  as  the 
aponeuroses  of  the  abdominal  muscles. 

The  aponeuroses  of  investment  form  a  sheath  for  the  entire  limb,  as  well  as  for 
each  individual  muscle.  Many  aponeuroses,  however,  serve  both  for  invest- 
ment and  insertion.  Thus  the  aponeurosis  given  off'  from  the  tendon  of  the 
Biceps  of  the  arm  near  its  insertion  is  continuous  with,  and  partly  forms,  the 
investing  fascia  of  the  forearm,  and  gives  origin  to  the  muscles  in  this  region. 
The  deep  fasciae  assist  the  muscles  in  their  action,  by  the  degree  of  tension  and 
pressure  they  make  upon  their  surface;  and,  in  certain  situations,  this  is  in- 
creased and  regulated  by  muscular  action,  as,  for  instance,  by  the  Tensor 
Vaginae  Femoris  and  Gluteus  Maximus  in  the  thigh,  by  the  Biceps  in  the  leg, 
and  Palmaris  Longus  in  the  hand.  In  the  limbs,  the  fasciae  not  only  invest  the 
entire  limb,  but  give  off"  septa,  which  separate  the  various  muscles,  and  are 
attached  beneath  to  the  periosteum ;  these  prolongations  of  fasciae  are  usually 
spoken  of  as  intermuscular  septa. 

The  Muscles  and  Fasciae  may  be  arranged,  according  to  the  general  division 
of  the  body,  into  those  of  the  head,  face,  and  neck ;  those  of  the  trunk ;  those 
of  the  upper  extremity ;  and  those  of  the  lower  extremity. 

MUSCLES  AND  FASCIA  OF  THE  HEAD  AND  FACE. 

The  Muscles  of  the  Head  and  Face  consist  of  ten  groups,  arranged  according 
to  the  region  in  which  they  are  situated. 

1.  Cranial  Region.  6.  Superior  Maxillary  Region. 

.2.  Auricular  Region.  7.  Inferior  Maxillary  Region. 

8.  Palpebral  Region.  8.  Intermaxillary  Region. 

4.  Orbital  Region.  9.  Temporo-maxillary  Region. 

5.  Nasal  Region.  10.  Pterygo-maxillary  Region. 

The  Muscles  contained  in  each  of  these  groups  are  the  following : — : 

1.   Cranial  Region. 
Occipito-frontalis.  ^'  Palpebral  Region. 

Orbicularis  Palpebrarum. 

2.  Auricular  Region.  Corrugator  Supercilii. 

Attollens  Aurem.  Levator  Palpebrae. 

Attrahens  Aurem.  Tensor  Tarsi. 
Retrahens  Aurem. 


CRANIAL    REGION. 


317 


4.  Orbital  Region. 
Levator  Palpebrae. 
Rectus  Superior. 

Rectus  Inferior. 
Rectus  Internus. 
Rectus  Externus. 
Obliquus  Superior. 
Obliquus  Inferior. 

5.  Nasal  Region. 
Pyramidalis  Nasi. 

Levator  Labii  Superioris  Alseque  Nasi. 
Dilatator  Naris  Posterior. 
Dilatator  Naris  Anterior. 
Compressor  Nasi. 
Compressor  Narium  Minor. 
Depressor  Alas  Nasi. 

6.  Siiperior  Maxillary  Region. 
Levator  Labii  Superioris. 
Levator  Anguli  Oris. 


Zygomaticus  Major. 
Zjgomaticus  Minor. 

7.  Inferior  Maxillary  Region. 
Levator  Labii  Inferioris. 
Depressor  Labii  Inferioris. 
Depressor  Anguli  Oris. 

8.  Intermaxillary  Region. 
Orbicularis  Oris. 
Buccinator. 
Risorius. 

9.  Temporo- Maxillary  Region. 
Masseter. 

Temporal. 

10.  Pterygo-Maxillary  Region. 
Pterygoideus  Externus. 
Pterygoideus  Internus. 


1.  Cranial  Region — Occipito-frontalis. 

Dissection  (Fig.  214).  The  bead  being  shaved,  and  a  block  placed  beneath  the  back  of  the 
neck,  make  a  vertical  incision  through  the  skin  from  before  backwards,  commencing  at  the  root 
of  the  nose  in  front,  and  terminating  behind  at  the  occipital  protuberance  ;  make  a  second  in- 
cision in  a  horizontal  direction  along  the  forehead  and  round  the  side  of  the  head,  from  the  an- 

Fig.  214, — Dissection  of  the  Head,  Face,  and  Neck. 


terior  to  the  posterior  extremity  of  the  preceding.  Kaise  the  skin  in  front  from  the  subjacent 
muscle  from  below  upwards  ;  this  must  be  done  with  extreme  care,  on  account  of  their  intimate 
union.  The  tendon  of  the  muscle  is  best  avoided  by  removing  the  integument  from  the  outer 
surface  of  the  vessels  and  nerves  which  lie  between  the  two. 

The  superficial  fascia  in  the  cranial  region  is  a  firm,  dense  layer,  intimately 
adherent  to  the  integument,  and  to  the  Occipito-frontalis  and  its  tendinous  apo- 
neurosis ;  it  is  continuous,  behind,  with  the  superficial  fascia  at  the  back  part 
of  the  neck;  and,  laterally,  is  continued  over  the  temporal  aponeurosis;  it 
contains  between  its  layers  the  small  muscles  of  the  auricle,  and  the  superficial 
temporal  vessels  and  superficial  nerves. 


318  MUSCLES    AND    FASCIA. 

The  Occipito-frontalis  (Fig.  215)  is  a  broad  musculo-fibrous  layer,  which  covers 
the  whole  of  one  side  of  the  vertex  of  the  skull,  from  the  occiput  to  the  eye- 


Fig.  215. — Muscles  of  the  Head,  Face,  and  Neck. 


CVDRUeATeH  tUVIRCILII 


aiUTSU  NAKII  AUTII 
BlUTORNA>l>  rOSTCK 


LtVATOII  MCNTI 


brow.  It  consists  of  two  muscular  slips,  separated  by  an  intervening  tendinous 
aponeurosis.  The  occipital  portion,  thin,  quadrilateral  in  form,  and  about  an  inch 
and  a  half  in  length,  arises  from  the  outer  two-thirds  of  the  superior  curved  line 
of  the  occipital  bone,  and  from  the  mastoid  portion  of  the  temporal.  Its  fibres 
of  origin  are  tendinous,  but  they  soon  become  muscular,  and  ascend  in  a  parallel 
direction  to  terminate  in  the  tendinous  aponeurosis.  The  frontal  portion  is  thin, 
of  a  quadrilateral  form,  and  intimately  adherent  to  the  skin.  It  is  broader,  its 
fibres  are  longer,  and  their  structure  paler  than  the  occipital  portion.  Its  in- 
ternal fibres  are  continuous  with  those  of  the  Pyramidalis  Nasi.  Its  middle 
fibres  become  blended  with  the  Corrugator  Supercilii  and  Orbicularis:  and  the 
outer  fibres  are  also  blended  with  the  latter  muscle  over  the  external  angular 
process.     From  this  attachment,  the  fibres  are  directed  upwards  and  join  the 


AURICULAR    REGION.  319 

aponeurosis  below  the  coronal  suture.  The  inner  margins  of  the  two  frontal 
portions  of  the  muscle  are  joined  together  for  some  distance  above  the  root  of 
the  nose ;  but  between  the  occipital  portions  there  is  a  considerable  though 
variable  interval. 

The  aponeurosis  covers  the  upper  part  of  the  vertex  of  the  skull,  being  con- 
tinuous across  the  middle  line  with  the  aponeurosis  of  the  opposite  muscle. 
Behind,  it  is  attached,  in  the  interval  between  the  occipital  origins,  to  the  occi- 
pital protuberance  and  superior  curved  lines  above  the  attachment  of  the  Tra- 
pezius; in  front,  it  forms  a  short  angular  prolongation  between  the  frontal 
portions ;  and  on  each  side,  it  has  connected  with  it  the  Attollens  Aurera  and 
Attrahens  Aurem  muscles  ;  in  this  situation  it  loses  its  aponeurotic  character, 
and  is  continued  over  the  temporal  fascia  to  the  zygoma  by  a  layer  of  laminated 
areolar  tissue.  This  aponeurosis  is  closely  connected  to  the  integument  by  a 
dense  fibro-cellular  tissue,  which  contains  much  granular  fat,  and  in  which 
ramify  the  numerous  vessels  and  nerves  of  the  integument ;  it  is  loosely  con- 
nected with  the  pericranium  by  a  quantity  of  loose  cellular  tissue,  which  allows 
of  a  considerable  degree  of  movement  of  the  integument. 

Nerves.  The  frontal  portion  of  the  Occipito-frontalis  is  supplied  by  the  facial 
nerve ;  its  occipital  portion  by  the  posterior  auricujar  branch  of  the  facial,  and 
sometimes  by  the  small  occipital. 

Actions.  The  frontal  portion  of  the  muscle  raises  the  eyebrows  and  the  skin 
over  the  root  of  the  nose ;  at  the  same  time  throwing  the  integument  of  the 
forehead  into  transverse  wrinkles,  a  predominant  expression  in  the  emotions 
of  delight.  By  bringing  alternately  into  action  the  occipital  and  frontal  por- 
tions, the  entire  scalp  may  be  moved  from  before  backwards. 

2.  Auricular  Eegiox.    (Fig.  215.) 

Attollens  Aurem.  Attrahens  Aurem. 

Eetrahens  Aurem. 

These  three  small  muscles  are  placed  immediately  beneath  the  skin  around 
the  external  ear.  In  man,  in  whom  the  external  ear  is  almost  immovable,  they 
are  rudimentary.  They  are  the  analogues  of  large  and  important  muscles  in 
some  of  the  mammalia. 

Dissection.  This  requires  considerable  care,  and  should  be  performed  in  the  following 
manner :  To  expose  the  Attollens  Aurem  ;  draw  the  pinna  or  broad  part  of  the  ear  downwards, 
when  a  tense  band  will  be  felt  beneath  the  skin,  passing  from  the  side  of  the  head  to  the  upper 
part  of  the  concha ;  by  dividing  the  skin  over  the  tendon,  in  a  direction  from  below  upwards, 
and  then  reflecting  it  on  each  side,  the  mnscle  is  exposed.  To  bring  into  view  the  Attrahens 
Aurem.  draw  the  helix  backwards  by  means  of  a  hook,  when  the  muscle  will  be  made  tense,  and 
may  be  exposed  in  a  similar  manner  to  the  preceding.  To  expose  the  Retrahens  Aurem,  draw 
the  pinna  forwards,  when  the  muscle  being  made  tense  may  be  felt  beneath  the  skin,  at  its  inser- 
tion into  the  back  part  of  the  concha,  and  may  be  exposed  in  the  same  manner  as  the  other 
muscles. 

The  Attollens  Aurem.,  the  largest  of  the  three,  is  thin,  and  fan-shaped;  its 
fibres  arise  from  the  aponeurosis  of  the  occipito  frontalis,  and  converge  to  be 
inserted  by  a  thin,  flattened  tendon  into  the  upper  part  of  the  cranial  surface 
of  the  pinna. 

Relations.  Externally.,  with  the  integument;  internally,  with  the  temporal 
aponeurosis. 

The  Attrahens  Aurem.,  the  smallest  of  the  three,  is  thin,  fan-shaped,  and  its 
fibres  pale  and  indistinct ;  they  arise  from  the  lateral  edge  of  the  aponeurosis 
of  the  Occipito-frontalis,  and  converge  to  be  inserted  into  a  projection  on  the 
front  of  the  helix. 

Relations.  Externally.,  with  the  skin;  internally,  with  the  temporal  fascia, 
which  separates  it  from  the  temporal  artery  and  vein. 

The  Retrahens  Aurem  consists  of  two  or  three  fleshy  fasciculi,  which  arise 


820  MUSCLES    AND    FASCIA. 

from  the  mastoid  portion  of  the  temporal  bone  by  short  aponeurotic  fibres. 
They  are  inserted  into  the  lower  part  of  the  cranial  surface  of  the  concha. 

Relations.  Externally,  with  the  integument;  internally,  with  the  mastoid 
portion  of  the  temporal  bone. 

Nerves.  The  Attollens  Aurem  is  supplied  by  the  small  occipital ;  the  Attra- 
hens  Aurem,  by  the  facial ;  and  the  Eetrahens  Aurem,  by  the  posterior  auricular 
branch  of  the  facial. 

Actions.  In  man,  these  muscles  possess  very  little  action;  the  Attollens 
Aurem  slightly  raises  the  ear ;  the  Attrahens  Aurem  draws  it  forwards  and 
upwards ;  and  the  Eetrahens  Aurem  draws  it  backwards. 

3.  Palpebral  Eegion.    (Fig.  215.) 

Orbi-cularis  Palpebrarum.  Levator  Palpebras. 

Corrugator  Supercilii.  Tensor  Tarsi. 

Dissection  (Fig.  2141.  In  order  to  expose  the  muscles  of  the  face,  continue  the  longitndinal 
incision,  made  in  the  dissection  of  the  Occipito-frontalis,  down  the  median  line  of  the  face  to  the 
tip  of  the  nose,  and  from  this  point  onwards  to  the  upper  lip  ;  and  carry  another  incision  along 
the  margin  of  the  lip  to  the  angle  of  the  mouth,  and  transversely  across  the  face  to  the  angle  of 
the  jaw.  Then  make  an  incision  in  front  of  the  external  ear,  from  the  angle  of  the  jaw  upwards, 
to  join  the  transverse  incision  made  in  exposing  the  Occipito-frontalis.  These  incisions  include 
a  square-shaped  flap,  which  should  be  removed  in  the  direction  marked  in  the  figure,  with  care, 
as  the  muscles  at  some  points  are  intimately  adherent  to  the  integument. 

The  Orbicularis  Palpebrarum  is  a  sphincter  muscle,  which  surrounds  the  cir- 
cumference of  the  orbit  and  eyelids.  It  arises  from  the  internal  angular  process 
of  the  frontal  bone,  from  the  nasal  process  of  the  superior  maxillary  in  front 
of  the  lachrymal  groove,  and  from  the  anterior  surface  and  borders  of  a  short 
tendon,  the  tendo-palpebrarum,  placed  at  the  inner  angle  of  the  orbit.  From 
this  origin,  the  fibres  are  directed  outwards,  forming  a  broad,  thin,  and  flat  layer, 
which  covers  the  eyelids,  surrounds  the  circumference  of  the  orbit,  and  spreads 
out  over  the  temple,  and  downwards  on  the  cheek,  becoming  blended  with  the 
Occipito-frontalis  and  Corrugator  Supercilii.  The  palpebral  portion  (ciliaris) 
of  the  Orbicularis  is  thin  and  pale ;  it  arises  from  the  bifurcation  of  the  tendo 
palpebrarum,  and  forms  a  series  of  concentric  curves,  which  are  united  on  the 
outer  side  of  the  eyelids  at  an  acute  angle  by  a  cellular  raphd,  some  being 
inserted  into  the  external  tarsal  ligament  and  malar  bone.  The  orbicular  por- 
tion (orbicularis  latus)  is  thicker  and  of  a  reddish  color:  its  fibres  are  well 
developed,  and  form  complete  ellipses. 

Relations.  By  its  superficial  surface,  with  the  integument.  By  its  deep  surface, 
above,  with  the  Occipito-frontalis  and  Corrugator  Supercilii,  with  which  it  is 
intimately  blended,  and  with  the  supra-orbital  vessels  and  nerve;  below,  it 
covers,  the  lachrymal  sac,  and  the  origin  of  the  Levator  Labii  Superioris,  and 
the  Levator  Labii  Superioris  Alaeque  Nasi  muscles.  Internally,  it  is  occasionally 
blended  with  the  Pyramidalis  Nasi.  Externally,  it  lies  on  the  temporal  fascia. 
On  the  eyelids,  it  is  separated  from  the  conjunctiva  by  a  fibrous  membrane  and 
the  tarsal  cartilages. 

The  tendo  palpebrarum  (tendo  oculi)  is  a  short  tendon,  about  two  lines  in 
length  and  one  in  breadth,  attached  to  the  nasal  process  of  the  superior  maxillary 
bone  in  front  of  the  lachrymal  groove.  Crossing  the  lachrymal  sac,  it  divides 
into  two  parts,  each  division  being  attached  to  the  inner  extremity  of  the  corre- 
sponding tarsal  cartilage.  As  the  tendon  crosses  the  lachrymal  sac,  a  strong 
aponeurotic  lamina  is  given  off  from  the  posterior  surface,  which  expands  over 
the  sac,  and  is  attached  to  the  ridge  on  the  lachrymal  bone.  This  is  the  reflected 
aponeurosis  of  the  tendo  palpebrarum. 

The  Corrugator  Supercilii  is  a  small,  narrow,  pyramidal  muscle,  placed  at  the 
inner  extremity  of  the  eyebrow,  beneath  the  Occipito-frontalis  and  Orbicularis 
Palpebrarum  muscles.     It  arises  from  the  inner  extremity  of  the  sAperciliary 


ORBITAL    REGION.  321 

ridge ;  from  wTience  its  fibres  pass  upwards  and  outwards,  to  be  inserted  into 
the  under  surface  of  the  orbicularis,  opposite  the  middle  of  the  orbital  arch. 

Relations.  By  its  anterior  surface^  with  the  Occipito-frontalis  and  Orbicularis 
Palpebrarum  muscles.  By  its  posterior  surface^  with  the  frontal  bone  and  supra- 
trochlear nerve. 

The  Levator  Paljjehree  will  be  described  with  the  muscles  of  the  orbital  region. 

The  Tensor  Tarsi  is  a  small  thin  muscle,  about  three  lines  in  breadth  and  six 
in  length,  situated  at  the  inner  side  of  the  orbit,  behind  the  tendo  oculi.  It 
arises  from  the  crest  and  adjacent  part  of  the  orbital  surface  of  the  lachrymal 
bone,  and  passing  across  the  lachrymal  sac,  divides  into  two  slips,  which  cover 
the  lachrymal  canals,  and  are  inserted  into  the  tarsal  cartilages  near  the  puncta 
lachrymalia.  Its  fibres  appear  to  be  continuous  with  those  of  the  palpebral 
portion  of  the  Orbicularis;  it  is  occasionally  very  indistinct. 

Nerves.  The  Orbicularis  Palpebrarum,  Corrugator  Supercilii,  and  Tensor 
Tarsi  are  supplied  by  the  facial  nerve. 

Actions.  The  Orbicularis  Palpebrarum  is  the  sphincter  muscle  of  the  eyelids. 
The  palpebral  portion  acts  involuntarily  in  closing  the  lids,  and  independently 
of  the  orbicular  portion,  which  is  subject  to  the  will.  When  the  entire  muscle 
is  brought  into  action,  the  integument  of  the  forehead,  temple,  and  cheek  is 
drawn  inwards  towards  the  inner  angle  of  the  eye,  and  the  eyelids  are  firmly 
closed.  The  Levator  Palpebraa  is  the  direct  antagonist  of  this  muscle ;  it  raises 
the  upper  eyelid  and  exposes  the  globe.  The  Corrugator  Supercilii  draws  the 
eyebrow  downwards  and  inwards,  producing  the  vertical  wrinkles  of  the  fore- 
head. This  muscle  may  be  regarded  as  the  principal  agent  in  the  expression 
of  grief.  The  Tensor  Tarsi  draws  the  eyelids  and' the  extremities  of  the  lachry- 
mal canals  inwards,  and  compresses  them  against  the  surface  of  the  globe  of  the 
eye;  thus  placing  them  in  the  most  favorable  situation  for  receiving  the  tears. 
It  serves,  also,  to  compress  the  lachrymal  sac. 

4.  Orbital  Eegion.    (Fig.  216.) 

Levator  Palpebroe  Superioris.  Rectus  Internus. 

Rectus  Superior.  Rectus  Externus. 

Rectus  Inferior.  Obliquus  Superior. 

Obliquus  Inferior. 

Disa'ection.  To  open  the  cavity  of  the  orbit,  remove  the  skullcap  and  brain  ;  then  saw  through 
the  frontal  bone  at  the  inner  extremity  of  the -supraorbital  ridge,  and  externally  at  its  junction 
with  the  malar.  Break  in  pieces  the  thin  roof  of  the  orbit  by  a  few  slight  blows  of  the  hammer 
and  take  it  away ;  drive  forward  the  superciliary  portion  of  the  frontal  bone  by  a  smart  stroke, 
but  do  not  remove  it,  as  that  would  destroy  the  pulley  of  the  Obliquus  Superior.  When  the 
fragments  are  cleared  away,  the  periosteum  of  the  orbit  will  be  exposed :  this  being  removed, 
together  with  the  fat  which  fills  the  cavity  of  the  orbit,  the  several  muscles  of  this  region  can 
be  examined.  The  dissection  will  be  facilitated  by  distending  the  globe  of  the  eye.  In  order  to 
effect  this,  puncture  the  optic  nerve  near  the  eyeball,  with  a  curved  needle,  and  push  the  needle 
onwards  into  the  globe ;  insert  the  point  of  a  blowpipe  through  this  aperture,  and  force  a  little 
air  into  the  cavity  of  the  eyeball ;  then  apply  a  ligature  round  the  nerve  so  as  to  prevent  the  air 
escaping.    The  globe  being  now  drawn  forwards,  the  muscles  will  be  put  upon  the  stretch. 

The  Levator  Palpelrse  Superioris  is  thin,  flat,  and  triangular  in  shape.  It 
arises  from  the  under  surface  of  the  lesser  wing  of  the  sphenoid,  immediately 
in  front  of  the  optic  foramen;  and  is  inserted,  by  a  broad  aponeurosis,  into  the 
upper  border  of  the  superior  tarsal  cartilage.  At  its  origin,  it  is  narrow  and 
tendinous;  but  soon  becomes  broad  and  fleshy,  and  finally  terminates  in  a  broad 
aponeurosis. 

Relations.  By  its  upj^er  surface,  with  the  frontal  nerve  and  artery,  the  perios- 
teum of  the  orbit;  and,  in  front,  with  the  inner  surface  of  the  broad  tarsal 
ligament.  By  its  under  surface,  with  the  Superior  Rectus ;  and  in  the  lid,  with 
the  conjunctiva.     A  small  branch  of  the  third  nerve  enters  its  under  surface. 

The  Rectus  Superior^  the  thinnest  and  narrowest  of  the  four  Recti,  arises 
from  the  upper  margin  of  the  optic  foramen,  beneath  the  Levator  Palpebrce 
21 


322 


MUSCLES    AXD    FASCIA. 


and  Superior  Oblique,  and  from  the  fibrous  sbeatb  of  the  optic  nerve ;  and  13 
inserted,  by  a  tendinous  expansion,  into  the  sclerotic  coat,  about  three  or  four 
lines  from  the  margin  of  the  cornea, 

Relatioiis.     By  its  upper  sxirface^  with  the  Levator  Palpebrae.     By  its  under 
surface^  with  the  optic  nerve,  the  ophthalmic  artery,  the  nasal  nerve,  and  the 

Fig.  216.— Muscles  of  the  Right  Orbit. 


branch  of  the  third  nerve,  which  supplies  it ;  and,  in  front,  with  the  tendon  of 
the  Superior  Oblique,  and  the  globe  of  the  eye. 

The  Inferior  and  Internal  Recti  arise  by  a  common  tendon  (the  ligament  of 
Zinn),  which  is  attached  round  the  circumference  of  the  optic  foramen,  except 

at  its  upper  and  outer  part.  The  External 
Rectus  has  two  heads :  the  upper  one  arises 
from  the  outer  margin  of  the  optic  foramen, 
immediately  beneath  the  Superior  Rectus ;  the 
lower  head,  partly  from  the  ligament  of  Zinn, 
and  partly  from  a  small  pointed  process  of 
bone  on  the  lower  margin  of  the  sphenoidal 
fissure.  Each  muscle  passes  forward  in  the 
position  implied  by  its  name,  to  be  inserted,  by 
a  tendinous  expansion  (the  tunica  alhuginea\ 
into  the  sclerotic  coat,  about  three  or  four 
lines  from  the  margin  of  the  cornea.  Between 
the  two  heads  of  the  External  Rectus  is  a 
narrow  interval,  through  which  pass  the  third, 
nasal  branch  of  the  fifth,  and  sixth  nerves, 
and  the  ophthalmic  vein.  Although  nearly  all  these  muscles  present  a  com- 
mon origin,  and  are  inserted  in  a  similar  manner  in  the  sclerotic  coat,  there 
are  certain  differences  to  be  observed  in  them,  as  regards  their  length  and 
breadth.  The  Internal  Rectus  is  the  broadest ;  the  External,  the  longest ;  and 
the  Superior,  the  thinnest  and  narrowest. 

The  Sxiperior  Oblique  is  a  fusiform  muscle,  placed  at  the  upper  and  inner  side 
of  the  orbit,  internal  to  the  Levator  Palpebraj.  It  arises  about  a  line  above 
the  inner  margin  of  the  optic  foramen,  and,  passing  forwards  to  the  inner 
angle  of  the  orbit,  terminates  in  a  rounded  tendon,  which  plays  in  a  ring  or 
pulley,  formed  by  fibro-cartilaginous  tissue  attached  to  a  depression  beneath 
the  internal  angular  process  of  the  frontal  bone,  the  contiguous  surfaces  of  the 
tendon  and  ring  being  lined  by  a  delicate  synovial  membrane,  and  inclosed  in 
a  thin  fibrous  investment.     The  tendon  is  reflected  backwards  and  outwards 


Fig.  217. — The  relative  position  and 
attachment  of  the  Muscles  of  the 
Left  Eyeball. 

Ji^rtus  Simriar 
-Lsvafar 

t^liaiuts  Superior 


•i>r  lit  tui 


BcetuM  Jn^rrior 


It4ntf€T  Miuui 


ORBITAL    REGION.  323 

beneath  the  Superior  Rectus  to  the  outer  part  of  the  globe  of  the  eye,  and  is 
inserted  into  the  sclerotic  coat,  midway  between  the  cornea  and  entrance  of 
the  optic  nerve,  the  insertion  of  the  muscle  lying  between  the  Superior  and 
External  Recti. 

Relations.  By  its  upper  surface^  with  the  periosteum  covering  the  roof  of 
the  orbit,  and  the  fourth  nerve.  The  tendon,  where  it  lies  on  the  globe  of  the 
eye,  is  covered  by  the  Superior  Rectus.  By  its  under  surface^  with  the  nasal 
nerve,  and  the  upper  border  of  the  Internal  Rectus. 

The /w/enor  Oblique  is  a  thin,  narrow  muscle,  placed  near  the  anterior  margin 
of  the  orbit.  It  arises  from  a  depression  in  the  orbital  plate  of  the  superior 
maxillary  bone,  external  to  the  lachrymal  groove.  Passing  outwards  and 
backwards  beneath  the  Inferior  Rectus,  and  between  the  eyeball  and  the 
External  Rectus,  it  is  inserted  into  the  outer  part  of  the  sclerotic  coat  between 
the  Superior  and  External  Rectus,  near  the  tendon  of  insertion  of  the  Superior 
Oblique. 

Relations.  By  its  upper  surface^  with  the  globe  of  the  eye,  and  with  the 
Inferior  Rectus.  By  its  under  surface^  with  the  periosteum  covering  the  floor 
of  the  orbit,  and  with  the  External  Rectus.  Its  borders  look  forwards  and 
backwards ;  the  posterior  one  receives  a  branch  of  the  third  nerve. 

Nerves.  The  Levator  Palpebrse,  Inferior  Oblique,  and  all  the  Recti  excepting 
the  External,  are  supplied  by  the  third  nerve ;  the  Superior  Oblique,  by  the 
fourth ;  the  External  Rectus,  by  the  sixth. 

Actions.  The  Levator  Palpebr£e  raises  the  upper  eyelid,  and  is  the  direct 
antagonist  of  the  Orbicularis  Palpebrarum.  The  four  Recti  muscles  are 
attached  in  such  a  manner  to  the  globe  of  the  eye,  that,  acting  singly,  they 
will  turn  it  either  upwards,  downwards,  inwards,  or  outwards,  as  expressed  by 
their  names.  If  any  two  Recti  act  together,  they  carry  the  globe  of  the  eye 
in  the  diagonal  of  these  directions,  viz.,  upwards  and  inwards,  upwards  and 
outwards,  downwards  and  inwards,  or  downwards  and  outwards.  The  move- 
ment of  circumduction,  as  in  looking  round  a  room,  is  performed  by  the  alter- 
nate action  of  the  four  Recti.  By  some  anatomists,  these  muscles  have  been 
considered  the  chief  agents  in  adjusting  the  sight  at  different  distances,  by 
compressing  the  globe,  and  so  lengthening  its  antero-posterior  diameter.  The 
Oblique  muscles  rotate  the  eyeball  on  its  antero-jDosierior  axis^  this  kind  of 
movement  being  required  for  the  correct  viewing  of  an  object,  when  the  head 
is  moved  laterally,  as  from  shoulder  to  shoulder,  in  order  that  the  picture  may 
fall  in  all  respects  on  the  same  part  of  the  retina  of  each  eye.^ 

Surgical  Anatomy.  The  position  and  exact  point  of  insertion  of  the  tendons  of  the  Internal 
and  External  Recti  muscles  into  the  globe,  should  be  carefully  examined  from  the  front  of  the 
eyeball,  as  the  surgeon  is  often  required  to  divide  one  or  the  other  muscle  for  the  cure  of  stra- 
bismus. In  convergent  strabismus,  which  is  the  most  common  form  of  the  disease,  the  eye  is 
turned  inwards,  requiring  the  division  of  the  Internal  Rectus.  In  the  divergent  form,  which  is 
more  rare,  the  eye  is  turned  outwards,  the  External  Rectus  being  especially  implicated.  The 
deformity  produced  in  either  case  is  to  be  remedied  by  division  of  one  or  the  other  muscle.  The 
operation  is  thus  effected  :  the  lids  are  to  be  well  separated ;  the  eyeball  being  drawn  outwards, 
the  conjunctiva  should  be  raised  by  a  pair  of  forceps,  and  divided  immediately  beneath  the  lower 
border  of  the  tendon  of  the  Internal  Rectus,  a  little  behind  its  insertion  into  the  sclerotic ;  the 
submucous  areolar  tissue  is  then  divided,  and  into  the  small  aperture  thus  made,  a  blunt  hook 
is  passed  upwards  between  the  muscle  and  the  globe,  and  the  tendon  of  the  muscle  and  con- 
junctiva covering  it,  divided  by  a  pair  of  blunt-pointed  scissors.  Or  the  tendon  may  be  divided 
by  a  subconjunctival  incision,  one  blade  of  the  scissors  being  passed  upwards  between  the  tendon 
and  the  conjunctiva,  and  the  other  between  the  tendon  and  the  sclerotic.  The  student,  when 
dissecting  these  muscles,  should  remove  on  one  side  of  the  subject  the  conjunctiva  from  the 
front  of  the  eye,  in  order  to  see  more  accurately  the  position  of  the  tendons,  while  on  the  op- 
posite side  the  operation  may  be  performed. 


'  "  On  the  Oblique  Muscles  of  the  Eye  in  Man  and  Vertebrate  Animals,"  by  John  Struthers, 
M,  D.,  "  Anatomical  and  Physiological  Observations." 


324  MUSCLES    AND    FASCIA. 

5.  Nasal  Region.    (Fig.  215.) 

Pyramidalis  Nasi. 

Levator  Labii  Superioris  Alaeque  Nasi. 

Dilatator  Naris  Posterior 

Dilatator  Naris  Anterior. 

Compressor  Nasi. 

Compressor  Narium  Minor. 

Depressor  Alae  Nasi. 

The  Pyramidalis  Nasi  is  a  small  pyramidal  slip,  prolonged  downwards  from 
the  Occipito-frontalis  upon  the  side  of  the  nose,  where  it  becomes  tendinous 
and  blends  with  the  compressor  Nasi.  As  the  two  muscles  descend,  they  di- 
verge, leaving  an  angular  interval  between  them. 

Relations.  By  its  upper  surface^  with  the  skin.  By  its  under  surface^  with  the 
frontal  and  nasal  bones. 

The  Levator  Ldbii  Superioris  Alseque  Nasi  is  a  thin  triangular  muscle,  placed 
by  the  side  of  the  nose,  and  extending  between  the  inner  margin  of  the  orbit 
and  upper  lip.  It  arises  by  a  pointed  extremity  from  the  upper  part  of  the 
nasal  process  of  the  superior  maxillary  bone,  and  passing  obliquely  downwards 
and  outwards,  divides  into  two  slips,  one  of  which  is  inserted  into  the  cartilage 
of  the  ala  of  the  nose ;  the  other  is  prolonged  into  the  upper  lip,  becoming 
blended  with  the  Orbicularis  and  Levator  Labii  Proprius. 

Relations.  In  front,  with  the  integument;  and  with  a  small  part  of  the 
Orbicular  Palpebrarum  above. 

Lying  upon  the  superior  maxillary  bone,  beneath  this  muscle,  is  a  longitu- 
dinal muscular  fasciculus  about  an  inch  in  length.  It  is  attached  by  one  end 
near  the  origin  of  the  Compressor  Nasi,  and  by  the  other  to  the  nasal  process 
about  an  inch  above  it;  it  was  described  by  Albinus  as  the  "Musculus  Anoma- 
lus,"  and  by  Santorini,  as  the  "  Ehomboideus." 

The  Dilatator  Naris  Posterior  is  a  small  muscle,  which  is  placed  partly  be- 
neath the  proper  elevator  of  the  nose  and  lip.  It  arises  from  the  margin  of  the 
nasal  notch  of  the  superior  maxilla,  and  from  the  sesamoid  cartilages,  and  is 
inserted  into  the  skin  near  the  margin  of  the  nostril. 

The  Dilatator  Naris  Anterior  is  a  thin  delicate  fasciculus,  passing  from  the 
cartilage  of  the  ala  of  the  nose  to  the  integument  near  its  margin.  This  muscle 
is  situated  in  front  of  the  preceding. 

The  Comjiressor  Nasi  is  a  small,  thin,  triangular  muscle,  arising  by  its  apex 
from  the  superior  maxillary  bone,  above  and  a  little  external  to  the  incisive 
fossa;  its  fibres  proceed  upwards  and  inwards,  expanding  into  a  thin  aponeu- 
rosis which  is  attached  to  the  fibro-cartilage  of  the  nose,  and  is  continuous  on 
the  bridge  of  the  nose  with  that  of  the  muscle  of  the  opposite  side,  and  with 
the  aponeurosis  of  the  Pyramidalis  Nasi. 

The  Compressor  Narium  Minor  is  a  small  muscle,  attached  by  one  end  to  the 
alar  cartilage,  and  by  the  other  to  the  integument  at  the  end  of  the  nose. 

The  Depressor  Alse  Nasi  is  a  short,  radiated  muscle,  arising  from  the  incisive 
fossa  of  the  superior  maxilla;  its  fibres  ascend  to  be  inserted  into  the  septum, 
and  back  part  of  the  ala  of  the  nose.  This  muscle  lies  between  the  mucous 
membrane  and  muscular  structure  of  the  lip. 

Nerves.     All  the  muscles  of  this  group  are  supplied  by  the  facial  nerve. 

Actions.  The  Pyramidalis  Nasi  draws  down  the  inner  angle  of  the  eyebrows; 
by  some  anatomists  it  is  also  considered  as  an  elevator  of  the  ala,  and,  conse- 
quently, a  dilatator  of  the  nose.  The  Levator  Labii  Superioris  Alteque  Nasi 
draws  upwards  the  upper  lip  and  ala  of  the  nose;  its  most  important  action  is 
upon  the  nose,  which  it  dilates  to  a  considerable  extent.  The  action  of  this 
muscle  produces  a  marked  influence  over  the  countenance,  and  it  is  the  prin- 
cipal agent  in  the  expression  of  contempt.     The  two  Dilatatores  Nasi  enlarge 


INFERIOR    MAXILLARY    REGION.  325 

the  aperture  of  the  nose,  and  the  Compressor  Nasi  appears  to  press  upon  the 
nose  so  as  to  increase  its  breadth,  and  thus  tends  rather  to  open  than  to  close 
the  nostrils.  The  Depressor  Alae  Nasi  is  a  direct  antagonist  of  the  preceding 
muscles,  drawing  the  ala  of  the  nose  downwards,  and  thereby  constricting  the 
aperture  of  the  nares. 

6.  Superior  Maxillary  Region-.    (Fig.  215.) 

Levator  Labii  Superioris.  Zygomaticus  major. 

Levator  Anguli  Oris.  Zygomaticus  minor. 

The  Levator  Labii  Superioris  is  a  thin  muscle  of  a  quadrilateral  form.  It 
arises  from  the  lower  margin  of  the  orbit  immediately  above  the  infraorbital 
foramen,  some  of  its  fibres  being  attached  to  the  superior  maxilla,  others  to  the 
malar  bone;  its  fibres  converge  to  be  inserted  into  the  muscular  substance  of 
the  upper  lip. 

Relations.  By  its  superficial  surface,  with  the  lower  segment  of  the  Orbicu- 
laris Palpebrarum ;  below,  it  is  subcutaneous.  By  its  deep  surface,  it  conceals 
the  origin  of  the  Compressor  Nasi  and  Levator  Anguli  Oris  muscles,  and  the 
infraorbital  vessels  and  nerves,  as  they  escape  from  the  infraorbital  foramen. 

The  Levator  Anguli  Oris  arises  from  the  canine  fossa,  immediately  below  the 
infraorbital  foramen ;  its  fibres  incline  downwards  and  a  little  outwards,  to  be 
inserted  into  the  angle  of  the  mouth,  intermingling  with  those  of  the  Zygoma- 
tici,  the  Depressor  Anguli  Oris,  and  the  Orbicularis. 

Relations.  By  its  superficial  surface,  with  the  Levator  Labii  Superioris  and 
the  infraorbital  vessels  and  nerves.  By  its  deep  surface,  with  the  superior 
maxilla,  the  Buccinator,  and  the  mucous  membrane. 

The  Zygomaticus  major  is  a  slender  fasciculus,  which  arises  from  the  malar 
bone,  in  front  of  the  zygomatic  suture,  and,  descending  obliquely  downwards 
and  inwards,  is  inserted  into  the  angle  of  the  mouth,  where  it  blends  with  the 
fibres  of  the  Orbicularis  and  Depressor  Anguli  Oris. 

Relations.  By  its  superficial  surface,  with  the  subcutaneous  adipose  tissue. 
By  its  deep  surface,  with  the  malar  bone,  and  the  Masseter  and  Buccinator 
muscles. 

The  Zygomaticus  minor  arises  from  the  malar  bone,  immediately  behind  the 
maxillary  suture,  and,  passing  downwards  and  inwards,  is  continuous  with  the 
outer  margin  of  the  Levator  Labii  Superioris.    It  lies  in  front  of  the  preceding. 

Relations.  By  its  superficial  surface,  with  the  integument  and  the  Orbicularis 
Palpebrarum  above.     By  its  deep  surface,  with  the  Levator  Anguli  Oris. 

Nerves.     This  group  of  muscles  is  supplied  by  the  facial  nerve. 

Actions.  The  Levator  Labii  Superioris  is  the  proper  elevator  of  the  upper 
lip,  carrying  it  at  the  same  time  a  little  outwards.  The  Levator  Anguli  Oris 
raises  the  angle  of  the  mouth  and  draws  it  inwards ;  whilst  the  Zygomatici 
raise  the  upper  lip  and  draw  it  somewhat  outwards,  as  in  laughing. 

7.  Inferior  Maxillary  Region.    (Fig.  215.) 

Levator  Labii  Inferioris  (Levator  Menti). 
Depressor  Labii  Inferioris  (Quadratus  Menti). 
Depressor  Anguli  Oris  (Triangularis  Menti). 

Dissection.  The  muscles  in  this  region  may  be  dissected  by  making  a  vertical  incision 
through  the  integument  from  the  margin  of  the  lower  lip  to  the  chin  ;  a  second  incision  should 
then  be  carried  along  the  margin  of  the  lower  jaw  as  far  as  the  angle,  and  the  integument  care- 
fully removed  in  the  direction  shown  in  Fig.  214. 

The  Levator  Labii  Inferioris  {Levator  Menti)  is  to  be  dissected  by  everting  the 
lower  lip  and  raising  the  mucous  membrane.  It  is  a  small  conical  fasciculus, 
placed  on  the  side  of  the  fr^num  of  the  lower  lip.  It  arises  from  the  incisive 
fossa,  external  to  the  symphysis  of  the  lower  jaw :  its  fibres  descend  to  be  in- 
serted into  the  integument  of  the  chin. 


326  MUSCLES    AND    FASCIA. 

Relations.  On  its  inner  surface^  witli  the  mucous  membrane ;  in  the  median 
line,  it  is  blended  with  the  muscle  of  the  opposite  side ;  and  on  its  outer  side, 
with  the  Depressor  Labii  Inferioris. 

The  Depressor  Labii  Inferioris  {Quadratus  Menti)  is  a  small  quadrilateral 
muscle,  situated  at  the  outer  side  of  the  preceding.  It  arises  from  the  external 
oblique  line  of  the  lower  jaw,  between  the  symphysis  and  mental  foramen,  and 
passes  obliquely  upwards  and  inwards,  to  be  inserted  into  the  integument  of 
the  lower  lip,  its  fibres  blending  with  the  Orbicularis,  and  with  those  of  its 
fellow  of  the  opposite  side.  It  is  continuous  with  the  fibres  of  the  Platysma 
at  its  origin.    This  muscle  contains  much  yellow  fat  intermingled  with  its  fibres. 

Relations.  By  its  superficial  surface,  with  part  of  the  Depressor  Anguli  Oris, 
and  with  the  integument,  to  which  it  is  closely  connected.  By  its  deep  surface, 
with  the  mental  vessels  and  nerves,  the  mucous  membrane  of  the  lower  lip,  the 
labial  glands,  and  the  Levator  Menti,  with  which  it  is  intimately  united. 

The  Depressor  Anguli  Oris  is  triangular  in  shape,  arising,  by  its  broad  base, 
from  the  external  oblique  line  of  the  lower  jaw,  from  whence  its  fibres  pass 
upwards,  to  be  inserted,  by  a  narrow  fasciculus,  into  the  angle  of  the  mouth. 
It  is  continuous  with  the  Platysma  at  its  origin,  and  with  the  Orbicularis  and 
Risorius  at  its  insertion,  and  some  of  its  fibres  are  directly  continuous  with  those 
of  the  Levator  Anguli  Oris. 

Relations.  By  its  superficial  surface,  with  the  integument.  By  its  deep  surface, 
with  the  Depressor  Labii  Inferioris  and  Buccinator. 

Nerves.     This  group  of  muscles  is  supplied  by  the  facial  nerve. 

Actions.  The  Levator  Labii  Inferioris  raises  the  lower  lip,  and  protrudes  it 
forwards,  and  at  the  same  time  wrinkles  the  integument  of  the  chin.  The  De- 
pressor Labii  Inferioris  draws  the  lower  lip  directly  downwards  and  a  little 
outwards.  The  Depressor  Anguli  Oris  depresses  the  angle  of  the  mouth,  being 
the  antagonist  to  the  Levator  Anguli  Oris  and  Zygomaticus  Major :  acting  with 
these  muscles,  it  will  draw  the  angle  of  the  mouth  directly  backwards. 

8.  Intermaxillary  Region. 
Orbicularis  Oris.  Buccinator.  Risorius. 

Dissection.  The  dissection  of  these  muscles  may  be  considerably  facilitated  by  filling  the 
cavity  of  the  mouth  with  tow,  so  as  to  distend  the  cheeks  and  lips  ;  the  mouth  should  then  be 
closed  by  a  few  stitches,  and  the  integument  carefully  removed  from  the  surface. 

The  Orbicularis  Oris  is  a  sphincter  muscle,  elliptic  in  form,  composed  of  con- 
centric fibres,  which  surround  the  orifice  of  the  mouth.  It  consists  of  two  thick 
semicircular  planes  of  muscular  fibre,  which  interlace  on  either  side  with  those 
of  the  Buccinator  and  other  muscles  inserted  into  the  lips.  On  the  free  margin 
of  the  lips  the  muscular  fibres  are  continued  uninterruptedly  from  one  lip  to 
the  other,  around  the  corner  of  the  mouth,  forming  a  roundish  fasciculus  of  fine 
pale  fibres  closely  approximated.  To  the  outer  part  of  each  segment  some 
special  fibres  are  added,  by  which  the  lips  are  connected  directly  with  the  maxil- 
lary bones  and  septum  of  the  nose.  The  additional  fibres  for  the  upper  segment 
consists  of  four  bands,  two  of  which  (accessorii  orbicularis  superiores)  arise 
from  the  alveolar  border  of  the  superior  maxilla,  opposite  the  incisor  teeth,  and 
arching  outwards  on  each  side,  are  continuous  at  the  angles  of  the  mouth  with 
the  other  muscles  inserted  into  this  part.  The  two  remaining  muscular  slips, 
called  the  Naso-labialis,  connect  the  upper  lip  to  the  septum  of  the  nose:  as 
they  descend  from  the  septum,  an  interval  is  left  between  them,  which  corre- 
sponds to  that  left  by  the  divergence  of  the  accessory  portions  of  the  Orbicu- 
laris above  described.  It  is  this  interval  which  forms  the  depression  seen  on 
the  surface  of  the  skin  beneath  the  septum  of  the  nose.  The  additional  fibres 
for  the  lower  segment  (accessorii  orbicularis  inferiores)  arise  from  the  inferior 
maxilla,  externally  to  the  Levator  Labii  Inferioris,  and  arch  outwards  to  the 
angles  of  the  mouth,  to  join  the  Buccinator  and  the  other  muscles  attached  to 
this  part. 


TEMPORO-MAXILLARY    REGION.  327 

delations.  By  its  superficial  surface,  with  the  integument,  to  which  it  is  closely 
connected.  By  its  deep  stir/ace,  with  the  buccal  mucous  membrane,  the  labial 
glands,  and  coronary  vessels.  By  its  outer  circumference,  it  is  blended  with  the 
numerous  muscles  which  converge  to  the  mouth  from  various  parts  of  the  face. 

Its  inner  circumference  is  free,  and  covered  by  the  mucous  membrane. 

The  Buccinator  is  a  broad,  thin  muscle,  quadrilateral  in  form,  which  occupies 
the  interval  between  the  jaws  at  the  side  of  the  face.  It  arises  from  the  outer 
surface  of  the  alveolar  processes  of  the  upper  and  lower  jaws,  corresponding  to 
the  three  molar  teeth ;  and,  behind,  from  the  anterior  border  of  the  pterygo- 
maxillary  ligament.  The  fibres  converge  towards  the  angle  of  the  mouth, 
where  the  central  fibres  intersect  each  other,  those  from  below  being  continuous 
with  the  upper  segment  of  the  Orbicularis  Oris ;  and  those  from  above  with  the 
inferior  segment ;  the  highest  and  lowest  fibres  continue  forward  uninterruptedly 
into  the  corresponding  segment  of  the  lip,  without  decussation. 

Relations.  By  its  superficial  surface,  behind,  with  a  large  mass  of  fat,  which 
separates  it  from  the  ramus  of  the  lower  jaw,  the  Masseter,  and  a  small  portion 
of  the  Temporal  muscle ;  anteriorly,  with  the  Zygomatici,  Risorius,  Levator 
Anguli  Oris,  Depressor  Anguli  Oris,  and  Steno's  duct,  which  pierces  it  opposite 
the  second  molar  tooth  of  the  upper  jaw ;  the  facial  artery  and  vein  cross  it 
from  below  upwards ;  it  is  also  crossed  by  the  branches  of  the  facial  and  buccal 
nerve.  By  its  internal  surface,  with  the  buccal  glands  and  mucous  membrane 
of  the  mouth. 

The  ptery go-maxillary  ligament  separates  the  Buccinator  muscle  from  the  Su- 
perior Constrictor  of  the  pharynx.  It  is  a  tendinous  band,  attached  by  one 
extremity  to  the  apex  of  the  internal  pterygoid  plate,  and  by  the  other  to  the 
posterior  extremity  of  the  internal  oblique  line  of  the  lower  jaw.  Its  inner 
surface  corresponds  to  the  cavity  of  the  mouth,  and  is  lined  by  mucous  mem- 
brane. Its  outer  surface  is  separated  from  the  ramus  of  the  jaw  by  a  quantity 
of  adipose  tissue.  Its  pjosierior  border  gives  attachment  to  the  Superior  Con- 
strictor of  the  pharynx :  its  anterior  border,  to  the  fibres  of  the  Buccinator. 

The  Risorius  {Santorini)  consists  of  a  narrow  bundle  of  fibres,  which  arises 
in  the  fascia  over  the  Masseter  muscle,  and  passing  horizontally  forwards,  is 
inserted  into  the  angle  of  the  mouth,  joining  with  the  fibres  of  the  Depressor 
Anguli  Oris.  It  is  placed  superficial  to  the  Platysma,  and  is  broadest  at  its 
outer  extremity.     This  muscle  varies  much  in  its  size  and  form. 

Nerves.  The  Orbicularis  Oris  is  supplied  by  the  facial,  the  Buccinator  by  the 
facial  and  by  the  buccal  branch  of  the  inferior  maxillary  nerve. 

Actions.  Tne  Orbicularis  Oris  is  the  direct  antagonist  of  all  those  muscles 
which  converge  to  the  lips  from  the  various  parts  of  the  face,  its  ordinary  action 
producing  the  direct  closure  of  the  lips ;  and  its  forcible  action  throwing  the 
integument  into  wrinkles,  on  account  of  the  firm  connection  between  the  latter 
and  the  surface  of  the  muscle.  The  Buccinators  contract  and  compress  the 
cheeks,  so  that,  during  the  process  of  mastication,  the  food  is  kept  under  the 
immediate  pressure  of  the  tee.th. 

9.  Temporo-maxillary  Region". 

Masseter.  Temporal. 

The  Masseter  has  been  already  exposed  by  the  removal  of  the  integument 
from  the  side  of  the  face  (Fig,  215) ;  it  is  a  short  thick  muscle,  somewhat  quad- 
rilateral in  form,  consisting  of  two  portions,  superficial  and  deep.  The  superficial 
portion,  the  larger,  arises  by  a  thick  tendinous  aponeurosis  from  the  malar  pro- 
cess of  the  superior  maxilla,  and  from  the  anterior  two-thirds  of  the  lower 
border  of  the  zygomatic  arch :  its  fibres  pass  downwards  and  backwards,  to  be 
inserted  into  the  angle  and  lower  half  of  the  ramus  of  the  jaw.  The  deep)  p>ortion 
is  much  smaller,  and  more  muscular  in  texture ;  it  arises  from  the  posterior 
third  of  the  lower  border  and  the  whole  of  the  inner  surface  of  the  zygomatic 


828 


MUSCLES    AND    FASCIA. 


arcli ;  its  fibres  pass  downwards  and  forwards,  to  be  inserted  into  the  upper  lial! 
of  the  ramus  and  outer  surface  of  the  coronoid  process  of  the  jaw.  The  deep 
portion  of  the  muscle  is  partly  concealed,  in  front,  by  the  superficial  portion  ; 
behind,  it  is  covered  by  the  parotid  gland.  The  fibres  of  the  two  portions  are 
united  at  their  insertion. 

Relations.  By  its  superficial  surface^  with  the  integument ;  above,  with  the 
Orbicularis  Palpebrarum  and  Zygomatici ;  and  with  Steno's  duct,  the  branches 
of  the  facial  nerve,  and  the  transverse  facial  vessels,  which  cross  it.  By  its  deep 
surface,  with  the  ramus  of  the  jaw,  and  the  Buccinator,  from  which  it  is  separated 
by  a  mass  of  fat.  Its  posterior  margin  is  overlapped  by  the  parotid  gland.  Its 
anterior  margin  projects  over  the  Buccinator  muscle ;  and  the  facial  artery  lies 
on  it  below. 

The  temporal  fascia  is  seen,  at  this  stage  of  the  dissection,  covering  in  the 
Temporal  muscle.  It  is  a  strong  aponeurotic  investment,  afibrdiug  attachment, 
by  its  inner  surface,  to  the  superficial  fibres  of  the  muscle.  Above,  it  is  a  single 
layer,  attached  to  the  entire  extent  of  the  temporal  ridge ;  but  below,  where  it 
is  attached  to  the  zygoma,  it  consists  of  two  layers,  one  of  which  is  inserted 
into  the  outer  and  the  other  into  the  inner  border  of  the  zygomatic  arch.  A 
small  quantity  of  fat,  the  orbital  branch  of  the  temporal  artery,  and  a  filament 
from  the  orbital  branch  of  the  superior  maxillary  nerve,  are  contained  between 
these  two  layers.  It  is  covered,  on  its  outer  surface,  by  the  aponeurosis  of  the 
Occipito-frontalis,  the  Orbicularis  Palpebrarum,  and  Attollens  Aurem  and  At- 
trahens  Aurem  muscles ;  the  temporal  vessels  and  nerves  cross  it  from  below 
upwards. 

Fig.  218. — The  Temporal  Muscle,  the  Zypotna  and  Miisseter  having  been  removed. 


Diascdion.  In  order  to  expose  the  Temporal  mnscle,  remove  the  temporal  fascia,  •which  may 
be  effected  by  separating  it  at  its  attachment  along  the  upper  border  of  the  zygoma,  and  dis- 
secting it  upwards  from  the  surface  of  the  muscle.  The  zygomatic  arch  should  then  be  divided, 
in  front,  at  its  junction  with  the  malar  bone  ;  and  behind,  near  the  external  auditory  meatus,  and 
drawn  downwards  with  the  Masseter,  which  should  be  detached  from  its  insertion  into  the  ramus 
and  angle  of  the  jaw.     The  whole  extent  of  the  Temporal  muscle  is  then  exposed. 

The  Temporal  (¥\g.  218)  is  a  broad  radiating  muscle,  situated  at  the  side  of  the 
head,  and  occupying  the  entire  extent  of  the  temporal  fossa.  It  arises  from  the 
whole  of  the  temporal  fossa,  which  extends  from  the  external  angular  process 
of  the  frontal  in  front,  to  the  mastoid  portion  of  the  temporal  behind;  and  from 


PTERYGO-MAXILLARY    REGION. 


329 


the  curved  line  on  the  frontal  and  parietal  bones  above,  to  the  pterygoid  ridge 
on  the  great  wing  of  the  sphenoid  below.  It  is  also  attached  to  the  inner  sur- 
face of  the  temporal  favscia.  Its  fibres  converge  as  they  descend,  and  terminate 
in  an  aponeurosis,  the  fibres  of  which,  radiated  at  its  commencement,  converge 
into  a  thick  and  flat  tendon,  which  is  inserted  into  the  inner  surface,  apex,  and 
anterior  border  of  the  coronoid  process  of  the  jaw,  nearly  as  far  forwards  as  the 
last  molar  tooth. 

Relations. .  By  its  superficial  surface^  with  the  integument,  the  temporal  fascia, 
the  aponeurosis  of  the  Occipito-frontalis,  the  Attollens  Aurem  and  Attrahens 
Aurem  muscles,  the  temporal  vessels  and  nerves,  the  zygoma  and  Masseter. 
By  its  deep  surface,  with  the  temporal  fossa,  the  External  Pterygoid  and  part 
of  the  Buccinator  muscles,  the  internal  maxillary  artery,  its  deep  temporal 
branches,  and  the  temporal  nerves. 

Nerves.     Both  muscles  are  supplied  by  the  inferior  maxillary  nerve. 

10.   PtERYGO- MAXILLARY  REGION.      (Fig.  219.) 

Internal  Pterygoid.  External  Pterygoid. 

Dissection.  The  Temporal  muscle  having  been  examined,  saw  through  the  base  of  the  coro- 
noid process,  and  draw  it  upwards,  together  with  the  Temporal  muscle,  which  should  be  detached 
from  the  surface  of  the  temporal  fossa.  Divide  the  ramus  of  the  jaw  just  below  the  condyle, 
and  also,  by  a  transverse  incision  extending  across  the  commencement  of  its  lower  third,  just 
above  the  dental  foramen;  remove  the  fragment,  and  the  Pterygoid  muscles  will  be  exposed. 

Fig.  219. — The  Pterygoid  Muscles;  the  Zygomatic  Arch  and  a  portion  of  the 
Ramus  of  the  J^^w  having  been  removed. 


The  Internal  Pterygoid  is  a  thick  quadrilateral  muscle,  and  resembles  the 
Masseter,  in  form,  structure,  and  the  direction  of  its  fibres.  It  arises  from  the 
pterygoid  fossa,  being  attached  to  the  inner  surface  of  the  external  pterygoid 
plate,  and  to  the  grooved  surface  of  the  tuberosity  of  the  palate  bone ;  its  fibres 
pass  downwards,  outwards,  and  backwards,  to  be  inserted,  by  strong  tendinous 
lamince,  into  the  lower  and  back  part  of  the  inner  side  of  the  ramus  and  angle 
of  the  lower  jaw,  as  high  as  the  dental  foramen. 

Relations.  By  its  external  surface,  with  the  ramus  of  the  lower  jaw,  from 
which  it  is  separated,  at  its  upper  part,  by  the  External  Pterygoid,  the  internal 
lateral  ligament,  the  internal  maxillary  artery,  and  the  dental  vessels  and  nerves. 


330  MUSCLES    AND    FASCIA. 

By  its  internal  surface,  with  the  Tensor  Palati,  being  separated  from  the  Superior 
Constrictor  of  the  pharynx  by  a  cellular  interval. 

The  External  Pterygoid  is  a  short  thick  muscle,  somewhat  conical  in  form, 
which  extends  almost  horizontally  between  the  zygomatic  fossa  and  the  condyle 
of  the  jaw.  It  arises  from  the  pterygoid  ridge  on  the  great  wing  of  the  sphe- 
noid, and  the  portion  of  bone  included  between  it  and  the  base  of  the  pterygoid 
process;  from  the  outer  surface  of  the  external  pterygoid  plate;  and  from  the 
tuberosity  of  the  palate  and  superior  maxillary  bones.  Its  fibres  pass  horizon- 
tally backwards  and  outwards,  to  be  inserted  into  a  depression  in  front  of  the 
neck  of  the  condyle  of  the  lower  jaw,  and  into  the  corresponding  part  of  the 
interarticular  fibro-cartilage.  This  muscle,  at  its  origin,  appears  to  consist  of 
two  portions  separated  by  a  slight  interval;  hence  the  terms  upper  and  lower 
head  sometimes  used  in  the  description  of  the  muscle. 

Relations.  By  its  external  surface,  with  the  ramus  of  the  lower  jaw,  the  in- 
ternal maxillary  artery,  which  crosses  it,'  the  tendon  of  the  Temporal  muscle, 
and  the  Masseter.  By  its  internal  surface,  it  rests  against  the  upper  part  of  the 
Internal  Pterygoid,  the  internal  lateral  ligament,  the  middle  meningeal  artery, 
and  inferior  maxillary  nerve ;  by  its  upper  border  it  is  in  relation  with  the  tem- 
poral and  masseteric  branches  of  the  inferior  maxillary  nerve. 

Nerves.     These  muscles  are  supplied  by  the  inferior  maxillary  nerve. 

Actions.  The  Temporal,  Masseter,  and  Internal  Pterygoid  raise  the  lower 
jaw  against  the  upper  with  great  force.  The  superficial  portion  of  the  Masseter, 
and  the  Internal  Pterygoid,  assist  the  External  Pterygoid  in  drawing  the  lower 
jaw  forwards  upon  the  upper,  the  jaw  being  drawn  back  again  by  the  deep 
fibres  of  the  Masseter,  and  posterior  fibres  of  the  Temporal.  The  External 
Pterygoid  muscles  are  the  direct  agents  in  the  trituration  of  the  food,  drawing 
the  lower  jaw  directly  forwards,  so  as  to  make  the  lower  teeth  project  beyond 
the  upper.  If  the  muscle  of  one  side  acts,  the  corresponding  side  of  the  jaw 
is  drawn  forwards,  and  the  other  condyle  remaining  fixed,  the  symphysis 
deviates  to  the  opposite  side.  The  alternation  of  these  movements  on  the  two 
sides  produces  trituration. 

MUSCLES  AND  FASCIA  OF  THE  NECK. 

The  Muscles  of  the  Neck  may  be  arranged  into  groups,  corresponding  with 
the  region  in  which  they  are  situated. 

These  groups  are  nine  in  number  l — 

1.  Superficial  Region.  6.  Muscles  of  the  Soft  Palate. 

2.  Depressors  of  the  Os  Hyoides  7.  Muscles  of  the  Anterior  Yerte- 

and  Larynx.  bral  Region. 

8.  Elevators  of  the  Os  Hyoides —  8.  Muscles  of  the  Lateral  Vertebral 
Depressors  of  the  Lower  Jaw.  Region. 

4.  Muscles  of  the  Tongue.  9.  Muscles  of  the  Larynx. 

5.  Muscles  of  the  Pharynx. 

1.  Superficial  Cervical  Region.  Sterno-thyroid. 

Platysma  Myoides.  Thyro-hyoid. 

Sterno-cleido-mastoid.  Omo-hyoid. 
Mylo-hyoid. 
Geuio-hyoid.  8.  Stipra-hyoid  Region. 

Elevators  of  the  Os  Hyoides — Depressors 
2.  Infra-hyoid  Region.  of  the  Lower  Jaw. 

Depressors  of  the  Os  Hyoides  and  Larynx.  Digastric. 

Sterno-hyoid.  Stylo-hyoid. 

'  This  is  the  usual  relation ;  but  in  many  cases  the  artery  will  be  found  below  the  muscle. 


SUPERFICIAL    CERVICAL    REGION. 


331 


4.  Lingual  Region. 
Muscles  of  the  Tongue. 
Genio-hyo-glossus. 
Hyo-glossus. 
Lingualis. 
Stylo-glossus. 
Palato-glossus. 

5.  Pharyngeal  Region. 

Muscles  of  the  Pharynx. 
Constrictor  Inferior. 
Constrictor  Medius. 
Constrictor  Superior. 
Stylo-pharyngeus. 
Palato-pharyngeus. 

6,  Palatal  Region. 
Muscles  of  the  Soft  Palate. 
Levator  Palati. 


Tensor  Palati. 
Azygos  Uvulae. 
Palato-glossus. 
Palato-pharyngeus. 

7.  Anterior  Vertebral  Region. 
Rectus  Capitis  Anticus  Major. 
Rectus  Capitis  Anticus  Minor. 
Rectus  Lateralis. 
Longus  Colli. 

8.  Lateral  Vertebral  Region. 
Scalenus  Anticus. 
Scalenus  Medius. 
Scalenus  Posticus. 

9.  Muscles  of  the  Larynx. 
(Included   in   the   description    of  the 
Larynx.) 


1.  SuPEEFiciAL  Cervical  Region. 


Platysma  Myoides. 


Sterno-cleido-mastoid. 


Dissection.  A  block  having  been  placed  at  the  back  of  the  neck,  and  the  face  turned  to  the 
side  opposite  to  that  to  be  dissected,  so  as  to  place  the  parts  upon  the  stretch,  make  two  trans- 
verse incisions ;  one  from  the  chin,  along  the  margin  of  the  lower  jaw,  to  the  mastoid  process ; 
and  the  other  along  the  upper  border  of  the  clavicle.  Connect  these  by  an  oblique  incision 
made  in  the  course  of  the  Sterno-mastoid  muscle,  from  the  "mastoid  process  to  the  sternum ;  the 
two  flaps  of  integument  having  been  removed  in  the  direction  shown  jn  Fig.  214,  the  superficial 
fascia  will  be  exposed. 

The  superficial  cervical  fascia  is  exposed  on  the  removal  of  the  integument 
from  the  side  of  the  neck ;  it  is  an  extremely  thin  aponeurotic  lamina,  which 
is  hardly  demonstrable  as  a  separate  membrane.  Beneath  it  is  found  the 
Platysma  Myoides  muscle,  the  external  jugular  vein,  and  some  superficial 
branches  of  the  cervical  plexus  of  nerves. 

The  Platysma  Myoides  (Fig.  215)  is  a  broad  thin  plane  of  muscular  fibres, 
placed  immediately  beneath  the  skin  on  each  side  of  the  neck.  It  arises  from 
the  clavicle  and  acromion,  and  from  the  fascia  covering  the  upper  part  of  the 
Pectoral,  Deltoid,  and  Trapezius  muscles ;  its  fibres  proceed  obliquely  upwards 
and  inwards  along  the  side  of  the  neck,  to  be  inserted  into  the  lower  jaw 
beneath  the  external  oblique  line,  some  passing  forwards  to  the  angle  of  the 
mouth,  and  others  becoming  lost  in  the  cellular  tissue  of  the  face.  The  most 
anterior  fibres  interlace,  in  front  of  the  jaw,  with  the  fibres  of  the  muscle  of 
the  opposite  side;  those  next  in  order  become  blended  with  the  Depressor 
Labii  Inferioris  and  the  Depressor  Anguli  Oris ;  others  are  prolonged  upon 
the  side  of  the  cheek,  and  interlace,  near  the  angle  of  the  mouth,  with  the 
muscles  in  this  situation,  and  may  occasionally  be  traced  to  the  Zygomatic 
muscles,  or  to  the  margin  of  the  Orbicularis  Palpebrarum.  Beneath  the 
Platysma,  the  external  jugular  vein  may  be  seen  descending  from  the  angle  of 
the  jaw  to  the  clavicle.  It  is  essential  to  remember  the  direction  of  the  fibres 
of  the  Platysma,  in  connection  with  the  operation  of  bleeding  from  this  vessel; 
for  if  the  point  of  the  lancet  is  introduced  in  the  direction  of  the  muscular 
fibres,  the  orifice  made  will  be  filled  up  by  the  contraction  of  the  muscle,  and 
blood  will  not  flow ;  but  if  the  incision  is  made  across  the  course  of  the  fibres, 
they  will  retract,  and  expose  the  orifice  in  the  vein,  and  so  facilitate  the  flow 
of  blood. 

Relations.     By  its  external  surface^  with  the  integument,  to  which  it  is  united 


332  MUSCLES    AND    FASCIA. 

closely  below,  but  more  loosely  above.  By  its  internal  surface,  ■with  the  Pec- 
toralis  Major,  Deltoid,  and  Trapezius,  and  with  the  clavicle.  In  the  neck,  with 
the  external  and  anterior  jugular  veins,  the  deep  cervical  fascia,  the  superficial 
cervical  plexus,  the  Sterno-mastoid,  Sterno-hyoid,  Omo-hyoid,  and  Digastric 
muscles.  In  front  of  the  Sterno-mastoid,  it  covers  the  sheath  of  the  carotid 
vessels;  and  behind  it,  the  Scaleni  muscles  and  the  nerves  of  the  brachial 
plexus.  On  the  face,  it  is  in  relation  with  the  parotid  gland,  the  facial  artery 
and  vein,  and  the  Masseter  and  Buccinator  muscles. 

The  deep  cervical  fascia  is  exposed  on  the  removal  of  the  Platysma  Myoides. 
It  is  a  strong  fibrous  layer,  which  invests  the  muscles  of  the  neck,  and  incloses 
the  vessels  and  nerves.  It  commences,  as  an  extremely  thin  layer,  at  the  back 
part  of  the  neck,  where  it  is  attached  to  the  spinous  processes  of  the  cervical 
vertebrae,  and  to  the  ligamentum  nuchas ;  and,  passing  forwards  to  the  posterior 
border  of  the  Sterno-mastoid  muscle,  divides  into  two  layers,  one  of  which 
passes  in  front,  and  the  other  behind  that  muscle.  These  join  again  at  the 
anterior  border  of  the  Sterno-mastoid ;  and,  being  continued  forwards  to  the 
front  of  the  neck,  blend  with  the  fascia  of  the  opposite  side.  The  superficial 
layer  of  the  deep  cervical  fascia  (that  which  passes  in  front  of  the  Sterno- 
mastoid),  if  traced  upwards,  is  found  to  pass  across  the  parotid  gland  and 
Masseter  muscle,  forming  the  parotid  and  masseteric  fascia,  and  is  attached  to 
the  lower  border  of  the  zygoma,  and  more  anteriorly  to  the  lower  border  of 
the  body  of  the  jaw ;  if  the  same  layer  is  traced  downwards,  it  is  seen  to  pass 
to  the  upper  border  of  the  clavicle  and  sternum,  being  pierced  just  above  the 
former  bone  by  the  external  jugular  vein.  In  the  middle  line  of  the  neck,  the 
fkscia  is  thin  above,  and  connected  to  the  hyoid  bone ;  but  it  becomes  thicker 
below,  and  divides,  just  below  the  thyroid  gland,  into  two  layers,  the  more 
superficial  of  which  is  attached  to  the  upper  border  of  the  sternum  and  inter- 
clavicular ligament ;  the  deeper  and  stronger  layer  is  connected  to  the  posterior 
border  of  that  bone,  covering  in  the  Sterno-hyoid  and  Sterno-thyroid  muscles. 
Between  these  two  layers  is  a  little  areolar  tissue  and  fat,  and  occasionally  a 
small  lymphatic  gland.  The  deep  layer  of  the  cervical  fascia  (that  which  lies 
behind  the  posterior  surface  of  the  Sterno-mastoid)  sends  numerous  prolonga- 
tions, which  invest  the  muscles  and  vessels  of  the  neck ;  if  traced  upwards,  a 
process  of  the  fascia,  of  extreme  density,  is  found  passing  behind  and  to  the 
inner  side  of  the  parotid  gland,  to  be  attached  to  the  base  of  the  styloid  pro- 
cess and  angle  of  the  lower  jaw,  termed  the  stylo-maxillary  ligament;  if  traced 
downwards  and  outwards,  the  fascia  will  be  found  to  inclose  the  posterior  belly 
of  the  Omo-hyoid  muscle,  binding  it  down  by  a  distinct  process,  which  descends 
to  be  inserted  into  the  clavicle  and  cartilage  of  the  first  rib.  The  deep  layer 
of  the  cervical  fascia  also  assists  in  forming  the  sheath  which  incloses  the 
common  carotid  artery,  internal  jugular  vein,  and  pneumogastric  nerve.  There 
are  fibrous  septa  intervening  between  each  of  these  parts,  which,  however,  are 
included  together  in  one  common  investment.  More  internally,  a  thin  layer  is 
continued  across  the  trachea  and  thyroid  gland,  beneath  the  Sterno-thyroid 
muscles ;  and  at  the  root  of  the  neck  this  may  be  traced,  over  the  large  vessels, 
to  be  continuous  with  the  fibrous  layer  of  the  pericardium. 

The  Stemo-ckido-mastoid  (Fig.  220)  is  a  large  thick  muscle  which  passes 
obliquely  across  the  side  of  the  neck,  being  inclosed  between  the  two  layers 
of  the  deep  cervical  fascia.  It  is  thick  and  narrow  at  its  central  part,  but  is 
broader  and  thinner  at  each  extremity.  It  arises,  by  two  heads,  from  the 
sternum  and  clavicle.  The  sternal  portion  is  a  rounded  fasciculus,  tendinous  in 
front,  fleshy  behind,  which  arises  from  the  upper  and  anterior  part  of  the  first 
piece  of  the  sternum,  and  is  directed  upwards  and  backwards.  The  clavictdar 
portion  arises  from  the  inner  third  of  the  superior  border  of  the  clavicle,  being 
composed  of  fleshy  and  aponeurotic  fibres ;  it  is  directed  almost  vertically  up- 
wards. These  two  portions  are  separated  from  one  another,  at  their  origin,  by 
a  triangular  cellular  interval ;  but  become  gradually  blended,  below  the  middle 


SUPERFICIAL    CERVICAL    REGION.  333 

of  the  neck,  into  a  thick  rounded  muscle,  which  is  inserted,  by  a  strong  tendon, 
into  the  outer  surface  of  the  mastoid  process,  from  its  apex  to  its  superior  bor- 
der, and  by  a  thin  aponeurosis  into  the  outer  two-thirds  of  the  superior  curved 
line  of  the  occipital  bone.     The  Sterno-mastoid  varies  much  in  its  extent  of 

Fig.  220. — Muscles  of  the  Neck,  and  Boundaries  of  the  Triangles. 


attachment  to  the  clavicle :  in  one  case  the  clavicular  may  be  as  narrow  as  the 
sternal  portion ;  in  another,  as  much  as  the  three  inches  in  breadth.  "When 
the  clavicular  origin  is  broad,  it  is  occasionally  subdivided  into  numerous  slips, 
separated  by  narrow  intervals.  More  rarely,  the  corresponding  margins  of  the 
Sterno-mastoid  and  Trapezius  have  been  found  in  contact.  In  the  application 
of  a  ligature  to  the  third  part  of  the  subclavian  artery,  it  will  be  necessary, 
where  the  muscles  come  close  together,  to  divide  a  portion  of  one  or  of  both. 

This  muscle  divides  the  quadrilateral  space  at  the  side  of  the  neck  into  two 
triangles,  an  anterior  and  a  posterior.  The  boundaries  of  the  anterior  triangle 
are  in  front,  the  median  line  of  the  neck ;  above,  the  lower  border  of  the  body 
of  the  jaw,  and  an  imaginary  line  drawn  from  the  angle  of  the  jaw  to  the* 
mastoid  process ;  behind,  the  anterior  border  of  the  Sterno-mastoid  muscle. 
The  boundaries  of  the  posterior  triangle  are,  in  front,  the  posterior  border  of  the 
Sterno-mastoid  ;  below,  the  upper  border  of  the  clavicle ;  behind,  the  anterior 
margin  of  the  Trapezius.^ 

The  anterior  edge  of  the  muscle  forms  a  very  prominent  ridge  beneath  the 
skin,  which  it  is  important  to  notice,  as  it  forms  a  guide  to  the  surgeon  in 
making  the  necessary  incisions  for  ligature  of  the  common  carotid  arfery,  and 
for  oesophagotomy. 

Relations.     By  its  swperjidal  surface^  with  the  integument  and  Platysma,  from 

•  The  anatomy  of  these  triangles  will  be  more  exactly  described  with  that  of  the  vessels  of  the 
neck. 


334  MUSCLES    AND    FASCIA. 

which  it  is  separated  bj  the  external  jugular  vein,  the  superiScial  branches  of 
the  cervical  plexus,  and  the  anterior  layer  of  the  deep  cervical  fascia.  By  its 
deep  surface,  it  rests  on  the  sterno-clavicular  articulation,  the  deep  layer  of  the 
cervical  fascia,  the  Sterno-hyoid,  Sterno-thyroid,  Oino-hyoid,  the  posterior  belly 
of  the  Digastric,  Levator  Anguli  Scapulae,  the  Splenius  and  Scaleni  muscles. 
Below,  it  is  in  relation  with  the  lower  part  of  the  common  carotid  artery, 
internal  jugular  vein,  pneumogastric,  descendens  noni,  and  communicans  noni 
nerves,  and  with  the  deep  lymphatic  glands ;  with  the  spinal  accessory  nerve, 
which  pierces  its  upper  third,  the  cervical  plexus,  the  occipital  artery,  and  a 
part  of  the  parotid  gland. 

Nerves.  The  Platysma  Myoides  is  supplied  by  the  facial  and  superficial 
cervical  nerves;  the  sterno-cleido-mastoid  by  the  spinal  accessory  and  deep 
branches  of  the  cervical  plexus. 

Actions.  The  Platysma  Myoides  produces  a  slight  wrinkling  of  the  surface 
of  the  skin  of  the  neck,  in  a  vertical  direction,  when  the  entire  muscle  is 
brought  into  action.  Its  anterior  portion,  the  thickest  part  of  the  muscle, 
depresses  the  lower  jaw;  it  also  serves  to  draw  down  the  lower  lip  and  angle 
of  the  mouth  on  each  side,  being  one  of  the  chief  agents  in  the  expression  of 
melancholy.  The  Sterno-mastoid  muscles,  when  both  are  brought  into  action, 
serve  to  depress  the  head  upon  the  neck,  and  the  neck  upon  the  chest.  Either 
muscle,  acting  singly,  flexes  the  head,  and  (combined  with  the  Splenius)  draws 
it  towards  the  shoulder  of  the  same  side,  and  rotates  it  so  as  to  carry  the  face 
towards  the  opposite  side. 

Surgical  Anatomy.  The  relations  of  the  sternal  and  clavicular  parts  of  the  Sterno-mastoid 
should  be  carefully  examined,  as  the  surgeon  is  sometimes  required  to  divide  one  or  both  portions 
of  the  muscle  in  wiy  neck.  One  variety  of  this  distortion  is  produced  by  spasmodic  contraction 
or  rigidity  of  the  Sterno-mastoid ;  the  head  being  carried  down  towards  the  shoulder  of  the  same 
side,  and  the  face  turned  to  the  opposite  side,  and  fixed  in  that  position.  When  all  other  reme- 
dies for  the  relief  of  this  disease  have  failed,  subcutaneous  division  of  the  muscle  is  resorted  to. 
This  is  performed  by  introducing  a  long  narrow  bistoury  beneath  it,  about  half  an  inch  above  its 
origin,  and  dividing  it  from  behind  forwards  whilst  the  muscle  is  put  well  upon  the  stretch. 
There  is  seldom  any  difficultv  in  dividing  the  sternal  portion.  In  dividing  the  clavicular  portion 
care  must  be  taken  to  avoid  wounding  the  external  jugular  vein,  which  runs  parallel  with  the 
posterior  border  of  the  muscle  in  this  situation. 

2.— Infra-hyoid  Eegion.    (Figs.  220,  221.) 

Depeessors  of  the  Os  Hyoides  and  Larynx. 

Sterno-hyoid.  Thyro-hyoid. 

Sterno-thyroid.  Omo-hyoid. 

Dissection.  The  muscles  in  this  region  may  be  exposed  by  removing  the  deep  fascia  from  the 
front  of  the  neck.  In  order  to  see  the  entire' extent  of  the  Omo-hyoid,  it  is  necessary  to  divide 
the  Sterno-mastoid  at  its  centre,  and  turn  its  ends  aside,  and  to  detach  the  Trapezius  from  the 
clavicle  and  scapula.    This,  however,  should  not  be  done  unless  the  Trapezius  has  been  dissected. 

The  Sterno-hyoid  is  a  thin,  narrow,  riband-like  muscle,  which  arises  from  the 
inner  extremity  of  the  clavicle,  and  the  upper  and  posterior  part  of  the  first 
piece  of  the  sternum ;  and,  passing  upwards  and  inwards,  is  inserted,  by  short 
tendinous  fibres,  into  the  lower  border  of  the  body  of  the  os  hyoides.  This 
muscle  is  separated,  below,  from  its  fellow  by  a  considerable  interval ;  but  they 
approach  one  another  in  the  middle  of  their  course,  and  again  diverge  as  they 
ascend.  It  often  presents,  immediately  above  its  origin,  a  transverse  tendinous 
intersection,  like  those  in  the  Rectus  Abdominis. 

Variations.  This  muscle  sometimes  arises  from  the  inner  extremity  of  the  clavicle,  and  the 
posterior  s^crno-clavicular  ligament ;  or  from  the  sternum  and  this  ligament ;  from  either  ])one 
alone,  or  from  all  these  parts ;  and  occasionally  has  a  fasciculus  connected  with  the  cartilage 
of  the  first  rib. 

Relations.  By  its  superficial  surface,  below,  with  the  sternum,  the  sternal  end 
of  the  clavicle,  and  the  Sterno-mastoid;  and  above,  with  the  Platysma  and  deep 
cervical  fascia.     By  its  deep  surface,  with  the  Sterno-thyroid,  Crico-thyroid,  and 


INFRA-HYOID    REGION". 


335 


Thyro-hyoid  muscles,  tlie  thyroid  gland,  tlie  superior  thyroid  vessels,  the  crico- 
thyroid and  thyro-hyoid  membranes. 

The  Sterno-thyroid  is  situated  beneath  the  preceding  muscle,  but  is  shorter 
and  wider  than  it.  It  arises  from  the  posterior  surface  of  the  first  bone  of  the 
sternum,  below  the  origin  of  the  Sterno-hyoid,  and  occasionally  from  the  edge 
of  the  cartilage  of  the  first  rib;  and  is  inserted  into  the  oblique  line  on  the  side 


Fig.  221.— Muscles  of  the  Neck. 


Anterior  View. 


of  the  ala  of  the  thyroid  cartilage.  This  muscle  is  in  close  contact  with  its  fel- 
low at  the  lower  part  of  the  neck ;  and  is  frequently  traversed  by  a  transverse 
or  oblique  tendinous  intersection,  like  those  in  the  Eectus  Abdominis. 

Variations.  This  muscle  is  sometimes  continuous  with  the  Thyro-hyoid  and  Inferior  Con- 
strictor of  the  pharynx ;  and  a  lateral  prolongation  from  it  sometimes  passes  as  far  as  the  os 
hyoides. 

Relations.  By  its  anterior  surface,  with  the  Sterno-hyoid,  Omo-hyoid,  and 
Sterno-mastoid.  By  its  posterior  surface.,  from  below  upwards,  with  the  trachea, 
vena  innominata,  common  carotid  (and  on  the  right  side  the  arteria  innominata), 
the  thyroid  gland  and  its  vessels,  and  the  lower  part  of  the  larynx.  The  mid- 
dle thyroid  vein  lies  along  its  inner  border,  a  relation  which  it  is  important  to 
remember  in  the  operation  of  tracheotomy. 

The  Thyro-hyoid  is  a  small  quadrilateral  muscle  appearing  like  a  continuation 
of  the  Sterno-thyroid.  It  arises  from  the  oblique  line  on  the  side  of  the  thyroid 
cartilage,  and  passes  vertically  upwards  to  be  inserted  into  the  lower  border 
of  the  body  and  greater  cornu  of  the  hyoid  bone. 

Relations.  By  its  external  surface.,  with  the  Sterno-hyoid  and  Omo-hyoid 
muscles.  By  its  internal  surface.,  with  the  thyroid  cartilage,  the  thyro-hyoid 
membrane,  and  the  superior  laryngeal  vessels  and  nerve. 

The  Omo-hyoid  passes  across  the  side  of  the  neck,  from  the  scapula  to  the 
hyoid  bone.     It  consists  of  two  fleshy  bellies,  united  by  a  central  tendon.     It 


336  MUSCLES    AND    FASCIA. 

arises  from  the  upper  border  of  the  scapula,  and  occasionally  from  the  trans- 
verse ligament  which  crosses  the  suprascapular  notch ;  its  extent  of  attachment 
to  the  scapul^  varying  from  a  few  lines  to  an  inch.  From  this  origin,  the 
posterior  belly  forms  a  flat,  narrow  fasciculus,  which  inclines  forwards  across 
the  lower  part  of  the  neck ;  behind  the  Sterno- mastoid  muscle,  where  it  becomes 
tendinous,  it  changes  its  direction,  forming  an  obtuse  angle,  and  ascends  almost 
vertically  upwards,  close  to  the  outer  border  of  the  Sterno-hyoid,  to  be  inserted 
into  the  lower  border  of  the  body  of  the  os  hyoides,  just  external  to  the  inser- 
tion of  the  Sterno-hyoid.  The  tendon  of  this  muscle,  which  varies  much  in  its 
length  and  form  in  dift'erent  subjects,  is  held  in  its  position  by  a  process  of  the 
deep  cervical  fascia,  which  includes  it  in  a  sheath,  and  is  prolonged  down  to  be 
attached  to  the  cartilage  of  the  first  rib.  It  is  by  this  means  that  the  angular 
form  of  the  muscle  is  maintained. 

This  muscle  subdivides  each  of  the  two  large  triangles  at  the  side  of  the  neck 
into  two  smaller  triangles;  the  two  posterior  ones  being  the  posterior  su2)erior  or 
suboccipital,  and  the  posterior  inferior  or  subclavian ;  the  two  anterior,  the  anterior 
superior  or  superior  carotid,  and  the  anterior  inferior  or  inferior  carotid  triangle. 

Relations.  By  its  superficial  surface,  with  the  Trapezius,  Subclavius,  the  cla- 
vicle, the  Sterno-mastoid,  deep  cervical  fascia,  Platysma,  and  integument.  By 
its  deep  surface,  with  the  Scaleni,  brachial  plexus,  sheath  of  the  common  carotid 
artery,  and  internal  jugular  vein,  the  descendens  noni  nerve,  Sterno-thyroid  and 
Thyro-hyoid  muscles. 

Nerves.  The  Thyro-hyoid  is  supplied  by  the  hypoglossal;  the  other  muscles 
of  this  group  by  branches  from  the  loop  of  communication  between  the  descen- 
dens and  communicans  noni. 

Actions.  These  muscles  depress  the  larynx  and  hyoid  bone,  after  they  have 
been  drawn  up  with  the  pharynx  in  the  act  of  deglutition.  The  Omo-hyoid 
muscles  not  only  depress  the  hyoid  bone,  but  carry  it  backwards,  and  to  one  or 
the  other  side.  They  are  also  tensors  of  the  cervical  fascia.  The  Thyro-hyoid 
may  act  as  an  elevator  of  the  thyroid  cartilage,  when  the  hyoid  bone  ascends, 
drawing  upwards  the  thyroid  cartilage  behind  the  os  hyoides. 

3.  SUPRA-HYOID  Eegion.     (Figs.  220,  221.) 

Elevators  of  the  Os  Hyoides — Depressors  of  the  Lower  Jaw. 

Digastric.  Mylo-hyoid. 

Stylo-hyoid.  Genio-hyoid. 

Dissection.  To  dissect  these  muscles,  a  block  should  be  placed  beneath  the  back  of  the  neck, 
and  the  head  drawn  backwards,  and  retained  in  that  position.  On  the  removal  of  the  deep 
fascia,  the  muscles  are  at  once  exposed. 

The  Digastric  consists  of  two  fleshy  bellies  united  by  an  intermediate  rounded 
tendon.  It  is  a  small  muscle,  situated  below  the  side  of  the  body  of  the  lower 
jaw,  and  extending,  in  a  curved  form,  from  the  side  of  the  head  to  the  sym- 
physis of  the  jaw.  The  posterior  belly,  longer  than  the  anterior,  arises  from  the 
aigastric  groove  on  the  inner  side  of  the  mastoid  process  of  the  temporal  bone, 
and  passes  downwards,  forwards,  and  inwards.  The  anterior  belly,  being  reflected 
upwards  and  forwards,  is  inserted  into  a  depression  on  the  inner  side  of  the 
lower  border  of  the  jaw,  close  to  the  symphysis.  The  tendon  of  the  muscle 
perforates  the  Stylo-hyoid,  and  is  held  in  connection  with  the  side  of  the  body 
of  the  hyoid  bone  by  an  aponeurotic  loop,  lined  by  a  synovial  membrane.  A 
broad  aponeurotic  layer  is  given  off  from  the  tendon  of  the  Digastric  on  eacli 
side,  which  is  attached  to  the  body  and  great  cornu  of  the  hyoid  bone:  this  is 
termed  the  supra-hyoid  aponeurosis.  It  forms  a  strong  layer  of  fascia  between 
the  anterior  portion  of  the  two  muscles,  and  a  firm  investment  for  the  other 
muscles  of  the  supra-hyoid  region  which  lie  beneath  it. 

The  Digastric  muscle  divides  the  anterior  superior  triangle  of  the  neck  into 
two  smaller  triangles ;  the  upper,  or  submaxillary,  being  bounded,  above,  by 


SUPRA-HYOID    REGION.  337 

tlie  lower  jaw  and  mastoid  process;  below,  by  the  two  bellies  of  the  Digastric 
muscle :  the  lower,  or  superior,  carotid  triangle  being  bounded,  above,  by  the 
posterior  belly  of  the  Digastric;  behind,  by  the  Sterno-mastoid;  below,  by  the 
Omo-hyoid. 

Relations.  By  its  superficial  surface,  with  the  Platysma,  Sterno-mastoid  and 
Trachelo-mastoid,  part  of  the  Stylo-hyoid  muscle,  and  the  parotid  and  sub- 
maxillary glands.  By  its  deep  surface^  the  anterior  belly  lies  on  the  Mylo-hyoid; 
the  posterior  belly  on  the  Stylo-glossus,  Stylo-pharyngeus,  and  Hyo-glossus 
muscles,  the  external  carotid  artery  and  its  lingual  and  facial  branches,  the 
internal  carotid  artery,  internal  jugular  vein,  and  hypoglossal  nerve. 

The  Stylo-hyoid  is  a  small,  slender  muscle,  lying  in  front  of,  and  above,  the 
posterior  belly  of  the  Digastric.  It  arises  from  the  middle  of  the  outer  surface 
of  the  styloid  process;  and,  passing  downwards  and  forwards,  is  inserted  into 
the  body  of  the  hyoid  bone,  just  at  its  junction  with  the  greater  cornu,  and  im- 
mediately above  the  Omo-hyoid.  This  muscle  is  perforated,  near  its  insertion, 
by  the  tendon  of  the  Digastric. 

Relations.     The  same  as  the  posterior  belly  of  the  Digastric. 

The  Digastric  and  Stylo-hyoid  should  be  removed,  in  order  to  expose  the 
next  muscle. 

The  Mylo-hyoid  is  a  flat  triangular  muscle,  situated  immediately  beneath  the 
anterior  belly  of  the  Digastric,  and  forming,  with  its  fellow  of  the  opposite  side, 
a  muscular  floor  for  the  cavity  of  the  mouth.  It  arises  from  the  whole  length 
of  the  mylo-hyoid  ridge,  from  the  symphysis  in  front  to  the  last  molar  tooth 
behind.  The  posterior  fibres  pass  obliquely  forwards,  to  be  inserted  into  the 
body  of  the  os  hyoides.  The  middle  and  anterior  fibres  are  inserted  into  a 
median  fibrous  raphe,  where  they  join  at  an  angle  with  the  fibres  of  the  opposite 
muscle.  This  median  raphe  is  sometimes  wanting;  the  muscular  fibres  of  the 
two  sides  are  then  directly  continuous  with  one  another. 

Relations.  By  its  cutaneous  surface^  with  the  Platysma,  the  anterior  belly  of 
the  Digastric,  the  supra-hyoid  fascia,  the  submaxillary  gland,  and  submental 
vessels.  By  its  deep  or  superior  surface,  with  the  Geuio-hyoid,  part  of  the  Hyo- 
glossus,  and  Stylo-glossus  muscles,  the  lingual  and  gustatory  nerves,  the  sub- 
lingual gland,  and  the  buccal  mucous  membrane.  Wharton's  duct  curves  round 
its  posterior  border  in  its  passage  to  the  mouth. 

Dissection.  The  Mylo-hyoid  should  uow  be  removed,  in  order  to  expose  the  muscles  which 
lie  beneath ;  this  is  effected  by  detaching  it  from  its  attachments  to  the  hyoid  bone  and  jaw,  and 
separating  it  by  a  vertical  incision  from  its  fellow  of  the  opposite  side. 

The  Genio-hyoid  is  a  narrow  slender  muscle,  situated  immediately  beneath^ 
the  inner  border  of  the  preceding.  It  arises  from  the  inferior  genial  tubercle 
on  the  inner  side  of  the  symphysis  of  the  jaw,  and  passes  downwards  and  back- 
wards, to  be  inserted  into  the  anterior  surface  of  the  body  of  the  os  hyoides. 
This  muscle  lies  in  close  contact  with  its  fellow  of  the  opposite  side,  and 
increases  slightly  in  breadth  as  it  descends. 

Relations.    It  is  covered  by  the  Mylo-hyoid,  and  lies  on  the  Genio-hyo-glossus. 

Nerves.  The  Digastric  is  supplied,  its  anterior  belly,  by  the  mylo-hyoid 
branch  of  the  inferior  dental;  its  posterior  belly,  by  the  facial;  the  Stylo-hyoid, 
by  the  facial;  the  Mylo-hyoid,  by  the  ijiylo-hyoid  branch  of  the  inferior  dental; 
the  Genio-hyoid,  by  the  hypoglossal. 

Actions.  This  group  of  muscles  performs  two  very  important  actions.  They 
raise  the  hyoid  bone,  and  with  it  the  base  of  the  tongue,  during  the  act  of 
deglutition;  or,  when  the  hyoid  bone  is  fixed  by  its  depressors  and  those  of  the 
larynx,  they  depress  the  lower  jaw.  During  the  first  act  of  deglutition,  when 
the  mass  is  being  driven  from  the  mouth  into  the  pharynx,  the  hyoid  bone,  and 
with  it  the  tongue,  is  carried  upwards  and  forwards  by  the  anterior  belly  of  the 

'  This  refers  to  the  depth  of  the  muscles  from  the  skin  in  dissecting.     In  the  erect  position 
of  the  body,  each  of  these  muscles  lies  above  the  preceding. 
22 


338 


MUSCLES    AND    FASCIA. 


Digastric,  the  Mylo-hyoid,  and  Genio-hjoid  muscles.  In  the  second  act,  when 
the  mass  is  passing  through  the  pharynx,  the  direct  elevation  of  the  hyoid  bone 
takes  place  by  the  combined  action  of  all  the  muscles;  and  after  the  food  has 
passed,  the  hyoid  bone  is  carried  upwards  and  backwards  by  the  posterior  belly 
of  the  Digastric  and  Stylo- hyoid  muscles,  which  assist  in  preventing  the  return 
of  the  morsel  into  the  mouth. 


4.  Lingual  Eegion. 

Genio-hyo-glossus.  Lingualis. 

Hyo-glossus.  Stylo-glossus. 

Palato-glossus. 

Dissection. — After  completing  the  dissection  of  the  preceding  muscles,  saw  through  the  lower 
jaw  just  external  to  the  symphysis.  Then  draw  the  tongue  forwards,  and  attach  it,  by  a  stitch, 
to  the  nose ;  and  its  muscles,  which  are  thus  put  on  the  stretch,  may  be  examined. 

The  Genio-hip-glossus  has  received  its  name  from  its  triple  attachment  to  the 
chin,  hyoid  bone,  and  tongue ;  it  is  a  thin,  flat,  triangular  muscle,  placed  ver- 
tically on  either  side  of  the  middle  line,  its  apex  corresponding  with  its  point 
of  attachment  to  the  lower  jaw,  its  base  with  its  insertion  into  the  tongue  and 
hyoid  bone.  It  arises  by  a  short  tendon  from  the  superior  genial  tubercle  on 
the  inner  side  of  the  symphysis  of  the  chin,  immediately  above  the  Genio- 
hyoid; from  this  point,  the  muscle  spreads  out  in  a  fan-like  form,  the  inferior 
fiores  passing  downwards,  to  be  inserted  into  the  upper  part  of  the  body  of  the 

Fig.  222.— Muscles  of  the  Tongue.    Left  8ide. 


hyoid  bone,  a  few  being  continued  into  the  side  of  the  pharynx;  the  middle 
fibres  passing  backwards,  and  the  superior  ones  upwards  and  forwards,  to  be 
attached  to  the  whole  length  of  the  under  surface  of  the  tongue,  from  the  base 
to  the  apex. 


LINGUAL    REGION.  339 

Relations.  By  its  internal  surface,  it  is  in  contact  with  its  fellow  of  the  oppo- 
site side,  from  which  it  is  separated,  at  the  back  part  of  the  tongue,  by  the 
fibrous  septum,  which  extends  through  the  middle  of  the  organ.  By  its  external 
surface,  with  the  Lingualis,  Hyo-glossus,  and  Stylo-glossus,  the  lingual  artery 
and  hypoglossal  nerve,  the  gustatory  nerve,  and  sublingual  gland.  Qj  its  upper 
border,  with  the  mucous  membrane  of  the  floor  of  the  mouth  (fraenum  linguae). 
By  its  lower  border,  with  the  Genio-hyoid. 

The  Hijo-glossus  is  a  thin,  flat,  quadrilateral  muscle,  which  arises  from  the 
side  of  the  body,  the  lesser  cornu,  and  whole  length  of  the  greater  cornu  of  the 
hyoid  bone,  and  passing  almost  vertically  upwards,  is  inserted  into  the  side  of 
the  tongue,  between  the  Stylo-glossus  and  Lingualis.  Those  fibres  of  this 
muscle  which  arise  from  the  body,  are  directed  upwards  and  backwards,  over- 
lapping those  from  the  greater  cornu,  which  are  directed  obliquely  forwards. 
Those  from  the  lesser  cornu  extend  forwards  and  outwards  along  the  side  of 
the  tongue,  under  cover  of  the  portion  arising  from  the  body. 

The  difference  in  the  direction  of  the  fibres  of  this  muscle,  and  their  separate 
origin  from  different  parts  of  the  hj^oid  bone,  led  Albinus  and  other  anatomists 
to  describe  it  as  three  muscles,  under  the  names  of  the  Basio-glossus,  the 
Kerato-glossus,  and  the  Chondro-glossus. 

Relations.  By  its  external  surface,  with  the  Digastric,  the  Stylo-hyoid,  Stylo- 
glossus, and  Mylo-hyoid  muscles,  the  gustatory  and  hypoglossal  nerves,  Whar- 
ton's duct,  and  the  sublingual  gland.  By  its  deep  surface,  with  the  Genio- 
hyo-glossus,  Lingualis,  and  Middle  Constrictor,  the  lingual  vessels,  and  the 
glosso-pharyngeal  nerve. 

The  Lingualis  is  a  longitudinal  band  of  muscular  fibres,  situated  on  the  under 
surface  of  the  tongue,  lying  in  the  interval  between  the  Hyo-glossus  and  the 
Genio-hyo-glossus,  and  extending  from  the  base  to  the  apex  of  the  organ. 
Posteriorly,  some  of  its  fibres  are  lost  in  the  base  of  the  tongue,  and  others  are 
occasionally  attached  to  the  hyoid  bone.  It  blends  with  the  fibres  of  the 
Stylo-glossus,  in  front  of  the  Hyo-glossus,  and  is  continued  forwards  as  far 
as  the  apex  of  the  tongue.  It  is  in  relation,  by  its  under  surface,  with  the 
ranine  artery. 

The  Stylo-glossus,  the  shortest  and  smallest  of  the  three  styloid  muscles,  arises 
from  the  anterior  and  outer  side  of  the  styloid  process,  near  its  centre,  and 
from  the  stylo-maxillary  ligament,  to  which  its  fibres,  in  most  cases,  are  at- 
tached by  a  thin  aponeurosis.  Passing  downwards  and  forwards,  so  as  to 
become  nearly  horizontal  in  its  direction,  it  divides  upon  the  side  of  the  tongue 
into  two  portions ;  one  longitudinal,  which  is  inserted  along  the  side  of  the 
tongue,  blending  with  the  fibres  of  the  Lingualis  in  front  of  the  Hyo-glossus ; 
the  other  oblique,  which  overlaps  the  Hyo-glossus  muscle,  and  decussates  with 
its  fibres. 

Relations.  By  its  external  surface,  from  above  downwards,  with  the  parotid 
gland,  the  Internal  Pterygoid  muscle,  the  sublingual  gland,  the  gustatory  nerve, 
and  the  mucous  membrane  of  the  mouth.  By  its  internal  surface,  with  the  tonsil, 
the  Superior  Constrictor,  and  the  Hyo-glossus  muscle. 

The  Palato-glossus,  or  Constrictor  Isthmi  Faucium,  although  it  is  one  of  the 
muscles  of  the  tongue,  serving  to  draw  its  base  upwards  during  the  act  of  de- 
glutition, is  more  nearly  associated  with  the  soft  palate,  both  in  its  situation 
and  function ;  it  will,  consequently,  be  described  with  that  group  of  muscles. 

Nerves.  The  Palato-glossus  is  supplied  by  the  palatine  branches  of  Meckel's 
ganglion ;  the  Lingualis,  by  the  chorda  tympani ;  the  remaining  muscles  of 
this  group,  by  the  hypoglossal. 

Actions.  The  movements  of  the  tongue,  although  numerous  and  complicated, 
may  be  understood  by  carefully  considering  the  direction  of  the  fibres  of  its 
muscles.  The  Genio-hyo-glossi,  by  means  of  their  posterior  and  inferior  fibres, 
draw  upwards  the  hyoid  bone,  bringing  it  and  the  base  of  the  tongue  forwards, 
so  as  to  protrude  the  apex  from  the  mouth.     The  anterior  fibres  will  draw  the 


BiO 


MUSCLES    AND    FASCIAE. 


tongae  back  into  the  mouth.  The  whole  length  of  these  two  muscles  acting 
along  the  middle  line  of  the  tongue  will  draw  it  downwards,  so  as  to  make  it 
concave  from  side  to  side,  forming  a  channel  along  which  fluids  may  pass 
towards  the  pharynx,  as  in  sucking.  The  Hyo-glossi  muscles  draw  down  the 
sides  of  the  tongue,  so  as  to  render  it  convex  from  side  to  side.  The  Linguales, 
by  drawing  downwards  the  centre  and  apex  of  the  tongue,  render  it  convex 
from  before  backwards.  The  Palato-glossi  draw  the  base  of  the  tongue  up- 
wards, and  the  Stylo-glossi  upwards  and  backwards. 


5.  Pharyngeal  Eegion. 

Constrictor  Inferior.  Constrictor  Superior. 

Constrictor  Medius.  Stylo-pharyngeus. 

Palato-pharyngeus. 

Dissection  (Fig.  223).    Tn  order  to  examine  the  muscles  of  the  pharynx,  cut  through  the 
trachea  and  oesophagas  just  above  the  sternum,  and  draw  them  upwards  by  dividing  the  loose 

areolar  tissue  connecting  the  pharynx  with  the 


Fig.  223.— Muscles  of  the  Pharynx. 
View. 


External  front  of  the  vertebral  column.  The  parts  being 
drawn  well  forwards,  apply  the  edge  of  the  saw 
immediately  behind  the  styloid  processes,  and 
saw  the  base  of  the  skull  through  from  below 
upwards.  The  pharynx  and  mouth  should  then 
be  stuffed  with  tow,  in  order  to  distend  its 
cavity  and  render  the  muscles  tense  and  easier 
of  dissection. 

The  Inferior  Constrictor^  the  most 
superficial  and  thickest  of  the  three 
constrictors,  arises  from  the  side  of  the 
cricoid  and  thyroid  cartilages.  To  the 
cricoid  cartilage  it  is  attached  in  the 
interval  between  the  crico-thyroid 
muscle,  in  front,  and  the  articular  facet 
for  the  th3'roid  cartilage  behind.  To 
the  thyroid  cartilage,  it  is  attached  to 
the  oblique  line  on  the  side  of  the 
great  ala,  the  cartilaginous  surface  be- 
hind it,  nearly  as  far  as  its  posterior 
border,  and  to  the  inferior  cornu. 
From  these  attachments,  the  fibres 
spread  backwards  and  inwards,  to  be 
inserted  into  the  fibrous  raphe  in  the 
posterior  median  line  of  the  pharynx. 
The  inferior  fibres  are  horizontal,  and 
continuous  with  the  fibres  of  the  oeso- 
phagus ;  the  rest  ascend,  increasing  in 
obliquity,  and  overlap  the  Middle  Con- 
strictor. The  superior  laryngeal  nerve 
passes  near  the  upper  border,  and  the  inferior,  or  recurrent  laryngeal,  beneath 
the  lower  border  of  this  muscle,  previous  to  their  entering  the  larynx. 

Relations.  It  is  covered  by  a  dense  cellular  membrane  which  surrounds  the 
entire  pharynx.  Behind,  it  is  in  relation  with  the  vertebral  column  and  the 
Lougus  Colli  muscle ;  laieralli/,  with  the  thyroid  gland,  the  common  carotid 
artery,  and  the  Storno-thyroid  muscle ;  by  its  internal  surface,  with  the  Middle 
Constrictor,  the  Stylo-pharyngeus,  Palato-pharyngeus,  and  the  mucous  mem- 
brane of  the  pharynx. 

The  Middle  Constrictor  is  a  flattened,  fan-shaped  muscle,  smaller  than  the  pre- 
ceding, and  situated  on  a  plane  anterior  to  it.     It  arises  from  the  whole  length 


PHARYNGEAL    REGION.  341 

of  the  greater  cornu  of  the  hyoid  bone,  from  the  lesser  cornu,  and  from  the 
stylo-hyoid  ligament.  The  fibres  diverge  from  their  origin;  the  lower  ones 
descending  beneath  the  Inferior  Constrictor,  the  middle  fibres  passing  trans- 
versely, and  the  upper  fibres  ascending  and  overlapping  the  Superior  Con- 
strictor. The  muscle  is  inserted  into  the  posterior  median  fibrous  raphe,  blending 
in  the  middle  line  with  that  of  the  opposite  side. 

Relations.  This  muscle  is  separated  from  the  Superior  Constrictor  by  the 
glosso-pharyngeal  nerve  and  the  Stylo-pharyngeus  muscle ;  and  from  the  Infe- 
rior Constrictor,  by  the  superior  laryngeal  nerve.  Behind^  it  lies  on  the  verte- 
bral column,  the  Longus  Colli,  and  the  Eectus  Anticus  Major.  On  each  side  it' 
is  in  relation  with  the  carotid  vessels,  the  pharyngeal  plexus  and  some  lym- 
phatic glands.  Near  its  origin,  it  is  covered  by  the  Hyo-glossus,  from  which 
it  is  separated  by  the  lingual  artery.  It  lies  upon  the  Superior  Constrictor,  the 
Stylo-pharyngeus,  the  Palato-pharyngeus,  and  the  mucous  membrane. 

The  Superior  Constrictor  is  a  quadrilateral  muscle,  thinner  and  paler  than  the 
other  constrictors,  and  situated  at  the  upper  part  of  the  pharynx.  It  arises 
from  the  lower  third  of  the  margin  of  the  internal  pterygoid  plate  and  its 
hamular  process,  from  the  contiguous  portion  of  the  palate  bone  and  the  reflected 
tendon  of  the  Tensor  Palati  muscle,  from  the  pterygo-maxillary  ligament,  from 
the  alveolar  process  above  the  posterior  extremity  of  the  mylo-hyoid  ridge,  and 
by  a  few  fibres  from  the  side  of  the  tongue  in  connection  with  the  Genio-hyo- 
glossus.  From  these  points,  the  fibres  curve  backwards,  to  be  inserted  into  the 
median  raphe,  being  also  prolonged  by  means  of  a  fibrous  aponeurosis  to  the 
pharyngeal  spine  on  the  basilar  process  of  the  occipital  bone.  The  superior 
fibres  arch  beneath  the  Levator  Palati  and  the  Eustachian  tube,  the  interval 
between  the  upper  border  of  the  muscle  and  the  basilar  process  being  deficient 
in  muscular  fibres,  and  closed  by  fibrous  membrane. 

Relations.  By  its  outer  surface^  with  the  vertebral  column,  the  carotid  vessels, 
the  internal  jugular  vein,  the  three  divisions  of  the  eighth  nerve  and  the  ninth 
nerve,  the  Middle  Constrictor  which  overlaps  it,  and  the  Stylo-pharyngeus.  It 
covers  the  Palato-pharyngeus  and  the  tonsil,  and  is  lined  by  mucous  membrane. 

The  Stylo-pharyngeus  is  a  long,  slender  muscle,  round  above,  broad  and  thin 
below.  It  arises  from  the  inner  side  of  the  base  of  the  styloid  process,  passes 
downwards  along  the  side  of  the  pharynx  between  the  Superior  and  Middle 
Constrictors,  and  spreads  out  beneath  the  mucous  membrane,  where  some  of  its 
fibres  are  lost  in  the  constrictor  muscle,  and  others  joining  with  the  Palato- 
pharyngeus,  are  inserted  into  the  posterior  border  of  the  thyroid  cartilage.  The 
glosso-pharyngeal  nerve  runs  on  the  outer  side  of  this  muscle,  and  crosses  over 
it  in  passing  forward  to  the  tongue. 

Relations.  Externally,  with  the  Stylo-glossus  muscle,  the  external  carotid 
artery,  the  parotid  gland,  and  the  Middle  Constrictor.  Internally,  with  the 
internal  carotid,  the  internal  jugular  vein,  the  Superior  Constrictor,  Palato- 
pharyngeus  and  mucous  membrane. 

Nerves.  The  muscles  of  this  group  are  supplied  by  branches  from  the  pha- 
ryngeal plexus  and  glosso-pharyngeal  nerve ;  and  the  Inferior  Constrictor,  by 
an  additional  branch  from  the  external  laryngeal  nerve. 

Actions.  When  deglutition  is  about  to  be  performed,  the  pharynx  is  drawn 
upwards  and  dilated  in  different  directions,  to  receive  the  morsel  propelled  into 
it  from  the  mouth.  The  Stylo-pharyngei,  which  are  much  farther  removed 
from  one  another  at  their  origin  than  at  their  insertion,  draw  the  sides  of  the 
pharynx  upwards  and  outwards,  its  breadth  in  the  antero-posterior  direction 
being  increased  by  the  larynx  and  tongue  being  carried  forwards  in  their  ascent. 
As  soon  as  the  morsel  is  received  in  the  pharynx,  the  elevator  muscles  relax, 
the  bag  descends,  and  the  Constrictors  contract  upon  the  morsel,  and  convey  it 
gradually  downwards  into  the  oesophagus.  Besides  its  action  in  deglutition, 
the  pharynx  also  exerts  an  important  influence  in  the  modulation  of  the  voice, 
especially  in  the  production  of  the  higher  tones. 


342 


MUSCLES    AND    FASCIA. 


6.  Palatal  Eegion. 

Levator  Palati.  Azygos  Uvulae. 

Tensor  Palati.  Palato-glossus. 

Palato-pharyngeus. 

Dissection.  (Fig.  224).  Lay  open  the  pharynx  from  behind,  by  a  vertical  incision  extending 
from  its  upper  to  its  lower  part,  and  partially  divide  the  occipital  attachment  by  a  transverse 
incision  on  each  side  of  the  vertical  one  ;  the  posterior  surface  of  the  soft  palate  is  then  exposed. 
Having  fixed  the  uvula  so  as  to  make  it  tense,  the  mucous  membrane  and  glands  should  be  care- 
fully removed  from  the  posterior  surface  of  the  soft  palate,  and  the  muscles  of  this  part  are  at 
once  exposed. 

The  Levator  Palati  is  a  long,  thick,  rounded  muscle,  placed  on  the  outer  side 
of  the  posterior  nares.  It  arises  from  the  under  surface  of  the  apex  of  the 
petrous  portion  of  the  temporal  bone,  and  from  the  adjoining  cartilaginous 
portion  of  the  Eustachian  tube ;  after  passing  into  the  pharynx,  above  the  upper 

Fig.  224. — Muscles  of  the  Soft  Palate.    The  Pharynx  being  laid  open  from  behind. 


concave  margin  of  the  Superior  Constrictor,  it  descends  obliquely  downwards 
and  inwards,  its  fibres  spreading  out  in  the  posterior  surface  of  the  soft  palate 
as  far  as  the  middle  line,  where  they  blend  with  those  of  the  opposite  side. 

Relations.  Externally^  with  the  Tensor  Palati  and  Superior  Constrictor. 
Internally,  with  the  mucous  membrane  of  the  pharynx.  Posteriorly,  with  the 
mucous  lining  of  the  soft  palate.  This  muscle  must  be  removed,  and  the 
pterygoid  attachment  of  the  Superior  Constrictor  dissected  away,  in  order  to 
expose  the  next  muscle. 

The  Circumjlexus  or  Tejisor  Palati  is  a  broad,  thin,  ribbon-like  muscle,  placed 


PALATAL    REGION.  343 

on  the  outer  side  of  the  preceding,  and  consisting  of  a  vertical  and  a  horizontal 
portion.  The  vertical  portion  arises  by  a  broad,  thin,  and  flat  lamella  from  the 
scaphoid  fossa  at  the  base  of  the  internal  pterygoid  plate,  its  origin  extending 
as  far  back  as  the  spine  of  the  sphenoid ;  it  also  arises  from  the  anterior  aspect 
of  the  cartilaginous  portion  of  the  Eustachian  tube ;  descending  vertically  be- 
tween the  internal  pterygoid  plate  and  the  inner  surface  of  the  Internal  Ptery- 
goid muscle,  it  terminates  in  a  tendon  which  winds  round  the  hamular  process, 
being  retained  in  this  situation  by  some  of  the  fibres  of  origin  of  the  Internal 
Pterygoid  muscle,  and  lubricated  by  a  bursa.  The  tendon  or  horizontal  por- 
tion then  passes  horizontally  inwards,  and  expands  into  a  broad  aponeurosis 
on  the  anterior  surface  of  the  soft  palate,  which  unites  in  the  median  line  v/ith 
the  aponeurosis  of  the  opposite  muscle,  the  fibres  being  attached  in  front  to 
the  transverse  ridge  on  the  posterior  border  of  the  horizontal  portion  of  the 
palate  bone. 

Relations.  Externally^  with  the  Internal  Pterygoid.  Internally,  with  the 
Levator  Palati,  from  which  it  is  separated  by  the  Superior  Constrictor,  and  the 
internal  pterygoid  plate.  In  the  soft  palate,  its  aponeurotic  expansion  is  an- 
terior to  that  of  the  Levator  Palati,  being  covered  by  mucous  membrane. 

The  Azygos  Uvulse  is  not  a  single  muscle,  as  implied  by  its  name,  but  a  pair 
of  narrow  cylindrical  fleshy  fasciculi,  placed  side  by  side  in  the  median  line  of 
the  soft  palate.  Each  muscle  arises  from  the  posterior  nasal  spine  of  the  palate 
bone,  and  from  the  contiguous  tendinous  aponeurosis  of  the  soft  palate,  and 
descends  to  be  inserted  into  the  uvula. 

Relations.  Anteriorly,  with  the  tendinous  expansion  of  the  Levatores  Palati ; 
behind,  with  the  mucous  membrane. 

The  two  next  muscles  are  exposed  by  removing  the  mucous  membrane  from  the  pillars  of  the 
soft  palate  throughout  nearly  the  whole  extent. 

The  Palato-glossus  (Constrictor  Isthmi  Faucium)  is  a  small  fleshy  fasciculus, 
narrower  in  the  middle  than  at  either  extremity,  forming,  with  the  mucous 
membrane  covering  its  surface,  the  anterior  pillar  of  the  soft  palate.  It  arises 
from  the  anterior  surface  of  the  soft  palate  on  each  side  of  the  uvula,  and 
passing  forwards  and  outwards  in  front  of  the  tonsil,  is  inserted  into  the  side 
and  dorsum  of  the  tongue,  where  it  blends  with  the  fibres  of  the  Stylo-glossus 
muscle.  In  the  soft  palate,  the  fibres  of  this  muscle  are  continuous  with  those 
of  the  muscle  of  the  opposite  side. 

The  Palato-pharyngeus  is  a  long  fleshy  fasciculus,  narrower  in  themiddle  than 
at  either  extremity,  forming,  with  the  mucous  membrane  covering  its  surface, 
the  posterior  pillar  of  the  soft  palate.  It  is  separated  from  the  preceding  by 
an  angular  interval,  in  which  the  tonsil  is  lodged.  It  arises  from  the  soft 
palate  by  an  expanded  fasciculus,  which  is  divided  into  two  parts  by  the  Levator 
Palati.  The  anterior  fasciculus^  the  thickest,  enters  the  soft  palate  between  the 
Levator  and  Tensor,  and  joins  in  the  middle  line  the  corresponding  part  of  the 
opposite  muscle ;  the  posterior  fasciculus  lies  in  contact  with  the  mucous  mem- 
brane, and  also  joins  with  the  corresponding  muscle  in  the  middle  line.  Passing 
outwards  and  downwards  behind  the  tonsil,  the  Palato-pharyngeus  joins  the 
Stylo-pharyngeus,  and  is  inserted  with  that  muscle  into  the  posterior  border  of 
the  thyroid  cartilage,  some  of  its  fibres  being  lost  on  the  side  of  the  pharynx, 
and  others  passing  across  the  middle  line  posteriorly,  to  decussate  with  the 
muscle  of  the  opposite  side. 

Relations.  In  the  soft  palate,  its  anterior  and  posterior  surfaces  are  covered 
by  mucous  membrane,  from  which  it  is  separated  by  a  layer  of  palatine  glands. 
By  its  superior  border,  it  is  iji  relation  with  the  Levator  Palati.  Where  it  forms 
the  posterior  pillar  of  the  fauces,  it  is  covered  by  mucous  membrane,  excepting 
on  its  outer  surface.  In  the  pharynx  it  lies  between  the  mucous  membrane  and 
the  constrictor  muscles. 

Nerves.     The  Tensor  Palati  is  supplied  by  a  branch  from  the  ctic  ganglion, 


844  MUSCLES    AND    FASCIA. 

the  Levator  Palati,  and  Azygos  Uvulae,  by  the  facial,  through  the  connection 
of  its  trunk  with  the  Vidian,  by  the  petrosal  nerves ;  the  other  muscles,  by  the 
palatine  branches  of  Meckel's  ganglion. 

Actions.  During  ihQ  first  act  of  deglutition,  the  morsel  of  food  is  driven  back 
into  the  fauces  by  the  pressure  of  the  tongue  against  the  hard  palate ;  the  base 
of  the  tongue  being,  at  the  same  time,  retracted,  and  the  larynx  raised  with 
the  pharynx,  and  carried  forwards  under  it.  During  the  second  stage,  the 
epiglottis  is  pressed  over  the  superior  aperture  of  the  larynx,  and  the  morsel 
glides  past  it;  then  the  Palato-glossi  muscles,  the  constrictors  of  the  fauces, 
contract  behind  the  food ;  the  soft  palate  is  slightly  raised  by  the  Levator 
Palati,  and  made  tense  by  the  Tensor  Palati;  and  the  Palato-pharyngei  con- 
tract, and  come  nearly  together,  the  uvula  filling  up  the  slight  interval  between 
them.  By  these  means,  the  food  is  prevented  passing  into  the  upper  part  of 
the  pharynx  or  the  posterior  nares ;  at  the  same  time,  the  latter  muscles  form 
an  inclined  plane,  directed  obliquely  downwards  and  backwards,  along  which 
the  morsel  descends  into  the  lower  part  of  the  pharynx. 

Surgical  Anatomy.  The  mnscles  of  the  soft  palate  should  be  carefully  dissected,  the  relationg 
they  bear  to  the  surrounding  parts  especially  examined,  and  their  action  attentively  studied  upon 
the  dead  subject,  as  the  surgeon  is  required  to  divide  one  or  more  of  these  muscles  in  the  opera- 
tion of  staphyloraphy.  Sir  W.  Fergusson  has  shown  that  in  the  congenital  deficiency  called 
cleft  palate  the  edges  of  the  fissure  are  forcibly  separated  by  the  action  of  the  Levatores  Palati 
and  Palato-pharyngei  muscles,  producing  very  considerable  impediment  to  the  healing  process 
after  the  performance  of  the  operation  for  uniting  their  margins  by  adhesion ;  he  has  consequently 
recommended  the  division  of  these  muscles  as  one  of  the  most  important  steps  in  the  operation. 
This  he  efiects  by  an  incision  made  with  a  curved  knife  introduced  behind  the  flap.  'I'he  incision 
is  to  be  half-way  between  the  hamular  process  and  Eustachian  tube,  and  perpendicular  to  a  line 
drawn  between  them.  This  incision  perfectly  accomplishes  the  division  of  the  Levator  Palati. 
The  Palato-pharyngeus  may  be  divided  by  cutting  across  the  posterior  pillar  of  the  soft  palate, 
just  below  the  tonsil,  with  a  pair  of  blunt^pointed  curved  scissors  ;  and  the  anterior  pillar  may 
be  divided  also,  'i'o  divide  the  Levator  Palati,  the  plan  recommended  by  Mr.  Pollock  is  to  be 
greatly  preferred.  The  flap  being  put  upon  the  stretch,  a  double-edged  knife  is  passed  through 
the  soft  palate,  just  on  the  inner  side  of  the  hamular  process,  and  above  the  line  of  the  Levator 
Palati.  The  handle  being  now  alteniately  raised  and  depressed,  a  sweeping  cut  is  made  along 
the  posterior  surface  of  the  soft  palate,  and  the  knife  withdrawn,  leaving  only  a  small  opening  in 
the  mucous  membrane  on  the  anterior  surface.  If  this  operation  is  performed  on  the  dead  body, 
and  the  parts  afterwards  dissected,  the  Levator  Palati  will  be  found  completely  divided. 

7.  Anterior  Vertebral  Kegion. 

Eectus  Capitis  Anticus  Major.  Rectus  Lateralis. 

Rectus  Capitis  Anticus  Minor.  Longus  Colli. 

The  Rectus  Capitis  Anticus  Major  (Fig.  225),  broad  and  thick  above,  narrow 
below,  appears  like  a  continuation  upwards  of  the  Scalenus  Anticus.  It  arises 
by  four  tendinous  slips  from  the  anterior  tubercles  of  the  transverse  processes 
of  the  third,  fourth,  fifth,  and  sixth  cervical  vertebras,  and  ascends,  converging 
towards  its  fellow  of  the  opposite  side,  to  be  inserted  into  the  basilar  process 
of  the  occipital  bone. 

Relations.  By  its  anterior  surface,  with  the  pharynx,  the  sympathetic  nerve, 
and  the  sheath  inclosing  the  carotid  artery,  internal  jugular  vein,  and  pneumo- 
gastric  nerve.  By  its  posterior  surface,  with  the  Longus  Colli,  the  Rectus  An- 
ticus Minor,  and  the  upper  cervical  vertebrae. 

The  Rectus  Capitis  Anticus  Minor  is  a  short  flat  muscle,  situated  immediately 
beneath  the  upper  part  of  the  preceding.  It  arises  from  the  anterior  surface 
of  the  lateral  mass  of  the  atlas,  and  from  the  root  of  its  transverse  process,  and 
pa.sising  obliquely  upwards  and  inwards,  is  inserted  into  the  basilar  process 
immediately  behind  the  preceding  muscle. 

Relations.  By  its  anterior  surface,  with  the  Rectus  Anticus  Major.  By  its 
posterior  surface,  with  the  front  of  the  occipito-atlantal  articulation.  Externally, 
with  the  superior  cervical  ganglion  of  the  sympathetic. 

The  Rectus  Lateralis  is  a  short,  flat  muscle,  which  arises  from  the  upper  sur- 


ANTERIOR    VERTEBRAL    REGION. 


345 


face  of  the  transverse  process  of  the  atlas,  and  is  inserted  into  the  under  surface 
of  the  jugular  process  of  the  occipital  bone. 

Relations.     By  its  anterior  surface,  with  the  internal  jugular  vein.     By  its 
posterior  surface,  with  the  vertebral  artery. 


Fiff.  225. — The  Pre-vertebral  Muscles. 


The  Longus  Colli  is  a  long,  flat  muscle,  situated  on  the  anterior  surface  of 
the  spine,  between  the  atlas  and  the  third  dorsal  vertebra.  It  is  broad  in  the 
middle,  narrow  and  pointed  at  each  extremity,  and  consists  of  three  portions, 
of  a  superior  oblique,  an  inferior  oblique,  and  a  vertical  portion.  The  superior 
ohlique  portion  arises  from  the  anterior  tubercles  of  the  transverse  processes  of 
the  third,  fourth,  and  fifth  cervical  vertebrae ;  and,  ascending  obliquely  inwards, 
is  inserted  by  a  narrow  tendon  into  the  tubercle  on  the  anterior  arch  of  the 
atlas.  The  inferior  ohlique  portion,  the  smallest  part  of  the  muscle,  arises  from 
the  bodies  of  the  first  two  or  -three  dorsal  vertebrae ;  and,  passing  obliquely 
outwards,  is  inserted  into  the  transverse  processes  of  the  fifth  and  sixth  cervical 
Tertebrae. 

The  vertical  portion  lies  directly  on  the  front  of  the  spine,  and  is  extended 
between  the  bodies  of  the  lower  three  cervical  and  the  upper  three  dorsal  ver- 
tebrae below,  and  the  bodies  of  the  second,  third,  and  fourth  cervical  vertebrae 
above. 

Relatione.  By  its  anterior  surface,  with  the  pharynx,  the  oesophagus,  sym- 
pathetic nerve,  the  sheath  of  the  great  vessels  of  the  neck,  the  inferior  thyroid 
artery,  and  recurrent  laryngeal  nerve.  By  its  posterior  surface,  with  the  cervical 
and  dorsal  portions  of  the  spine.  Its  inner  border  is  separated  from  the  opposite 
muscle  by  a  considerable  interval  below,  but  they  approach  each  other  above. 


346  MUSCLES    AND    FASCIA. 

8.  Lateral  Vertebral  Region". 

Scalenus  Auticus.  Scalenus  Medius. 

Scalenus  Posticus. 

The  Scalenus  Anticus  is  a  conical-shaped  muscle,  situated  deeply  at  tlie  side 
of  the  neck,  behind  the  Sterno-mastoid.  It  arises  by  a  narrow,  flat  tendon  from 
the  tubercle  on  the  inner  border  and  upper  surface  of  the  first  rib;  and,  ascend- 
ing almost  vertically,  is  inserted  into  the  anterior  tubercles  of  the  transverse 
processes  of  the  third,  fourth,  fifth,  and  sixth  cervical  vertebrae.  The  lower 
part  of  this  muscle  separates  the  subclavian  artery  and  vein ;  the  latter  being 
in  front,  and  the  former,  with  the  brachial  plexus,  behind. 

Relations.  In  front,  with  the  clavicle,  the  Subclavius,  Sterno-mastoid,  and 
Omo-hyoid  muscles,  the  transversalis  colli,  and  ascending  cervical  arteries,  the 
subclavian  vein,  and  the  phrenic  nerve.  By  its  posterior  surface,  with  the 
pleura,  the  subclavian  artery,  and  brachial  plexus  of  nerves.  It  is  separated 
from  the  Longus  Colli,  on  the  inner  side,  by  the  vertebral  artery. 

The  Scalenus  Medius,  the  largest  and  longest  of  the  three  Scaleni,  arises,  by 
a  broad  origin,  from  the  upper  surface  of  the  first  rib,  behind  the  groove  for  the 
subclavian  artery,  as  far  back  as  the  tubercle ;  and,  ascending  along  the  side 
of  the  vertebral  column,  is  inserted,  by  separate  tendinous  slips,  into  the  poste- 
rior tubercles  of  the  transverse  processes  of  the  lower  six  cervical  vertebrae. 
It  is  separated  from  the  Scalenus  Anticus  by  the  subclavian  artery  below,  and 
the  cervical  nerves  above. 

Relations,  By  its  anterior  surface,  with  the  Sterno-mastoid ;  it  is  crossed  by 
the  clavicle,  the  Omo-hyoid  muscle,  and  subclavian  artery.  To  its  outer  side  is 
the  Levator  Anguli  Scapulae,  and  the  Scalenus  Posticus  muscle. 

The  Scalenus  Posticus,  the  smallest  of  the  three  Scaleni,  arises  by  a  thin 
tendon  from  the  outer  surface  of  the  second  rib,  behind  the  attachment  of  the 
Serratus  Magnus,  and,  enlarging  as  it  ascends,  is  inserted,  by  two  or  three 
separate  tendons,  into  the  posterior  tubercles  of  the  transverse  processes  of  the 
lower  two  or  three  cervical  vertebrae.  This  is  the  most  deeply  placed  of  the 
three  Scaleni,  and  is  occasionally  blended  with  the  Scalenus  Medius. 

Nerves.  The  Rectus  Capitis  Anticus  Major  and  Minor  are  supplied  by  the 
suboccipital  and  deep  branches  of  the  cervical  plexus ;  the  Rectus  Lateralis,  by 
the  suboccipital ;  and  the  Longus  Colli  and  Scaleni,  by  branches  from  the  lower 
cervical  nerves. 

Actions.  The  Rectus  Anticus  Major  and  Minor  are  the  direct  antagonists  of 
the  muscles  at  the  back  of  the  neck,  serving  to  restore  the  head  to  its  natural 
position  after  it  has  been  drawn  backwards.  These  muscles  also  serve  to  flex 
the  head,  and,  from  their  obliquity,  rotate  it,  so  as  to  turn  the  face  to  one  or 
the  other  side.  The  Longus  Colli  will  flex  and  slightly  rotate  the  cervical 
portion  of  the  spine.  The  Scaleni  muscles,  taking  their  fixed  point  from  below, 
draw  down  the  transverse  processes  of  the  cervical  vertebrae,  bending  the  spinal 
column  to  one  or  the  other  side.  If  the  muscles  of  both  sides  act,  the  spine 
will  be  kept  erect.  When  they  take  their  fixed  point  from  above,  they  elevate 
the  first  and  second  ribs,  and  are,  therefore,  inspiratory  muscles. 

MUSCLES  AND  FASCIA  OF  THE  TRUNK. 

The  Muscles  of  the  Trunk  may  be  arranged  in  four  groups:  the  muscles  of 
the  Back,  of  the  Abdomen,  of  the  Thorax,  and  of  the  Perinaeum. 

MUSCLES  OF  THE  BACK 

The  Muscles  of  the  Back  are  very  numerous,  and  may  be  subdivided  into 
five  layers : — 


OF    THE    BACK. 


347 


First  Layer. 
Trapezius. 
Latissimua  Dorsi. 

Second  Layer. 
Levator  Anguli  Scapulge. 
Rhomboideus  Minor. 
Ehomboideus  Major 

Third  Layer. 
Serratus  Posticus  Superior. 
Serratus  Posticus  Inferior. 
Splenius  Capitis. 
Splenius  Colli. 

Fourth  Layer. 

Sacral  and  Lumbar  Regions. 
Erector  Spinas. 

Dorsal  Region. 
Sacro-lumbalis. 

Musculus  Accessorius  ad  Sacro-lum- 
balem. 


Longissimus  Dorsi. 
Spinalis  Dorsi. 

Cervical  Region, 
Cervicalis  A  seen  dens. 
Transversalis  Colli. 
Trachelo-mastoid. 
Complexus. 
Biventer  Cervicis. 
Spinalis  Cervicis. 

Fifth  Layer. 
Semispinalis  Dorsi. 
Semispinalis  Colli. 
Multifidus  Spinee. 
Eotatores  Spinge. 
Supraspinales. 
Interspinales. 
Extensor  Coccjgis. 
Intertransversales. 
Rectus  Capitis  Posticus  Major. 
Eectus  Capitis  Posticus  Minor. 
Obliquus  Capitis  Superior. 
Obliquus  Capitis  Inferior. 


First  Layer. 


Trapezius. 


Latissimus  Dorsi. 


Dissection  (Fig.  226).  Place  the  body  in  the  prone 
position,  with  the  arms  extended  over  the  sides  of  the 
table,  and  the  chest  and  abdomen  supported  by  several 
blocks,  so  as  to  render  the  muscles  tense.  Then  make 
an  incision  along  the  middle  line  of  the  back,  from  the 
occipital  protuberance  to  the  coccyx.  Make  a  trans- 
verse incision  from  the  upper  end  of  this  to  the  mastoid 
process ;  and  a  third  incision  from  its  lower  end,  along 
the  crest  of  the  ilium  to  about  its  middle.  This  large 
intervening  space  should,  for  convenience  of  dissection, 
be  subdivided  by  a  fourth  incision,  extending  obliquely 
from  the  spinous  process  of  the  last  dorsal  vertebra, 
upwards  and  outwards,  to  the  acromion  process.  This 
incision  corresponds  with  the  lower  border  of  the 
Trapezius  muscle.  The  flaps  of  integument  are  then 
to  be  removed  in  the  direction  shown  in  the  figure. 

The  Trapezius  is  a  broad,  flat,  triangular 
muscle,  placed  immediately  beneath  the  skin, 
and  covering  the  upper  and  back  part  of  the 
neck  and  shoulders.  It  arises  from  the  inner 
third  of  the  superior  curved  line  of  the  occi- 
pital bone;  from  the  ligamentum  nuchse,  the 
spinous  process  of  the  seventh  cervical,  and 
those  of  all  the  dorsal  vertebrae;  and  from 
the  corresponding  portion  of  the  supraspinous 
ligament.  From  this  origin,  the  superior 
fibres  proceed  downwards  and  outwards,  the 
inferior  ones,  upwards  and  outwards;  and  the 
middle  fibres,  horizontally;  and  are  inserted, 
the  superior  ones,  into  the  outer  third  of  the 
posterior  border  of  the  clavicle;  thf   uiiddle 


Fig. 


226. — Dissection  of  the  Muscles 
of  the  Back. 


348  MUSCLES    AND    FASCIA. 

fibres  into  the  upper  margin  of  tlie  acromion  process,  and  into  tlie  whole  length 
of  the  upper  border  of  the  spine  of  the  scapula ;  the  inferior  fibres  converge 
near  the  scapula,  and  are  attached  to  a  triangular  aponeurosis,  which  glideg 
over  a  smooth  surface  at  the  inner  extremity  of  the  spine,  and  is  inserted  into 
a  tubercle  at  the  outer  part  of  the  surface.  The  Trapezius  is  fleshy  in  the 
greater  part  of  its  extent,  but  tendinous  at  its  origin  and  insertion.  At  its 
occipital  origin,  it  is  connected  to  the  bone  by  a  thin  fibrous  lamina,  firmly 
adherent  to  the  skin,  and  wanting  the  lustrous,  shining  appearance  of  aponeu- 
rosis. At  its  origin  from  the  spines  of  the  vertebrae,  it  is  connected  to  the 
bones  by  means  of  a  broad  semi-elliptical  aponeurosis,  which  occupies  the  space 
between  the  sixth  cervical  and  the  third  dorsal  vertebrae,  and  forms,  with  the 
aponeurosis  of  the  opposite  muscle,  a  tendinous  ellipse.  The  rest  of  the  muscle 
arises  by  numerous  short  tendinous  fibres.  If  the  Trapezius  is  dissected  on 
both  sides,  the  two  muscles  resemble  a  trapezium,  or  diamond-shaped  quad- 
rangle; two  angles  corresponding  to  the  shoulders;  a  third  to  the  occipital 
protuberance;  and  the  fourth  to  the  spinous  process  of  the  last  dorsal  vertebra. 

The  clavicular  insertion  of  this  muscle  varies  as  to  the  extent  of  its  attach- 
ment ;  it  sometimes  advances  as  far  as  the  middle  of  the  clavicle,  and  may 
even  become  blended  with  the  posterior  edge  of  the  Sterno-mastoid,  or  overlap 
it.  This  should  be  borne  in  mind  in  the  operation  for  tying  the  third  part  of 
the  subclavian  artery. 

Relations.  By  its  superficial  surface^  with  the  integument,  to  which  it  is 
closely  adherent  above,  but  separated  below  by  an  aponeurotic  lamina.  By  its 
deep  surface^  in  the  neck,  with  the  Complexus,  Splenius,  Levator  Anguli  Sca- 
pulae, and  Ehomboideus  Minor;  in  the  back,  with  the  Ehomboideus  Major, 
Supraspinatus,  Infraspinatus,  a  small  portion  of  the  Serratus  Posticus  Superior, 
the  vertebral  aponeurosis  (which  separates  it  from  the  Erector  Spinae)  and  the 
Latissimus  Dorsi.  The  spinal  accessory  nerve  passes  beneath  the  anterior 
border  of  this  muscle,  near  the  clavicle.  The  outer  margin  of  its  cervical 
portion  forms  the  posterior  boundary  of  the  posterior  triangle  of  the  neck,  the 
other  boundaries  being  the  Sterno-mastoid  in  front,  and  the  clavicle  below. 

The  ligamentum  niichse  (Fig.  227)  is  a  thin  band  of  condensed  cellulo-fibrous 
membrane,  placed  in  the  line  of  union  between  the  two  Trapezii  in  the  neck. 
It  extends  from  the  external  occipital  protuberance  to  the  spinous  process  of 
the  seventh  cervical  vertebra,  where  it  is  continuous  with  the  supraspinous 
ligament.  From  its  anterior  surface  a  fibrous  slip  is  given  off  to  the  spinous 
process  of  each  of  the  cervical,  vertebrae,  excepting  the  atlas,  so  as  to  form  a 
septum  between  the  muscles  on  each  side  of  the  neck.  In  man,  it  is  merely 
the  rudiment  of  an  important  elastic  ligament,  which,  in  some  of  the  lower 
animals,  serves  to  sustain  the  weight  of  the  head. 

The  Latissirnns  Dorsi  is  a  broad,  flat  muscle,  which  covers  the  lumbar  and 
the  lower  half  of  the  dorsal  regions,  and  is  gradually  contracted  into  a  narrow 
fasciculus  at  its  insertion  into  the  humerus.  It  arises  by  an  aponeurosis  from 
the  spinous  processes  of  the  six  inferior  dorsal,  from  those  of  the  lumbar  and 
sacral  vertebrae,  and  from  the  supraspinous  ligament.  Over  the  sacrum,  the 
aponeuroses  of  this  muscle  blends  with  the  tendon  of  the  Erector  Spinae.  It 
also  arises  from  the  external  lip  of  the  crest  of  the  ilium,  behind  the  origin  of 
the  External  Oblique,  and  by  fleshy  digitations  from  the  three  or  four  lower 
ribs,  which  are  interposed  between  similar  processes  of  the  External  Oblique 
muscle  (Fig.  230).  From  this  extensive  origin  the  fibres  pass  in  different 
directions,  the  upper  ones  horizontally,  the  middle  obliquely  upwards,  and  the 
lower  vertically  upwards,  so  as  to  converge  and  form  a  thick  fasciculus,  which 
crosses  the  inferior  angle  of  the  scapula,  and  occasionally  receives  a  few  fibres 
from  it.  The  muscle  then  curves  around  the  lower  border  of  the  Teres  Major, 
and  is  twisted  upon  itself,  so  that  the  superior  fibres  become  at  first  posterior 
and  then  inferior,  and  the  vertical  fibres  at  first  anterior  and  then  superior.     It 


OF    THE    BACK. 


349 


Fig.  227.— Muscles  of  the  Back.     On  the  Left  Side  is  exposed  the  First  Layer ;  on  the  Eight 
Side,  the  Second  Layer  and  part  of  the  Third. 


350  MUSCLES    AND    FASCIA. 

then  terminates  in  a  short  quadrilateral  tendon,  about  three  inches  in  length, 
which,  passing  in  front  of  the  tendon  of  the  Teres  Major,  is  inserted  into  the 
bottom  of  the  bicipital  groove  of  the  humerus,  above  the  insertion  of  the  ten- 
don of  the  Pectoralis  Major.  The  lower  border  of  the  tendon  of  this  muscle 
is  united  with  the  Teres  Major,  the  surfaces  of  the  two  being  separated  by  a 
bursa ;  another  bursa  is  sometimes  interposed  between  the  muscle  and  the 
inferior  angle  of  the  scapula. 

A  muscular  slip,  varying  from  3  to  4  inches  in  length,  and  from  ^  to  f  of  an  inch  in  breadth, 
occasionally  arises  from  the  upper  edge  of  the  Latissimus  Dorsi,  about  the  middle  of  the  poste- 
rior fold  of  the  axilla,  and  crosses  the  axilla  in  front  of  the  axillary  vessels  aud  nerves,  to  join 
the  under  surface  of  the  tendon  of  the  Pectoralis  Major,  the  Coraco-brachialis,  or  of  the  fascia 
over  the  Biceps.  'J'he  position  of  this  abnormal  slip  is  a  point  of  interest  in  its  relation  to  the 
axillary  artery,  as  it  crosses  the  vessel  just  above  the  spot  usually  selected  for  the  application 
of  a  ligature,  and  may  mislead  the  surgeon  during  the  operation.  It  may  be  easily  recognized 
by  the  transverse  direction  of  its  fibres.  Dr.  Struthers  found  it,  in  8  out  of  105  subjects, 
occurring  seven  times  on  both  sides. 

Relations.  Its  superficial  surface  is  subcutaneous,  excepting  at  its  upper  part, 
where  it  is  covered  by  the  Trapezius.  By  its  deej-)  surface,  it  is  in  relation  with 
the  Erector  Spinas,  the  Serratus  Posticus  Inferior,  the  lower  Intercostal  muscles 
and  ribs,  the  Serratus  Magnus,  inferior  angle  of  the  scapula,  Ehomboideus 
Major,  Infraspinatus,  and  Teres  Major.  Its  outer  margin  is  separated  below, 
from  the  External  Oblique,  by  a  small  triangular  interval ;  and  another  trian- 
gular interval  exists  between  its  upper  border  and  the  margin  of  the  Trapezius, 
in  which  the  Intercostal  and  Ehomboideus  Major  muscles  are  exposed. 

Nerves.  The  Trapezius  is  supplied  by  the  spinal  accessory,  and  cervical 
plexus ;  the  Latissimus  Dorsi  by  the  subscapular  nerves. 

Second  Layer. 

Levator  Anguli  Scapulae.  Ehomboideus  Minor. 

Ehomboideus  Major. 

Dissection.  The  Trapezius  must  be  removed  in  order  to  expose  the  next  layer ;  to  effect 
this,  detach  the  muscle  from  its  attachment  to  the  clavicle  and  spine  of  the  scapula,  and  turn  it 
back  towards  the  spine. 

The  Levator  Anguli  Scapulse  is  situated  at  the  back  part  and  side  of  the  neck. 
It  arises  by  four  tendinous  slips  from  the  posterior  tubercles  of  the  transverse 
processes  of  the  three  or  four  upper  cervical  vertebrae ;  these  becoming  fleshy 
are  united  so  as  to  form  a  flat  muscle,  which,  passing  downwards  and  back- 
wards, is  inserted  into  the  posterior  border  of  the  scapula,  between  the  superior 
angle  and  the  triangular  smooth  surface  at  the  root  of  the  spine. 

Relations.  By  its  superficial  [anterior)  surface,  with  tlie  integument,  Trape- 
zius, and  Sterno-mastoid.  By  its  deep  {posterior)  surface,  with  the  Splenius  Colli, 
Transversalis  Colli,  Cervicalis  Ascendens,  and  Serratus  Posticus  Superior,  and 
with  the  transverse  cervical  and  posterior  scapular  arteries. 

The  Rhomhoideus  Minor  arises  from  the  ligamentum  nuchas,  and  spinous 
processes  of  the  seventh  cervical  and  first  dorsal  vertebrae.  Passing  down- 
wards and  outwards,  it  is  inserted  into  the  margin  of  the  triangular  smooth 
surface  at  the  root  of  the  spine  of  the  scapula.  This  small  muscle  is  usually 
separated  from  the  Ehomboideus  Major  by  a  slight  cellular  interval. 

The  Rhomhoideus  Major  is  situated  immediately  below  the  preceding,  the 
adjacent  margins  of  the  two  being  occasionally  united.  It  arises  by  tendinous 
fibres  from  the  spinous  processes  of  the  four  or  five  upper  dorsal  vertebrae  and 
the  supraspinous  ligament,  and  is  inserted  into  a  narrow  tendinous  arch,  at- 
tached above,  to  the  triangular  surface  ne.ar  the  spine ;  below,  to  the  inferior 
angle,  the  arch  being  connected  to  the  border  of  the  sca}>ula  by  a  thin  mem- 
brane. When  the  arch  extends,  as  it  occasionally  does,  but  a  short  distance, 
the  muscular  fibres  are  inserted  into  the  scapula  itself. 


OF    THE    BACK.  351 

Relations.  By  their  superficial  {posterior)  surface,  with  the  integument  and 
Trapezius ;  the  Rhomboideus  Major,  with  the  Latissimus  Dorsi.  By  their  deep 
{anterior)  surface,  with  the  Serratus  Posticus  Superior,  posterior  scapular  artery, 
part  of  the  Erector  Spinoe,  the  Intercostal  muscles  and  ribs. 

Nerves.  These  muscles  are  supplied  by  branches  from  the  fifth  cervical 
nerve,  and  additional  filaments  from  the  deep  branches  of  the  cervical  plexus 
are  distributed  to  the  Levator  Anguli  Scapulae. 

Actions.  The  movements  effected  by  the  preceding  muscles  are  numerous, 
as  may  be  conceived  from  their  extensive  attachment.  If  the  head  is  fixed,  the 
upper  part  of  the  Trapezius  will  elevate  the  point  of  the  shoulder,  as  in  sup- 
porting weights ;  when  the  middle  4ind  lower  fibres  are  brought  into  action, 
partial  rotation  of  the  scapula  upon  the  side  of  the  chest  is  produced.  If  the 
shoulders  are  fixed,  both  Trapezii  acting  together  will  draw  the  head  directly 
backwards,  or  if  only  one  acts,  the  head  is  drawn  to  the  corresponding  side. 

The  Latissimus  Dorsi,  when  it  acts  upon  the  humerus,  draws  it  backwards 
and  downwards,  and  at  the  same  time  rotates  it  inwards.  If  the  arm  is  fixed, 
the  muscle  may  act  in  various  ways  upon  the  trunk ;  thus,  it  may  raise  the 
lower  ribs  and  assist  in  forcible  inspiration,  or  if  both  arms  are  fixed,  the  two 
muscles  may  assist  the  abdominal  and  great  Pectoral  muscles  in  drawing  the 
whole  trunk  forwards,  as  in  climbing  or  walking  on  crutches. 

The  Levator  Anguli  Scapulas  raises  the  superior  angle  of  the  scapula  after  it 
has  been  depressed  by  the  lower  fibres  of  the  Trapezius,  whilst  the.Ehomboid 
muscles  carry  the  inferior  angle  backwards  and  upwards,  thus  producing  a 
slight  rotation  of  the  scapula  upon  the  side  of  the  chest.  If  the  shoulder  be 
fixed,  the  Levator  Anguli  Scapulae  may  incline  the  neck  to  the  corresponding 
side.  The  Rhomboid  muscles  acting  together  with  the  middle  and  inferior 
fibres  of  the  Trapezius,  will  draw  the  scapula  directly  backwards  towards  the 
spine. 

Third  Layer. 

Serratus  Posticus  Superior.  Serratus  Posticus  Inferior. 

o   1     •       i  Splenius  Capitis. 
Splenius  \  o^i     •      n  ir 
^  (  Splenius  Colli. 

Dissection.  To  bring  into  view  the  third  layer  of  muscles,  remove  the  whole  of  the  second, 
together  with  the  Latissimus  Dorsi ;  by  cutting  through  the  Levator  Anguli  Scapulae  and 
Ehomboid  muscles  near  their  insertion,  and  reflecting  them  upwards,  to  expose  the  Serratus 
Posticus  Superior,  dividing  the  Latissimus  Dorsi  in  the  middle  by  a  vertical  incision  carried 
from  its  upper  to  its  lower  part,  and  reflecting  the  two  halves  of  the  muscle. 

The  Serratus  Posticus  Superior  is  a  thin,  flat,  quadrilateral  muscle,  situated 
at  the  upper  and  back  part  of  the  thorax.  It  arises  by  a  thin  and  broad  apo- 
neurosis, from  the  ligamentum  nuchae,  and  from  the  spinous  processes  of  the 
last  cervical  and  two  or  three  upper  dorsal  vertebrae.  Inclining  downwards 
and  outwards,  it  becomes  muscular,  and  is  inserted,  by  four  fleshy  digitations, 
into  the  upper  borders  of  the  second,  third,  fourth,  and  fifth  ribs,  a  little  beyond 
their  angles. 

Relations.  By  its  superficial  surface,  with  the  Trapezius,  Rhomboidei,  and 
Serratus  Magnus.  By  its  deep  surface,  with  the  Splenius,  upper  part  of  the 
Erector  Spinae,  Intercostal  muscles  and  ribs. 

The  Serratus  Postictis  Inferior  is  situated  at  the  junction  of  the  dorsal  and 
lumbar  regions:  it  is  of  an  irregularly  quadrilateral  form,  broader  than  the 
preceding,  and  separated  from  it  by  a  considerable  interval.  It  arises  by  a 
thin  aponeurosis  from  the  spinous  processes  of  the  last  two  dorsal  and  two  or 
three  upper  lumbar  vertebrae,  and  from  the  interspinous  ligaments.  Passing 
obliquely  upwards  and  outwards,  it  becomes  fleshy,  and  divides  into  four  flat 
digitations,  which  are  inserted  into  the  lower  borders  of  the  four  iower  ribs,  a 
little  beyond  their  angles. 


352  MUSCLES    AND    FASCIA. 

Relations.  Bj  its  superjicial  surface,  with  the  Latissimus  Dorsi,  with  the 
aponeurosis  of  which  its  own  aponeurotic  origin  is  inseparably  blended.  By 
its  deep  surface,  with  the  lumbar  fascia,  the  Erector  Spinas,  ribs,  and  Intercostal 
muscles.     Its  upper  margin  is  continuous  with  the  vertebral  aponeurosis. 

The  vertebral  aponeurosis  is  a  thin  aponeurotic  lamina,  extending  along  the 
whole  length  of  the  back  part  of  the  thoracic  region,  serving  to  bind  down  the 
Erector  Spinas,  and  separating  it  from  those  muscles  which  connect  the  spine 
to  the  upper  extremity.  It  consists  of  longitudinal  and  transverse  fibres  blended 
together,  forming  a  thin  lamella,  which  is  attached  in  the  median  line  to  the 
spinous  processes  of  the  dorsal  vertebrae  ;  externally,  to  the  angles  of  the  ribs  ; 
and  below,  to  the  upper  border  of  the  Inferior  Serratus  and  tendon  of  the  Latis- 
simus Dorsi ;  above,  it  passes  beneath  the  Splenius,  and  blends  with  the  deep 
fascia  of  the  neck. 

Now  detach  the  Serratus  Posticus  Superior  from  its  origin,  and  turn  it  outwards,  when  the 
Splenius  muscle  will  be  brought  into  view. 

The  Splenius  is  situated  at  the  back  of  the  neck  and  upper  part  of  the  dorsal 
region.  At  its  origin,  it  is  a  single  muscle,  narrow  and  pointed  in  form ;  but 
it  soon  becomes  broader,  and  divides  into  two  portions,  w^hich  have  separate 
insertions.  It  arises,  by  tendinous  fibres,  from  the  lower  half  of  the  ligamentura 
nuchae,  from  the  spinous  processes  of  the  last  cervical  and  of  the  six  upper 
dorsal  vertebrae,  and  from  the  supraspinous  ligament.  From  this  origin,  the 
fleshy  fibres  proceed  obliquely  upwards  and  outwards,  forming  a  broad  flat 
muscle,  which  divides  as  it  ascends  into  two  portions,  the  Splenius  Capitis  and 
Splenius  Colli. 

The  Splenius  Capitis  is  inserted  into  the  mastoid  process  of  the  temporal  bone, 
and  into  the  rough  surface  on  the  occipital  bone  beneath  the  superior  curved  line. 

The  Sjolenius  Colli  is  inserted,  by  tendinous  fasciculi,  into  the  posterior  tuber- 
cles of  the  transverse  processes  of  the  three  or  four  upper  cervical  vertebrae. 

The  Splenius  is  separated  from  its  fellow  of  the  opposite  side  by  a  triangular 
interval,  in  which  is  seen  the  Complexus. 

Relations.  By  its  sup)erficial  surface,  with  the  Trapezius,  from  which  it  is 
separated  below  by  the  Rhomboidei  and  the  Serratus  Posticus  Superior.  It  is 
covered  at  its  insertion  by  the  Sterno-mastoid.  By  its  deep  surface,  with  the 
Spinalis  Dorsi,  Longissimus  Dorsi,  Semispinalis  Colli,  Complexus,  Trachelo- 
mastoid,  and  Transversalis  Colli. 

Nerves.  The  Splenius  and  Superior  Serratus  are  supplied  from  the  external 
posterior  branches  of  the  cervical  nerves ;  the  Inferior  Serratus,  from  the  ex- 
ternal branches  of  the  dorsal  nerves. 

Actions.  The  Serrati  are  respiratory  muscles  acting  in  antagonism  to  each 
other.  The  Serratus  Posticus  Superior  elevates  the  ribs ;  it  is,  therefore,  an 
inspiratory  muscle ;  while  the  Serratus  Inferior  draws  the  lower  ribs  down- 
wards, and  is  a  muscle  of  expiration.  This  muscle  is  also  probably  a  tensor 
of  the  vertebral  aponeurosis.  The  Splenii  muscles  of  the  two  sides,  acting 
together,  draw  the  head  directly  backwards,  assisting  the  Trapezius  and  Com- 
plexus; acting  separately,  they  draw  the  head  to  one  or  the  other  side,  and 
slightly  rotate  it,  turning  the  face  to  the  same  side.  They  also  assist  in  sup- 
porting the  head  in  the  erect  position. 

Fourth  Layer. 
Sacral  and  Lumbar  Regions.  Cei'vical  Region. 

Erector  Spinse.  Cervicalis  Ascendens. 

Transversalis  Colli. 

Dorsal  Region.  Trachelo-mastoid. 

Sacro-lumbalis.  Complexus. 

Musculus  Accessorius  ad  Sacro-lumbalem.  Biventer  Cervicis. 

Longissimus  Dorsi.  Spinalis  Colli. 
Spinalis  Dorsi. 


OF    THE    BACK. 


353 


Fig.  228.— Muscles  of  the  Back.    Deep  Layers. 


mULTIPIDUS    SPINA 


mJiumbar 


ffSacmlY: 


23 


364  MUSCLES    AND    FASCIA. 

Diisedion.  To  expose  the  muscles  of  the  fourth  layer,  remove  entirely  the  Serrati  and  ver- 
tebral aponeurosis.  Then  detach  the  Splenius  by  separating  its  attachment  to  the  spinous  pro- 
cesses, and  reflecting  it  outwards. 

The  Erector  Spinse  (Fig.  228),  and  its  prolongations  in  the  dorsal  and  cervical 
regions,  fill  up  the  vertebral  groove  on  each  side  of  the  spine.  It  is  covered 
in  the  lumbar  region  by  the  lumbar  aponeurosis ;  in  the  dorsal  region  by  the 
Serrati  muscles  and  the  vertebral  aponeurosis ;  and  in  the  cervical  region  by  a 
layer  of  cervical  fascia  continued  beneath  the  Trapezius.  This  large  muscular 
and  tendinous  mass  varies  in  size  and  structure  at  different  parts  of  the  spine. 
In  the  sacral  region,  the  Erector  Spinae  is  narrow  and  pointed,  and  its  origin 
chiefly  tendinous  in  structure.  In  the  lumbar  region,  the  muscle  becomes  en- 
larged, and  forms  a  large  fleshy  mass.  In  the  dorsal  region,  it  subdivides  into 
two  parts,  which  gradually  diminish  in  size  as  they  ascend,  to  be  inserted  into 
the  vertebraB  and  ribs,  and  are  gradually  lost  in  the  cervical  region,  where  a 
number  of  special  muscles  are  superadded,  which  are  continued  upwards  to  the 
head,  and  support  it  upon  the  spine. 

The  Erector  Spinae  arises  from  the  sacro-iliac  groove,  and  from  the  anterior 
surface  of  a  very  broad  and  thick  tendon,  which  is  attached,  internally,  to  the 
spines  of  the  sacrum,  to  the  spinous  processes  of  the  lumbar  and  three  lower 
dorsal  vertebrae,  and  the  supraspinous  ligament ;  externally,  to  the  back  part 
of  the  inner  lip  of  the  crest  of  the  ilium,  and  to  the  series  of  eminences  on  the 
posterior  part  of  the  sacrum,  which  represent  the  transverse  processes,  where 
it  blends  with  the  great  sacro-sciatic  ligament.  The  muscular  fibres  form  a 
single  large  fleshy  mass,  bounded  in  front  by  the  transverse  processes  of  the 
lumbar  vertebrae,  and  by  the  middle  lamella  of  the  aponeurosis  of  origin  of  the 
Transversalis  muscle.  Opposite  the  last  rib,  it  divides  into  two  parts,  the  Sacro- 
lumbalis,  and  the  Longissimus  Dorsi. 

The  Sacro-lumhalis  [Ilio-costalis),  the  external  and  smaller  portion  of  the 
Erector  Spinae,  is  inserted,  by  six  or  seven  flattened  tendons  into  the  angles  of 
the  six  lower  ribs.  If  this  muscle  is  reflected  outwards,  it  will  be  seen  to  be 
reinforced  by  a  series  of  muscular  slips,  which  arise  from  the  angles  of  the  ribs ; 
by  means  of  these  the  Sacro-lumbalis  is  continued  upward  to  the  upper  ribs,  and 
the  cervical  portion  of  the  spine.  The  accessory  portions  form  two  additional 
muscles,  the  Musculus  Accessorius  and  the  Cervicalis  Ascendens. 

The  Musculus  Accessorius  ad  Sacro-lumhalem  arises  by  separate  flattened  ten- 
dons from  the  angles  of  the  six  lower  ribs ;  these  become  muscular,  and  are 
finally  inserted,  by  separate  tendons,  into  the  angles  of  the  six  upper  ribs. 

The  Cervicalis  Ascendens^  is  the  continuation  of  the  Accessorius  upwards  into 
the  neck ;  it  is  situated  on  the  inner  side  of  the  tendons  of  the  Accessorius, 
arising  from  the  angles  of  the  four  or  five  upper  ribs,  and  is  inserted  by  a  series 
of  slender  tendons  into  the  posterior  tubercles  of  the  transverse  processes  of 
the  fourth,  fifth,  and  sixth  cervical  vertebrae. 

The  Lonrjissimus  Dorsi,  the  inner  and  larger  portion  of  the  Erector  Spinae, 
arises,  with  the  Sacro-lumbalis,  from  the  common  origin  above  described.  In 
the  lumbar  region,  where  it  is  as  yet  blended  with  the  Sacro-lumbalis,  some  of 
the  fibres  are  attached  to  the  whole  length  of  the  posterior  surface  of  the  trans- 
verse processes  of  the  lumbar  vertebrae,  to  the  tubercles  at  the  back  of  the 
articular  processes,  and  to  the  layer  of  lumbar  fascia  connected  with  the  apices 
of  the  transverse  processes.  In  the  dorsal  region,  the  Longissimus  Dorsi  is 
inserted,  by  long  thin  tendons,  into  the  tips  of  the  transverse  processes  of  all 
the  dorsal  vertebrae,  and  into  from  seven  to  eleven  ribs  between  their  tubercles 
and  angles.     This  muscle  is  continued  upwards,  to  the  cranium  and  cervical  por- 

'  This  muscle  is  sometimes  called  "  Cervicalis  Descendcns."  The  student  should  remember 
that  these  long  muscles  take  their  fixed  point  from  above  or  from  below,  according  to  circum- 
stances. 


OF    THE    BACK.  355 

tion  of  the  spine,  by  means  of  two  additional  muscles,  the  Transversalis  Colli, 
and  Trachelo-mastoid, 

The  Transversalis  Colli,  placed  on  the  inner  side  of  the  Longissimus  Dorsi, 
arises  by  long  thin  tendons  from  the  summit  of  the  transverse  processes  of  the 
third,  fourth,  fifth,  and  sixth  dorsal  vertebrae,  and  is  inserted  by  similar  tendons 
into  the  posterior  tubercles  of  the  transverse  processes  of  the  five  lower  cervical. 

The  Trachelo-mastoid  lies  on  the  inner  side  of  the  preceding,  between  it  and 
the  Complexus  muscle.  It  arises  by  four  tendons,  from  the  transverse  processes 
of  the  third,  fourth,  fifth,  and  sixth  dorsal  vertebrae,  and  by  additional  separate 
tendons  from  the  articular  processes  of  the  three  or  four  lower  cervical.  The 
fibres  form  a  small  muscle,  which  ascends  to  be  inserted  into  the  posterior  mar- 
gin of  the  mastoid  process,  beneath  the  Splenius  and  Sterno-mastoid  muscles. 
This  small  muscle  is  almost  always  crossed  by  a  tendinous  intersection  near  its 
insertion  into  the  mastoid  process. 

The  Spiiialis  Dorsi  connects  the  spinous  processes  of  the  upper  lumbar  and 
the  dorsal  vertebrae  together  by  a  series  of  muscular  and  tendinous  slips,  which 
are  intimately  blended  with  the  Longissimus  Dorsi.  It  is  situated  at  the  inner 
side  of  the  Longissimus  Dorsi,  arising,  by  three  or  four  tendons,  from  the  spi- 
nous processes  of  the  first  two  lumbar  and  the  last  two  dorsal  vertebrae ;  these 
uniting,  form  a  small  muscle,  which  is  inserted,  by  separate  tendons,  into  the 
spinous  processes  of  the  dorsal  vertebrae,  the  number  varying  from  four  to  eight. 
It  is  intimately  united  with  the  Semispinalis  Dorsi,  which  lies  beneath  it. 

The  Spinalis  Colli  is  a.  small  muscle,  connecting  together  the  spinous  processes 
of  the  cervical  vertebrae,  and  analogous  to  the  Spinalis  Dorsi  in  the  dorsal  re- 
gion. It  varies  considerably  in  its  size,  and  in  its  extent  of  attachment  to  the 
vertebras,  not  only  in  different  bodies,  but  on  the  two  sides  of  the  same  body. 
It  usually  arises  by  fleshy  or  tendinous  slips,  varying  from  two  to  four  in  num- 
ber, from  the  spinous  processes  of  the  fifth  and  sixth  cervical  vertebra3,  and 
occasionally  from  the  first  and  second  dorsal,  and  is  inserted  into  the  spinous 
process  of  the  axis,  and  occasionally  into  the  spinous  process  of  the  two  verte- 
brae below  it.     This  muscle  was  found  absent  in  five  cases  out  of  twenty-four. 

The  Complexus  is  a  broad  thick  muscle,  situated  at  the  upper  and  back  part 
of  the  neck,  beneath  the  Splenius,  and  internal  to  the  Transversalis  Colli  and 
Trachelo-mastoid,  It  arises,  by  a  series  of  tendons,  about  seven  in  number, 
from  the  tips  of  the  transverse  processes  of  the  upper  three  dorsal  and  seventh 
cervical,  and  from  the  articular  processes  of  the  three  cervical  above  this.  The 
tendons  uniting  form  a  broad  muscle,  which  passes  obliquely  upwards  and  in- 
wards, and  is  inserted  into  the  innermost  depression  between  the  two  curved 
lines  of  the  occipital  bone.  This  muscle,  about  its  middle,  is  traversed  by  a 
transverse  tendinous  intersection. 

The  Biventer  Cervicis  is  a  small  fasciculus,  situated  on  the  inner  side  of  the 
preceding,  and  in  the  majority  of  cases  blended  with  it ;  it  has  received  its  name 
from  having  a  tendon  intervening  between  two  fleshy  bellies.  It  is  sometimes 
described  as  a  separate  muscle,  arising,  by  from  two  to  four  tendinous  slips,  from 
the  transverse  processes  of  as  many  of  the  upper  dorsal  vertebrie,  and  inserted, 
on  the  inner  side  of  the  Complexus,  into  the  superior  curved  line  of  the  occi- 
pital bone. 

Relations,  The  muscles  of  the  fourth  layer  are  bound  down  to  the  vertebrae 
and  ribs  in  the  dorsal  and  lumbar  regions  by  the  lumbar  fascia  and  vertebral 
aponeurosis.  Their  inner  part  covers  the  muscles  of  the  fifth  layer.  In  the 
neck  they  are  in  relation,  by  their  superficial  surface,  with  the  Trapezius  and 
Splenius ;  by  their  deep  surface,  with  the  Semispinalis  Dorsi  and  Semispinalis 
Colli  and  the  Eecti  and  Obliqui.  The  Biventer  Cervicis  is  separated  from  its 
fellow  of  the  opposite  side  by  the  ligamentum  nuchae,  and  the  Complexus  from 
the  Semispinalis  Colli  by  the  profunda  cervicis  artery,  the  princeps  cervicis 
artery,  and  by  the  posterior  cervical  plexus  of  nerves. 

Nerves.  The  Erector  Spinae  and  its  subdivisions  in  the  dorsal  region  are  sup- 


356  MUSCLES    AND    FASCIA. 

plied  by  the  external  posterior  branches  of  the  lumbar  and  dorsal  nerves ;  the 
Cervicalis  Ascendens,  Transversalis  Colli,  Trachelo-mastoid,  and  Spinalis  Cer- 
vicis,  by  the  external  posterior  branches  of  the  cervical  nerves  ;  the  Cornplexus 
by  the  internal  posterior  branches  of  the  cervical  nerves,  the  suboccipital  and 
great  occipital. 

Fifth  Layer. 

Semispinalis  Dorsi.  Extensor  Coccygis. 

Semispinalis  Colli.  Intertransversales. 

Multifidus  Spinse.  Eectus  Capitis  Posticus  Major. 

Eotatores  Spinas.  Rectus  Capitis  Posticus  Minor. 

Supraspinales.  "               Obliquus  Capitis  Superior. 

Interspinales.  Obliquus  Capitis  Inferior. 

Dissection.  Kemove  the  muscles  of  the  preceding  layer  by  dividing  and  turning  aside  the 
Cornplexus ;  then  detaching  the  Spinalis  and  Longissimus  Dorsi  from  their  attachments,  dividing 
the  Erector  Spinas  at  its  connection  below  to  the  sacral  and  lumbar  spines,  and  turning  it  out- 
wards. The  muscles  filling  up  the  interval  between  the  spinous  and  transverse  processes  are 
then  exposed. 

The  Semispinalis  muscles  (Fig.  228)  connect  the  transverse  and  articular  pro- 
cesses to  the  spinous  processes  of  the  vertebrae,  extending  from  the  lower  part 
of  the  dorsal  region  to  the  upper  part  of  the  cervical. 

The  /Semispinalis  Dorsi  consists  of  thin,  narrow,  fleshy  fasciculi,  interposed 
between  tendons  of  considerable  length.  It  arises  by  a  series  of  small  tendons 
from  the  transverse  processes  of  the  lower  dorsal  vertebrae,  from  the  tenth  or 
eleventh  to  the  fifth  or  sixth ;  and  is  inserted  by  five  or  six  tendons  into  the 
spinous  processes  of  the  upper  four  dorsal  and  lower  two  cervical  vertebrae. 

The  Semispinalis  Colli,  thicker  than  the  preceding,  arises  by  a  series  of  ten- 
dinous and  fleshy  points  from  the  transverse  processes  of  the  upper  four  dorsal 
vertebrae,  and  from  the  articular  processes  of  the  lower  four  cervical  vertebrae; 
and  is  inserted  into  the  spinous  processes  of  four  cervical  vertebrae,  from  the 
axis  to  the  fifth  cervical.  The  fasciculus  connected  with  the  axis  is  the  largest, 
and  chiefly  muscular  in  structure. 

Relations.  By  their  superficial  surface,  from  below  upwards,  with  the  Longis- 
simus Dorsi,  Spinalis  Dorsi,  Splenius,  Cornplexus,  the  profunda  cervicis  artery, 
the  princeps  cervicis  artery,  and  the  posterior  cervical  plexus  of  nerves.  By 
their  deep  surface,  with  the  Multifidus  Spinae. 

The  Multifidus  Spinte  consists  of  a  number  of  fleshy  and  tendinous  fasciculi, 
which  fill  up  the  groove  on  either  side  of  the  spinous  processes  of  the  vertebrae, 
from  the  sacrum  to  the  axis.  In  the  sacral  region,  these  fasciculi  arise  from  the 
back  of  the  sacrum,  as  low  as  the  fourth  sacral  foramen,  and  from  the  aponeu- 
rosis of  origin  of  the  Erector  Spinae;  in  the  iliac  region,  from  the  inner  surface 
of  the  posterior  superior  spine,  and  posterior  sacro-iliac  ligaments;  in  the  lum- 
bar and  cervical  regions,  from  the  articular  processes;  and  in  the  dorsal  region, 
from  the  transverse  processes.  Each  fasciculus,  ascending  obliquely  upwards 
and  inwards,  is  inserted  into  the  lamina  and  whole  length  of  the  spinous  process 
of  one  of  the  vertebrae  above.  These  fasciculi  vary  in  length :  the  most  super- 
ficial, the  longest,  pass  from  one  vertebra  to  the  third  or  fourth  above;  those 
next  in  order  pass  from  one  vertebra  to  the  second  or  third  above;  whilst  the 
deepest  connect  two  contiguous  vertebrae. 

Relations.  By  its  superficial  surface,  with  the  Longissimus  Dorsi,  Spinalis 
Dorsi,  Semispinalis  Dorsi,  and  Semispinalis  Colli.  By  its  deep  surface,  with  the 
laminae,  and  spinous  processes  of  the  vertebrae,  and  with  the  Eotatores  Spin» 
in  the  dorsal  region. 

The  Rotatores  Spince  are  found  only  in  the  dorsal  region  of  the  spine,  beneath 
the  Multifidus  Spinae;  they  are  eleven  in  number  on  each  side.  Each  muscle  is 
small  and  somewhat  quadrilateral  in  form ;  it  arises  from  the  upper  and  back 
part  of  the  transverse  process,  and  is  inserted  into  the  lower  border  and  outer 


OP    THE    BACK.  3&7 

surface  of  the  lamina  of  the  vertebra  above,  the  fibres  extending  as  far  inwards 
as  the  root  of  the  spinous  process.  The  first  is  found  between  the  first  and 
second  dorsal;  the  last,  between  the  eleventh  and  twelfth.  Sometimes  the 
number  of  these  muscles  is  diminished  by  the  absence  of  one  or  more  from  the 
upper  or  lower  end. 

The  Supraspinales  consist  of  a  series  of  fleshy  bands,  which  lie  on  the  spinous 
processes  in  the  cervical  region  of  the  spine. 

The  Inters2nnales  are  short  muscular  fasciculi,  placed  in  pairs  between  the 
spinous  processes  of  the  contiguous  vertebrae.  In  the  cervical  region  they  .are 
most  distinct,  and  consist  of  six  pairs,  the  first  being  situated  between  the  axis 
and  third  vertebra,  and  the  last  between  the  last  cervical  and  the  first  dorsal. 
They  are  small,  narrow  bundles,  attached,  above  and  below,  to  the  apices  of  the 
spinous  processes.  In  the  dorsal  region  they  are  found  between  the  first  and 
second  vertebra3,  and  occasionally  between  the  second  and  third;  and  below, 
between  the  eleventh  and  twelfth.  In  the  lumbar  region  there  are  four  pairs  of 
these  muscles  in  the  intervals  between  the  five  lumbar  vertebrae.  There  is  also 
occasionally  one  in  the  interspinous  space,  between  the  last  dorsal  and  first 
lumbar,  and  between  the  fifth  lumbar  and  the  sacrum. 

The  Extensor  Coccygis  is  a  slender  muscular  fasciculus,  occasionally  present, 
which  extends  over  the  lower  part  of  the  posterior  surface  of  the  sacrum  and 
coccyx.  It  arises  by  tendinous  fibres  from  the  last  bone  of  the  sacrum,  or  first 
piece  of  the  coccyx,  and  passes  downwards  to  be  inserted  into  the  lower  part 
of  the  coccyx.  It  is  a  rudiment  of  the  extensor  muscle  of  the  caudal  vertebrae 
which  exists  in  some  animals. 

The  Intertransversales  are  small  muscles  placed  between  the  transverse  pro- 
cesses of  the  vertebree.  In  the  cervical  region  they  are  most  developed,  con- 
sisting of  two  rounded  muscular  and  tendinous  fasciculi,  which  pass  between 
the  anterior  and  posterior  tubercles  of  the  transverse  processes  of  two  contiguous 
vertebrae,  separated  from  one  another  by  the  anterior  branch  of  a  cervical  nerve, 
which  lies  in  the  groove  between  them,  and  by  the  vertebral  artery  and  vein. 
In  this  region  there  are  seven  pairs  of  these  muscles,  the  first  being  between 
the  atlas  and  axis,  and  the  last  between  the  seventh  cervical  and  first  dorsal 
vertebrae.  In  the  dorsal  region  they  are  least  developed,  consisting  chiefly  of 
rounded  tendinous  cords  in  the  intertransverse  spaces  of  the  upper  dorsal  ver- 
tebrae; but  between  the  transverse  processes  of  the  lower  three  dorsal  vertebrae 
and  the  first  lumbar  they  are  muscular  in  structure.  In  the  lumbar  region  they 
are  four  in  number,  and  consist  of  a  single  muscular  layer,  which  occupies  the 
entire  interspace  between  the  transverse  processes  of  the  lower  lumbar  vertebrae, 
whilst  those  between  the  transverse  processes  of  the  upper  lumbar  are  not 
attached  to  more  than  half  the  breadth  of  the  process. 

The  Rectus  Capitis  Posticus  Major  arises  by  a  pointed  tendinous  origin  from 
the  spinous  process  of  the  axis,  and,  becoming  broader  as  it  ascends,  is  inserted 
into  the  inferior  curved  line  of  the  occipital  bone  and  the  surface  of  bone  im- 
mediately below  it.  As  the  muscles  of  the  two  sides  ascend  upwards  and  out- 
wards, they  leave  between  them  a  triangular  space,  in  which  are  seen  the  Eecti 
Capitis  Postici  Minores  muscles. 

Relations.  By  its  superficial  surface^  with  the  Complexus,  and,  at  its  insertion, 
with  the  superior  oblique.  By  its  deep  surface,  with  the  posterior  arch  of  the 
atlas,  the  posterior  occipito-atloid  ligament,  and  part  of  the  occipital  bone. 

The  Rectus  Capitis  Posticus  Minor,  the  smallest  of  the  four  muscles  in  this 
region,  is  of  a  triangular  shape;  it  arises  by  a  narrow  pointed  tendon  from  the 
tubercle  on  the  posterior  arch  of  the  atlas,  and,  becoming  broader  as  it  ascends, 
is  inserted  into  the  rough  surface  beneath  the  inferior  curved  line,  nearly  as  far 
as  the  foramen  magnum,  nearer  to  the  middle  line  than  the  preceding. 

Relations.  By  its  superficial  surface,  with  the  Complexus.  By  its  deep  sur- 
face, with  the  posterior  occipito-atloid  ligament. 

The  Obliquus  Inferior,  the  larger  of  the  two  oblique  muscles,  arises  from  the 


358  MUSCLES    AND    FASCIA. 

apex  of  the  spinous  process  of  the  axis,  and  passes  almost  horizontally  outwards, 
to  be  inserted  into  the  apex  of  the  transverse  process  of  the  atlas. 

Relations.  By  its  superficial  surface^  with  the  Complexus,  and  with  the  pos- 
terior branch  of  the  second  cervical  nerve  which  crosses  it.  By  its  deep  surface^ 
with  the  vertebral  artery,  and  posterior  atlo-axoid  ligament. 

The  Ohliquus  Superior,  narrow  below,  wide  and  expanded  above,  arises  by 
tendinous  fibres  from  the  upper  part  of  the  transverse  process  of  the  atlas, 
joining  with  the  insertion  of  the  preceding,  and,  passing  obliquely  upwards  and 
inwards,  is  inserted  into  the  occipital  bone,  between  the  tAvo  curved  lines, 
external  to  the  Complexus.  Between  the  two  Oblique  muscles  and  the  Rectus' 
Posticus  Major  a  triangular  interval  exists,  in  which  is  seen  the  vertebral  artery, 
and  the  posterior  branch  of  the  suboccipital  nerve. 

Relations.  By  its  superficial  surface,  with  the  Complexus  and  Trachelo- 
mastoid.     By  its  deep  surface,  with  the  posterior  occipito-atloid  ligament. 

Nerves.  The  Semispinalis  Dorsi  and  Rotatores  Spinoe  are  supplied  by  the 
internal  posterior  branches  of  the  dorsal  nerves;  the  Semispinalis  Colli,  Supra- 
spinales,  and  Interspinales,  by  the  internal  posterior  branches  of  the  cervical 
nerves;  the  Intertransversales,  by  the  internal  posterior  branches  of  the  cervi- 
cal, dorsal,  and  lumbar  nerves;  the  Multifidus  Spinas,  by  the  same,  with  the 
addition  of  the  internal  posterior  branches  of  the  sacral  nerves.  The  Recti  and 
Obliqui  muscles  are  all  supplied  by  the  suboccipital  and  great  occipital  nerves. 

Actions.  The  Erector  Spinae,  comprising  the  Sacro-lumbalis,  with  its  acces- 
sory muscles,  the  Longissimus  Dorsi  and  Spinalis  Dorsi,  serves,  as  its  name 
implies,  to  maintain  the  spine  in  the  erect  posture ;  it  also  serves  to  bend  the 
trunk  backwards  when  it  is  required  to  counterbalance  the  influence  of  any 
weight  at  the  front  of  the  body,'  as,  for  instance,  when  a  heavy  weight  is  sus- 
pended from  the  neck,  or  when  there  is  any  great  abdominal  development,  as 
in  pregnancy  or  dropsy ;  the  peculiar  gait  under  such  circumstances  depends 
upon  the  spine  being  drawn  backwards,  by  the  counterbalancing  action  of  the 
Erector  Spinae  muscles.  The  muscles  which  form  the  continuation  of  the 
Erector  Spinae  upwards  steady  the  head  and  neck,  and  fix  them  in  the  upright 
position.  If  the  Sacro-lumbalis  and  Longissimus  Dorsi  of  one  side  act,  they 
serve  to  draw  down  the  chest  and  spine  to  the  corresponding  side.  The  Cervi- 
calis  Ascendens,  taking  its  fixed  point  from  the  cervical  vertebrae,  elevates 
those  ribs  to  which  it  is  attached.  The  Multifidus  Spinae  acts  successively 
upon  the  different  parts  of  the  spine ;  thus,  the  sacrum  furnishes  a  fixed  point 
from  which  the  fasciculi  of  this  muscle  act  upon  the  lumbar  region;  these  then 
become  the  fixed  points  for  the  fasciculi  moving  the  dorsal  region,  and  so  on 
throughout  the  entire  length  of  the  spine ;  it  is  by  the  successive  contraction 
and  relaxation  of  the  separate  fasciculi  of  this  and  other  muscles,  that  the  spine 
preserves  the  erect  posture  without  the  fatigue  that  would  necessarily  have 
been  produced,  had  this  position  been  maintained  by  the  action  of  a  single 
muscle.  The  Multifidus  Spinae,  besides  preserving  the  erect  position  of  the 
spine,  serves  to  rotate  it,  so  that  the  front  of  the  trunk  is  turned  to  the  side 
opposite  to  that  from  which  the  muscle  acts,  this  muscle  being  assisted  in  its 
action  by  the  Obliquus  Externus  Abdominis.  The  Complexi,  the  analogues 
of  the  Multifidus  Spinas  in  the  neck,  draw  the  head  directly  backward;  if  one 
muscle  acts,  it  draws  the  head  to  one  side,  and  rotates  it  so  that  the  face  is 
turned  to  the  opposite  side.  The  Rectus  Capitis  Posticus  Minor  and  the  Supe- 
rior Oblique  draw  the  head  backwards ;  and  the  latter,  from  the  obliquity  in 
the  direction  of  its  fibres,  may  turn  the  face  to  the  opposite  side.  The  Rectus 
Capitis  Posticus  Major  and  the  Obliquus  Inferior  rotate  the  atlas,  and,  with  it, 
the  cranium  round  the  odontoid  process,  and  turn  the  face  to  the  same  side. 


OF    THE    ABDOMEN". 


359 


MUSCLES  OF  THE  ABDOMEN. 


The  muscles  in  this  region  are,  the 

Obliquus  Externus. 
Obliquus  Internus. 
Transversalis. 


Eectus. 
Pyramidalis. 
Quadratus  Lumborum. 


Fi<?.  229. — Dissection  of  Abdomen. 


Dissection  (Fig.  229).  To  dissect  the  abdominal  muscles,  make  a  vertical  incision  from  the 
ensiform  cartilage  to  the  pubes,  a  second  incision  from  the  umbilicus  obliquely  upwards  and  out- 
wards to  the  outer  surface  of  the  chest,  as  high  as  the  lower  border  of  the  fifth  or  sixth  rib,  and 
a  third,  commencing  midway  between  the  umbilicus  and  pubes,  transversely  outwards  to  the 
anterior  superior  iliac  spine,  and  along  the  crest  of  the 
ilium  as  far  as  its  posterior  third.  Then  reflect  the  three 
flaps  included  between  these  incisions  from  within  out- 
wards, in  the  line  of  direction  of  the  muscular  fibres.  If 
necessary,  the  abdominal  muscles  may  be  made  tense  by 
inflating  the  peritoneal  cavity  through  the  umbilicus. 

The  External  or  Descending  Oblique  muscle 
(Fig.  230)  is  situated  on  the  side  and  fore  part 
of  the  abdomen  ;  being  the  largest  and  the  most 
superficial  of  the  three  flat  muscles  in  this 
region.  It  is  broad,  thin,  and,  irregularly  quad- 
rilateral, its  muscular  portion  occupying  the 
side,  its  aponeurosis  the  anterior  wall  of  the 
abdomen.  It  arises,  by  eight  fleshy  digitations, 
from  the  external  surface  and  lower  borders  of 
the  eight  inferior  ribs;  these  digitations  are 
arranged  in  an  oblique  line  running  downwards 
and  backwards ;  the  upper  ones  being  attached 
close  to  the  cartilages  of  the  corresponding  ribs; 
the  lowest,  to  the  apex  of  the  cartilage  of  the 
last  rib;  the  intermediate  ones,  to  the  ribs  at 
some  distance  from  their  cartilages.  The  five 
superior  serrations  increase  in  size  from  above 
downwards,  and  are  received  between  corres- 
ponding processes  of  the  Serratus  Magnus;  the 
three  lower  ones  diminish  in  size  from  above 

downwards,  receiving  between  them  corresponding  processes  from  the  Latissi- 
mus  Dorsi.  From  these  attachments,  the  fleshy  fibres  proceed  in  various  direc- 
tions. Those  from  the  lowest  ribs  pass  nearly  vertically  downwards,  to  be 
inserted  into  the  anterior  half  of  the  outer  lip  of  the  crest  of  the  ilium ;  the 
middle  and  upper  fibres,  directed  downwards  and  forwards,  terminate  in  ten- 
dinous fibres,  which  spread  out  into  a  broad  aponeurosis.  This  aponeurosis, 
joined  with  that  of  the  opposite  muscle  along  the  median  line,  covers  the  whole 
of  the  front  of  the  abdomen :  above,  it  is  connected  with  the  lower  border  of 
the  Pectoral  is  Major ;  below,  its  fibres  are  closely  aggregated  together,  and 
extend  obliquely  across  from  the  anterior  superior  spine  of  the  ilium  to  the 
spine  of  the  os  pubis  and  the  pectineal  line.  In  the  median  line,  it  interlaces 
with  the  aponeurosis  of  the  opposite  muscle,  forming  the  linea  alba,  and  extends 
from  the  ensiform  cartilage  to  the  symphysis  pubis. 

That  portion  of  the  aponeurosis  which  extends  between  the  anterior  superior 
spine  of  the  ilium  and  the  spine  of  the  os  pubis,  is  a  broad  band,  folded  inwards, 
and  continuous  below  with  the  fascia  lata;  it  is  called  Pouparth  ligament.  The 
portion  which  is  reflected  from  Poupart's  ligament  into  the  pectineal  line  is 
called  Qimhernat'' s  ligament}  From  the  point  of  attachment  of  the  latter  to  the 
pectineal  line,  a  few  fibres  pass  upwards  and  inwards,  beneath  the  inner  pillar 


'  All  these  parts  will  be  found  more  particularly  described  with  the  Surgical  Anatomy  of 
Hernia. 


360 


MUSCLES    AND    FASCIiE. 


of  the  ring,  to  the  linea  alba.     They  diverge  as  they  ascend,  and  form  a  thin, 
triangular,  fibrous  band,  -which  is  called  the  triangular  ligament. 

In  the  aponeurosis  of  the  External  Oblique,  immediately  above  the  crest  of 
the  OS  pubis,  is  a  triangular  opening,  the  external  abdominal  ring,  formed  by  a 
separation  of  the  fibres  of  the  aponeurosis  in  this  situation :  it  serves  for  the 
transmission  of  the  spermatic  cord  in  the  male,  and  the  round  ligament  in  the 

Fig.  230.— The  External  Oblique  Muscle. 


iTt.AUominttl'Rinj' 
fliiubcrnott  Liq^—t 


female.  This  opening  is  directed  obliquely  upwards  and  outwards,  and  cor- 
responds with  the  course  of  the  fibres  of  the  aponeurosis.  It  is  bounded,  below, 
by  the  crest  of  the  os  pubis ;  above,  by  some  curved  fibres,  which  pass  across 
the  aponeurosis  at  the  upper  angle  of  the  ring,  so  as  to  increase  its  strength ; 
and,  on  cither  side,  by  the  margins  of  the  aponeurosis,  which  are  called  the 
pillars  of  the  ring.  Of  these,  the  external,  which  is,  at  the  same  time,  inferior, 
from  the  obliquity  of  its  direction,  is  inserted  into  the  spine  of  the  os  pubis. 
The  internal,  or  superior  pillar  is  attached  to  the  front  of  the  symphysis  pubis, 
and  interlaces  with  the  corresponding  fibres  of  the  opposite  muscle,  the  fibres 


OF    THE    ABDOMEN. 


361 


of  the  right  muscle  being  superficial.  To  the  margins  of  the  pillars  of  the 
external  abdominal  ring  is  attached  an  exceedingly  thin  and  delicate  fascia, 
which  is  prolonged  down  over  the  outer  surface  of  the  cord  and  testis.  This 
has  received  the  name  of  iniercolumnar  fascia^  from  its  attachment  to  the  pillars 
of  the  ring.  It  is  also  called  the  external  spermatic  fascia^  from  being  the  most 
external  of  the  fasciae  which  cover  the  spermatic  cord. 

Relations.  By  its  external  surface^  with  the  superficial  fascia,  superficial  epi- 
gastric and  circumflex  iliac  vessels,  and  some  cutaneous  nerves.  By  lisinternal 
mrface^  with  the  Internal  Oblique,  the  lower  part  of  the  eight  inferior  ribs,  and 
Intercostal  muscles,  the  Cremaster,  the  spermatic  cord  in  the  male,  and  round 
ligament  in  the  female.  Its  posterior  border  is  occasionally  overlapped  by  the 
Latissimus  Dorsi ;  sometimes  an  interval  exists  between  the  two  muscles,  in 
which  is  seen  a  portion  of  the  Internal  Oblique. 

Dissection.  Detach  the  External  Oblique  by  dividing  it  across,  just  in  front  of  its  attach- 
ment to  the  ribs,  as  far  as  its  posterior  border,  and  separating  it  below  from  the  crest  of  ilium 
as  far  as  the  spine  ;  then  separate  the  muscle  carefully  from  the  Internal  Oblique,  which  lies 
beneath,  and  turn  it  towards  the  opposite  side. 

The  Internal  ov  Ascending  0/;%we  muscle  (Fig.  231),  thinner  and  smaller  than 
the  preceding,  beneath  which  it  lies,  is  of  an  irregularly  quadrilateral  form. 


Fig.  231.— The  Internal  Oblique  Muscle. 


Conjoined  Tent/o 
CRCMASTER 


and  situated  at  the  side  and  fore  part  of  the  abdomen.  It  arises,  by  fleshy 
fibres,  from  the  outer  half  of  Poupart's  ligament,  being  attached  to  the  groove 
on  its  upper  surface ;  from  the  anterior  two-thirds  of  the  middle  lip  of  the 


362  MUSCLES    AND    FASCIA. 

crest  of  the  ilium,  and  from  the  lumbar  fascia.  From  this  origin,  the  fibres 
diverge;  those  from  Poupart's  ligament,  few  in  number  and  paler  in  color  than 
the  rest,  arch  downwards  and  inwards  across  the  spermatic  cord,  to  be  inserted, 
conjointly  with  those  of  the  Transversalis,  into  the  crest  of  the  os  pubis  and 
pectineal  line,  to  the  extent  of  half  an  inch,  forming  what  is  known  as  the 
conjoined  tendon  of  the  Internal  Oblique  and  Transversalis ;  those  from  the 
anterior  superior  iliac  spine  are  horizontal  in  their  direction ;  whilst  those 
which  arise  from  the  fore  part  of  the  crest  of  the  ilium  pass  obliquely  upwards 
and  inwards,  and  terminate  in  an  aponeurosis,  which  is  continued  forwards  to 
the  linea  alba;  the  most  posterior  fibres  ascend  almost  vertically  upwards,  to 
be  inserted  into  the  lower  borders  of  the  cartilages  of  the  four  lower  ribs, 
being  continuous  with  the  Internal  Intercostal  muscles. 

The  conjoined  tendon  of  the  Internal  Oblique  and  Transversalis  is  inserted 
into  the  crest  of  the  os  pubis  and  pectineal  line,  immediately  behind  the  exter- 
nal abdominal  ring,  serving  to  protect  what  would  otherwise  be  a  weak  point 
in  the  abdomen.  Sometimes  this  tendon  is  insufficient  to  resist  the  pressure 
from  within,  and  is  carried  forward  in  front  of  the  protrusion  through  the  ex- 
ternal ring,  forming  one  of  the  coverings  of  direct  inguinal  hernia. 

The  aponeurosis  of  the  Internal  Oblique  is  continued  forward  to  the  middle 
line  of  the  abdomen,  where  it  joins  with  the  aponeurosis  of  tlie  opposite  mus- 
cle at  the  linea  alba,  and  extends  from  the  margin  of  the  thorax  to  the  pubes. 
At  the  outer  margin  of  the  Rectus  muscles,  this  aponeurosis,  for  the  upper 
three-fourths  of  its  extent,  divides  into  two  lamellae,  which  pass,  one  in  front 
and  the  other  behind  the  muscle,  inclosing  it  in  a  kind  of  sheath,  and  reuniting 
on  its  inner  border  at  the  linea  alba ;  the  anterior  layer  is  blended  with  the 
aponeurosis  of  the  External  Oblique  muscle;  the  posterior  layer  with  that  of 
the  Transversalis.  Along  the  lower  fourth,  the  aponeurosis  passes  altogether 
in  front  of  the  Rectus  without  any  separation. 

Relations.  By  its  external  surface,  with  the  External  Oblique,  Latissimus 
Dorsi,  spermatic  cord,  and  external  ring.  By  its  internal  surface,  with  tlie 
Transversalis  muscle,  fascia  transversalis,  internal  ring  and  spermatic  cord.  Its 
lower  border  forms  the  upper  boundary  of  the  spermatic  canal. 

Dissection.  Detach  the  Internal  Oblique  in  order  to  expose  the  Transversalis  beneath.  This 
may  be  effected  by  dividing  the  muscle,  above,  at  its  attachment  to  the  ribs  ;  below,  at  its  con- 
nection with  Poupart's  ligament  and  the  crest  of  the  ilium  ;  and  behind,  by  a  vertical  incision 
extending  from  the  last  rib  to  the  crest  of  the  ilium.  The  muscle  should  previously  be  made 
tense  by  drawing  upon  it  with  the  fingers  of  the  left  hand,  and  if  its  division  is  carefully  effected, 
the  cellular  interval  between  it  and  the  Transversalis,  as  well  as  the  direction  of  the  fibres  of 
the  latter  muscle,  will  afford  a  clear  guide  to  their  separation  ;  along  the  crest  of  the  ilium  the 
circumflex  iliac  vessels  are  interposed  between  them,  and  form  an  important  guide  in  separating 
them.     The  muscle  should  then  be  thrown  forwards  towards  the  linea  alba. 

The  Transversalis  (Fig.  232),  so  called  from  the  direction  of  its  fibres,  is  the 
most  internal  flat  muscle  of  the  abdomen,  being  placed  immediately  beneath 
the  Internal  Oblique.  It  arises  by  fleshy  fibres  from  the  outer  third  of  Pou- 
part's ligament,  from  the  inner  lip  of  the  crest  of  the  ilium,  its  anterior  three- 
fourths,  from  the  inner  surface  of  the  cartilages  of  the  six  lower  ribs,  inter- 
digitating  with  the  Diaphragm,  and  by  a  broad  aponeurosis  from  the  spinous 
and  transverse  processes  of  the  lumbar  vertebne.  The  lower  fibres  curve 
downwards,  and  are  inserted,  together  with  those  of  the  Internal  Oblique,  into 
the  crest  of  the  os  pubis  and  pectineal  line,  forming  what  was  described  above 
as  the  conjoined  tendon  of  these  muscles.  Throughout  the  rest  of  its  extent 
the  fibres  pass  horizontally  inwards,  and  near  the  outer  margin  of  the  Rectus, 
terminate  in  an  aponeurosis,  which  is  inserted  into  the  linea  alba;  its  upper 
three-fourths  passing  behind  the  Rectus  muscle,  blending  with  the  posterior 
lamella  of  the  Internal  Oblique;  its  lower  fourth  passing  in  front  of  the  Rectus. 

Relations.  By  its  external  surface,  with  the  Internal  Oblique,  the  inner  sur- 
face of  the  lower  ribs,  and  Internal  Intercostal  muscles.     Its  inner  surface  is 


OF    THE    ABDOMEN. 


563 


lined  by  the  fascia  transversalis,  which  separates  it  from  the  peritoneum.     Its 
lower  border  forms  the  upper  boundary  of  the  spermatic  canal. 

Fig.  232. — ^The  Transversalis,  Rectus,  and  Pyramidalis  Muscles. 


Z  in  ea    a 


Lumbar  Fascia  (Fig.  233).  The  vertebral  aponeurosis  of  the  Transversalis 
divides  into  three  layers ;  an  anterior,  very  thin,  which  is  attached  to  the  front 
part  of  the  apices  of  the  transverse  processes  of  the  lumbar  vertebrae,  and, 
above,  to  the  lower  margin  of  the  last  rib,  where  it  forms  the  ligamentum 
arcuatum  externum ;  a  middle  layer,  much  stronger,  which  is  attached  to  the 
apices  of  the  transverse  processes ;  and  a  posterior  layer,  attached  to  the  apices 
of  the  spinous  processes.  Between  the  anterior  and  middle  layers  is  situated 
the  Quadratus  Lumborum ;  between  the  middle  and  posterior,  the  Erector 
Spinae.  The  posterior  lamella  of  this  aponeurosis  receives  the  attachment  of 
the  Internal  Oblique;  it  is  also  blended  with  the  aponeurosis  of  the  Serratus 
Posticus  Inferior  and  with  that  of  the  Latissimug  Dorsi,  forming  the  lumbar 
fascia. 


864 


MUSCLES    AND    FASCI-E. 


Dissection.  To  expose  the  Rectus  muscle,  open  its  sheath  by  a  vertical  incision  extending 
from  the  margin  of  the  thorax  to  the  pubes,  and  then  reflect  the  two  portions  from  the  surface 
of  the  muscle,  which  is  easily  done,  excepting  at  the  linese  transversas,  where  so  close  an  adhesion 
exists,  that  the  greatest  care  is  requisite  in  separating  them.  Now  raise  the  outer  edge  of  the 
muscle,  in  order  to  examine  the  posterior  layer  of  the  sheath.  By  dividing  the  muscle  in  tlie 
centre,  and  turning  its  lower  part  downwards,  the  point  where  the  posterior  wall  of  the  sheath 
terminates  in  a  thin  curved  margin  will  be  seen. 

Fig.  233. — A  Transverse  Section  of  the  Abdomen  in  the  Lumbar  Region. 


The  Beckis  Ahdominis  is  a  long  flat  muscle,  which  extends  along  the  whole 
length  of  the  front  of  the  abdomen,  being  separated  from  its  fellow  of  the 
opposite  side  by  the  linea  alba.  It  is  much  broader  above  than  below,  and 
arises  by  two  tendons,  the  external  or  larger  being  attached  to  the  crest  of  the 
OS  pubis ;  the  internal,  smaller  portion,  interlacing  with  its  fellow  of  the  oppo- 
site side,  and  being  connected  with  the  ligaments  covering  the  symphysis  pubis. 
The  fibres  ascend  vertically,  and  the  muscle,  becoming  broader  and  thinner  at 
its  upper  part,  is  inserted  by  three  portions  of  unequal  size  into  the  cartilages 
of  the  fifth,  sixth,  and  seventh  ribs.  Some  fibres  are  occasionally  connected 
with  the  costo-xiphoid  ligaments,  and  side  of  the  ensiform  cartilage. 

The  Eectus  muscle  is  traversed  by  a  series  of  tendinous  intersections,  which 
vary  from  two  to  five  in  number,  and  have  received  the  name  lineae  transversse. 
One  of  these  is  usually  situated  opposite  the  umbilicus,  and  two  above  that  point; 
of  the  latter,  one  corresponds  to  the  ensiform  cartilage,  and  the  other,  to  the 
interval  between  the  ensiform  cartilage  and  the  umbilicus ;  there  is  occasionally 
one  below  the  umbilicus.  These  intersections  pass  transversely  or  obliquely 
across  the  muscle  in  a  zigzag  course ;  they  rarely  extend  completely  through 
its  substance,  sometimes  pass  only  halfway  across  it,  and  are  intimately  adherent 
to  the  sheath  in  which  the  muscle  is  inclosed. 

The  Rectus  is  inclosed  in  a  sheath  (Fig.  233)  formed  by  the  aponeuroses  of 
the  Oblique  and  Transversalis  muscles,  which  are  arranged  in  the  following 
manner.  When  the  aponeurosis  of  the  Internal  Oblique  arrives  at  the  margin 
of  the  Rectus,  it  divides  into  two  lamella),  one  of  which  passes  in  front  of  the 
Rectus,  blending  with  the  aponeurosis  of  the  External  Oblique;  the  other, 
behind  it,  blending  with  the  aponeurosis  of  the  Transversalis;  and  these,  join- 
ing again  at  its  inner  border,  are  inserted  into  the  linea  alba.  This  arrange- 
ment of  the  fascia3  exists  along  the  upper  three-fourths  of  the  muscle;  at  the 
commencement  of  the  lower  fourth,  the  posterior  wall  of  the  sheath  terminates 
in  a  thin  curved  margin,  ov  falciform  edr/e,  the  concavity  of  which  looks  down- 
wards towards  the  pubes ;  the  aponeuroses  of  all  three  muscles  passing  in  front 
of  the  Rectus  without  any  separation.     The  Rectus  muscle,  in  the  situation 


OF    THE    ABDOMEX.  365 

where  its  sheath  is  deficient,  is  separated  from  the  peritoneum  by  the  trans- 
versalis  fascia. 

►  The  Pyramidalis  is  a  small  muscle,  triangular  in  shape,  placed  at  the  lower 
part  of  the  abdomen,  in  front  of  the  Rectus,  and  contained  in  the  same  sheath 
with  that  muscle.  It  arises  by  tendinous  fibres  from  the  front  of  the  os  pubis 
and  the  anterior  pubic  ligament ;  the  fleshy  portion  of  the  muscle  passes  up- 
wards, diminishing  in  size  as  it  ascends,  and  terminates  by  a  pointed  extremity, 
which  is  inserted  into  the  linea  alba,  midway  between  the  umbilicus  and  the  os 
pubis.  This  muscle  is  sometimes  found  wanting  on  one  or  both  sides;  the 
lower  end  of  the  Rectus  then  becomes  proportionately  increased  in  size.  Occa- 
sionally it  has  been  found  double  on  one  side,  or  the  muscles  of  the  two  sides 
are  of  unequal  size.     Sometimes  its  length  exceeds  what  is  stated  above. 

The  Quadratiis  Lumborum  (Fig.  228,  p.  853)  is  situated  in  the  lumbar  region; 
it  is  irregularly  quadrilateral  in  shape,  broader  below  than  above,  and  consists 
of  two  portions.  One  portion  arises  by  aponeurotic  fibres  from  the  ilio-lumbar 
ligament,  and  the  adjacent  portion  of  the  crest  of  the  ilium  for  about  two  inches, 
and  is  inserted  into  the  lower  border  of  the  last  rib,  about  half  its  length,  and 
by  four  small  tendons,  into  the  apices  of  the  transverse  processes  of  the  third, 
fourth,  and  fifth  lumbar  vertebrae.  The  other  portion  of  the  muscle,  situated 
in  front  of  the  preceding,  arises  from  the  upper  borders  of  the  transverse  pro- 
cesses of  the  third,  fourth,  and  fifth  lumbar  vertebras,  and  is  inserted  into  the 
lower  margin  of  the  last  rib.  The  Quadratus  Lumborum  is  contained  in  a 
sheath  formed  by  the  anterior  and  middle  lamellse  of  the  aponeurosis  of  origin 
of  the  Transversalis. 

Nerves.  The  abdominal  muscles  are  supplied  by  the  lower  intercostal,  ilio- 
hypogastric, and  ilio-inguinal  nerves.  The  Quadratus  Lumborum  receives 
filaments  from  the  anterior  branches  of  the  lumbar  nerves. 

In  the  description  of  the  abdominal  muscles,  mention  has  frequently  been 
made  of  the  linea  alba,  lineas  semilunares,  lineae  transversse ;  when  the  dissection 
of  the  muscles  is  completed,  these  structures  should  be  examined. 

The  linea  alba  is  a  tendinous  raphe  or  cord  seen  along  the  middle  line  of  the 
abdomen,  extending  from  the  ensiform  cartilage  to  the  pubes.  It  is  placed 
between  the  inner  borders  of  the  Recti  muscles,  and  formed  by  the  blending  of 
the  aponeuroses  of  the  Oblique  and  Transversalis  muscles.  It  is  narrow  below, 
corresponding  to  the  narrow  interval  existing  between  the  Recti,  but  broader 
above,  as  these  muscles  diverge  from  one  another  in  their  ascent,  becoming  of 
considerable  breadth  after  great  distension  of  the  abdomen  from  pregnancy  or 
ascites.  It  presents  numerous  apertures  for  the  passage  of  vessels  and  nerves; 
the  largest  of  these  is  the  umbilicus,  which  in  the  foetus  transmits  the  umbilical 
vessels,  but  in  the  adult  is  obliterated,  the  cicatrix  being  stronger  than  the 
neighboring  parts;  hence  umbilical  hernia  occurs  in  the  adult  above  the 
umbilicus,  whilst  in  the  foetus  it  occurs  at  the  umbilicus.  The  linea  alba  is  in 
relation,  in  front,  with  the  integument,  to  which  it  is  adherent,  especially  at  the 
umbilicus;  behind,  it  is  separated  from  the  peritoneum  by  the  transversalis 
fascia ;  and  below,  by  the  urachus,  and  the  bladder,  when  that  organ  is  dis- 
tended. 

The  linese  semilunares  are  two  curved  tendinous  lines,  placed  one  on  each  side 
of  the  linea  alba.  Bach  corresponds  with  the  outer  border  of  the  Rectus  muscle, 
extends  from  the  cartilage  of  the  eighth  rib  of  the  pubes,  and  is  formed  by  the 
aponeurosis  of  the  Internal  Oblique  at  its  point  of  division  to  inclose  the  Rectus, 
where  it  is  reinforced  in  front  and  behind  by  the  External  Oblique  and  Trans- 
versalis. 

The  lineae  transversse  are  three  or  four  narrow  transverse  lines  which  intersect 
the  Rectus  muscle  as  already  mentioned :  they  connect  the  linese  semilunares 
with  the  linea  alba. 

Actions.     The  abdominal  muscles  perform  a  threefold  action. 

When  the  pelvis  and  thorax  are  fixed,  they  compress  the  abdominal  viscera, 


366  MUSCLES    AND    FASCIA. 

by  constricting  the  cavity  of  the  abdomen,  in  which  action  they  are  materially 
assisted  by  the  descent  of  the  Diaphragm.  By  these  means  the  foetus  is  expelled 
from  the  uterus,  the  feces  from  the  rectum,  the  urine  from  the  bladder,  and  ite 
contents  from  the  stomach  in  vomiting. 

If  the  spine  is  fixed,  these  muscles  compress  the  lower  part  of  the  thorax, 
materially  assisting  in  expiration.  If  the  spine  is  not  fixed,  the  thorax  is  bent 
directly  forward,  when  the  muscles  of  both  sides  act,  or  to  either  side  when 
those  of  the  two  sides  act  alternately,  rotation  of  the  trunk  at  the  same  time 
taking  place  to  the  opposite  side. 

If  the  thorax  is  fixed,  these  muscles,  acting  together,  draw  the  pelvis  upwards, 
as  in  climbing ;  or,  acting  singly,  they  draw  the  pelvis  upwards,  and  rotate  the 
vertebral  column  to  one  side  or  the  other.  The  Eecti  muscles,  acting  from 
below,  depress  the  thorax,  and  consequently  flex  the  vertebral  column ;  when 
acting  from  above,  they  flex  the  pelvis  upon  the  vertebral  column.  The  Pyra- 
midales  are  tensors  of  the  linea  alba. 

The  Quadratus  Luraborum,  by  the  portion  inserted  into  the  last  rib,  draws 
down  and  fixes  that  bone,  acting  thereby  as  a  muscle  of  forced  expiration :  by 
the  portion  inserted  into  the  lumbar  vertebrae,  it  draws  the  spine  towards  the 
ilium,  and  thus  inclines  the  trunk  towards  its  own  side :  or  if  the  thorax  and 
spine  be  fixed,  it  may  act  upon  the  pelvis — raising  it  towards  its  own  side  when 
only  one  muscle  is  put  in  action,  and  when  both  muscles  act  together,  either 
from  below  or  above,  they  flex  the  trunk. 

MUSCLES  OF  THE  THORAX. 

The  muscles  exclusively  connected  with  the  bones  in  this  region  are  few  in 
number.     They  are  the 

Intercostales  Externi.  Infracostales. 

Intercostales  Interni.  Triangularis  Sterni. 

Levatores  Costarum. 

Intercostal  Fascise.  A  thin  but  firm  layer  of  fascia  covers  the  outer  surface  of 
the  External  Intercostal  and  the  inner  surface  of  the  Internal  Intercostal  mus- 
cles; and  a  third  layer,  more  delicate,  is  interposed  between  the  two  planes  of 
muscular  fibres.  These  are  the  intercostal  fascias ;  they  are  best  marked  in 
those  situations  where  the  muscular  fibres  are  deficient,  as  between  the  External 
Intercostal  muscles  and  sternum,  in  front ;  and  between  the  Internal  Intercos- 
tals  and  spine,  behind. 

The  Intercostal  Mtiscles  (Fig.  237)  are  two  thin  planes  of  muscular  and  ten- 
dinous structure,  placed  one  over  the  other,  filling  up  the  intercostal  spaces,  and 
being  directed  obliquely  between  the  margins  of  the  adjacent  ribs.  They  have 
received  the  name  "  external"  and  "  internal,"  from  the  position  they  bear  to  one 
another. 

The  External  Intercostals  are  eleven  in  number  on  each  side,  being  attached  to 
the  adjacent  margins  of  each  pair  of  ribs,  and  extending  from  the  tubercles  of 
the  ribs,  behind,  to  the  commencement  of  the  cartilages  of  the  ribs,  in  front, 
where  they  terminate  in  a  thin  membranous  aponeurosis,  which  is  continued  for- 
wards to  the  sternum.  They  arise  from  the  outer  lip  of  the  groove  on  the  lower 
border  of  each  rib,  and  are  inserted  into  the  upper  border  of  the  rib  below. 
In  the  two  lowest  spaces  they  extend  to  the  end  of  the  ribs.  Their  fibres  are 
directed  obliquely  downwards  and  forwards,  in  a  similar  direction  with  those  of 
the  External  Oblique  muscle.     They  are  thicker  than  the  Internal  Intercostals. 

Belattons.  By  their  outer  surface^  with  the  muscles  which  immediately  invest 
the  chest,  viz.,  the  Pectoralis  Major  and  Pectoralis  Minor,  Serratus  Magnus, 
Rhomboideus  Major,  Serratus  Posticus  Superior  and  Inferior,  Scalenus  Posticus, 
Sacro-lumbalis,  Longissimus  Dorsi,  Cervicalis  Ascendens,  Transversalis  Colli, 
Levatores  Costarum,  and  the  Obliquus  Externus  Abdominis.  By  their  intertml 
surface^  with  a  thin  layer  of  fascia,  which  separates  them  from  the  intercostal 


OF    THE    THORAX.  367 

vessels  and  nerve,  and  the  Internal  Intercostal  muscles,  and,  behind,  from  the 
pleura. 

The  Internal  Intercosials,  also  eleven  in  number  on  each  side^  are  placed  on 
the  inner  surface  of  the  preceding,  commencing  anteriorly  at  the  sternum,  in  the 
interspaces  between  the  cartilages  of  the  true  ribs,  and  from  the  anterior  extre- 
mities of  the  cartilages  of  the  false  ribs ;  and  extend  backwards  as  far  as  the 
angles  of  the  ribs,  where  they  are  continued  to  the  vertebral  column  by  a  thin 
aponeurosis.  They  arise  from  the  inner  lip  of  the  groove  on  the  lower  border 
of  each  rib,  as  well  as  from  the  corresponding  costal  cartilage,  and  are  inserted 
into  the  upper  border  of  the  rib  below.  Their  fibres  are  directed  obliquely 
downwards  and  backwards,  decussating  with  the  fibres  of  the  preceding. 

delations.  By  their  external  surface,  with  the  External  Tntercostals,  and  the 
intercostal  vessels  and  nerves.  By  their  interndl  surface,  with,  the  pleura  costalis, 
Triangularis  Sterni,  and  Diaphragm. 

The  Intercostal  muscles  consist  of  muscular  and  tendinous  fibres,  the  latter 
being  longer  and  more  numerous  than  the  former  ;  hence  the  walls  of  the  inter- 
costal spaces  possess  very  considerable  strength,  to  which  the  crossing  of  the 
muscular  fibres  materially  contributes. 

The  Infracostales  consist  of  muscular  and  aponeurotic  fasciculi,  which,  vary  in 
number  and  length ;  they  arise  from  the  inner  surface  of  one  rib,  and  are  inserted 
into  the  inner  surface  of  the  first,  second,  or  third  rib  below.  Their  direction 
is  most  usually  oblique,  like  the  Internal  Intercostals.  They  are  most  frequent 
between  the  lower  ribs. 

The  Triangularis  Sterni  is  a  thin  plane  of  muscular  and  tendinous  fibres, 
situated  upon  the  inner  wall  of  the  front  of  the  chest.  It  arises  from  the  lower 
part  of  the  side  of  the  sternum,  from  the  inner  surface  of  the  ensiform  cartilage, 
and  from  the  sternal  ends  of  the  costal  cartilages  of  the  three  or  four  lower  true 
ribs.  Its  fibres  diverge  upwards  and  outwards,  to  be  inserted  by  fleshy  digita- 
tions  into  the  lower  border  and  inner  surfaces  of  the  costal  cartilages  of  the 
second,  third,  fourth,  and  fifth  ribs.  The  lowest  fibres  of  this  muscle  are  hori- 
zontal in  their  direction,  and  are  continuous  with  those  of  the  Transversalis ; 
those  which  succeed  are  oblique,  whilst  the  superior  fibres  are  almost  vertical. 
This  muscle  varies  much  in  its  attachment,  not  only  in  different  bodies,  but  on 
opposite  sides  of  the  same  body. 

delations.  In  front  with  the  sternum,  ensiform  cartilage,  costal  cartilages.  In- 
ternal Intercostal  muscles,  and  internal  mammary  vessels.  Behind,  witb  the 
pleura,  pericardium,  and  anterior  mediastinum. 

The  Levatores  Cosiarum  (Fig.  228),  twelve  in  number  on  eacb  side,  are  small 
tendinous  and  fleshy  bundles,  which  arise  from  the  extremities  of  the  transverse 
processes  of  the  dorsal  vertebra?,  and  passing  obliquely  downwards  and  out- 
wards, are  inserted  into  the  upper  rough  surface  of  the  rib  below  them,  between 
the  tubercle  and  the  angle.  That  for  the  first  rib  arises  from  the  transverse 
process  of  the  last  cervical  vertebra,  and  that  for  the  last  from  the  eleventh 
dorsal.  The  inferior  Levatores  divide  into  two  fasciculi,  one  of  which  is  in- 
serted as  above  described  ;  the  other  fasciculus  passes  down  to  the  second  rib 
below  its  origin  ;  thus,  each  of  the  lower  ribs  receives  fibres  from  the  transverse 
processes  of  two  vertebrge. 

Nerves.  The  muscles  of  this  group  are  supplied  by  the  intercostal  nerves. 

Actions.  The  Intercostals  are  the  chief  agents  in  the  movement  of  the  ribs 
in  ordinary  respiration.  The  External  Intercostals  raise  the  ribs,  especially 
their  fore  part,  and  so  increase  the  capacity  of  the  chest  from  before  backwards; 
at  the  same  time  they  evert  their  lower  borders,  and  so  enlarge  the  thoracic 
cavity  transversely.  The  Internal  Intercostals,  at  the  side  of  the  thorax,  de- 
press the  ribs,  and  invert  their  lower  borders,  and  so  diminish  the  thoracic  cavity ; 
but  at  the  fore  part  of  the  chest  these  muscles  assist  the  External  Intercostals 
in  raising  the  cartilages.     The  Levatores  Costarum  assist  the  External  Inter- 


368 


MUSCLES    AND    FASCIA. 


costals  in  raising  the  ribs.  The  Triangularis  Sterni  draws  down  the  costal  car- 
tilages ;  it  is  therefore  an  expiratory  muscle. 

Muscles  of  inspiration  and  expiration.  The  muscles  which  assist  the  action  of 
the  Diaphragm  in  inspiration  are  the  Intercostals  and  the  Levatores  Costarum 
as  above  stated,  the  Scaleni,  the  Serratus  Posticus  Superior,  and  to  a  slight 
extent  the  Subclavius.  When  the  need  for  more  forcible  action  exists,  the 
shoulders  and  the  base  ot  the  scapula  are  fixed,  and  then  the  powerful  muscles 
of  forced  inspiration  come  into  play ;  the  chief  of  these  are  the  Serratus  Mag- 
nus, Latissimus  Dorsi,  and  the  Pectorales,  particularly  the  Pectoralis  Minor. 

The  ordinary  action  of  expiration  is  merely  passive,  the  resilience  of  the  ribs 
and  the  plasticity  of  the  lungs  producing  a  tendency  to  a  vacuum.  This  causes 
the  ascent  of  the  abdominal  viscera  covered  by  the  Diaphragm.  Forced  expi- 
ratory actions  are  performed  mainly  by  the  flat  muscles  (Obliqui  and  Trans- 
versalis)  of  the  abdomen,  assisted  also  by  the  Rectus.  Other  muscles  of  forced 
expiration  are  the  Internal  Intercostals  and  Triangularis  Sterni  (as  above  men- 
tioned), the  Serratus  Posticus  Inferior,  the  Quadratus  Lumborum  and  the  Sacro- 
lumbalis. 

DlAEHRAGMATIO   EeGION. 

Diaphragm. 

The  Diaphragm  (Atatpoy/to,  a  partition  wall)  (Fig.  234)  is  a  thin  musculo-fibrous 
septum,  placed  obliquely  at  the  junction  of  the  upper  with  the  middle  third  of 


Fig.  234.— The  Diaphragm.    Under  Surface. 


OMni>^ 


t.^^y'"''" 


the  trunk,  and  separating  the  thorax  from  the  abdomen,  forming  the  floor  of  the 
former  cavity  and  the  roof  of  the  latter.     It  is  elliptical,  its  longest  diameter 


DIAPHRAGM.  369 

"being  from  side  to  side,  somewhat  fan-shaped,  the  broad  elliptical  portion  being 
horizontal,  the  narrow  part,  which  represents  the  handle  of  the  fan,  vertical,  and 
joined  at  right  angles  to  the  former.  It  is  from  this  circumstance  that  some  an- 
atomists describe  it  as  consisting  of  two  portions,  the  upper  or  great  muscle  of 
the  Diaphragm,  and  the  lower  or  lesser  muscle.  It  arises  from  the  whole  of  the 
internal  circumference  of  the  thorax,  being  attached,  in  front,  by  fleshy  fibres 
to  the  ensiform  cartilage ;  on  either  side,  to  the  inner  surface  of  the  cartilages 
and  bony  portions  of  the  six  or  seven  inferior  ribs,  interdigitating  with  the 
Transversalis ;  and  behind,  to  two  aponeurotic  arches,  named  the  ligamentum 
arcuatum  externum  and  internum,  and  to  the  lumbar  vertebrae.  The  fibres  from 
these  sources  vary  in  length  ;  those  arising  from  the  ensiform  appendix  are  very 
short  and  occasionally  aponeurotic  ;  those  from  the  ligamenta  arcuata,  and  more 
especially  those  from  the  ribs  at  the  side  of  the  chest,  are  longer,  describe  well- 
marked  curves  as  they  ascend,  and  finally  converge  to  be  inserted  into  the  cir- 
cumference of  the  central  tendon.  Between  the  sides  of  the  muscular  slip  from 
the  ensiform  appendix  and  the  cartilages  of  the  adjoining  ribs,  the  fibres  of  the 
Diaphragm  are  deficient,  the  interval  being  filled  by  areolar  tissue,  covered  on 
the  thoracic  side  by  the  pleurae ;  on  the  abdomini,  by  the  peritoneum.  This  is, 
consequently,  a  weak  point,  and  a  portion  of  the  contents  of  the  abdomen  may 
protude  into  the  chest,  forming  phrenic  or  diaphragmatic  hernia,  or  a  collection 
of  pus  in  the  mediastinum  may  descend  through  it,  so  as  to  point  at  the  epi- 
gastrium. 

The  ligamentum  arcuatum  internum^  is  a  tendinous  arch,  thrown  across  the 
upper  part  of  the  Psoas  Magnus  muscle,  on  each  side  of  the  spine.  It  is  con- 
nected, by  one  end,  to  the  outer  side  of  the  body  of  the  first,  and  occasionally 
the  second  lumbar  vertebra,  being  continuous  with  the  outer  side  of  the  tendon 
of  the  corresponding  crus;  and,  by  the  other  end,  to  the  front  of  the  transverse 
process  of  the  second  lumbar  vertebra. 

The  ligamentum  arcuatum,  externum  is  the  thickened  upper  margin  of  the 
anterior  lamella  of  the  transversalis  fascia ;  it  arches  across  the  upper  part  of 
the  Quadratus  Lumborum,  being  attached,  by  one  extremity,  to  the  front  of  the 
transverse  process  of  the  second  lumbar  vertebra ;  and,  by  the  other,  to  the 
apex  and  lower  margin  of  the  last  rib. 

To  the  spine,  the  Diaphragm  is  connected  by  two  crura,  which  are  situated 
on  the  bodies  of  the  lumbar  vertebrae,  one  on  each  side  of  the  aorta.  The 
crura,  at  their  origin,  are  tendinous  in  structure;  the  right  crus,  larger  and 
longer  than  the  left,  arising  from  the  anterior  surface  of  the  bodies  and  inter- 
vertebral substances  of  the  second,  third,  and  fourth  lumbar  vertebrae ;  the  left, 
from  the  second  and  third ;  both  blending  with  the  anterior  common  ligament 
of  the  spine.  A  tendinous  arch  is  thrown  across  the  front  of  the  vertebral 
column,  from  the  tendon  of  one  crus  to  that  of  the  other,  beneath  which  passes 
the  aorta,  vena  azygos  major,  and  thoracic  duct.  The  tendons  terminate  in  two 
large  fleshy  bellies,  which,  with  the  tendinous  portions  above  alluded  to,  are 
called  the  crura,  or  pillars  of  the  Diaphragm.  The  outer  fasciculi  of  the  two 
crura  are  directed  upwards  and  outwards  to  the  central  tendon ;  but  the  inner 
fasciculi  decussate  in  front  of  the  aorta,  and  then  diverge,  so  as  to  surround 
the  oesophagus  before  ending  in  the  central  tendon.  The  anterior  and  larger 
of  these  fasciculi  is  formed  by  the  right  crus. 

The  Central  or  Gordiform  Tendon  of  the  Diaphragm  is  a  thin  tendinous  apo- 
neurosis, situated  at  the  centre  of  the  vault  formed  by  the  muscle,  immediately 
beneath  the  pericardium,  with  which  its  circumference  is  blended.  It  is  shaped 
somewhat  like  a  trefoil  leaf,  consisting  of  three  divisions,  or  leaflets,  separated 
from  one  another  by  slight  indentations.  The  right  leaflet  is  the  largest ;  the 
middle  one,  directed  towards  the  ensiform  cartilage,  the  next  in  size;  and  the 
left,  the  smallest.  In  structure,  the  tendon  is  composed  of  several  planes  of 
fibres,  which  intersect  one  another  at  various  angles,  and  unite  into  straight  or 
curved  bundles,  an  arrangement  which  affords  it  additional  strength. 
24 


370  MUSCLES    AND    FASCIA. 

The  Openings  connected  with  the  Diaphragm  are  three  large  and  several 
smaller  apertures.  The  former  are  the  aortic,  the  oesophageal,  and  the  opening 
for  the  vena  cava. 

The  aortic  opening  is  the  lowest  and  the  most  posterior  of  the  three  large 
apertures  connected  with  this  muscle.  It  is  situated  in  the  middle  line,  im- 
mediately in  front  of  the  bodies  of  the  vertebrfe ;  and  is,  therefore,  behind  the 
Diaphragm,  not  in  it.  It  is  an  osseo-aponeurotic  aperture,  formed  by  a  ten- 
dinous arch  thrown  across  the  front  of  the  bodies  of  the  vertebrce,  from  the  crus 
on  one  side  to  that  on  the  other,  and  transmits  the  aorta,  vena  azygos  major, 
thoracic  duct,  and  occasionally  the  left  sympathetic  nerve. 

The  oesophageal  opening,  elliptical  in  form,  muscular  in  structure,  and  formed 
by  the  two  crura,  is  placed  above,  and,  at  the  same  time,  anterior,  and  a  little 
to  the  left  of  the  preceding.  It  transmits  the  oesophagus  and  pneumogastric 
nerves.  The  anterior  margin  of  this  aperture  is  occasionally  tendinous,  being 
formed  by  the  margin  of  the  central  tendon. 

The  opening  for  the  vena  cava  is  the  highest;  it  is  quadrilateral  in  form,  ten- 
dinous in  structure,  and  placed  at  the  junction  of  the  right  and  middle  leaflets 
of  the  central  tendon,  its  margins  being  bounded  by  four  bundles  of  tendinous 
fibres,  which  meet  at  right  angles. 

The  right  crus  transmits  the  sympathetic  and  the  greater  and  lesser  splanchnic 
nerves  of  the  right  side ;  the  left  crus,  the  greater  and  lesser  splanchnic  nerves 
of  the  left  side,  and  the  vena  azygos  minor. 

The  Serous  Membranes  in  relation  with  the  Diaphragm  are  four  in  number ; 
three  lining  its  upper  or  thoracic  surface;  one  its  abdominal.  The  three  serous 
membranes  on  its  upper  surface  are  the  pleura  on  either  side,  and  the  serous 
layer  of  the  pericardium,  which  covers  the  middle  portion  of  the  tendinous 
centre.  The  serous  membrane  covering  its  under  surface  is  a  portion  of  the 
general  peritoneal  membrane  of  the  abdominal  cavity. 

The  Diaphragm  is  arched,  being  convex  towards  the  chest,  and  concave  to 
the  abdomen.  The  right  portion  forms  a  complete  arch  from  before  backwards, 
being  accurately  moulded  over  the  convex  surface  of  the  liver,  and  having 
resting  upon  it  the  concave  base  of  the  right  lung.  The  left  portion  is  arched 
from  before  backwards  in  a  similar  manner;  but  the  arch  is  narrower  in  front, 
being  encroached  upon  by  the  pericardium,  and  lower  than  the  right,  at  its 
summit,  by  about  three-quarters  of  an  inch.  It  supports  the  base  of  the  left 
lung,  and  covers  the  great  end  of  the  stomach,  the  spleen,  and  left  kidney. 
The  central  portion,  which  supports  the  heart,  is  higher,  in  front  at  the  sternum, 
and  behind  at  the  vertebrae,  than  the  lateral  portions ;  the  reverse  is  the  case 
in  the  parts  further  removed  from  the  surface  of  the  body. 

The  height  of  the  Diaphragm  is  constantly  varying  during  respiration,  the 
muscle  being  carried  upwards  or  downwards  from  the  average  level ;  its  height 
also  varies  according  to  the  degree  of  distension  of  the  stomach  and  intestines, 
and  the  size  of  the  liver.  After  a  forced  expiration,  the  right  arch  is  on  a 
level,  in  front,  with  the  fourth  costal  cartilage ;  at  the  side,  with  the  fifth,  sixth, 
and  seventh  rib.s ;  and  behind,  with  the  eighth  rib ;  the  left  arch  being  usually 
from  one  to  two  ribs  breadth  below  the  level  of  the  right  one.  In  a  forced 
inspiration,  it  descends  from  one  to  two  inches ;  its  slope  would  then  be  repre- 
sented by  a  line  drawn  from  the  ensiform  cartilage  towards  the  tenth  rib. 

Nerves.     The  Diaphragm  is  supplied  by  the  phrenic  nerves. 

Actions.  The  action  of  the  Diaphragm  modifies  considerably  the  size  of  the 
chest,  and  the  position  of  the  thoracic  and  abdominal  viscera.  During  a  forcnl 
inspiration,  the  cavity  of  the  thorax  is  enlarged  in  the  vertical  direction  from 
two  to  three  inches,  partly  by  the  ascent  of  the  walls  of  the  chest,  partly  by 
the  descent  of  the  Diaphragm.  The  chest,  consequently,  encroaches  upon  the 
abdomen;  the  lungs  are  expanded,  and  lowered,  in  relation  with  the  ribs, 
nearly  two  inches;  the  heart  being  drawn  down  about  an  inch  and  a  half;  the 
descent  of  the  latter  organ  taking  place  indirectly  through  the  medium  of  its 


ANTERIOR    THORACIC    REGION. 


373 


the  anterior  surface  of  the  sternal  half  of  the  clavicle ;  from  half  the  breadth 
of  the  front  of  the  sternum,  as  low  down  as  the  attachment  of  the  cartilage  of 
the  sixth  or  seventh  rib;  its  origin  consisting  of  aponeurotic  fibres,  which 
intersect  with  those  of  the  opposite  muscle ;  it  also  arises  from  the  cartilages 

Fig.  23C.— Muscles  of  the  Chest  and  Front  of  the  Arm.     Superficial  View. 


of  all  the  true  ribs,  with  the  exception,  frequently,  of  the  first,  or  of  the  seventh, 
or  both  ;  and  from  the  aponeurosis  of  the  External  Oblique  muscle  of  the  abdo- 
men. The  fibres  from  this  extensive  origin  converge  towards  its  insertion,  giv- 
ing to  the  muscle  a  radiated  appearance.  Those  fibres  which  arise  from  the 
clavicle,  pass  obliquely  outwards  and  downwards,  and  are  usually  separated 
from  the  rest  by  a  cellular  interval :  those  from  the  lower  part  of  the  sternum 
and  the  cartilages  of  the  lower  true  ribs,  pass  upwards  and  outwards ;  whilst 
the  middle  fibres  pass  horizontally.  As  these  three  sets  of  fibres  converge, 
they  are  so  disposed  that  the  upper  overlap  the  middle,  and  the  middle  the 
lower  portion,  the  fibres  of  the  lower  portion  being  folded  backwards  upon 
themselves ;  so  that  those  fibres  which  are  lowest  in  front,  become  highest  at 


872 


MUSCLES    AND    FASCIA. 


Abductor  Minimi  Digiti. 
Flexor  Brevis  Minimi  Digiti. 
Flexor  Ossis  Metacarpi  Minimi  Digiti 
(Opponens). 


Palmar  Region. 
Lumbricales. 
Interossei  Palmares, 
luterossei  Dorsales. 


Dissection  of  Pectoral  Region  and  Axilla  (Fig.  235).  The  arm  being  drawn  away  from  the 
side  at  nearly  right  angles  with  the  trunk,  and  rotated  outwards,  make  a  vertical  incision  through 
the  integument  in  the  median  line  of  the  chest,  from  the  upper  to  the  lower  part  of  the  sternum  ; 
a  secoad  incision  along  the  lower  border  of  the  Pectoral  muscle,  from  the  ensiform  cartilage  to 

the  other  side  of  the  axilla  ;  a  third,  from 


Fig.  235.— Dissection  of  Upper  Extremity. 


3.Disaeetlo7i  erf" 
SHOULDER  ft  ARM 


/.  Jiiascction  of 

PECTORAL  RECION 
and     AXILLA 


the  sternum  along  the  clavicle,  as  far  as  its 
centre;  and  a  fourth,  from  the  middle  of 
the  clavicle  obliquely  downwards,  along 
the  Interspace  between  the  Pectoral  and 
Deltoid  muscles,  as  low  as  the  fold  of  the 
armpit.  The  flap  of  integument  is  then 
to'be  dissected  off  in  the  direction  indicated 
in  the  figure,  but  not  entirely  removed,  as 
it  should  be  replaced  on  completing  the 
dissection.  If  a  transverse  incision  is  now 
made  from  the  lower  end  of  the  sternum  to 
the  side  of  the  chest,  as  far  as  the  poste- 
rior fold  of  the  armpit,  and  the  integument 
reflected  outwards,  the  axillary  space  will 
be  more  completely  exposed. 

Fascia  of  the  Thorax. 


2.BCN0^EL80M 


U  . FORE-ARM 


PALM  ^HANO 


The  superficial  fascia  of  the  tho- 
racic region  is  a  loose  celiulo-fibrous 
layer,  continuous  with  the  super- 
ficial fascia  of  the  neck  and  upper 
extremity  above,  and  of  the  ab- 
domen below;  opposite  the  mamma, 
it  subdivides  into  two  layers,  one 
of  which  passes  in  front,  the  other 
behind  that  gland ;  and  from  both 
of  these  layers  numerous  septa  pass 
into  its  substance,  supporting  its 
various  lobes.  From  the  anterior 
layer,  fibrous  processes  pass  forward 
to  the  integument  and  nipple,  in- 
closing in  their  areolae  masses  of 
fat.  These  processes  were  called  by  Sir  A.  Cooper  the  ligamenta  siispensoria, 
from  the  support  they  afford  to  the  gland  in  this  situation.  On  removing  the 
superficial  fascia,  the  deep)  fascia  of  the  thoracic  region  is  exposed.  It  is  a  thin 
aponeurotic  lamina,  covering  the  surface  of  the  great  Pectoral  muscle,  and 
sending  numerous  prolongations  between  its  fasciculi.  It  is  attached,  in  the 
middle  line,  to  the  front  of  the  sternum ;  and,  above,  to  the  clavicle.  It  is  very 
thin  over  the  upper  part  of  the  muscle,  somewhat  thicker  in  the  interval  between 
the  Pectoralis  Major  and  Latissimus  Dorsi,  where  it  closes  in  the  axillary  space, 
and  divides  at  the  margin  of  the  latter  muscle  into  two  layers,  one  of  which 
passes  in  front,  and  the  other  behind  it;  these  proceed  as  far  as  the  spinous 
processes  of  the  dorsal  vertebrae,  to  which  they  are  attached.  At  the  lower 
part  of  the  thoracic  region,  this  fascia  is  well  developed,  and  is  continuous  with 
the  fibrous  sheath  of  the  Recti  muscles. 

Anterior  Thoracic  Region. 

Pectoralis  Major.  Pectoralis  Minor. 

Subclavius. 

The  Pectoralis  Major  (Fig.  236)  is  a  broad,  thick,  triangular  muscle,  situated 

at  the  upper  and  fore  part  of  the  chest,  in  front  of  the  axilla.     It  arises  from 


ANTERIOR    THORACIC    REGION. 


373 


the  anterior  surface  of  the  sternal  half  of  the  clavicle ;  from  half  the  breadth 
of  the  front  of  the  sternum,  as  low  down  as  the  attachment  of  the  cartilage  of 
the  sixth  or  seventh  rib;  its  origin  consisting  of  aponeurotic  fibres,  which 
intersect  with  those  of  the  opposite  muscle ;  it  also  arises  from  the  cartilages 

Fig.  236.— Muscles  of  the  Chest  and  Front  of  the  Arm.     Superficial  View. 


of  all  the  true  ribs,  with  the  exception,  frequently,  of  the  first,  or  of  the  seventh, 
or  both  ;  and  from  the  aponeurosis  of  the  External  Oblique  muscle  of  the  abdo- 
men. The  fibres  from  this  extensive  origin  converge  towards  its  insertion,  giv- 
ing to  the  muscle  a  radiated  appearance.  Those  fibres  which  arise  from  the 
clavicle,  pass  obliquely  outwards  and  downwards,  and  are  usually  separated 
from  the  rest  by  a  cellular  interval :  those  from  the  lower  part  of  the  sternum 
and  the  cartilages  of  the  lower  true  ribs,  pass  upwards  and  outwards ;  whilst 
the  middle  fibres  pass  horizontally.  As  these  three  sets  of  fibres  converge, 
they  are  so  disposed  that  the  upper  overlap  the  middle,  and  the  middle  the 
lower  portion,  the  fibres  of  the  lower  portion  being  folded  backAvards  upon 
themselves ;  so  that  those  fibres  which  are  lowest  in  front,  become  highest  at 


374  MUSCLES    AND    FASCIA. 

their  point  of  insertion.  They  all  terminate  in  a  flat  tendon,  about  two  inches 
broad,  which  is  inserted  into  the  anterior  bicipital  ridge  of  the  humerus.  This 
tendon  consists  of  two  laminae,  placed  one  in  front  of  the  other,  and  usually- 
blended  together  below.  The  anterior,  the  thicker,  receives  the  clavicular 
and  upper  half  of  the  sternal  portion  of  the  muscle ;  the  posterior  lamina  re- 
ceiving the  attachment  of  the  lower  half  of  the  sternal  portion.  From  this 
arrangement  it  results,  that  the  fibres  of  the  upper  and  middle  portions  of  the 
muscle  are  inserted  into  the  lower  part  of  the  bicipital  ridge ;  those  of  the  lower 
portion,  into  the  upper  part.  The  tendon,  at  its  insertion,  is  connected  with 
that  of  the  Deltoid ;  it  sends  up  an  expansion  over  the  bicipital  groove  to  the 
head  of  the  humerus ;  another  backwards,  which  lines  the  groove ;  and  a  third 
to  the  fascia  of  the  arm. 

Relations.  By  its  anterior  surface^  ^ith  the  Platysma,  the  mammary  gland, 
the  superficial  fascia,  and  integument.  By  its  posterior  surface — its  thoracic  por- 
tion, with  the  sternum,  the  ribs  and  costal  cartilages,  the  Subclavius,  Pectoralis 
Minor,  Serratus  Magnus,  and  the  Intercostals ;  its  axillary  portion  forms  the 
anterior  wall  of  the  .axillary  space,  .and  covers  the  axillary  vessels  and  nerves. 
Its  upper  border  lies  parallel  with  the  Deltoid,  from  which  it  is  separated  by  the 
cephalic  vein  and  descending  branch  of  the  thoracico-acromialis  artery.  Its 
lower  border  forms  the  anterior  margin  of  the  axilla,  being  at  first  separated  from 
the  Latissimus  Dorsi  by  a  considerable  interval ;  but  both  muscles  gradually 
converge  towards  the  outer  part  of  the  space. 

Peculiarities.  In  muscular  subjects,  the  sternal  origins  of  the  two  Pectoral  muscles  are 
separated  only  by  a  narrow  interval ;  but  this  interval  is  enlarged  where  these  muscles  are  ill 
developed.  Yery  rarely,  the  whole  of  the  sternal  portion  is  deficient.  Occasionally,  one  or  two 
additional  muscular  slips  arise  from  the  aponeurosis  of  the  Extenial  Oblique,  and  become  united 
to  the  lower  margin  oi  the  Pectoralis  Major.  A  slender  muscular  slip  is  occasionally  found 
lying  parallel  with  the  outer  margin  of  the  sternum,  overlapping  the  origin  of  the  Pectoral 
muscle.  It  is  attached,  by  one  end,  to  the  upper  part  of  the  sternum,  near  the  origin  of  the 
Sterno-mastoid ;  and,  by  the  other,  to  the  anterior  wall  of  the  sheath  of  the  Rectus  Abdominis. 
It  has  received  the  name  "  Rectus  Sternalis." 

DisRedion.  Detach  the  Pectoralis  Major  by  dividing  the  muscle  along  its  attachment  to  the 
clavicle,  and  by  making  a  vertical  incision  through  its  substance  a  little  external  to  its  line  of 
attachment  to  the  sternum  and  costal  cartilages.  The  muscle  should  then  be  reflected  out- 
wards, and  its  tendon  carefully  examined.  The  Pectoralis  Minor  is  now  exposed,  and  imme- 
diately above  it,  in  the  interval  between  its  upper  border  and  the  clavicle,  a  strong  fascia,  the 
costo-coracoid  membrane. 

The  costo-coracoid  membrane  protects  the  axillary  vessels  and  nerves ;  it  is 
very  thick  and  dense  externally,  where  it  is  attached  to  the  coracoid  process, 
and  is  continuous  with  the  fascia  of  the  arm ;  more  internally,  it  is  connected 
with  the  lower  border  of  the  clavicle,  as  far  as  the  sternal  extremity  of  the  first 
rib:  traced  downwards,  it  passes  behind  the  Pectoralis  Minor,  surrounding,  in 
a  more  or  less  complete  sheath,  the  axillary  vessels  and  nerves ;  and  above,  it 
sends  a  prolongation  behind  the  Subclavius,  which  is  attached  to  the  lower 
border  of  the  clavicle,  and  so  incloses  the  muscle  in  a  kind  of  sheath.  The 
costo-coracoid  membrane  is  pierced  by  the  cephalic  vein,  the  thoracico-acro- 
mialis artery  and  vein,  superior  thoracic  artery,  and  anterior  thoracic  nerve. 

The  Pectoralis  Minor  (Fig.  237)  is  a  thin,  flat,  triangular  muscle,  situated  at 
the  upper  part  of  the  thorax,  beneath  the  Pectoralis  Major.  It  arises,  by  three 
tendinous  digitations,  from  the  upper  margin  and  outer  surface  of  the  third, 
fourth,  and  fifth  ribs,  near  their  cartilages,  and  from  the  aponeurosis  covering 
the  Intercostal  muscles;  the  fibres  pass  upwards  and  outwards,  and  converge 
to  form  a  flat  tendon,  which  is  inserted  into  the  anterior  border  of  the  coracoid 
process  of  the  scapula. 

Belations.  By  its  anterior  surface^  with  the  Pectoralis  Major,  and  the  superior 
thoracic  vessels  and  nerves.  By  its  posterior  surface,  with  the  ribs.  Intercostal 
muscles,  Serratus  Magnus,  the  axillary  space,  and  the  axillary  vessels  and 
nerves.  Its  upper  border  is  separated  from  the  clavicle  by  a  triangular  inter- 
val, broad  internally,  narrow  externally,  bounded  in  front  by  the  costo-coracoid 


ANTERIOR    THORACIC    REGION. 


375 


merabrane,  and  internally  by  the  ribs. 
vessels  and  nerves. 


In  this  space  are  seen  the  axillary 


The  costo-coracoid  membrane  should  now  be  removed,  when  the  Subclavius  muscle  will  be 
seen. 

The  Subclavius  is  a  long,  thin,  spindle-shaped  muscle,  placed  in  the  interval 
between  the  clavicle  and  the  first  rib.  It  arises  by  a  short,  thick  tendon  from 
the  cartilage  of  the  first  rib,  in  front  of  the  rhomboid  ligament;  the  fleshy 
fibres  proceed  obliquely  outwards,  to  be  inserted  into  a  deep  groove  on  the 
under  surface  of  the  middle  third  of  the  clavicle. 

Fi;?.  237.— Muscles  of  the  Chest  and  Front  of  the  Arm,  with  the  Boundaries  of  the  Axilla. 


Relations.  By  its  upper  surface^  with  the  clavicle.  By  its  under  aurface^  it  is 
separated  from  the  first  rib  by  the  axillary  vessels  and  nerves.  Its  anterior 
surface  is  separated  from  the  Pectoralis  Major  by  a  strong  aponeurosis,  which, 
with  the  clavicle,  forms  an  osteo-fibrous  sheath  in  which  the  muscle  is  inclosed. 

If  the  costal  attachment  of  the  Pectoralis  Minor  is  divided  across,  and  the  muscle  reflected 
outwards,  the  axillary  vessels  and  nerves  are  brought  fully  into  view,  and  should  be  examined. 

Nerves.  The  Pectoral  muscles  are  supplied  by  the  anterior  thoracic  nerves; 
the  Subclavius,  by  a  filament  from  the  cord  formed  by  the  union  of  the  fifth 
and  sixth  cervical  nerves. 

Actions.  ^  If  the  arm  has  been  raised  by  the  Deltoid,  the  Pectoralis  Major 
will,  conjointly  with  the  Latissimus  Dorsi  and  Teres  Major,  depress  it  to  the 
side  of  the  chest;  and,  if  acting  singly,  it  will  draw  the  arm  across  the  front 
of  the  chest.     The  Pectoralis  Minor  depresses  the  point  of  the  shoulder,  draw- 


376  MUSCLES    AND    FASCIA. 

ing  the  scapula  downwards  and  inwards  to  the  thorax.  The  Subclavius  de- 
presses the  shoulder,  drawing  the  clavicle  downwards  and  forwards.  When 
the  arms  are  fixed,  all  three  muscles  act  upon  the  ribs,  drawing  them  upwards 
and  expanding  the  chest,  and  thus  becoming  very  important  agents  in  forced 
inspiration.  Asthmatic  patients  always  assume  this  attitude,  fixing  the  shoul- 
ders, so  that  all  these  muscles  may  be  brought  into  action  to  assist  in  dilating 
the  cavity  of  the  chest. 

Lateral  Thoracic  Eegion. 
Serratus  Magnus. 

The  Serratus  Magnus  (Fig.  237)  is  a  broad,  thin,  and  irregularly  quadrilateral 
muscle,  situated  at  the  upper  part  and  side  of  the  chest.  It  arises  by  nine 
fleshy  digitations  from  the  outer  surface  and  upper  border  of  the  eight  upper 
ribs  (the  second  rib  having  two),  and  from  the  aponeurosis  covering  the  upper 
intercostal  spaces,  and  is  inserted  into  the  whole  length  of  the  inner  margin  of 
the  posterior  border  of  the  scapula.  This  muscle  has  been  divided  into  three 
portions,  a  superior,  middle,  and  inferior,  on  account  of  the  difterence  in  the 
direction,  and  in  the  extent  of  attachment  of  each  part.  The  upper  portion, 
separated  from  the  rest  by  a  cellular  interval,  is  a  narrow,  but  thick  fasciculus, 
which  arises  by  two  digitations  from  the  first  and  second  ribs,  and  from  the 
aponeurotic  arch  between  them;  its  fibres  proceed  upwards,  outwards,  and 
backwards,  to  be  inserted  into  the  triangular  smooth  surface  on  the  inner  side 
of  the  superior  angle  of  the  scapula.  The  middle  portion  of  the  muscle  arises 
by  three  digitations  from  the  second,  third,  and  fourth  ribs;  it  forms  a  thin  and 
broad  muscular  layer,  which  proceeds  horizontally  backwards  to  be  inserted 
into  the  posterior 'border  of  the  scapula,  between  the  superior  and  inferior 
angles.  The  lower  portion  arises  from  the  fifth,  sixth,  seventh,  and  eighth  ribs, 
by  four  digitations,  in  the  intervals  between  which  are  received  corresponding 
processes  of  the  External  Oblique;  the  fibres  pass  upwards,  outwards,  and 
backwards,  to  be  inserted  into  the  inner  surface  of  the  inferior  angle  of  the 
scapula,  by  an  attachment  partly  muscular,  partly  tendinous. 

Relations.  This  muscle  is  covered,  in  front,  by  the  Pectoral  muscles;  behind, 
by  the  Subscapularis ;  above,  by  the  axillary  vessels  and  nerves.  Its  deep 
surface  rests  upon  the  ribs  and  Intercostal  muscles. 

Nerves.     The  Serratus  Magnus  is  supplied  by  the  posterior  thoracic  nerve. 

Actions.  The  Serratus  Magnus  is  the  most  important  external  inspiratory 
muscle.  When  the  shoulders  are  fixed,  it  elevates  the  ribs,  and  so  dilates  the 
cavity  of  the  chest,  assisting  the  Pectoral  and  Subclavius  muscles.  This  mus- 
cle, especially  its  middle  and  lower  segments,  draws  the  base  and  inferior  angle 
of  the  scapula  forwards,  and  so  raises  the  point  of  the  shoulder  by  causing  a 
rotation  of  the  bone  on  the  side  of  the  chest;  assisting  the  Trapezius  muscle  in 
supporting  weights  upon  the  shoulder,  the  thorax  being  at  the  same  time  fixed 
by  preventing  the  escape  of  the  included  air. 

Dissection.  After  completing  the  dissection  of  the  axilla,  if  the  muscles  of  the  back  have 
been  dissected,  the  upper  extremity  should  be  separated  from  the  trunk.  Saw  through  the 
clavicle  at  its  centre,  and  then  cut  through  the  muscles  which  connect  the  scapula  and  arm  with 
the  trunk,  viz.,  the  Pectoralis  Minor  in  front,  Serratus  Magnus  at  the  side,  and  the  Levator 
Anguli  Scapulae,  the  Rhomboids,  Trapezius,  and  Latissimus  Dorsi  behind.  These  muscles 
should  be  cleaned  and  traced  to  their  respective  insertions.  Then  make  an  incision  through  the 
integument,  commencing  at  the  outer  third  of  the  clavicle,  and  extending  along  the  margin  of 
that  bone,  the  acromion  process,  and  spine  of  the  scapula;  the  integument  should  be  dissected 
from  above  downwards  and  outwards,  when  the  fascia  covering  the  Deltoid  is  exposed  (Fig.  235, 
No.  3). 

The  superficial  fascia  of  the  upper  extremity  is  a  thin  cellulo-fibrous  lamina, 
containing  between  its  layers  the  superficial  veins  and  lymphatics,  and  the 
cutaneous  nerves.  It  is  most  distinct  in  front  of  the  elbow,  and  contains  very 
large  superficial  veins  and  nerves;  in  the  hand  it  is  hardly  demonstrable,  the 


ACROMIAL    AND    SCAPULAR    REGIONS.  377 

integument  being  closely  adherent  to  the  deep  fascia  by  dense  fibrous  bands. 
Small  subcutaneoas  bursae  are  found  in  this  fascia,  over  the  acromion,  the  ole- 
cranon, and  the  knuckles.  The  deep  fascia  of  the  upper  extremity  comprises 
the  aponeurosis  of  the  shoulder,  arm,  and  forearm,  the  anterior  and  posterioi 
annular  ligaments  of  the  carpus,  and  the  palmar  fascia.  These  will  be  con- 
sidered in  the  description  of  the  muscles  of  the  several  regions. 

Acromial  Region. 
Deltoid. 

The  deep  fascia  covering  the  Deltoid  (deltoid  aponeurosis),  is  a  thick  and 
strong  fibrous  layer,  which  incloses  the  outer  surface  of  the  muscle,  and  sends 
down  numerous  prolongations  between  its  fasciculi ;  it  is  continuous,  internally, 
with  the  fascia  covering  the  great  Pectoral  muscle ;  behind,  with  that  covering 
the  Infraspinatus  and  back  of  the  arm;  above  it  is  attached  to  the  clavicle, 
the  acromion,  and  spine  of  the  scapula. 

The  Deltoid  (Fig.  236)  is  a  large,  thick,  triangular  muscle,  which  forms  the 
.convexity  of  the  shoulder,  and  has  received  its  name  from  its  resemblance  to 
the  Greek  letter  a  reversed.  It  surrounds  the  shoulder  joint  in  the  greater 
part  of  its  extent,  covering  it  on  its  outer  side,  and  in  front  and  behind.  It 
arises  from  the  outer  third  of  the  anterior  border  and  upper  surface  of  the 
clavicle ;  from  the  outer  margin  and  upper  surface  of  the  acromion  process ; 
and  from  the  whole  length  of  the  lower  border  of  the  spine  of  the  scapula. 
From  this  extensive  origin,  the  fibres  converge  towards  their  insertion,  the 
middle  passing  vertically,  the  anterior  obliquely  backwards,  the  posterior 
obliquely  forwards ;  they  unite  to  form  a  thick  tendon,  which  is  inserted  into 
a  rough  prominence  on  the  middle  of  the  outer  side  of  the  shaft  of  the  humerus. 
This  muscle  is  remarkably  coarse  in  texture,  and  intersected  by  three  or  four 
tendinous  laminae;  these  are  attached,  at  intervals,  to  the  clavicle  and  acromion, 
extend  into  the  substance  of  the  muscle,  and  give  origin  to  a  number  of  fleshy 
fibres.     The  largest  of  these  laminae  extends  from  the  summit  of  the  acromion. 

Relations.  By  its  superficial  surface,  with  the  Platysma,  supra-acromial 
nerves,  the  superficial  fascia,  and  integument.  Its  deep  surface  is  separated  from 
the  head  of  the  humerus  by  a  large  sacculated  synovial  bursa,  and  covers  the 
coracoid  process,  coraco-acromial  ligament,  Pectoralis  Minor,  Coraco-brachialis, 
both  heads  of  the  Biceps,  tendon  of  the  Pectoralis  Major,  Teres  Minor,  Triceps 
(its  scapular  and  external  heads),  the  circumflex  vessels  and  nerve,  and  the 
humerus.  Its  anterior  border  is  separated  from  the  Pectoralis  Major  by  a  cellu- 
lar interspace,  which  lodges  the  cephalic  vein  and  descending  branch  of  the 
thoracico-acroraialis  artery.  Its  posterior  horder  rests  on  the  Infraspinatus  and 
Triceps  muscles. 

Nerves.     The  Deltoid  is  supplied  by  the  circumflex  nerve. 

Actions.  The  Deltoid  raises  the  arm  directly  from  the  side,  so  as  to  bring  it 
at  right  angles  with  the  trunk.  Its  anterior  fibres,  assisted  by  the  Pectoralis 
Major,  draw  the  arm  forwards ;  and  its  posterior  fibres,  aided  by  the  Teres  Major 
and  Latissimus  Dorsi,  draw  it  backwards. 

Dissection.  Divide  the  Deltoid  across,  near  its  upper  part,  by  an  incision  carried  along  the 
margin  of  the  clavicle,  the  acromion  process,  and  spine  of  the  scapula,  and  reflect  it  downwards  ; 
the  bursa  will  be  seen  on  its  under  surface,  as  well  as  the  circumflex  vessels  and  nerve.  The 
insertion  of  the  muscle  should  be  carefully  examined. 

Anterior  Scapular  Region. 

Subscapularis. 

The  suhscapular  aponeurosis  is  a  thin  membrane,  attached  to  the  entire  cir- 
cumference of  the  subscapular  fossa,  and  affording  attachment  by  its  inner 
surface  to  some  of  the  fibres  of  the  Subscapularis  muscle.  "When  this  is 
removed,  the  Subscapularis  muscle  is  exposed. 


S7S  MUSCLES    AND    FASCIA. 

The  Subscapularis  (Fig,  237)  is  a  large  triangular  muscle,  which  fills  up  the 
subscapular  fossa,  arising  from  its  internal  two-thirds,  with  the  exception  of  a 
narrow  margin  along  the  posterior  border,  and  the  inner  side  of  the  superior 
and  inferior  angles,  which  afford  attachment  to  the  Serratus  Magnus.  Some 
fibres  arise  from  tendinous  laminae,  which  intersect  the  muscle,  and  are  attached 
to  ridges  on  the  bone ;  and  others  from  an  aponeurosis,  which  separates  the 
muscle  from  the  Teres  Major  and  the  long  head  of  the  Triceps.  The  fibres 
pass  outwards,  and,  gradually  converging,  terminate  in  a  tendon,  which  is  in- 
serted into  the  lesser  tuberosity  of  the  humerus.  Those  fibres  which  arise  from 
the  axillary  border  of  the  scapula,  are  inserted  into  the  neck  of  the  humerus 
to  the  extent  of  an  inch  below  the  tuberosity.  The  tendon  of  the  muscle  is  in 
close  contact  with  the  capsular  ligament  of  the  shoulder-joint,  and  glides  over 
a  large  bursa,  which  separates  it  from  the  base  of  the  coracoid  process.  This 
bursa  communicates  with  the  cavity  of  the  joint  by  an  aperture  in  the  capsular 
ligament. 

Relations.  By  its  anterior  surface^  with  the  Serratus  Magnus,  Coraco-brachialis, 
and  Biceps,  and  the  axillary  vessels  and  nerves.  By  its  posterior  surface,  with 
the  scapula,  the  subscapular  vessels  and  nerves,  and  the  capsular  ligament  of 
the  shoulder-joint.  Its  lower  border  is  contiguous  with  the  Teres  Major  and 
Latissimus  Dorsi. 

Nerves.     It  is  supplied  by  the  subscapular  nerves. 

Actions.  The  Subscapularis  rotates  the  head  of  the  humerus  inwards;  when 
the  arm  is  raised,  it  draws  the  humerus  downwards.  It  is  a  powerful  defence 
to  the  front  of  the  shoulder-joint,  preventing  displacement  of  the  head  of  the 
bone  forwards. 

Posterior  Scapular  Eegion.    (Fig.  238.) 

Supraspinatus.  Teres  Minor. 

Infraspinatus.  Teres  Major. 

Dissection.  To  expose  these  muscles,  and  to  examine  their  mode  of  insertion  into  the 
humerus,  detach  the  Deltoid  and  Trapezius  from  their  attachment  to  the  spine  of  the  scapula 
and  acromion  process.  Remove  the  clavicle  by  dividing?  the  ligaments  connecting  it  with  the 
coracoid  process,  and  separate  it  at  its  articulation  with  its  scapula ;  divide  the  acromion  pro- 
cess near  its  root  with  a  saw.  The  fragments  being  removed,  the  tendons  of  the  posterior 
Scapular  muscles  will  be  fully  exposed,  and  can  be  examined.  A  block  should  be  placed  beneath 
the  shoulder-joint,  so  as  to  make  the  muscles  tense. 

The  supraspinous  aponeurosis  is  a  thick  and  dense  membranous  layer,  which 
completes  the  osseo-fibrous  case  in  which  the  Supraspinatus  muscle  is  con- 
tained; affording  attachment,  by  its  inner  surface,  to  some  of  the  fibres  of 
the  muscle.  It  is  thick  internally,  but  thinner  externally  under  the  coraco- 
acromial  ligament.  When  this  fascia  is  removed,  the  Supraspinatus  muscle  is 
exposed. 

The  Supraspinatus  muscle  occupies  the  whole  of  the  supraspinous  fossa, 
arising  from  its  internal  two-thirds,  and  from  the  strong  fascia  which  covers 
its  surface.  The  muscular  fibres  converge  to  a  tendon,  which  passes  across  the 
capsular  ligament  of  the  shoulder-joint,  to  which  it  is  intimately  adherent, 
and  is  inserted  into  the  highest  of  the  three  facets  on  the  great  tuberosity  of 
the  humerus. 

Relations.  By  its  upper  surface,  with  the  Trapezius,  the  clavicle,  the  acro- 
mion, the  coraco-acromial  ligament,  and  the  Deltoid.  By  its  und^^r  surface,  with 
the  scapula,  the  suprascapular  vessels  and  nerve,  and  upper  part  of  the  shoulder- 
joint. 

The  infraspinous  aponeurosis  is  a  dense  fibrous  membrane,  covering  in  the 
Infraspinatus  muscle,  and  attached  to  the  circumference  of  the  infraspinous 
fossa.  It  affords  attachment,  by  its  inner  surface,  to  some  fibres  of  that  muscle, 
is  continuous  externally  with  the  fascia  of  the  arm,  and  gives  off  from  its  under 
surface  intermuscular  septa,  which  separate  the  Infraspinatus  from  the  Teres 
Minor,  and  the  latter  from  the  Teres  Major. 


SCAPULAR    REGION. 


379 


The  Infraspinatus  is  a  thick  triangular  muscle,  which  occupies  the  chief  part 
of  the  infraspinous  fossa,  arising  by  flesy  fibres,  from  its  internal  two-thirds; 
and  by  tendinous  fibres,  from  the  ridges  on  its  surface.  It  also  arises  from  a 
strong  fascia  which  covers  it  externally,  and  separates  it  from  the  Teres  Major 
and  Teres  Minor.  The  fibres  converge  to  a  tendon,  which  glides  over  the  con- 
cave border  of  the  spine  of  the  scapula,  and,  passing  across  the  capsular  liga- 
ment of  the  shoulder -joint,  is  inserted  into  the  middle  facet  on  the  great  tube- 
rosity of  the  humerus.  The  tendon  of  this  muscle  is  occasionally  separated 
from  the  spine  of  the  scapula  by  a  synovial  bursa,  which  communicates  with 
the  synovial  membrane  of  the  shoulder -joint. 

Fig.  238. — Muscles  on  the  Dorsum  of  the  Scapula  and  the  Triceps. 


Relations.  By  its  posterior  surface^  with  the  Deltoid,  the  Trapezius,  Latissimus 
Dorsi,  and  the  integument.  By  its  anterior  surface^  with  the  scapula,  from  which 
it  is  separated  by  the  suprascapular  and  dorsalis  scapulae  vessels,  and  with  the 
capsular  ligament  of  the  shoulder-joint.  Its  lower  border  is  in  contact  with  the 
Teres  Minor,  and  occasionally  united  with  it,  and  with  the  Teres  Major. 

The  Teres  Minor  is  a  narrow,  elongated  muscle,  which  lies  along  the  inferior 
border  of  the  scapula.  It  arises  from  the  dorsal  surface  of  the  axillary  border 
of  the  scapula  for  the  upper  two-thirds  of  its  extent,  and  from  two  aponeurotic 
laminae,  one  of  which  separates  this  muscle  from  the  Infraspinatus,  the  other 
from  the  Teres  Major;  its  fibres  pass  obliquely  upwards  and  outwards,  and  ter- 
minate in  a  tendon,  which  is  inserted  into  the  lowest  of  the  three  facets  on  the 
great  tuberosity  of  the  humerus,  and,  by  fleshy  fibres,  into  the  humerus  imme- 
diately below  it.  The  tendon  of  this  muscle  passes  across  the  capsular  ligament 
of  the  shoulder-joint. 

Relations.  By  its  posterior  surface,  with  the  Deltoid,  Latissimus  Dorsi,  and 
integument.  By  its  anterior  surface,  with  the  scapula,  the  dorsal  branch  of  the 
subscapular  artery,  the  long  head  of  the  Triceps,  and  the  shoulder-joint.     By 


880  MUSCLES    AND    FASCIA. 

its  upper  border^  with  the  Infraspinatus.  By  its  lower  border^  with  the  Teres 
Major,  from  which  it  is  separated  anteriorly  by  the  long  head  of  the  Triceps. 

The  Teres  Major  is  a  broad  and  somewhat  flattened  muscle,  which  arises  from 
the  dorsal  aspect  of  the  inferior  angle  of  the  scapula,  and  from  the  fibrous  septa 
interposed  between  it  and  the  Teres  Minor  and  Infraspinatus ;  the  fibres  are 
directed  upwards  and  outwards,  and  terminate  in  a  flat  tendon  about  two  inches 
in  length,  which  is  inserted  into  the  posterior  bicipital  ridge  of  the  humerus. 
The  tendon  of  this  muscle,  at  its  insertion  into  the  humerus,  lies  behind  that 
of  the  Latissimus  Dorsi,  from  which  it  is  separated  by  a  synovial  bursa. 

Relations.  By  its  posterior  surface,  with  the  integument,  from  which  it  is 
separated,  internally,  by  the  Latissimus  Dorsi ;  and  externally,  by  the  long  head 
of  the  Triceps.  By  its  anterior  surface,  with  the  Subscapularis,  Latissimus  Dorsi, 
Coraco-brachialis,  short  head  of  the  Biceps,  the  axillary  vessels,  and  brachial 
plexus  of  nerves.  Its  upper  border  is  at  first  in  relation  with  the  Teres  Minor, 
from  which  it  is  afterwards  separated  by  the  long  head  of  the  Triceps.  Its 
lower  border  forms,  in  conjunction  with  the  Latissimus  Dorsi,  part  of  the  pos- 
terior boundary  of  the  axilla. 

Nerves.  The  Supraspinatus  and  Infraspinatus  muscles  are  supplied  by  the 
suprascapular  nerve;  the  Teres  Minor  by  the  circumflex,  and  the  Teres  Major 
by  the  subscapular. 

Actions,  The  Supraspinatus  assists  the  Deltoid  in  raising  the  arm  from  the 
side;  its  action  must,  therefore,  be  very  feeble,  from  the  very  disadvantageous 
manner  in  which  the  force  is  applied.  The  Infraspinatus  and  Teres  Minor 
rotate  the  head  of  the  humerus  outwards;  when  the  arm  is  raised,  they  assist 
in  retaining  it  in  that  position,  and  carrying  it  backwards.  One  of  the  most 
important  uses  of  these  three  muscles  is  the  great  protection  they  afford  to  the 
shoulder-joint,  the  Supraspinatus  supporting  it  above,  and  preventing  displace- 
ment of  the  head  of  the  humerus  upwards,  whilst  the  Infraspinatus  and  Teres 
Minor  protect  it  behind,  and  prevent  dislocation  backwards.  The  Teres  Major 
assists  the  Latissimus  Dorsi  in  drawing  the  humerus  downwards  and  backwards 
when  previously  raised,  and  rotating  it  inwards;  when  the  arm  is  fixed,  it  may 
assist  the  Pectoral  and  Latissimus  Dorsi  muscles  in  drawing  the  trunk  forwards. 

Anterior  Humeral  Eegion.    (Fig.  237.) 
Coraco-brachialis.  Biceps.  Brachialis  Anticus. 

Disttedion.  The  arm  being  placed  on  the  table,  with  the  front  surface  uppermost,  make  a 
vertical  incision  through  the  integument  along  the  middle  line,  from  the  middle  of  the  interval 
between  the  folds  of  the  axilla,  to  about  two  inches  below  the  elbow-joint,  where  it  should  be 
joined  by  a  transverse  incision,  extending  from  the  inner  to  the  outer  side  of  the  forearm  ;  the 
two  flaps  being  reflected  on  either  side,  the  fascia  should  be  examined. 

The  deej)  fascia  of  the  arm,  continuous  with  that  covering  the  shoulder  and 
front  of  the  great  Pectoral  muscle,  is  attached,  above,  to  the  clavicle,  acromion, 
and  spine  of  the  scapula;  it  forms  a  thin,  loose,  membranous  sheath  investing 
the  muscles  of  the  arm,  sending  down  septa  between  them,  and  composed  of 
fibres  disposed  in  a  circular  or  spiral  direction,  and  connected  together  by  ver- 
tical fibres.  It  differs  in  thickness  at  different  parts,  being  thin  over  the  Biceps, 
but  thicker  where  it  covers  the  Triceps,  and  over  the  condyles  of  the  humerus; 
it  is  strengthened  by  fibrous  aponeuroses,  derived  from  the  Pectoralis  Major 
»  and  Latissimus  Dorsi,  on  the  inner  side,  and  from  the  Deltoid  externally.  On 
either  side  it  gives  off  a  strong  intermuscular  septum,  which  is  attached  to  the 
condyloid  ridge  and  condyle  of  the  humerus.  These  septa  serve  to  separate 
the  muscles  of  the  anterior  from  those  of  the  posterior  brachial  region.  The 
external  intermuscular  septum  extends  from  the  lower  part  of  the  anterior 
bicipital  ridge,  along  the  external  condyloid  ridge,  to  the  outer  condyle;  it  is 
blended  with  the  tendon  of  the  Deltoid;  gives  attachment  to  the  Triceps  behind, 
to  the  Brachialis  Anticus,  Supinator  Longus,  and  Extensor  Carpi  Radialis  Lon- 
gior  in  front;  and  is  perforated  by  the  musculo-spiral  nerve,  and  superior  pro« 


ANTERIOR    HUMERAL    REGION.  381 

funda  artery.  The  internal  intermuscular  septum,  thicker  than  the  preceding, 
extends  from  the  lower  part  of  the  posterior  lip  of  the  bicipital  groove  below 
the  Teres  Major,  along  the  internal  condyloid  ridge,  to  the  inner  condyle ;  it  is 
blended  with  the  tendon  of  the  Coraco-brachialis,  and  affords  attachment  to  the 
Triceps  behind,  and  the  Brachialis  Anticus  in  front.  It  is  perforated  by  the 
ulnar  nerve,  and  the  inferior  profunda  and  anastomotic  arteries.  At  the  elbow, 
the  deep  fascia  is  attached  to  all  the  prominent  points  round  the  joint,  and  is 
continuous  with  the  fascia  of  the  forearm.  On  the  removal  of  this  fascia,  the 
muscles  of  the  anterior  humeral  region  are  exposed. 

The  Goraco-bmchialis,  the  smallest  of  the  three  muscles  in  this  region,  is  situ- 
ated at  the  upper  and  inner  part  of  the  arm.  It  arises  by  fleshy  fibres  from  the 
apex  of  the  coracoid  process,  in  common  with  the  short  head  of  the  Biceps,  and 
from  the  intermuscular  septum  between  the  two  muscles ;  the  fibres  pass  down- 
wards, backwards,  and  a  little  outwards,  to  be  inserted  by  means  of  a  flat  tendon 
into  a  rough  ridge  at  the  middle  of  the  inner  side  of  the  shaft  of  the  humerus. 
It  is  perforated  by  the  musculo-cutaneous  nerve.  The  inner  border  of  the 
muscle  forms  a  guide  to  the  position  of  the  vessel,  in  tying  the  brachial  artery 
in  the  upper  part  of  its  course. 

Relations.  By  its  anterior  surface,  with  the  Deltoid  and  Pectoralis  Major 
above,  and  at  its  insertion  with  the  brachial  vessels  and  median  nerve  which 
cross  it.  By  its  posterior  surface,  with  the  tendons  of  the  Subscapularis,  Latis- 
simus  Dorsi,  and  Teres  Major,  the  short  head  of  the  Triceps,  the  humerus,  and 
the  anterior  circumflex  vessels.  By  its  inner  border,  with  the  brachial  artery, 
and  the  median  and  musculo-cutaneous  nerves.  By  its  outer  border,  with  the 
short  head  of  the  Biceps  and  Brachialis  Anticus. 

The  Biceps  is  a  long  fusiform  muscle,  occupying  the  whole  of  the  anterior 
surface  of  the  arm,  and  divided  above  into  two  portions  or  heads,  from  which 
circumstance  it  has  received  its  name.  The  short  head  arises  by  a  thick  flat 
tened  tendon  from  the  apex  of  the  coracoid  process,  in  common  with  the  Coraco- 
brachialis.  The  long  head  arises  from  the  upper  margin  of  the  glenoid  cavity, 
by  a  long  rounded  tendon,  which  is  continuous  with  the  glenoid  ligament. 
This  tendon  arches  over  the  head  of  the  humerus,  being  inclosed  in  a  special 
sheath  of  the  synovial  membrane  of  the  shoulder-joint ;  it  then  pierces  the  cap- 
sular ligament  at  its  attachment  to  the  humerus,  and  descends  in  the  bicipital 
groove,  in  which  it  is  retained  by  a  fibrous  prolongation  from  the  tendon  of 
the  Pectoralis  Major.  The  fibres  from  this  tendon  form  a  rounded  belly,  and, 
about  the  middle  of  the  arm,  join  with  the  portion  of  the  muscle  derived  from 
the  short  head.  The  belly  of  the  muscle,  narrow  and  somewhat  flattened,  ter- 
minates above  the  elbow  in  a  flattened  tendon,  which  is  inserted  into  the  back 
part  of  the  tuberosity  of  the  radius,  a  synovial  bursa  being  interposed  between 
the  tendon  and  the  front  of  the  tuberosity.  The  tendon  of  the  muscle  is  thin 
and  broad ;  as  it  approaches  the  radius  it  becomes  narrow  and  twisted  upon 
itself,  being  applied  by  a  flat  surface  to  the  back  part  of  the  tuberosity ;  oppo- 
site the  bend  of  the  elbow  the  tendon  gives  off,  from  its  inner  side,  a  broad 
aponeurosis,  which  passes  obliquely  downwards  and  inwards  across  the  brachial 
artery,  and  is  continuous  with  the  fascia  of  the  forearm  (Fig.  236).  The  inner 
border  of  this  muscle  forms  a  guide  to  the  position  of  the  vessel,  in  tving  the 
brachial  artery  in  the  middle  of  the  arm.^ 

Relations.  Its  anterior  surface  is  overlapped  above  by  the  Pectoralis  Major 
and  Deltoid;  in  the  rest  of  its  extent  it  is  covered  by  the  superficial  and  deep 
lasciae  and  the  integument.     Its  posterior  surface  rests  on  the  shoulder-joint  and 

'  A  third  head  to  the  Biceps  is  occasionally  found  (Theile  says  as  often  as  once  in  eight  or 
nine  subjects),  arising  at  the  upper  and  inner  part  of  the  Brachialis  Anticus,  with  the  fibres  of 
winch  it  is  continuous,  and  inserted  into  the  bicipital  fascia  and  inner  side  of  the  tendon  of  the 
Biceps.  In  most  cases,  this  additional  shp  passes  behind  the  brachial  artery  in  its  course  down 
the  arm.  Occasionally  the  third  head  consists  of  two  slips,  which  pass  down,  one  in  front,  the 
other  behind  the  artery,  concealing  the  vessel  in  the  lower  half  of  the  arm. 


383  MUSCLES    AND    FASCIA. 

humerus,  from  which  it  is  separated  by  the  Subscapularis,  Teres  Major,  Latis- 
simus  Dorsi,  Brachialis  Anticus,  and  the  musculo-cutaneous  nerve.  Its  inner 
border  is  in  relation  with  the  Coraco-brachialis,  the  brachial  vessels,  and  median 
nerve ;  its  outer  border,  with  the  Deltoid  and  Supinator  Longus. 

The  Brachialis  Anticus  is  a  broad  muscle,  which  covers  the  elbow -joint  and 
the  lower  half  of  the  front  of  the  humerus.  It  is  somewhat  compressed  from 
before  backward,  and  is  broader  in  the  middle  than  at  either  extremity.  It 
arises  from  the  lower  half  of  the  outer  and  inner  surfaces  of  the  shaft  of  the 
humerus ;  ^nd  commences  above  at  the  insertion  of  the  Deltoid,  which  it  em- 
braces by  two  angular  processes.  Its  origin  extends  below,  to  within  an  inch 
of  the  margin  of  the  articular  surface,  and  is  limited  on  each  side  by  the  ex- 
ternal and  internal  borders  of  the  shaft  of  the  humerus.  It  also  arises  from 
the  intermuscular  septa  on  each  side,  but  more  extensively  from  the  inner  than 
the  outer.  Its  fibres  converge  to  a  thick  tendon,  which  is  inserted  into  a  rough 
depression  on  the  under  surface  of  the  coronoid  process  of  the  ulna,  being  re- 
ceived into  an  interval  between  two  fleshy  slips  of  the  Flexor  Digitorum  Pro- 
fundus. 

Relations.  By  its  anterior  surface,  with  the  Biceps,  the  brachial  vessels,  mus- 
culo-cutaneous, and  median  nerves.  By  its  posterior  surface,  with  the  humerus 
and  front  of  the  elbow-joint.  By  its  inner  border,  with  the  Triceps,  ulnar  nerve, 
and  Pronator  Eadii  Teres,  from  which  it  is  separated  by  the  intermuscular 
septum.  By  its  outer  border,  with  the  musculo-spiral  nerve,  radial  recurrent 
artery,  the  Supinator  Longus,  and  Extensor  Carpi  Radialis  Longior. 

Nerves.  The  muscles  of  this  group  are  supplied  by  the  musculo-cutaneous 
nerve.  The  Brachialis  Anticus  usually  receives  an  additional  filament  from 
the  musculo-spiral. 

Actions.  The  Coraco-brachialis  draws  the  humerus  forwards,  and  inwards, 
and  at  the  same  time  assists  in  elevating  it  towards  the  scapula.  The  Biceps 
and  Brachialis  Anticus  are  flexors  of  the  forearm ;  the  former  muscle  is  also 
a  supinator,  and  serves  to  render  tense  the  fascia  of  the  forearm  by  means  of 
the  broad  aponeurosis  given  off'  from  its  tendon.  When  the  forearm  is  fixed, 
the  Biceps  and  Brachialis  Anticus  flex  the  arm  upon  the  forearm,  as  is  seen  in 
efforts  of  climbing.  The  Brachialis  Anticus  forms  an  important  defence  to  the 
elbow-joint. 

Posterior  Humeral  Region. 

Triceps.  Subanconeus. 

The  TViceps  (Fig.  238)  is  situated  on  the  back  of  the  arm,  extending  the  entire 
length  of  the  posterior  surface  of  the  humerus.  It  is  of  large  size,  and  divided 
above  into  three  parts;  hence  its  name.  These  three  portions  have  been  named, 
(1)  the  middle,  scapular,  or  long  head,  (2)  the  external,  or  long  humeral,  and  (3) 
the  internal,  or  short  humeral  head. 

The  middle  or  scapular  head  arises,  by  a  flattened  tendon,  from  a  rough,  trian- 
gular depression,  immediately  below  the  glenoid  cavity,  being  blended  at  its 
upper  part  with  the  capsular  and  glenoid  ligaments;  the  muscular  fibres  pass 
downwards  between  the  two  other  portions  of  the  muscle,  and  join  with  them 
in  the  common  tendon  of  insertion. 

The  external  head  arises  from  the  posterior  surface  of  the  shaft  of  the  hume- 
rus, between  the  insertion  of  the  Teres  Minor  and  the  upper  part  of  the  mus- 
culo-spiral groove,  from  the  external  border  of  the  humerus  and  the  external 
intermuscular  septum:  the  fibres  from  this  origin  converge  towards  the  common 
tendon  of  insertion. 

The  internal  head  arises  from  the  posterior  surface  of  the  shaft  of  the  humerus, 
below  the  groove  for  the  musculo-spiral  nerve,  commencing  above,  narrow  and 
pointed,  below  the  insertion  of  the  Teres  Major,  and  extending  to  within  an 
inch  of  the  trochlear  surface :  it  also  arises  from  the  internal  border  of  the  hu- 
merus and  internal  intermuscular  septum.     The  fibres  of  this  portion  of  the 


OF    THE    FOREARM.  383 

muscle  are  directed,  some  downwards  to  the  olecranon,  whilst  others  converge 
to  the  common  tendon  of  insertion. 

The  common  teyidon  of  the  Triceps  commences  about  the  middle  of  the  back 
part  of  the  muscle :  it  consists  of  two  aponeurotic  lamina3,  one  of  which  is 
subcutaneous,  and  covers  the  posterior  surface  of  the  muscle  for  the  lower  half 
of  its  extent :  the  other  is  more  deeply  seated  in  the  substance  of  the  muscle ; 
after  receiving  the  attachment  of  the  muscular  fibres,  they  join  together  above 
the  elbow,  and  are  inserted  into  the  back  part  of  the  upper  surface  of  the 
olecranon  process,  a  small  bursa,  occasionally  multilocular,  being  interposed 
between  the  tendon  and  the  front  of  this  surface. 

The  long  head  of  the  Triceps  descends  between  the  Teres  Minor  and  Teres 
Major,  dividing  the  triangular  space  between  these  two  muscles  and  the  humerus 
into  two  smaller  spaces,  one  triangular,  the  other  quadrangular  (Fig.  238).  The 
triangular  space  contains  the  dorsalis  scapulas  vessels ;  it  is  bounded  by  the 
Teres  Minor  above,  the  Teres  Major  below,  and  the  scapular  head  of  the  Triceps 
externally :  the  quadrangular  space  transmits  the  posterior  circumflex  vessels 
and  nerve ;  it  is  bounded  by  the  Teres  Minor  above,  the  Teres  Major  below, 
the  scapular  head  of  the  Triceps  internally,  and  the  humerus  externally. 

Relations.  By  its  posterior  surface  with  the  Deltoid  above :  in  the  rest  of  its 
extent  it  is  subcutaneous.  By  its  anterior  surface^  with  the  humerus,  musculo- 
spiral  nerve,  superior  profunda  vessels,  and  back  part  of  the  elbow-joint.  Its 
middle  or  long  head  is  in  relation,  behind,  with  the  Deltoid  and  Teres  Minor ;  in 
front,  with  the  Subscapularis,  Latissimus  Dorsi,  and  Teres  Major. 

The  Suhanconeus  is  a  small  muscle,  distinct  from  the  Triceps,  and  analogous 
to  the  Subcrureus  in  the  lower  limb.  It  may  be  exposed  by  removing  the 
Triceps  from  the  lower  part  of  the  humerus.  It  consists  of  one  or  two  slender 
fasciculi,  which  arise  from  the  humerus,  immediately  above  the  olecranon  fossa, 
and  are  inserted  into  the  posterior  ligament  of  the  elbow-joint. 

Nerves.  The  Triceps  and  Subanconeus  are  supplied  by  the  musculo-spiral 
nerve. 

Actions.  The  Triceps  is  the  great  extensor  muscle  of  the  forearm ;  serving, 
when  the  forearm  is  flexed,  to  draw  it  into  a  right  line  with  the  arm.  It  is  the 
direct  antagonist  of  the  Biceps  and  Brachialis  Anticus.  When  the  arm  is 
extended,  the  long  head  of  the  muscle  may  assist  the  Teres  Major  and  Latissi- 
mus Dorsi  in  drawing  the  humerus  backwards.  The  long  head  of  the  Triceps 
protects  the  under  part  of  the  shoulder-joint,  and  prevents  displacement  of  the 
head  of  the  humerus  downwards  and  backwards. 

Muscles  of  the  Foreaem. 

Dissection.  To  dissect  the  forearm,  place  the  limb  in  the  position  indicated  in  Fig.  23.5 ; 
make  a  vertical  incision  along  the  middle  line  from  the  elbow  to  the  wrist,  and  a  transverse 
incision  at  each  extremity  of  this ;  the  flaps  of  integument  being  removed,  the  fascia  of  the 
forearm  is  exposed. 

The  deep  fascia  of  the  forearm,  continuous  above  with  that  inclosing  the  arm, 
is  a  dense  highly  glistening  aponeurotic  investment,  which  forms  a  general 
sheath  inclosing  the  muscles  in  this  region ;  it  is  attached  behind  to  the  olecranon 
and  posterior  border  of  the  ulna,  and  gives  off  from  its  inner  surface  numerous 
intermuscular  septa,  which  inclose  each  muscle  separately.  It  consists  of  cir- 
cular and  oblique  fibres,  connected  together  by  numerous  vertical  fibres.  It  is 
much  thicker  on  the  dorsal  than  on  the  palmar  surface,  and  at  the  lower  than 
at  the  upper  part  of  the  forearm,  and  is  strengthened  by  tendinous  fibres, 
derived  from  the  Brachialis  Anticus  and  Biceps  in  front,  and  from  the  Triceps 
behind.  Its  inner  surface  gives  origin  to  muscular  fibres,  especially  at  the 
upper  part  of  the  inner  and  outer  sides  of  the  forearm,  and  forms  the  bounda- 
ries of  a  series  of  conical-shaped  cavities,  in  which  the  muscles  are  contained. 
Besides  the  vertical  septa  separating  each  muscle,  transverse  septa  are  given 
off  both  on  the  anterior  and  posterior  surfaces  of  the  forearm,  separating  the 


384 


MUSCLES    AND    FASCIJ3. 


Fig.  239.— Front  of  the  Left 
Forearm.     Superficial  Muscles. 


deep  from  the  superficial  layer  of  muscles.  Numerous  apertures  exist  in  the 
fascia  for  the  passage  of  vessels  and  nerves ;  one  of  these,  of  large  size,  situated 
at  the  front  of  the  elbow,  serves  for  the  passage  of  a  communicating  branch 
between  the  superficial  and  deep  veins. 

The  muscles  of  the  forearm  may  be  subdivided  into  groups  corresponding  to 
the  region  they  occupy.     One  group  occupies  the  inner  and  anterior  aspect  of 

the  forearm,  and  comprises  the  flexor  and  pro- 
nator muscles.  Another  group  occupies  its  outer 
side ;  and  a  third,  its  posterior  aspect.  The  two 
latter  groups  include  all  the  extensor  and  supi- 
nator muscles. 

Anterior  Brachial  Eegion. 

Superficial  Layer. 

Pronator  Radii  Teres. 
Flexor  Carpi  Eadialis. 
Palmaris  Longus. 
Flexor  Carpi  Ulnaris. 
Flexor  Sublimis  Digitorum. 

These  muscles  take  origin  from  the  internal 
condyle  of  the  humerus  by  a  common  tendon. 

The  Pronator  Radii  Teres  arises  by  two  heads. 
One,  the  larger  and  more  superficial,  arises  from 
the  humerus,  immediately  above  the  internal  con- 
dyle, and  from  the  tendon  common  to  the  origin 
of  the  other  muscles ;  also  from  the  fascia  of  the 
forearm,  and  intermuscular  septum  between  it  and 
the  Flexor  Carpi  Radialis.  The  other  head  is  a 
thin  fasciculus,  which  arises  from  the  inner  side  of 
the  coronoid  process  of  the  ulna,  joining  the  pre- 
ceding at  an  acute  angle.  Between  the  two  heads 
f)asses  the  median  nerve.  The  muscle  passes  ob- 
iquely  across  the  forearm  from  the  inner  to  the 
outer  side,  and  terminates  in  a  flat  tendon,  which 
turns  over  the  outer  margin  of  the  radius,  and  is 
inserted  into  a  rough  ridge  at  the  middle  of  the 
outer  surface  of  the  shaft  of  that  bone. 

Relations.  By  its  anterior  surface^  with  the  deep 
fascia,  the  Supinator  Longus,  and  the  radial  vessels 
and  nerve.  IBy  its  j^osterior  sitrface,  with  the  Bra- 
chialis  Anticus,  Flexor  Sublimis  Digitorum,  the 
median  nerve,  and  ulnar  artery ;  the  small,  or 
deep,  head  bemg  interposed  between  the  two  lat- 
ter structures.  Its  outer  border  forms  the  inner 
boundary  of  a  triangular  space,  in  which  is  placed 
the  brachial  artery,  median  nerve,  and  tendon  of 
the  Biceps  muscle.  Its  inner  border  is  in  contact 
with  the  Flexor  Carpi  Radialis. 

The  Flexor  Cai'pi  Radialis  lies  on  the  inner  side 
of  the  preceding  muscle.  It  arises  from  the  internal 
condyle  by  the  common  tendon,  from  the  fascia  of 
the  forearm,  and  from  the  intermuscular  septa  between  it  and  the  Pronator 
Teres,  on  the  outside ;  the  Palmaris  Longus,  internally ;  and  the  Flexor  Sublimis 
Digitorum,  beneath.  Slender  and  aponeurotic  in  structure  at  its  commencement, 
it  increases  in  size,  and  terminates  in  a  tendon  which  forms  the  lower  two-thirds 
of  its  length.     This  tendon  passes  through  a  canal  on  the  outer  side  of  the 


ANTERIOR    BRACHIAL    REGION.  385 

annular  ligament,  runs  through  a  groove  in  the  os  trapezium  (which  is  converted 
into  a  canal  by  a  fibrous  sheath,  and  lined  by  a  synovial  membrane),  and  is 
inserted  into  the  base  of  the  metacarpal  bone  of  the  index  finger.  The  radial 
artery  lies  between  the  tendon  of  this  muscle  and  the  Supinator  Longus,  and 
may  easily  be  tied  in  this  situation. 

Relations.  By  its  superficial  surface^  with  the  deep  fascia  and  the  integument. 
By  its  deep  surface^  with  the  Flexor  Sublimis  Digitorum,  Flexor  Longus  Polli- 
cis  and  wrist-joint.  By  its  outer  horder^  with  the  Pronator  Radii  Teres,  and  the 
radial  vessels.  By  its  inner  border^  with  the  Palmaris  Longus  above,  and  the 
median  nerve  below. 

The  Palmaris  Longus  is  a  slender  fusiform  muscle,  lying  on  the  inner  side  of 
the  preceding.  It  arises  from  the  inner  condyle  of  the  humerus  by  the  common 
tendon,  from  the  deep  fascia,  and  the  intermuscular  septa,  between  it  and  the 
adjacent  muscles.  It  terminates  in  a  slender  flattened  tendon,  which  is  inserted 
into  the  annular  ligament,  expanding  to  end  in  the  palmar  fascia. 

Variations.  This  muscle  is  often  absent ;  when  present,  it  presents  many  varieties.  Its 
fleshy  belly  is  sometimes  very  long,  or  may  occupy  the  middle  of  the  muscle,  which  is  tendinous 
at  either  extremity ;  or  the  Palmaris  may  be  muscular  at  its  lower  extremity,  its  upper  part 
being  tendinous.  Occasionally  there  is  a  second  Palmaris  Longus  placed  on  the  inner  side  of 
the  preceding,  terminating,  below,  partly  in  the  annular  ligament  or  fascia,  and  partly  in  the 
small  muscles  of  the  little  finger. 

Relations.  By  its  anterior  surface^  with  the  deep  fascia.  By  its  posterior  sur- 
face^ with  the  Flexor  Digitorum  Sublimis.  Internally^  with  the  Flexor  Carpi 
Ulnaris.  Externally,  with  the  Flexor  Carpi  Radialis.  The  median  nerve  lies 
close  to  the  tendon,  just  above  the  wrist,  on  its  inner  and  posterior  side. 

The  Flexor  Carpi  Ulnaris  lies  along  the  ulnar  side  of  the  forearm.  It  arises 
by  two  heads,  separated  by  a  tendinous  arch,  beneath  which  passes  the  ulnar 
nerve,  and  posterior  ulnar  recurrent  artery.  One  head  arises  from  the  inner 
condyle  of  the  humerus  by  the  common  tendon ;  the  other,  from  the  inner  mar- 
gin of  the  olecranon,  by  an  aponeurosis  from  the  upper  two-thirds  of  the  pos- 
terior border  of  the  ulna,  and  from  the  intermuscular  septum  between  it  and 
the  Flexor  Sublimis  Digitorum.  The  fibres  terminate  in  a  tendon,  which 
occupies  the  anterior  part  of  the  lower  half  of  the  muscle,  and  is  inserted  into 
the  pisiform  bone,  some  fibres  being  prolonged  to  the  annular  ligament  and 
base  of  the  metacarpal  bone  of  the  little  finger.  The  ulnar  artery  lies  on  the 
outer  side  of  the  tendon  of  this  muscle,  in  the  lower  two-thirds  of  the  forearm  ; 
the  tendon  forming  a  guide  in  tying  the  vessel  in  this  situation. 

Relations.  By  its  anterior  surface,  with  the  deep  fascia,  with  which  it  is 
intimately  connected  for  a  considerable  extent.  By  its, posterior  surface,  with  the 
Flexor  Sublimis,  the  Flexor  Profundus,  the  Pronator  Quadratus,  and  the  ulnar 
vessels  and  nerve.  By  its  outer  or  radial  border,  with  the  Palmaris  Longus 
above,  and  the  ulnar  vessels  and  nerve  below. 

The  Flexor  Digitorum  Sublimis  {Perforatus)  is  placed  beneath  the  preceding 
muscles,  which  therefore  must  be  removed  in  order  to  bring  its  .attachment  into 
view.  It  is  the  largest  of  the  muscles  of  the  superficial  layer,  and  arises  by 
three  heads.  One  head  arises  from  the  internal  condyle  of  the  humerus  by  the 
common  tendon,  from  the  internal  lateral  ligament  of  the  elbow-joint,  and  from 
the  intermuscular  septum  common  to  it  and  the  preceding  muscles.  The  second 
head  arises  from  the  inner  side  of  the  coronoid  process  of  the  ulna,  above  the 
ulnar  origin  of  the  Pronator  Radii  Teres  (Fig.  157).  The  third  head  arises  from 
the  oblique  line  of  the  radius,  extending  from  the  tubercle  to  the  insertion  of 
the  Pronator  Radii  Teres.  The  fibres  pass  vertically  downwards,  forming  a 
broad  and  thick  muscle,  which  divides  into  four  tendons  about  the  middle  of 
the  forearm  ;  as  these  tendons  pass  beneath  the  annular  ligament  into  the  palm 
of  the  hand,  they  are  arranged  in  pairs,  the  anterior  pair  corresponding  to  the 
middle  and  ring  fingers  ;  the  posterior  pair  to  the  index  and  little  fingers.  The 
tendons  diverge  from  one  another  as  they  pass  onwards,  and  are  finally  inserted 
26 


386  MUSCLES    AND    FASCIA. 

into  the  lateral  margins  of  the  second  phalanges,  about  their  centre.  Opposite 
the  base  of  the  first  phalanges,  each  tendon  divides,  so  as  to  leave  a  fissured 
interval,  between  which  passes  one  of  the  tendons  of  the  Flexor  Profundus,  and 
the  tendons  of  both  the  Flexors  then  enter  an  osseo-aponeurotic  canal,  formed 
by  a  strong  fibrous  band,  which  arches  across  them,  and  is  attached  on  each 
side  to  the  margins  of  the  phalanges.  The  two  portions  into  which  the  tendon 
of  the  Flexor  Sublimis  divides,  so  as  to  admit  of  the  passage  of  the  deep  Flexor, 
expand  somewhat,  and  form  a  grooved  channel,  into  which  the  accompanying 
deep  flexor  tendon  is  received ;  the  two  divisions  then  unite,  and  finally  sub- 
divide a  second  time  to  be  inserted  into  the  fore  part  and  sides  of  the  second 
phalanges  (Fig.  244).  The  tendons,  whilst  contained  in  the  fibro-osseous  canals 
are  connected  to  the  phalanges  by  slender  tendinous  filaments,  called  vincula 
accessoria  tendinum.  A  synovial  sheath  invests  the  tendons  as  they  pass  be- 
neath the  annular  ligament ;  a  prolongation  from  which  surrounds  each  tendon 
as  it  passes  along  the  phalanges. 

Relations.  In  the  forearm,  by  its  anterior  surface,  with  the  deep  fascia  and  all 
the  preceding  superficial  muscles ;  by  its  posterior  surface^  with  the  Flexor  Pro- 
fundus Digitorum,  Flexor  Longus  Pollicis,  the  ulnar  vessels  and  nerve,  and  the 
median  nerve.  In  the  hand,  its  tendons  are  in  relation,  in  front,  with  the  palmar 
fascia,  superficial  palmar  arch,  and  the  branches  of  the  median  nerve ;  behind, 
with  the  tendons  of  the  deep  Flexor  and  the  Lumbricales. 

Anterior  Brachial  Eegion. 

Deep  Layer. 

Flexor  Profundus  Digitorum.  Flexor  Longus  Pollicis. 

Pronator  Quadratus. 

Dissection.  Divide  each  of  the  superficial  muscles  at  its  centre,  and  turn  either  end  aside ; 
the  deep  layer  of  muscles,  together  with  the  median  nerve  and  ulnar  vessels,  will  then  be 
exposed. 

The  Flexor  Profundus  Digitorum  {Perforans)  (Fig.  240)  is  situated  on  the 
ulnar  side  of  the  forearm,  immediately  beneath  the  superficial  Flexors.  It 
arises  from  the  upper  two-thirds  of  the  anterior  and  inner  surfaces  of  the  shaft 
of  the  ulna,  embracing  the  insertion  of  the  Brachialis  Anticus  above,  and 
extending,  below,  to  within  a  short  distance  of  the  Pronator  Quadratus.  It 
also  arises  from  a  depression  on  the  inner  side  of  the  coronoid  process,  by 
an  aponeurosis  from  the  upper  two-thirds  of  the  posterior  border  of  the 
ulna,  and  from  the  ulnar  half  of  the  interosseous  membrane.  The  fibres 
form  a  fleshy  belly  of  considerable  size  which  divides  into  four  tendons ;  these 
pass  under  the  annular  ligament  beneath  the  tendons  of  the  Flexor  Sublimis. 
Opposite  the  first  phalanges,  the  tendons  pass  between  the  two  slips  of  the 
tendons  of  the  Flexor  Sublimis,  and  are  finally  inserted  into  the  bases  of  the 
last  phalanges.  The  tendon  of  the  index  finger  is  distinct ;  the  rest  are  con- 
nected together  by  cellular  tissue  and  tendinous  slips,  as  far  as  the  palm  of  the 
hand. 

Four  small  muscles,  the  Lumbricales,  are  connected  with  the  tendons  of  the 
Flexor  Profundus  in  the  palm.  They  will  be  described  with  the  muscles  in 
that  region. 

Relations.  By  its  anterior  surface,  in  the  forearm,  with  the  Flexor  Sublimis 
Digitorum,  the  Flexor  Carpi  IJlnaris,  the  ulnar  vessels  and  nerve,  and  the 
median  nerve ;  and  in  the  hand,  with  the  tendons  of  the  superficial  Flexor.  By 
its  posterior  surface,  in  the  forearm,  with  the  ulnar,  the  interosseous  membrane, 
the  Pronator  Quadratus;  and  in  the  hand,  with  the  Interossei,  Adductor  Pollicis, 
and  deep  palmar  arch.  By  its  ulnar  border,  with  the  Flexor  Carpi  Ulnaris. 
By  its  radial  border,  with  the  Flexor  Longus  Pollicis,  the  anterior  interosseous 
vessels  and  nerve  being  interposed. 


ANTERIOR    BRACHIAL    REGION. 


387 


The  Flexor  Longus  PoIHcis  is 
situated  on  the  radial  side  of  the 
forearm,  lying  on  the  same  plane  as 
the  preceding.  It  arises  from  the 
upper  two-thirds  of  the  grooved 
anterior  surface  of  the  shaft  of  the 
radius;  commencing,  above,  im- 
mediately below  the  tuberosity 
and  oblique  line,  and  extending, 
below,  to  within  a  short  distance 
of  the  Pronator  Quadratus.  It 
also  arises  from  the  adjacent  part 
of  the  interosseous  membrane, 
and  occasionally  by  a  fleshy  slip 
from  the  inner  side  of  the  base 
of  the  coronoid  process.  The 
fibres  pass  downwards  and  termi- 
nate in  a  flattened  tendon,  which 
passes  beneath  the  annular  liga- 
ment, is  then  lodged  in  the  inter- 
space between  the  two  heads  of 
the  Flexor  Brevis  Pollicis,  and 
entering  a  tendino-osseous  canal 
similar  to  those  for  the  other 
flexor  tendons,  is  inserted  into 
the  base  of  the  last  phalanx  of 
the  thumb. 

Relations.  By  its  anterior  sur- 
face, with  the  Flexor  Sublimis 
Digitorum,  Flexor  Carpi  Radialis, 
Supinator  Longus,  and  radial  ves- 
sels. By  its  posterior  surface,  with 
the  radius,  interosseous  mem- 
brane, and  Pronator  Quadratus. 
By  its  ulnar  border,  with  the 
Flexor  Profundus  Digitorum, 
from  which  it  is  separated  by  the 
anterior  interosseous  vessels  and 
nerve. 

The  Pronator  Quadratus  is  a 
small,  flat,  quadrilateral  muscle, 
extending  transversely  across  the 
front  of  the  radius  and  ulna, 
above  their  carpal  extremities. 
It  arises  from  the  oblique  line  on 
the  lower  fourth  of  the  anterior 
surface  of  the  shaft  of  the  ulna,  and 
the  surface  of  bone  immediately 
below  it;  from  the  internal  border 
of  the  ulna;  and  from  a  strong 
aponeurosis  which  covers  the  in- 
ner third  of  the  muscle.  The 
fibres  pass  horizontally  outwards, 
to  be  inserted  into  the  lower 
fourth  of  the  anterior  surface  and 
external  border  of  the  shaft  of 
the  radius. 


Fig.  240.— Front  of  Left  Forearm.    Deep  Muscles. 


388  MUSCLES    AND    FASCIA. 

Relations.  By  its  anterior  surface^  with  the  Flexor  Profundus  Digitorum,  the 
Flexor  Longus  Pollicis,  Flexor  Carpi  Radialis,  and  the  radial  vessels.  By  its 
posterior  surface,  with  the  radius,  ulna,  and  interosseous  membrane. 

Nerves.  All  the  muscles  of  the  superficial  layer  are  supplied  by  the  median 
nerve,  excepting  the  Flexor  Carpi  Ulnaris,  which  is  supplied  by  the  ulnar.  Of 
the  deep  layer,  the  Flexor  Profundus  Digitorum  is  supplied  conjointly  by  the 
ulnar  and  by  the  median,  through  its  branch,  the  anterior  interosseous  nerve, 
which  also  supplies  the  Flexor  Longus  Pollicis  and  Pronator  Quadratus. 

Actions.  These  muscles  act  upon  the  forearm,  the  wrist,  and  hand.  Those 
acting  on  the  forearm,  are  the  Pronator  Radii  Teres  and  Pronator  Quadratus, 
which  rotate  the  radius  upon  the  ulna,  rendering  the  hand  prone ;  when  prona- 
tion has  been  fully  effected,  the  Pronator  Radii  Teres  assists  the  other  muscles 
in  flexing  the  forearm.  The  flexors  of  the  wrist  are  the  Flexor  Carpi  Ulnaris 
and  Flexor  Carpi  Radialis;  and  the  flexors  of  the  phalanges  are  the  Flexor 
Sublimis  and  Flexor  Profundus  Digitorum;  the  former  flexing  the  second  pha- 
langes, and  the  latter  the  last.  The  Flexor  Longus  Pollicis  flexes  the  last 
phalanx  of  the  thumb.  The  three  latter  muscles,  after  flexing  the  phalanges, 
by  continuing  their  action,  act  upon  the  wrist,  assisting  the  ordinary  flexors  of 
this  joint ;  and  all  those  which  are  attached  to  the  humerus  assist  in  flexing 
the  forearm  upon  the  arm.  The  Palmaris  Longus  is  a  tensor  of  the  palmar 
fascia ;  when  this  action  has  been  fully  effected,  it  flexes  the  hand  upon  the 
forearm. 

Radial  Region.    (Fig.  241.) 

Supinator  Longus.  Extensor  Carpi  Radialis  Longior. 

Extensor  Carpi  Radialis  Brevior. 

Dissection.  Divide  the  integument  in  the  same  manner  as  in  the  dissection  of  the  anterior 
brachial  region ;  and  after  having  examined  the  cutaneous  vessels  and  nerves  and  deep  fascia, 
remove  all  those  structures.  The  muscles  will  then  be  exposed.  The  removal  of  the  fascia  will 
be  considerably  facihtated  by  detaching  it  from  below  upwards.  Great  care  should  be  taken  to 
avoid  cutting  across  the  tendons  of  the  muscles  of  the  thumb,  which  cross  obliquely  the  larger 
tendons  running  down  the  back  of  the  radius. 

The  Supinator  Longus  is  the  most  superficial  muscle  on  the  radial  side  of 
the  forearm.  It  is  fleshy  for  the  upper  two-thirds  of  its  extent,  tendinous 
below.  It  arises  from  the  upper  two-thirds  of  the  external  condyloid  ridge  of 
the  humerus,  and  from  the  external  intermuscular  septum,  being  limited  above 
by  the  musculo-spinal  groove.  The  fibres  terminate  above  the  middle  of  the 
forearm  in  a  flat  tendon,  which  is  inserted  into  the  base  of  the  styloid  process 
of  the  radius. 

Relations.  By  its  superficial  surface,  with  the  integument  and  fascia  for  the 
greater  part  of  its  extent;  near  its  insertion  it  is  crossed  by  the  Extensor  Ossis 
Metacarpi  Pollicis  and  the  Extensor  Primi  Internodii  Pollicis.  By  its  deep 
surface,  with  the  humerus,  the  Extensor  Carpi  Radialis  Longior  and  Brevior, 
the  insertion  of  the  Pronator  Radii  Teres,  and  the  Supinator  Brevis.  By  its 
inner  border,  above  the  elbow,  with  the  Brachialis  Anticus,  the  musculo-spiral 
nerve,  and  radial  recurrent  artery;  and  in  the  forearm,  with  the  radial  vessels 
and  nerve. 
,  The  Extensor  Carpi  Radialis  Lonrjior  is  placed  partly  beneath  the  preceding 
muscle.  It  arises  from  the  lower  third  of  the  external  condyloid  ridge  of  the 
humerus,  and  from  the  external  intermuscular  septum.  The  fibres  terminate 
at  the  upper  third  of  the  forearm  in  a  flat  tendon,  which  runs  along  the  outer 
border  of  the  radius,  beneath  tlie  extensor  tendons  of  the  thumb ;  it  then  passes 
through  a  groove  common  to  it  and  the  Extensor  Carpi  Radialis  Brevior  im- 
mediately behind  the  styloid  process ;  and  is  inserted  into  the  base  of  the 
metacarpal  bone  of  the  index  finger,  on  its  radial  side. 

Relations.     By  its  superficial  surface,  with  the  Supinator  Longus,  and  fascia 


RADIAL    REGI0:N^. 


389 


of  the  forearm.  Its  outer  side 
is  crossed  obliquely  by  the  ex- 
tensor tendons  of  the  thumb. 
By  its  deep  surface,  with  the 
elbow-joint,  the  Extensor  Carpi 
Radialis  Brevior,  and  back  part 
of  the  wrist. 

The  Extensor  Carpi  Radialis 
Brevior  is  shorter,  as  its  name 
implies,  and  thicker  than  the  pre- 
ceding muscle,  beneath  which 
it  is  placed.  It  arises  from  the 
external  condyle  of  the  hume- 
rus by  a  tendon  common  to  it 
and  the  three  following  muscles ; 
from  the  external  lateral  liga- 
ment of  the  elbow-joint ;  from 
a  strong  aponeurosis  which 
covers  its  surface;  and  from 
the  intermuscular  septa  between 
it  and  the  adjacent  muscles. 
The  fibres  terminate  about  the 
middle  of  the  forearm  in  a  flat 
tendon,  which  is  closely  con- 
nected with  ,  that  of  the  pre- 
ceding muscle,  accompanies  it 
to  the  wrist,  lying  in  the  same 
groove  on  the  posterior  surface 
of  the  radius ;  passes  beneath 
the  annular  ligament,  and,  di- 
verging somewhat  from  its  fel- 
low, is  inserted  into  the  base 
of  the  metacarpal  bone  of  the 
middle  finger,  on  its  radial 
side. 

The  tendons  of  the  two  pre- 
ceding muscles  pass  through 
the  same  compartment  of  the 
annular  ligament,  and  are  lu- 
bricated by  a  single  synovial 
membrane,  but  are  separated 
from  each  other  by  a  small  ver- 
tical ridge  of  bone,  as  they  lie 
in  the  groove  at  the  back  of 
the  radius. 

Relations.  By  its  superficial 
surface,^  with  the  Extensor  Carpi 
Radialis  Longior,  and  with  the 
extensor  muscles  of  the  thumb 
which  cross  it.  By  its  deep 
surface,  with  the  Supinator 
B  re  vis,  tendon  of  the  Pronator 
Radii  Teres,  radius,  and  wrist- 
joint.  By  its  ulnar  harder,  with 
the  Extensor  Communis  Digi- 
torum. 


Fig.  241.— Posterior  Surface  of  Forearm. 
Superficial  Muscles. 


390  MUSCLES    AND    FASCIA. 

Posterior  Brachial  Eegion.    (Fig.  241.) 

Superficial  Layer, 

Extensor  Communis  Digitorum.  Extensor  Carpi  Ulnaris. 

Extensor  Minimi  Digiti.  Anconeus. 

TlhQ  Extensor  Communis  Digitorum  is  situated  at  the  back  part  of  the  forearm. 
It  arises  from  the  external  condyle  of  the  humerus  by  the  common  tendon,  from 
the  deep  fascia,  and  the  intermuscular  septa  between  it  and  the  adjacent  muscles. 
Just  below  the  middle  of  the  forearm  it  divides  into  three  tendons,  which  pass, 
together  with  the  Extensor  Indicis,  through  a  separate  compartment  of  the  an- 
nular ligament,  lubricated  by  a  synovial  membrane.  The  tendons  then  diverge, 
the  innermost  one  dividing  into  two ;  and  all,  after  passing  across  the  back  of 
the  hand,  are  inserted  into  the  second  and  third  phalanges  of  the  fingers  in  the 
following  manner :  Each  tendon  becomes  narrow  and  thickened  opposite  the 
metacarpo-phalangeal  articulation,  and  gives  off  a  thin  fasciculus  upon  each 
side  of  the  joint,  which  serves  as  the  posterior  ligament ;  after  having  passed 
the  joint,  it  spreads  out  into  a  broad  aponeurosis,  which  covers  the  whole  of 
the  dorsal  surface  of  the  first  phalanx ;  being  reinforced,  in  this  situation,  by 
the  tendons  of  the  Interossei  and  Lumbricales.  Opposite  the  first  phalangeal 
joint,  this  aponeurosis  divides  into  three  slips,  a  middle,  and  two  lateral ;  the 
former  is  inserted  into  the  base  of  the  second  phalanx ;  and  the  two  lateral, 
which  are  continued  onwards  along  the  sides  of  the  second  phalanx,  unite  by 
their  contiguous  margins,  and  are  inserted  into  the  dorsal  surface  of  the  last 
phalanx.  As  the  tendons  cross  the  phalangeal  joints,  they  furnish  them  with 
posterior  ligaments.  The  tendons  of  the  middle,  ring,  and  little  fingers  are 
connected  together,  as  they  cross  the  hand,  by  small  oblique  tendinous  slips. 
The  tendons  of  the  index  and  little  fingers  also  receive,  before  their  division, 
the  special  extensor  tendons  belonging  to  them. 

Relations.  By  its  superfi^cial  surface,  with  the  fascia  of  the  forearm  and  hand, 
the  posterior  annular  ligament,  and  integument.  By  its  deep  surface,  with  the 
Supinator  Brevis,  the  extensor  muscles  of  the  thumb  and  index  finger,  the 
posterior  interosseous  vessels  and  nerve,  the  wrist-joint,  carpus,  metacarpus, 
and  phalanges.  By  its  radial  border,  with  the  Extensor  Carpi  Eadialis  Bre- 
vior.  By  its  ulnar  border,  with  the  Extensor  Minimi  Digiti,  and  Extensor 
Carpi  Ulnaris. 

The  Extensor  Minimi  Digiti  is  a  slender  muscle,  placed  on  the  inner  side  of 
the  Extensor  Communis,  with  which  it  is  generally  connected.  It  arises  from 
the  common  tendon  by  a  thin  tendinous  slip ;  and  from  the  intermuscular  septa 
between  it  and  the  adjacent  muscles.  Its  tendon  runs  through  a  separate  com- 
partment in  the  annular  ligament  behind  the  inferior  radio-ulnar  joint,  subdi- 
vides into  two  as  it  crosses  the  hand,  and  at  the  metacarpo-phalangeal  articula- 
tion, unites  with  the  tendon  derived  from  the  common  Extensor.  The  common 
tendon  then  spreads  into  a  broad  aponeurosis,  which  is  inserted  into  the  second 
and  third  phalanges  of  the  little  finger  in  a  similar  manner  to  the  common  ex- 
tensor tendons  of  the  other  fingers. 

The  Extensor  Carpi  Ulnaris  is  the  most  superficial  muscle  on  the  ulnar  side 
of  the  forearm.  It  arises  from  the  external  condyle  of  the  humerus,  by  the 
common  tendon ;  from  the  middle  third  of  the  posterior  border  of  the  ulna 
below  the  Anconeus,  and  from  the  fascia  of  the  forearm,  This  muscle  termi- 
nates in  a  tendon,  which  runs  through  a  groove  behind  the  styloid  process  of 
the  ulna,  passes  through  a  separate  compartment  in  the  annular  ligament,  and 
is  inserted  into  the  base  of  the  metacarpal  bone  of  the  little  finger. 

Relations.  By  its  superficial  surface,  with  the  fascia  of  the  forearm.  By  its 
deep  surface,  with  the  uhia,  and  the  muscles  of  the  deep  layer. 

The  Anconeus  is  a  small  triangular  muscle,  placed  behind  and  below  the 
elbow-joint,  and  appears  to  be  a  continuation  of  the  external  portion  of  the 


POSTERIOR    BRACHIAL    REGION.  391 

Triceps.  It  arises  by  a  separate  tendon  from  the  back  part  of  the  outer  con- 
dyle of  the  humerus ;  and  is  inserted  into  the  side  of  the  olecranon,  and  upper 
third  of  the  posterior  surface  of  the  shaft  of  the  ulna ;  its  fibres  diverge  from 
their  origin,  the  upper  ones  being  directed  transversely,  the  lower  obliquely 
inwards. 

Relations.  By  its  superficial  surface  with  a  strong  fascia  derived  from  the 
Triceps.  By  its  deep  surface^  with  the  elbow-joint,  the  orbicular  ligament,  the 
ulna,  and  a  small  portion  of  the  Supinator  Brevis. 

Posterior  Brachial  Region.    (Fig.  242.) 
Deep  Layer. 

Supinator  Brevis.  Extensor  Primi  Internodii  Pollicis. 

Extensor  Ossis  Metacarpi  Pollicis.  Extensor  Secundi  Internodii  Pollicis. 

Extensor  Indicis. 

The  Supinator  Brevis  is  a  broad  muscle,  of  a  hollow  cylindrical  form,  curved 
round  the  upper  third  of  the  radius.  It  arises  from  the  external  condyle  of  the 
humerus,  from  the  external  lateral  ligament  of  the  elbow-joint,  and  the  orbicular 
ligament  of  the  radius,  from  the  ridge  on  the  ulna,  which  runs  obliquely  down- 
wards from  the  posterior  extremity  of  the  lesser  sigmoid  cavity,  from  the 
triangular  depression  in  front  of  it,  and  from  a  tendinous  expansion  which 
covers  the  surface  of  the  muscle.  The  muscle  surrounds  the  upper  part  of  the 
radius :  the  upper  fibres  forming  a  sling-like  fasciculus,  which  encircles  the 
neck  of  the  radius  above  the  tuberosity,  and  is  attached  to  the  back  part  of  its 
inner  surface ;  the  middle  fibres  are  attached  to  the  outer  edge  of  the  bicipital 
tuberosity;  the  lower  fibres  to  the  oblique  line  of  the  radius,  as  low  down  as 
the  insertion  of  the  Pronator  Radii  Teres.  This  muscle  is  pierced  by  the  pos- 
terior interosseous  nerve. 

Relations.  By  its  superficial  surface,  with  the  superficial  extensor  and  supi- 
nator muscles,  and  the  radial  vessels  and  nerve.  By  its  deep  surface,  with  the 
elbow-joint,  the  interosseous  membrane,  and  the  radius. 

The  Extensor  Ossis  Metacarpi  Pollicis  is  the  most  external  and  the  largest  of 
the  deep  extensor  muscles :  it  lies  immediately  below  the  Supinator  Brevis, 
with  which  it  is  sometimes  united.  It  arises  from  the  posterior  surface  of  the 
shaft  of  the  ulna  below  the  insertion  of  the  Anconeus,  from  the  interosseous 
ligament,  and  from  the  middle  third  of  the  posterior  surface  of  the  shaft  of  the 
radius.  Passing  obliquely  downwards  and  outwards,  it  terminates  in  a  tendon 
which  runs  through  a  groove  on  the  outer  side  of  the  styloid  process  of  the 
radius,  accompanied  by  the  tendon  of  the  Extensor  Primi  Internodii  Pollicis, 
and  is  inserted  into  the  base  of  the  metacarpal  bone  of  the  thumb. 

Relations.  By  its  superficial  surface,  with  the  Extensor  Communis  Digitorum, 
Extensor  Minimi  Digiti,  and  fascia  of  the  forearm ;  and  with  the  branches  of 
the  posterior  interosseous  artery  and  nerve  which  cross  it.  By  its  deep  surface, 
with  the  ulna,  interosseous  membrane,  radius,  the  tendons  of  the  Extensor 
Carpi  Radialis  Longior  and  Brevior,  which  it  crosses  obliquely ;  and,  at  the  outer 
side  of  the  wrist,  with  the  radial  vessels.  By  its  upp)er  harder,  with  the  Supi- 
nator Brevis.     By  its  loiver  harder,  with  the  Extensor  Primi  Internodii  Pollicis. 

The  Extensor  Primi  Internodii  Pollicis,  the  smallest  muscle  of  this  group,  lies 
on  the  inner  side  of  the  preceding.  It  arises  from  the  posterior  surface  of  the 
shaft  of  the  radius,  below  the  Extensor  Ossis  Metacarpi,  and  from  the  inter- 
osseous membrane.  Its  direction  is  similar  to  that  of  the  Extensor  Ossis  Meta- 
carpi, its  tendon  passing  through  the  same  groove  on  the  outer  side  of  the 
styloid  process,  to  be  inserted  into  the  base  of  the  first  phalanx  of  the  thumb. 

Relations.     The  same  as  those  of  the  Extensor  Ossis  Metacarpi  Pollicis. 

The  Extensor  Secundi  Internodii  Pollicis  is  much  larger  than  the  preceding 
muscle,  the  origin  of  which  it  partly  covers  in.  It  arises  from  the  posterior 
surface  of  the  shaft  of  the  ulna,  below  the  origin  of  the  Extensor  Ossis  Meta- 


892 


MUSCLES    AND    FASCIA. 


carpi  Pollicis,  and  from  the  interosseous  membrane.     It  terminates  in  a  tendon  . 

which  passes  through  a  separate  compartment  in  the  annular  ligament,  lying 

in  a  narrow  oblique  groove  at 
Fig.  242.-Fosterior  Surface  of  the  Forearm.    Deep     ^^^  ^^^^     ^^^  ^^  ^^^  j^^^j,  ^^^ 

Muscles.  -,  ,,  \-  T4.   Ai, 

ot  the  radius,     it  then  crosses 

obliquely  the  extensor  tendons 
of  the  carpus,  being  separated 
from  the  other  extensor  ten- 
dons of  the  thumb  by  a  trian- 
gular interval,  in  which  the 
radial  artery  is  found ;  and  is 
finally  inserted  into  the  base  of 
the  last  phalanx  of  the  thumb. 

Relations.  By  its  superficial 
surface^  with  the  same  parts  as 
the  Extensor  Ossis  Metacarpi 
Pollicis.  By  its  deep  surface^ 
with  the  ulna,  interosseous 
membrane,  radius,  the  wrist, 
the  radial  vessels,  and  metacar- 
pal bone  of  the  thumb. 

The  Extensor  Indicis  is  a  nar- 
row elongated  muscle,  placed 
on  the  inner  side  of,  and  parallel 
with,  the  preceding.  It  arises 
from  the  posterior  surface  of  the 
shaft  of  the  ulna,  below  the  ori- 
gin of  the  Extensor  Secundi 
Internodii  Pollicis,  and  from 
the  interosseous  membrane.  Its 
tendon  passes  with  the  Extensor 
Communis  Digitorum  through 
the  same  canal  in  the  annular 
ligament,  and  subsequently  joins 
that  tendon  of  the  Extensor 
Communis  which  belongs  to  the 
index  finger,  opposite  the  lower 
end  of  the  corresponding  meta- 
carpal bone.  It  is  finally  in- 
serted into  the  second  and  third 
phalanges  of  the  index  finger,  in 
the  manner  already  described. 

Relations.  They  are  similar  to 
those  of  the  preceding  muscles. 

Nerves.  The  Supinator  Lon- 
gus,  Extensor  Carpi  Radialis 
Longior,  and  Anconeus,  are 
supplied  by  branches  from  the 
musculo-spiral  nerve.  The  re- 
maining muscles  of  the  radial 
and  posterior  brachial  regions, 
by  the  posterior  interosseous 
nerve. 

Actions.  The  muscles  of  the 
radial  and  posterior  brachial 
regions,  which  comprise  all  the  extensor  and  supinator  muscles,  act  upon  the 
forearm,  wrist,  and  hand ;  they  are  the  direct  antagonists  of  the  pronator  and 


(VTENtOM 
CARPI    ULNABIt 


OF    THE    HAND. 


393 


flexor  muscles.  The  Anconeus  assists  the  Triceps  in  extending  the  forearm. 
fThe  Supinator  Longus  and  Supinator  Brevis  are  the  supinators  of  the  forearm 
'and  hand ;  the  former  muscle  more  especially  acting  as  a  supinator  when  the 
limb  is  pronated.  When  supination  has  been  produced,  the  Supinator  Longus, 
if  still  continuing  to  act,  flexes  the  forearm.  The  Extensor  Carpi  Eadialia 
Longior  and  Brevior,  and  Extensor  Carpi  Ulnaris  muscles,  are  the  extensors  of 
the  wrist ;  continuing  their  action,  they  serve  to  extend  the  forearm  upon  the 
arm ;  they  are  the  direct  antagonists  of  the  Flexor  Carpi  Eadialis  and  Flexor 
Carpi  Ulnaris.  The  common  Extensor  of  the  fingers,  the  Extensors  of  the 
t;humb,  and  the  Extensors  of  the  index  and  little  fingers,  serve  to  extend  the 
phalanges  into  which  they  are  inserted;  and  are  the  direct  antagonists  of  the 
Flexors.  By  continuing  their  action,  they  assist  in  extending  the  forearm. 
The  Extensors  of  the  thumb,  in  consequence  of  the  oblique  direction  of  their 
tendons,  assist  in  supinating  the  forearm,  when  the  thumb  has  been  drawn 
inwards  towards  the  palm. 

Muscles  and  Fascia  of  the  Hand. 

Dissection  (Fig.  235).  Make  a  transverse  incision  across  the  front  of  the  wrist,  and  a  second 
across  the  heads  of  the  metacarpal  bones :  connect  the  two  by  a  vertical  incision  in  the  middle 
line,  and  continue  it  through  the  centre  of  the  middle  finger.  The  anterior  and  posterior  annular 
ligaments,  and  the  palmar  fascia,  should  first  be  dissected. 

The  Anterior  Annular  Ligament  is  a  strong  fibrous  band,  which  arches  over 
the  carpus,  converting  the  deep  groove  on  the  front  of  the  carpal  bones  into  a 
canal,  beneath  which  pass  the  flexor  tendons  of  the  fingers.  It  is  attached, 
internally,  to  the  pisiform  bone,  and  unciform  process  of  the  unciform;  and. 
externally,  to  the  tuberosity  of  the  scaphoid,  and  ridge  on  the  trapezium.  It  is 
continuous,  above,  with  the  deep  fascia  of  the  forearm,  and  below,  with  the 
palmar  fascia.  It  is  crossed  by  the  tendon  of  the  Palmaris  Longus,  by  the 
ulnar  vessels    and    nerve,   and   the 

Fig.  243. — Transverse  Section  through  the 
Wrist,  showing  the  Annular  Ligaments  and  the 
Canals  for  the  Passage  of  the  Tendons. 


L*NC.     y\.E<-  CA'^'^R^rt 


cutaneous  branches  of  the  median 
and  ulnar  nerves.  It  has  inserted 
into  its  upper  and  inner  part  the 
greater  part  of  the  tendon  of  the 
Flexor  Carpi  Ulnaris ;  and  has,  aris- 
ing from  it  below,  the  small  muscles 
of  the  thumb  and  little  finger.  It  is 
pierced  by  the  tendon  of  the  Flexor 
Carpi  Eadialis ;  and,  beneath  it,  pass 
the  tendons  of  the  Flexor  Sublimis 
and  Flexor  Profundus  Digitorum,  the 
Flexor  Longus  Pollicis,  and  the  me- 
dian nerve.  There  are  two  synovial 
membranes  beneath  this  ligament; 
one  of  large  size,  inclosing  the  ten- 
dons  of  the   Flexor    Sublimis    and 

Flexor  Profundus;  and  a  separate  one  for  the  tendon  of  the  Flexor  Longus 
Pollicis,  which  is  also  very  extensive,  reaching  from  above  the  wrist  to  the 
extremity  of  the  last  phalanx  of  the  thumb. 

The  Posterior  Annular  Ligament  is  a  strong  fibrous  band,  extending  trans- 
versely across  the  back  of  the  wrist,  and  continuous  with  the  fascia  of  the  fore- 
arm. It  forms  a  sheath  for  the  extensor  tendons  in  their  passage  to  the  fingers, 
being  attached,  internally,  to  the  ulna,  the  cuneiform  and  pisiform  bones,  and 
palmar  fascia;  externally,  to  the  margin  of  the  radius:  and  in  its  passage  across 
the  wrist,  to  the  elevated  ridges  on  the  posterior  surface  of  the  radius.  It  pre- 
sents six  compartments  for  the  passage  of  tendons,  each  of  which  is  lined 
by  a  separate  synovial  membrane.  These  are,  from  without  inwards:  1.  On 
the  outer  side  of  the  styloid  process  for  the  tendons  of  the  Extensor  Ossis  Meta- 


^''T.COM.   Dl'o.  ^'^SEC.lia-^ 


394  MUSCLES    AND    FASCIA. 

carpi,  and  Extensor  Primi  Internodii  Pollicis.  2.  Behind  the  styloid  process, 
for  the  tendons  of  the  Extensor  Carpi  Radialis  Longior  and  Brevior.  3.  Oppo- 
site the  outer  side  of  the  posterior  surface  of  the  radius,  for  the  tendon  of  the 
Extensor  Secundi  Internodii  Pollicis.  4.  To  the  inner  side  of  the  latter,  for 
the  tendons  of  the  Extensor  Communis  Digitorum,  and  Extensor  Indicis.  5. 
For  the  Extensor  Minimi  Digiti,  opposite  the  interval  between  the  radius  and 
ulna.  6.  For  the  tendon  of  the  Extensor  Carpi  Ulnaris,  grooving  the  back 
of  the  ulna.  The  synovial  membranes  lining  these  sheaths  are  usually  very 
extensive,  reaching  from  above  the  annular  ligament,  down  upon  the  tendons 
almost  to  their  insertion. 

T\\Q  palmar  fascia  forms  a  common  sheath  which  invests  the  muscles  of  the 
hand.     It  consists  of  a  central  and  two  lateral  portions. 

The  central  portion  occupies  the  middle  of  the  palm,  is  triangular  in  shape, 
of  great  strength  and  thickness,  and  binds  down  the  tendons  in  this  situation. 
It  is  narrow  above,  being  attached  to  the  lower  margin  of  the  annular  ligament, 
and  receives  the  expanded  tendon  of  the  Palmaris  Longus  muscle.  Below,  it  is 
broad  and  expanded,  and  opposite  the  heads  of  the  metacarpal  bones  divides 
into  four  slips,  for  the  four  fingers.  Each  slip  subdivides  into  two  processes, 
which  inclose  the  tendons  of  the  flexor  muscles,  and  are  attached  to  the  sides 
of  the  first  phalanx,  and  to  the  glenoid  ligament ;  by  this  arrangement,  four 
arches  are  formed,  under  which  the  flexor  tendons  pass.  The  intervals  left  in 
the  fascia,  between  the  four  fibrous  slips,  transmit  the  digital  vessels  and 
nerves,  and  the  tendons  of  the  Lumbricales.  At  the  point  of  the  division  of  the 
palmar  fascia  into  the  slips  above  mentioned,  numerous  strong  transverse  fibres 
bind  the  separate  processes  together.  The  palmar  fascia  is  intimately  adherent 
to  the  integument  by  numerous  fibrous  bands,  and  gives  origin  by  its  inner 
margin  to  the  Palmaris  Brevis ;  it  covers  the  superficial  palmar  arch,  the  ten- 
dons of  the  flexor  muscles,  and  the  branches  of  the  median  and  ulnar  nerves; 
and  on  each  side  it  gives  off  a  vertical  septum,  which  is  continuous  with  the 
interosseous  aponeurosis,  and  separates  the  lateral  from  the  middle  palmar 
group  of  muscles. 

The  lateral  portions  of  the  palmar  fascia  are  thin  fibrous  layers,  which  cover, 
on  the  radial  side,  the  muscles  of  the  ball  of  the  thumb;  and,  on  the  ulnar  side, 
the  muscles  of  the  little  finger;  they  are  continuous  with  the  dorsal  fascia,  and 
in  the  palm  with  the  middle  portion  of  the  palmar  fascia. 

Muscles  of  the  Hand. 

The  Muscles  of  the  Hand  are  subdivided  into  three  groups :  1.  Those  of  the 
thumb  which  occupy  the  radial  side.  2.  Those  of  the  little  finger  which 
occupy  the  ulnar  side.  3.  Those  in  the  middle  of  the  palm  and  between  the 
interosseous  spaces. 

Eadial  Region'.    (Fig.  244.) 

Muscles  of  the  Thumb. 

Abductor  .Pollicis. 

Opponens  .Pollicis  (Flexor  Ossis  Metacarpi). 

Flexor  Brevis  Pollicis. 

Adductor  Pollicis. 

The  Abductor  Pollicis  is  a  thip,  flat  muscle,  placed  immediately  beneath  the 
integument.  It  arises  from  the  ridge  of  the  os  trapezium  and  annular  liga- 
ment ;  and  passing  outwards  and  downwards,  is  inserted  by  a  thin,  flat  tendon 
into  the  radial  side  of  the  base  of  the  first  phalanx  of  the  thumb. 

Relations.  By  its  superficial  surface^  with  the  palmar  fascia.  By  its  deep 
surface^  with  the  Opponens  Pollicis,  from  which  it  is  separated  by  a  thin  apo- 
neurosis. Its  inner  border  is  separated  from  the  Flexor  Brevis  Pollicis  by  a 
narrow  cellular  interval. 


OF    THE    HAND.  395 

The  Opponens  Pollicis  is  a  small  triangular  muscle,  placed  beneatli  the  pre- 
ceding. It  arises  from  the  palmar  surface  of  the  trapezium  and  annular  liga- 
nient,  passes  downwards  and  outwards,  and  is  inserted  into  the  whole  length 
of  the  metacarpal  bone  of  the  thumb  on  its  radial  side. 

Fig.  244. — Muscles  of  the  Left  Hand.     Palmar  Surface. 


Relations.  By  its  superficial  surface^  witn  the  Abductor  Pollicis.  Bj  its  deep 
surface^  with  the  trapezio-metacarpal  articulation.  By  its  iniier  border^  with  the 
Flexor  Brevis  Pollicis. 

The  Flexor  Brevis  Pollicis  is  much  larger  than  either  of  the  two  preceding 
muscles,  beneath  which  it  is  placed.  It  consists  of  two  portions,  in  the  interval 
between  which  lies  the  tendon  of  the  Flexor  Longus  Pollicis.     The  anterior  and 


396  MUSCLES    AND    FASCIA. 

more  superficial  portion  arises  from  the  trapezium  and  outer  two-thirds  of  the 
annular  ligament;  the  deeper  portion  from  the  trapezoides,  os  magnum,  base 
of  the.  third  metacarpal  bone,  and  sheath  of  the  tendon  of  the  Flexor  Carpi 
Radiaiis.  The  fleshy  fibres  unite  to  form  a  single  muscle;  this  divides  into  two 
portions,  which  are  inserted  one  on  either  side  of  the  base  of  the  first  phalanx 
of  the  thumb,  the  outer  portion  being  joined  with  the  Abductor,  and  the  inner 
with  the  Adductor.  A  sesamoid  bone  is  developed  in  each  tendon  as  it  passes 
across  the  metacarpo-phalangeal  joint. 

Relations.  By  its  superficial  surface^  with  the  palmar  fascia.  By  its  deep 
surface^  with  the  Adductor  Pollicis,  and  tendon  of  the  Flexor  Carpi  Radiaiis. 
By  its  external  surface,  with  the  Opponens  Pollicis.  By  its  internal  surface,  with 
the  tendon  of  the  Flexor  Longus  Pollicis. 

The  Adductor  Pollicis  (Fig.  240)  is  the  most  deeply-seated  of  this  group  of 
muscles.  It  is  of  a  triangular  form,  arising,  by  its  broad  base,  from  the  whole 
length  of  the  metacarpal  bone  of  the  middle  finger  on  its  palmar  surface ;  the 
fibres,  proceeding  outwards,  converge,  to  be  inserted  with  the  innermost  tendon 
of  the  Flexor  Brevis  Pollicis,  into  the  ulnar  side  of  the  base  of  the  first  phalanx 
of  the  thumb,  and  into  the  internal  sesamoid  bone. 

Relations.  By  its  superficial  surface,  with  the  Flexor  Brevis  Pollicis,  the 
tendons  of  the  Flexor  Profundus  and  the  Lumbricales.  Its  deep  surface  covers 
the  first  two  interosseous  spaces,  from  which  it  is  separated  by  a  strong 
aponeurosis. 

Nerves.  The  Abductor,  Opponens,  and  outer  head  of  the  Flexor  Brevis 
Pollicis,  are  supplied  by  the  median  nerve;  the  inner  head  of  the  Flexor 
Brevis,  and  the  Adductor  Pollicis,  by  the  ulnar  nerve. 

Actions.  The  actions  of  the  muscles  of  the  thumb  are  almost  suflBciently 
indicated  by  their  names.  This  segment  of  the  hand  is  provided  with  three 
extensors,  an  Extensor  of  the  metacarpal  bone,  an  Extensor  of  the  first,  and 
an  Extensor  of  the  second  phalanx ;  these  occupy  the  dorsal  surface  of  the 
forearm  and  hand.  There  are,  also,  three  flexors  on  the  palmar  surface,  a 
Flexor  of  the  metacarpal  bone,  the  Flexor  Ossis  Metacarpi  (Opponens  Pollicis), 
the  Flexor  Brevis  Pollicis,  and  the  Flexor  Longus  Pollicis ;  there  is  also  an 
Abductor  and  an  Adductor.  These  muscles  give  to  the  thumb  its  extensive 
range  of  motion. 

Ulnar  Region.    (Fig.  244.) 

Muscles  of  the  Little  Finger. 

Palmaris  Brevis,  Flexor  Brevis  Minimi  Digiti. 

Abductor  Minimi  Digiti.     Opponens  Minimi  Digiti  (Flexor  Ossis  Metacarpi). 

The  Palmaris  Brevis  is  a  thin  quadrilateral  muscle,  placed  beneath  the  integu- 
ment on  the  ulnar  side  of  the  hand.  It  arises  by  tendinous  fasciculi,  from  the 
annular  ligament  and  palmar  fascia;  the  fleshy  fibres  pass  horizontally  inwards, 
to  be  inserted  into  the  skin  on  the  inner  border  of  the  palm  of  the  hand. 

Relations.  By  its  superficial  surface,  with  the  integument  to  which  it  is  inti- 
mately adherent,  especially  by  its  inner  extremity.  By  its  deep)  surface,  with 
the  inner  portion  of  the  palmar  fascia,  which  separates  it  from  the  ulnar  vessels 
and  nerve,  and  from  the  muscles  of  the  ulnar  side  of  the  hand. 

The  Abductor  Minimi  Digiti  is  situated  on  the  ulnar  border  of  the  palm  of 
the  hand.  It  arises  from  the  pisiform  bone,  and  from  an  expansion  of  the  ten- 
don of  the  Flexor  Carpi  Ulnaris;  and  terminates  in  a  flat  tendon,  which  is 
inserted  into  the  ulnar  side  of  the  base  of  the  first  phalanx  of  the  little  finger. 

Relations.  By  its  superficial  surface,  with  the  inner  portion  of  the  palmar 
fascia,  and  the  Palmaris  Brevis.  By  its  deep  surface,  with  the  Flexor  Ossis 
Metacarpi.     By  its  mner  border,  with  the  Flexor  Brevis  Minimi  Digiti. 

The  Flexor  Brevis  Minimi  Digiti  lies  on  the  same  plane  as  the  preceding 
muscle,  on  its  radial  side.    It  arises  from  the  tip  of  the  unciform  process  of 


OF    THE    HAND. 


397 


the  unciform  bone,  and  anterior  surface  of  the  annular  ligament,  and  is  inserted 
into  the  base  of  the  first  phalanx  of  the  little  finger,  with  the  preceding.  It 
is  separated  from  the  Abductor  at  its  origin,  bj  the  deep  branches  of  the  ulnar 
artery  and  nerve.  This  muscle  is  sometimes  wanting;  the  Abductor  is  then, 
usually,  of  large  size. 

Relations.  By  its  superficial  surface,  with  the  internal  portion  of  the  palmar 
fascia,  and  the  Palmar  Brevis.     By  its  deep  surface,  with  the  Opponens. 

The  Opponens  Minimi  Digiti  (Fig.  240)  is  of  a  triangular  form,  and  placed 
immediately  beneath  the  preceding  muscles.  It  arises  from  the  unciform  pro- 
cess of  the  unciform  bone,  and  contiguous  portion  of  the  annular  ligament;  its 
fibres  pass  downwards  and  inwards,  to  be  inserted  into  the  whole  length  of 
the  metacarpal  bone  of  the  little  finger,  along  its  ulnar  margin. 

Relations.  By  its  superficial  surface,  with  the  Flexor  Brevis,  and  Abductor 
Minimi  Digiti.  By  its  deep  surface,  with  the  interossei  muscles  in  the  fourth  meta- 
carpal space,  the  metacarpal  bone,  and  the  flexor  tendons  of  the  little  finger. 

Nerves.     All  the  muscles  of  this  group  are  supplied  by  the  ulnar  nerve. 

Actions.  The  actions  of  the  muscles  of  the  little  finger  are  expressed  in  their 
names.  The  Palmaris  Brevis  corrugates  the  skin  on  the  inner  side  of  the  palm 
of  the  hand. 

Palmar  Eegiojs". 

Lumbricales.  Interossei  Palmares. 

Interossei  Dorsales. 

The  Lumhricales  (Fig.  244)  are  four  small  fleshy  fasciculi,  accessories  to  the 
deep  Flexor  muscle.  They  arise  by  fleshy  fibres  from  the  tendons  of  the  deep 
Flexor ;  the  first  and  second,  from  the  radial  side  and  palmar  surface  of  the 
tendons  of  the  index  and  middle  fingers ;  the  third,  from  the  contiguous  sides 
of  the  tendons  of  the  middle  and  ring  fingers ;  and  the  fourth,  from  the  con- 
tiguous sides  of  the  tendons  of  the  ring  and  little  fingers.  They  pass  forwards 
to  the  radial  side  of  the  corresponding 
fingers,  and  opposite  the  metacarpo-pha- 
langeal  articulation  each  tendon  terminates 
in  a  broad  aponeurosis,  which  is  inserted 
into  the  tendinous  expansion  from  the  Ex- 
tensor Communis  Digitorum,  covering  the 
dorsal  aspect  of  each  finger. 

The  Interossei  Muscles  are  so  named  from 
occupying  the  intervals  between  the  meta- 
carpal bones.  They  are  divided  into  two 
sets,  a  dorsal  and  palmar ;  the  former  are 
four  in  number,  one  in  each  metacarpal 
space ;  the  latter,  three  in  number,  lie  upon 
the  metacarpal  bones. 

The  Dorsal  Interossei  are  four  in  num- 
ber, larger  than  the  palmar,  and  occupy 
the  intervals  between  the  metacarpal  bones. 
They  are  bipenniform  muscles,  arising  by 
two  heads  from  the  adjacent  sides  of  the 
metacarpal  bones,  but  more  extensively 
from  that  side  of  the  metacarpal  bone  which 
corresponds  to  the  side  of  the  finger  in 
which  the  muscle  is  inserted.  They  are 
inserted  into  the  base  of  the  first  phalanges 
and  into  the  aponeurosis  of  the  common 
Extensor  tendon.  Between  the  double  origin  of  each  of  these  muscles  is  a 
narrow  triangular  interval,  through  which  passes  a  perforating  branch  from 
the  deep  palmar  arch. 


Fiff.  245. 


-The  Dorsal  Interossei  of  the 
Left  Hand. 


398 


MUSCLES    AND    FASCIA. 


The  First  Dorsal  Interosseous  muscle,  or  Abductor  Indicis,  is  larger  than  the 
others.  It  is  flat,  triangular  in  form,  and  arises  by  two  heads,  separated  by  a 
fibrous  arch,  for  the  passage  of  the  radial  artery  from  the  dorsum  to  the  palm 
of  the  hand.  The  outer  head  arises  from  the  upper  half  of  the  ulnar  border  of 
the  first  metacarpal  bone ;  the  inner  head,  from  almost  the  entire  length  of  the 
radial  border  of  the  second  metacarpal  bone ;  the  tendon  is  inserted  into  the 
radial  side  of  the  index  finger.  The  second  and  third  dorsal  interossei  are  in- 
serted into  the  middle  finger,  the  former  into  its  radial,  the  latter  into  its  ulnar 
side.     The  fourth  is  inserted  into  the  ulnar  side  of  the  ring  finger. 

The  Palmar  Interossei^  three  in  number,  are  smaller  than  the  Dorsal,  and 
placed  upon  the  palmar  surface  of  the  metacarpal  bones,  rather  than  between 

them.     They  arise  from  the  entire  length  of  the 
Fig.  246.-The^Pdinar  Interossei    metacarpal  bone  of  one  finger,  and  are  inserted 

into  the  side  of  the  base  of  the  first  phalanx  and 
aponeurotic  expansion  of  the  common  Extensor 
tendon  of  the  same  finger. 

The  first  arises  from  the  ulnar  side  of  the 
second  metacarpal  bone,  and  is  inserted  into  the 
same  side  of  the  index  finger.  The  second  arises 
from  the  radial  side  of  the  fourth  metacarpal 
bone,  and  is  inserted  into  the  same  side  of  the 
ring  finger.  The  third  arises  from  the  radial 
side  of  the  fifth  metacarpal  bone,  and  is  inserted 
into  the  same  side  of  the  little  finger.  From 
this  account  it  may  be  seen,  that  each  finger  is 
provided  with  two  Interossei  muscles,  with  the 
exception  of  the  little  finger,  in  which  the  Ab- 
ductor muscle  takes  the  place  of  one  of  the 
pair. 

Nerves.  The  two  outer  Lurabricales  are  sup- 
plied by  the  median  nerve ;  the  rest  of  the  mus- 
cles of  this  group,  by  the  ulnar. 

Actions.  The  Dorsal  Interossei  muscles  ab- 
duct the  fingers  from  an  imaginary  line  drawn 
longitudinally  through  the  centre  of  the  middle 
finger;  and  the  Palmar  Interossei  adduct  the 
fingers  towards  that  line.  They  usually  assist  the  extensor  muscles;  but 
when  the  fingers  are  slightly  bent,  they  assist  in  flexing  them.' 

SUEGICAL  ANATOMY. 

The  student,  having  completed  the  dissection  of  the  muscles  of  the  upper  extremity,  should 
consider  the  effects  likely  to  be  produced  by  the  action  of  the  various  muscles  in  fracture  of  the 
bones. 

In  considering  the  actions  of  the  various  muscles  upon  Fractures  of  the  Upper  Extremity,  I 
have  selected  the  most  common  forms  of  injury,  both  for  illustration  and  description. 


'  M.  Duchenne  gives  a  different  account  of  the  mechanism  of  the  extension  of  the  fingers 
and  of  the  action  of  the  interossei  muscles  from  that  usually  accepted.  According  to  him,  the 
extensor  communis  digitorum  acts  almost  entirely  on  the  first  phalanges,  extension  of  the 
second  and  third  phalanges  being  effected  by  the  interossei  muscles,  which  also  act  to  a  certain 
extent  as  flexors  of  the  first  pnalanges.  This  action  of  the  interossei  is  additional  to  their 
action  in  abduction  and  adduction  ("  Physiologic  des  Mouvements,"  pp.  2G1-298).  M.  Du- 
chenne's  view  of  the  action  of  these  muscles  certainly  derives  support  from  the  phenomena 
observed  in  lead-palsy  and  from  the  results  of  galvanizing  the  common  extensor  and  the  inter- 
ossei, as  Dr.  W.  Ogle  has  been  kind  enough  to  point  out  to  me.  Thus  also  in  a  case  related  by 
Mr.  Hutchinson,  in  which  the  ulnar  nerve  had  been  divided  below  the  part  from  which  the  ex- 
tensor communis  was  supplied  (and  therefore  the  interossei  were  paralyzed  while  the  extensor 
acted),  "the  first  phalanges  were  bent  backwards  on  the  metacarpal  bones"  (extended)  "while 
the  fingers  were  curved  into  the  palm"  (second  and  third  phalanges  flexed). — London  Hospital 
Reports,  vol.  iii.  p.  307. 


FRACTURES  OF  THE  UPPER  EXTREMITY. 


399 


Fig.  247. — Fracture  of  the  Middle  of  the 
Clavicle. 


Fracture  of  the  clavicle  is  an  exceedingly  common  accident,  and  is  usually  caused  by  indirect 
violence,  as  a  fall  upon  the  shoulder ;  it  occasionally,  however,  occurs  from  direct  force.  Its 
most  usual  situation  is  just  external  to  the  centre  of  the  bone,  but  it  may  occur  at  the  sternal 
or  acromial  end. 

Fracture  of  the  middle  of  the  clavicle  (Fig.  247)  is  always  attended  with  considerable  displace- 
ment, the  outer  fragment  being  drawn  downwards,  forwards,  and  inwards  ;  the  inner  fragment 
slightly  upwards.  The  outer  fragment  is  drawn  down 
by  the  weight  of  the  arm,  and  the  action  of  the  Del- 
toid, and  forwards  and  inwards  by  the  Pectoralis 
Minor  and  Subclavius  muscles  :  the  inner  fragment  is 
slightly  raised  by  the  Sterno-cleido-mastoid,  but  only 
to  a  very  limited  extent,  as  the  attachment  of  the 
costo-clavicular  ligament  and  Pectoralis  Major  below 
and  in  front  would  prevent  any  very  great  displace- 
ment upwards.  The  causes  of  displacement  having 
been  ascertained,  it  is  easy  to  apply  the  appropriate 
treatment.  The  outer  fragment  is  to  be  drawn  out- 
wards, and,  together  with  the  scapula,  raised  upwards 
to  a  level  with  the  inner  fragment,  and  retained  in  that 
position. 

In  fracture  of  the  acromial  end  of  the  clavicle, 
between  the  conoid  and  trapezoid  ligaments,  only 
slight  displacement  occurs,  as  these  ligaments,  from 
their  oblique  insertion,  serve  to  hold  both  portions  of 
the  bone  in  apposition.  Fracture,  also,  of  the  sternal 
end,  internal  to  the  costo-clavicular  ligament,  is  at- 
tended with  only  slight  displacement,  this  ligament 
serving  to  retain  the  fragments  in  close  apposition. 

Fracture  of  the  acromion  process  usually  arises 
from  violence  applied  to  the  upper  and  outer  part  of 
the  shoulder ;  it  is  generally  known  by  the  rotundity 
of  the  shoulder  being  lost,  from  the  Deltoid  drawing 
the  fractured  portion  downwards  and  forwards ;  and 
the  displacement  may  easily  be  discovered  by  tracing 
the  margin  of  the  clavicle  outwards,  when  the  frag- 
ment will  be  found  resting  on  the  front  and  upper 
part  of  the  head  of  the  humerus.  In  order  to  relax 
the  anterior  and  outer  fibres  of  the  Deltoid  (the  opposing  muscle),  the  arm  should  be  drawn 
forwards  across  the  chest,  and  the  elbow  well  raised,  so  that  the  head  of  the  bone  may  press  the 
acromion  process  upwards,  and  retain  it  in  its  position. 

Fracture  of  the  coracoid  process  is  an  extremely  rare  accident,  and  is  usually  caused  by  a 
sharp  blow  on  the  point  of  the  shoulder.  Displacement  is  here  produced  by  the  combined 
actions  of  the  Pectoralis  Minor,  short  head  of  the  Biceps,  and  Coraco-brachialis,  the  former 
muscle  drawing  the  fragment  inwards,  and  the  latter  di- 
rectly downwards,  the  amount  of  displacement  being  limited 
by  the  connection  of  this  process  to  the  acromion  by  means 
of  the  coraco-acromial  liguraent.  In  order  to  relax  these 
muscles  and  replace  the  fragments  in  close  apposition,  the 
forearm  should  be  flexed  so  as  to  relax  the  Biceps,  and  the 
arm  drawn  forwards  and  inwards  across  the  chest  so  as  to 
relax  the  Coraco-brachialis  ;  the  humerus  should  then  be 
pushed  upwards  against  the  coraco-acromial  ligament,  and 
the  arm  retained  in  that  position. 

Fracture  of  the  anatomical  neck  of  the  humerus  within 
the  capsular  ligament  is  a  rare  accident,  attended'with  very 
slight  displacement,  an  impaired  condition  of  the  motions 
of  the  joint,  and  crepitus. 

Fracture  of  the  surgical  necJc  (Fig.  248)  is  very  common, 
is  attended  with  considerable  displacement,  and  its  appear- 
ances correspond  somewhat  with  those  of  dislocation  of  the 
head  of  the  humerus  into  the  axilla.  The  upper  fragment  is 
slightly  elevated  under  the  coraco-acromial  ligament  by  the 
muscles  attached  to  the  greater  and  lesser  tuberosities ;  the 
lower  fragment  is  drawn  inwards  by  the  Pectoralis  Major, 
Latissimus  Dorsi,  and  Teres  Major;  and  the  humerus  is  thrown 
obliquely  outwards  from  the  side  by  the  Deltoid,  and  occa- 
sionally elevated  so  as  to  project  beneath  and  in  front  of  the 
coracoid  process.  The  deformity  is  reduced  by  fixing  the  shoulder,  and  drawing  the  arm  out- 
wards and  downwards.  To  counteract  the  opposing  muscles,  and  to  keep  the  fragments  in  position, 
the  arm  should  be  drawn  from  the  side,  and  pasteboard  splints  applied  on  its  four  sides,  a 
large  conical-shaped  pad  should  be  placed  in  the  axilla  with  the  base  turned  upwards,  and  tho 


248. — Fracture  of  the  Surgical 
Neck  of  the  Humerus. 


400 


SURGICAL    ANATOMY. 


249. — Fracture  of  the  Humerus 
above  the  Condyles. 


elbow  approximated  to  the  side,  and  retained  there  by  a  broad  roller  passed  round  the  chest ;  the 
forearm  should  then  be  flexed,  and  the  hand  supported  in  a  sling,  care  being  taken  not  to  raise 
the  elbow,  otherwise  the  lower  fragment  may  be  displaced  upwards. 

In  fracture  of  the  shaft  of  the  humerus  below  the  insertion  of  the  Pectoralis  Major,  Latissimus 
Dorsi,  and  Teres  Major,  and  above  the  insertion  of  the  Deltoid,  there  is  also  considerable  deformity, 
the  upper  fragment  being  drawn  inwards  by  the  first-mentioned  muscles,  and  the  lower  fragment 
upwards  and  outwards  by  the  Deltoid,  producing  shortening  of  the  limb,  and  a  considerable 
prominence  at  the  seat  of  fracture,  from  the  fractured  ends  of  the  bone  riding  over  one  another, 
especially  if  the  fracture  takes  place  in  an  oblique  direction.  The  fragments  may  be  brought 
into  apposition  by  extension  from  the  elbow,  and  retained  in  that  position  by  adopting  the  same 
means  as  in  the  preceding  injury. 

In  fracture  of  the  shaft  of  the  humerus  immediately  below  the  insertion  of  the  Deltoid,  the 
amount  of  deformity  depends  greatly  upon  the  direction  of  the  fracture.  If  the  fracture  occurs 
in  a  transverse  direction,  only  slight  displacertient  Oiccurs,  the  upper  fragment  being  drawn  a 
little  forwards  ;  but  in  oblique  fracture,  the  combined  actions  of  the  Biceps  and  Brachialis  Anti- 
cus  muscles  in  front,  and  the  Triceps  behind,  draw  upwards  the  lower  fragment,  causing  it  to 
glide  over  the  upper  fragment,  either  backwards  or  forwards,  according  to  the  direction  of  the 
fracture.  Simple  extension  reduces  the  deformity,  and  the 
application  of  splints  on  the  four  sides  of  the  arm  will 
retain  the  fragments  in  apposition.  Care  should  be  taken 
not  to  raise  the  elbow ;  but  the  forearm  and  hand  may  be 
Bupported  in  a  sling. 

Fracture  of  the  humerus  (Fig.  249)  immediately  above 
the  condyles  deserves  very  attentive  consideration,  as  the 
general  appearances  correspond  somewhat  with  those  pro- 
duced by  separation  of  the  epiphysis  of  the  humerus,  and 
with  those  of  dislocation  of  the  radius  and  ulna  backwards. 
If  the  direction  of  the  fracture  is  oblique  from  above, 
downwards,  and  forwards,  the  lower  fragment  is  drawn 
upwards  and  backwards  by  the  Brachialis  Anticus  and 
Biceps  in  front,  and  the  Triceps  behind.  This  injury  may 
be  diagnosed  from  dislocation,  by  the  increased  mobility  in 
fracture,  the  existence  of  crepitus,  and  the  fact  of  the 
deformity  being  remedied  by  extension,  on  the  discontinu- 
ance of  which  it  is  reproduced.  The  age  of  the  patient  is 
of  importance  in  distinguishing  this  form  of  injury  from 
separation  of  the  epiphysis.  If  fracture  occurs  in  the  op- 
posite direction  to  that  shown  in  the  accompanying  figure, 
the  lower  fragment  is  drawn  upwards  and  forwards,  causing 
a  considerable  prominence  in  front ;  and  the  upper  fragment 
projects  backwards  beneath  the  tendon  of  the  Triceps 
muscle. 

Fracture  of  the  coronoid  process  of  the  ulna  is  an  ac- 
cident of  rare  occurrence,  and  is  usually  caused  by  violent 

action  of  the  Brachialis  Anticus  muscle.  The  amount  of  displacement  varies  according  to  the 
extent  of  the  fracture.  If  the  tip  of  the  process  only  is  broken  off,  the  fragment  is  drawn  up- 
wards by  the  Brachialis   Anticus  on  a  level 

with  the  coronoid  depression  of  the  humerus,  2.50. — Fracture  of  the  Olecranon. 

and  the  power  of  flexion  is  partially  lost.  If 
the  process  is  broken  oS"  near  its  root,  the 
fragment  is  still  displaced  by  the  same  muscle  ; 
at  the  same  time,  on  extending  the  forearm, 
partial  dislocation  backwards  of  the  ulna 
occurs  from  the  action  of  the  Triceps  muscle. 
The  appropriate  treatment  would  be  to  relax 
the  Brachialis  Anticus  by  flexing  the  forearm, 
and  to  retain  the  fragments  in  apposition  by 
keeping  the  arm  in  this  position.  Union  is 
generally  ligamentous. 

Fracture  of  the  olecranon  process  (Fig.  2.50) 
is  a  more  frequent  accident,  and  is  caused 
either  by  violent  action  of  the  Triceps  muscle, 
cv  by  a  fall  or  blow  upon  the  point  of  the 
elbow.  The  detached  fragment  is  displaced 
upwards,  by  the  action  of  the  Tricens  muscle, 
from  half  an  inch  to  two  inches ;  the  promi- 
nence of  the  elbow  is  cimsequently  lost,  and  a 
deep  hollow  is  felt  at  the  back  part  of  the 
joint,  which  is  much  increased  on  flexing  the  limb.  The  patient  at  the  same  time  loses,  more  or 
less,  the  power  of  extending  the  forearm.  The  treatment  consists  in  relaxing  the  Triceps  by 
extending  the  limb,  and  retaining  it  in  the  extended  position  by  means  of  a  long  straight  splint 


FRACTURES  OF  THE  UPPER  EXTREMITY.     401 

applied  to  the  front  of  the  arm  ;  the  fragments  are  thus  brought  into  close  apposition,  and  may 
be  further  approximated  by  drawing  down  the  upper  fragment.     Union  is  generally  ligamentous. 

Fracture  of  the  neck  of  the  radius  is  an  exceedingly  rare  accident,  and  is  generally  caused 
bv  direct  violence.  Its  diagnosis  is  somewhat  obscure,  on  account  of  the  slight  deformity  visible; 
the  injured  part  being  surrounded  by  a  large  number  of  muscles;  but  the  movements  of  prona- 
tion and  supination  are  entirely  lost.  The  upper  fragment  is  drawn  outwards  by  the  Supinator 
Brevis,  its  extent  of  displacement  being  limited  by  the  attachment  of  the  orbicular  ligament. 
The  lower  fragment  is  drawn  forwards  and  slightly  upwards  by  the  Biceps,  and  inwards  by  the 
Pronator  Radii  Teres,  its  displacement  forwards  and  upwards  being  counteracted  in  some  degree 
by  the  Supinator  Brevis.  The  treatment  essentially  consists  in  relaxing  the  Biceps,  Supinator 
Brevis,  and  Pronator  Radii  Teres  muscles,  by  flexing  the  forearm,  and  placing  it  in  a  positirn 
midway  between  pronation  and  supination,  extension  having  been  previously  made  so  as  to  bring 
the  parts  in  apposition. 

Fracture  of  the  radius  (Fig.  251)  is  more  common  than  fracture  of  the  ulna,  on  account  of 
the  connection  of  the  former  bon^with  the  wrist.  Fracture  of  the  shaft  of  the  radius  near  its 
centre   may  occur   from   direct   violence,  but 

more  frequently  from  a  fall  forwards,  the  Fig.  251. — Fracture  of  the  Shaft  of  the  Radius. 
weight  of  the  body  being  received  on  the  wrist 
and  hand.  The  upper  fragment  is  drawn  up- 
wards by  the  Biceps,  and  inwards  by  the  Pro- 
nator Radii  Teres,  holding  a  position  midway 
between  pronation  and  supination,  and  a  de- 
gree of  fulness  in  the  upper  half  of  the  forearm 
is  thus  produced  ;  the  lower  fragment  is  drawn 
downwards  and  inwards  towards  the  ulna  by 
the  Pronator  Quadratus,  and  thrown  into  a 
state  of  pronation  by  the  same  muscle ;  at  the 
same  time,  the  Supinator  Longus,  by  elevating 
the  styloid  process,  into  which  it  is  inserted,  will  serve  to  depress  the  upper  end  of  the  lower 
fragment  still  more  towards  the  ulna.  In  order  to  relax  the  opposing  muscles,  the  forearm 
should  be  bent,  and  the  limb  placed  in  a  position  midway  between  pronation  and  supination ; 
the  fracture  is  then  easily  reduced  by  extension  from  the  wrist  and  elbow;  well-padded  splints 
should  then  be  applied  on  both  sides  of  the  forearm  from  the  elbow  to  the  wrist;  the  hand  being 
allowed  to  fall,  will,  by  its  own  weight,  counteract  the  action  of  the  Pronator  Quadratus  and 
Supinator  Longus,  and  elevate  the  lower  fragment  to  the  level  of  the  upper  one. 

Fracture  of  the  shaft  of  the  idna  is  not  a  common  accident ;  it  is  usually  caused  by  direct 
violence.  The  more  protected  position  of  the  ulna  on  the  inner  side  of  the  limb,  the  greater 
strength  of  its  shaft,  and  its  indirect  connection  with  the  wrist,  render  it  less  liable  to  .injury 
than  the  radius.  The  fracture  usually  occurs  a  little  below  the  middle,  which  is  the  weakest 
part  of  the  bone.  The  upper  fragment  retains  its  usual  position ;  but  the  lower  fragment  is 
drawn  outwards  towards  the  radius  by  the  Pronator  Quadratus,  producing  a  well-marked  de- 
pression at  the  seat  of  fracture,  and  some  fulness  on  the  dorsal  and  palmar  surfaces  of  the 
forearm.  The  fracture  is  easily  reduced  by  extension  from  the  wrist  and  forearm.  The  forearm 
should  be  flexed,  and  placed  in  a  position  midway  between  pi'bnation  and  supination,  and  well- 
padded  splints  applied  from  the  elbow  to  the  ends  of  the  fingers. 

Fracture  of  the  shafts  of  the  radius  and  ulna  together  is  not  a  very  common  accident;  it  may 
arise  from  a  direct  blow,  or  from  indirect  violence.  The  lower  fragments  are  drawn  upwards, 
sometimes  forwards,  sometimes  backwards,  according  to  the  direction  of  the  fracture,  by  the 
combined  actions  of  the  flexor  and  extensor  muscles,  producing  a  degree  of  fulness  on  the 
dorsal  or  palmar  surface  of  the  forearm  ;  at  the  same  time  the  two  fragments  are  drawn  into 
contact  by  the  Pronator  Quadratus,  the  radius  in  a  state  of  pronation ;  the  upper  fragment  of 
the  radius  is  drawn  upwards  and  inwards  by  the  Biceps  and  Pronator  Radii  Teres  to  a  higher 
level  than  the  ulna ;  the  upper  portion  of  the  ulna  is  slightly  elevated  by  the  Brachialis  Anticus. 
The  fracture  may  be  reduced  by  extension  from  the  wrist  and  elbow,  and  the  forearm  should  be 
placed  in  the  same  position  as  in  fracture  of  the  ulna. 

In  the  treatment  of  all  cases  of  fracture  of  the  bones  of  the  forearm,  the  greatest  care  is 
requisite  to  prevent  the  ends  of  the  bones  from  being  drawn  inwards  towards  the  interosseous 
space ;  if  this  point  is  not  carefully  attended  to,  the  radius  and  ulna  may  become  anchylosed, 
and  the  movements  of  pronation  and  supination  entirely  lost.  To  obviate  this,  the  splints 
applied  to  the  limb  should  be  well  padded,  so  as  to  press  the  muscles  down  into  their  normal 
situation  in  the  interosseous  space,  and  thus  prevent  the  approximation  of  the  fragments. 

Fracture  of  the  lower  end  of  the  radius  (Fig.  252)  is  usually  called  Colles's fracture,  from  the 
name  of  the  eminent  Dublin  surgeon  who  first  accurately  described  it.  It  is  generally  produced 
by  the  patient  falling  upon  the  hand,  which  receives  the  entire  weight  of  the  body.  This  frac- 
ture usually  takes  place  from  half  an  inch  to  an  inch  above  the  articular  surface,  if  it  occurs  in 
the  adult ;  but  in  the  child,  before  the  age  of  sixteen,  it  is  more  frequently  a  separation  of  the 
epiphysis  from  the  diaphysis.  The  displacement  which  is  produced  is  very  considerable,  and 
bears  some  resemblance  to  dislocation  of  the  carpus  backwards,  from  which  it  should  be  care- 
fully distinguished.  The  lower  fragment  is  drawn  upwards  and  backwards  behind  the  upper 
fragment  by  the  combined  actions  of  the  Supinator  Longus  and  the  flexors  and  the  extensors 
26 


402 


MUSCLES    AND    FASCIA. 


of  the  thumb  and  carpus,  producing  a  well-marked  prominence  on  the  back  of  the  wrist,  with  a 
deep  depression  above  it.  The  upper  fragment  projects  forwards,  often  lacerating  the  substance 
of  the  Pronator  Quadratus,  and  is  drawn  by  this  muscle  into  close  contact  with  the  lower  end 
of  the  ulna,  causing  a  projection  on  the  anterior  surface  of  the  forearm,  immediately  above  the 

Fig.  252. — Fracture  of  the  Lower  End  of  the  Radius. 


carpus,  from  the  flexor  tendons  being  thrust  forwards.  This  fracture  may  be  distinguished  from 
dislocation  by  the  deformity  being  removed  on  making  sufiBcient  extension,  when  crepitus  may 
be  occasionally  detected ;  at  the  same  time,  on  extension  being  discontinued,  the  parts  imme- 
diately resume  their  deformed  appearance.  The  age  of  the  patient  will  also  assist  in  determining 
whether  the  injury  is  fracture  or  separation  of  the  epiphysis.  The  treatment  consists  in  flexing 
the  forearm,  and  making  powerful  extension  from  the  wrist  and  elbow,  depressing  at  the  same 
time  the  radial  side  of  the  hand,  and  retaining  the  parts  in  that  position  by  well-padded  ptstul- 
shaped  splints. 


MUSCLES  AND  FASCIA  OF  THE  LOWER  EXTREMITY. 

The  Muscles  of  the  Lower  Extremity  are  subdivided  into  groups,  corre- 
sponding with  the  different  regions  of  the  limb. 

Iliac  Region.  Obturator  Internus. 

Psoas  Magnus.  Gemellus  Inferior. 

Psoas  Parvus.  Obturator  Extern  us. 

Iliacus.  Quadratus  Femoris. 


Thigh. 
Anterior  Femoral  Region. 
Tensor  VaginsB  Femoris. 
Sartorius. 
Rectus. 

Vastus  Externus. 
Vastus  Internus. 
Crureus. 
Subcrureus. 

Internal  Femoral  Region. 
Gracilis. 
Pectineus. 
Adductor  Longus. 
Adductor  Brevis. 
Adductor  Magnus. 

Hip. 
Gluteal  Region, 
Gluteus  Maximus. 
Gluteus  Medius. 
Gluteus. Minimus. 
Piriformis. 
Gemellus  Superior. 


Posterior  Femoral  Region. 

Biceps. 

Semitendinosus. 

Semimembranosus. 

Leg. 

Anterior  Tihio-Jihular  Region. 

Tibialis  Anticus. 
Extensor  Proprius  Pollicis. 
Extensor  Longus  Digitorum. 
Peroneus  Tertius. 

Posterior  Tihio-fihular  Region. 
Superficial  Layer. 

Gastrocnemius. 

Soleus. 

Plantaris. 

Deep  Layer. 

Popliteus. 

Flexor  Longus  Pollicis. 
Flexor  Longus  Digitorum. 
Tibialis  Posticus. 


OF    THE    LOWER    EXTREMITY. 


403 


Fibular  Begion. 

Peroneus  Longus. 
Peroneus  Brevis. 

Foot. 
Dorsal  Region. 
Extensor  Brevis  Digitorum. 

Plantar  Region. 
First  Layer. 

Abductor  Pollicis. 
Flexor  Brevis  Digitorum. 
Abductor  Minimi  Digiti. 


Psoas  Magnus. 


Second  Layer. 

Flexor  Accessorius. 
Lumbricales. 

Tliird  Layer. 

Flexor  Brevis  Pollicis. 
Adductor  Pollicis. 
Flexor  Brevis  Minimi  Digiti. 
Transversus  Pedis. 

Fourth  Layer. 
The  Interossei. 


Iliac  Region. 
Psoas  Parvus. 


Iliacus. 


Dissection.  No  detailed  description  is  required  for  the  dissection  of  these  muscles.  On  the 
removal  of  the  viscera  from  the  abdomen,  they  are  exposed,  covered  by  the  peritoneum  and  a 
thin  layer  of  fascia,  the  fascia  iliaca. 

The  iliac  fascia  is  the  aponeurotic  layer  which  lines  the  back  part  of  the 
abdominal  cavity,  and  incloses  the  Psoas  and  Iliacus  muscles  throughout  their 
whole  extent.  It  is  thin  above;  and  becomes  gradually  thicker  below,  as  it 
approaches  the  femoral  arch. 

The  portion  investing  the  Psoas  is  attached,  above,  to  the  ligamentum  arcua- 
tum  internum ;  internally,  to  the  sacrum ;  and  'by  a  series  of  arched  processes 
to  the  intervertebral  substances,  and  prominent  margins  of  the  bodies  of  the 
vertebrse ;  the  intervals  so  left,  opposite  the  constricted  portions  of  the  bodies, 
transmitting  the  lumbar  arteries  and  filaments  of  the  sympathetic  nerve.  Ex- 
ternally, this  portion  of  the  iliac  fascia  is  continuous  with  the  fascia  lumborum. 

The  portion  investiiig  the  Iliacus  is  connected,  externally,  to  the  whole  length 
of  the  inner  border  of  the  crest  of  the  ilium ;  and  internally,  to  the  brim  of 
the  true  pelvis,  where  it  is  continuous  with  the  periosteum,  and  receives  the 
tendon  of  insertion  of  the  Psoas  Parvus,  when  that  muscle  exists.  External 
to  the  femoral  vessels,  this  fascia  is  intimately  connected  with  Poupart's  liga- 
ment, and  is  continuous  with  the  fascia  transversalis ;  but,  as  the  femoral  ves- 
sels pass  down  into  the  thigh,  it  is  prolonged  down  behind  them,  forming  the 
posterior  wall  of  the  femoral  sheath.  Under  the  femoral  sheath,  the  iliac  fascia 
surrounds  the  Psoas  and  Iliacus  muscles  to  their  termination,  and  becomes  con- 
tinuous with  the  iliac  portion  of  the  fascia  lata.  Internal  to  the  femoral  ves- 
sels, the  iliac  fascia  is  connected  with  the  ilio-pectineal  line,  and  is  continuous 
with  the  pubic  portion  of  the  fascia  lata.  The  iliac  vessels  lie  in  front  of  the 
iliac  fascia,  but  all  the  branches  of  the  lumbar  plexus  behind  it ;  it  is  separated 
from  the  peritoneum  by  a  quantity  of  loose  areolar  tissue.  In  abscess  accom- 
panying caries  of  the  lower  part  of  the  spine,  the  matter  makes  its  way  to  the 
femoral  arch,  distending  the  sheath  of  the  Psoas ;  and  when  it  accumulates  in 
considerable  quantity,  this  muscle  becomes  absorbed,  and  the  nervous  cords 
contained  in  it  are  dissected  out,  and  lie  exposed  in  the  cavity  of  the  abscess; 
the  femoral  vessels,  however,  remain  intact,  and  the  peritoneum  seldom  becomes 
implicated. 

(Remove  this  fascia,  and  the  muscles  of  the  iliac  region  will  be  exposed.) 

The  Psoas  Magnus  (Fig.  254)  is  a  long  fusiform  muscle,  placed  on  the  side  of 
the  lumbar  region  of  the  spine  and  margin  of  the  pelvis.  It  arises  from  the 
sides  of  the  bodies,  from  the  corresponding  intervertebral  substances,  and  from 
the  front  of  the  bases  of  the  transverse  processes  of  the  last  dorsal  and  all  the 
lumbar  vertebrae.  The  muscle  is  connected  to  the  bodies  of  the  vertebrae  by 
five  slips  ;  eaxjh  slip  is  attached  to  the  upper  and  lower  margins  of  two  vertebrae, 


404  MUSCLES    AND    FASCIA. 

and  to  the  intervertebral  substance  between  them ;  the  slips  themselves  being 
connected  by  the  tendinous  arches  which  extend  across  the  constricted  part  of 
the  bodies,  and  beneath  which  pass  the  lumbar  arteries  and  sympathetic  nerves. 
These  tendinous  arches  also  give  origin  to  muscular  fibres  and  protect  the 
bloodvessels  and  nerves  from  pressure  during  the  action  of  the  muscle.  The 
first  slip  is  attached  to  the  contiguous  margins  of  the  last  dorsal  and  first  lumbar 
vertebrae ;  the  last  to  the  contiguous  margins  of  the  fourth  and  fifth  lumbar, 
and  to  the  intervertebral  substance.  From  these  points,  the  muscle  passes  down 
across  the  brim  of  the  pelvis,  and  diminishing  gradually  in  size,  passes  behind 
Poupart's  Jigament,  and  terminates  in  a  tendon,  which,  after  receiving  the  fibres 
of  the  Iliacus,  is  inserted  into  the  lesser  trochanter  of  the  femur. 

Relations.  In  the  lumbar  region.  By  its  anterior  surface,  which  is  placed 
behind  the  peritoneum,  with  the  ligamentum  arcuatum  internum,  the  kidney, 
Psoas  Parvus,  renal  vessels,  ureter,  spermatic  vessels,  genito-crural  nerve,  the 
colon,  and  along  its  pelvic  border,  with  the  common  and  external  iliac  artery 
and  vein.  By  its  posterior  surface,  with  the  transverse  processes  of  the  lumbar 
vertebrae  and  the  Quadratus  Lumborum,  from  which  it  is  separated  by  the  an- 
terior lamella  of  the  aponeurosis  of  the  Transversalis.  The  anterior  crural 
nerve  is  at  first  situated  in  the  substance  of  the  muscle,  and  emerges  from  its 
outer  border  at  the  lower  part.  The  lumbar  plexus  is  situated  in  the  posterior 
part  of  the  substance  of  the  muscle.  By  its  inner  side,  the  muscle  is  in  relation 
with  the  bodies  of  the  lumbar  vertebrae,  the  lumbar  arteries,  the  sympathetic 
ganglia,  and  their  branches  of  communication  with  the  spinal  nerves;  the 
lumbar  glands ;  the  vena  cava  on  the  right,  and  the  aorta  on  the  left  side.  In 
the  thigh  it  is  in  relation,  in  front,  with  the  fascia  lata ;  behind,  with  the  cap- 
sular ligament  of  the  hip,  from  which  it  is  separated  by  a  synovial  bursa,  which 
sometimes  communicates  with  the  cavity  of  the  joint  through  an  opening  of 
variable  size ;  by  its  inner  border,  with  the  Pectineus  and  the  femoral  artery, 
which  slightly  overlaps  it ;  by  its  outer  border,  with  the  anterior  crural  nerve 
and  Iliacus  muscle. 

The  Psoas  Parvus  is  a  long  slender  muscle,  placed  in  front  of  the  preceding. 
It  arises  from  the  sides  of  the  bodies  of  the  last  dorsal  and  first  lumbar  vertebrc^, 
and  from  the  intervertebral  substance  between  thera.  It  forms  a  small  flat 
muscular  bundle,  which  terminates  in  a  long  flat  tendon,  inserted  into  the  ilio- 
pectineal  eminence,  and  continuous,  by  its  outer  border,  with  the  iliac  fascia. 
This  muscle  is  present,  according  to  M.  Theile,  in  one  out  of  every  twenty 
subjects  examined. 

Relations.  It  is  covered  by  the  peritoneum,  and  at  its  origin  by  the  liga- 
mentum arcuatum  internum ;  it  rests  on  the  Psoas  Magnus. 

The  Iliacus  is  a  flat  radiated  muscle,  which  fills  up  the  whole  of  the  interpal 
iliac  fossa.  It  arises  from  the  iliac  fossa,  and  inner  margin  of  the  crest  of  the 
ilium;  behind,  from  the  ilio-lumbar  ligament,  and  base  of  the  sacrum;  in  front, 
from  the  anterior  superior  and  anterior  inferior  spinous  processes  of  the  ilium, 
from  the  notcli  between  them,  and  by  a  few  fibres  from  the  capsule  of  the  hip- 
joint.  The  fibres  converge  to  be  inserted  into  the  outer  side  of  the  tendon  of 
the  Psoas,  some  of  them  being  prolonged  into  the  oblique  line  which  extends 
from  the  lesser  trochanter  to  the  linea  aspera. 

Relations.  Within  the  'pelvis:  by  its  anterior  surface,  with  the  iliac  fascia,  which 
separates  the  muscle  from  the  peritoneum,  and  with  the  external  cutaneous 
nerve;  on  the  right  side,  with  the  ca3cum;  on  the  left  side,  with  the  sigmoid 
iiexure  of  the  colon.  By  its  posterior  surface,  with  the  iliac  fossa.  By  its  inner 
border,  with  the  Psoas  Magnus,  and  anterior  crural  nerve.  In  the  thigh,  it  is  in 
relation,  by  its  anterior  surface,  with  the  fascia  lata.  Rectus  and  Sartorius ;  be- 
hind, with  the  capsule  of  the  hip-joint,  a  synovial  bursa  common  to  it  and  the 
Psoas  Magnus  being  interposed. 

Nerves.  The  Psoas  is  supplied  by  the  anterior  branches  of  the  lumbar 
nerves,  the  Iliacus  by  the  anterior  crural. 


FASCIA    OF    THE    THIGH. 


405 


Actions.  The  Psoas  and  Iliacus  muscles,  acting  from  above,  flex  the  thigh 
upon  the  pelvis,  and,  at  the  same  time,  rotate  the  femur  outwards,  from  the 
obliquity  of  their  insertion  into  the  inner  and  back  part  of  that  bone.  Acting 
from  below,  the  femur  being  fixed,  the  muscles  on  both  sides  bend  the  lambar 
portion  of  the  spine  and  pelvis  forwards.  They  also  serve  to  maintain  the  erect 
position,  by  supporting  the  spine  and  pelvis  upon  the  femur,  and  assist  in  rais« 
mg  the  trunk  when  the  body  is  in  the  recumbent  posture. 

The  Psoas  Parvus  is  a  tensor  of  the  iliac  fascia. 


Anterior  Femoral  Eegion. 


Tensor  Yaginas  Femoris. 

Sartorius. 

Eectus. 

Subcrureus. 


Vastus  Externus. 
Vastus  Internus. 
Crureus. 


Fig.  253. — Dissection  of  Lower  Ex- 
tremity.    Front  View. 


7  .  DCsarcfion 

"f 
FEMORAL  HERNIA, 

&. 
SCARPAS  TRIANGLE 


Z.  .  FRONT  .-/"THICH 


sr- 


Dissection.     To  expose  the  muscles  and  fasciae  in  this  region,  make  an  incision  along  Pon- 
part's  ligament,  from  the  spine  of  the  ilium  to  the  pubes,  a  vertical  incision  from  the  centre  of 
this,  along  the  middle  line  of  the  thigh  to  below  the  knee-joint,  and  a  transverse  incision  from 
the  inner  to  the  outer  side  of  the  leg,  at  the  lower  end 
of  the  vertical  incision.     The  flaps  of  integument 
having  been  removed,  the  superficial  and  deep  fasciae 
should  be  examined.     The  more  advanced  student 
should  commence  the  study  of  this  region  by  an  exa- 
mination of  the  anatomy  of  femoral  hernia,  and  Scar- 
pa's triangle,  the  incisions  for  the  dissection  of  which 
are  marked  out  in  the  accompanying  figure. 

Fasciee  of  the  Thigh,  The  superficial  fascia 
forms  a  continuous  layer  over  the  whole 
of  the  lower  extremity,  consisting  of  areolar 
tissue,  containing  in  its  meshes  much  adi- 
pose matter,  and  capable  of  being  separated 
into  two  or  more  layers,  between  which  are 
found  the  superficial  vessels  and  nerves. 
It  varies  in  thickness,  in  different  parts  of 
the  limb;  in  the  sole  of  the  foot  it  is  so 
thin  as  to  be  scarcely  demonstrable,  the 
integument  being  closely  adherent  to  the 
deep  fascia  beneath,  but  in  the  groin  it  is 
thicker,  and  the  two  layers  are  separated 
from  one  another  by  the  superficial  inguinal 
glands,  the  internal  saphenous  vein,  and 
several  smaller  vessels.  Of  these  two  lay- 
ers, the  superficial  is  continuous  above 
with  the  superficial  fascia  of  the  abdomen, 
the  deep  layer  becoming  blended  with  the 
fascia  lata,  a  little  below  Poupart's  ligament. 
The  deep  layer  of  superficial  fascia  is  inti- 
mately adherent  to  the  margins  of  the  sa- 
phenous opening  in  the  fascia  lata,  and 
pierced  in  this  situation  by  numerous  small 
blood  and  lymphatic  vessels ;  hence  the  name 
crihriform  fascia,  which  has  been  applied  to 
it.  Subcutaneous  bursae  are  found  in  the 
superficial  fascia  over  the  patella,  point  of 
the  heel,  and  phalangeal  articulations  of 
the  toes. 

The  deep  fascia  of  the  thigh  is  exposed  on  the  removal  of  the  superficial 
fascia,  and  is  named,  from  its  great  extent,  the  fascia  lata ;  it  forms  a  uniform 
investment  for  the  whole  of  this  rei>;ion  of  the  limb,  but  varies  in  thickness  in 


V 


A\    >^  .  DORSUM  gf  FOOT 


406 


MUSCLES    AND    FASCIA. 


Fi^.  254 

Anterior  F 


Muscles  of  the 
emoral  Reffions. 


\9y 


/■I'-Vf 


Iliac  and  different  parts ;  thus,  it  is  thickest  in  the 
upper  and  outer  part  of  the  thigh,  where  it 
receives  a  fibrous  expansion  from  the  Glu- 
teus Maximus  muscle,  and  the  Tensor  Va- 
ginae Femoris  is  inserted  between  its  layers: 
it  is  very  thin  behind,  and  at  the  upper  and 
inner  part,  where  it  covers  the  Adductor 
muscles,  and  again  becomes  stronger  around 
the  knee,  receiving  fibrous  expansions  from 
the  tendon  of  the  Biceps  externally,  and 
from  the  Sartorius,  Gracilis,  Semitendinosus, 
and  Quadriceps  Extensor  Cruris  in  front. 
The  fascia  lata  is  attached,  above,  to  Pou- 
part's  ligament,  and  the  crest  of  the  ilium; 
behind,  to  the  margin  of  the  sacrum  and 
coccyx;  internally,  to  the  pubic  arch,  and 
pectineal  line ;  and  below,  to  all  the  promi- 
nent points  around  the  knee-joint,  the  con- 
dyles of  the  femur,  tuberosities  of  the  tibia, 
and  head  of  the  fibula.  That  portion  which 
invests  the  Gluteus  Medius  (the  gluteal  apo- 
neurosis) is  very  thick  and  strong,  and  gives 
origin,  by  its  inner  surface,  to  some  of  the 
fibres  of  that  muscle ;  at  the  upper  border 
of  the  Gluteus  Maximus,  it  divides  into  two 
layers,  the  upper  of  which,  very  thin,  covers 
'^  the  surface  of  the  Gluteus  Maximus,  and  is 

continuous  below  with  the  fascia  lata :  the 
deep  layer  is  thick  above,  where  it  blends 
with  the  great  sacro-sciatic  ligament,  thin 
below,  where  it  separates  the  Gluteus  Maxi- 
mus from  the  deeper  muscles.  From  the 
inner  surface  of  the  fascia  lata  are  given  off 
two  strong  intermuscular  septa,  which  are 
attached  \o  the  whole  length  of  the  linea 
aspera;  the  external  and  stronger  one,  which 
extends  from  the  insertion  of  the  Gluteus 
Maximus  to  the  outer  condyle,  separates  the 
Vastus  Externus  in  front  from  the  short  head 
of  the  Biceps  behind,  and  gives  partial  origin 
to  those  muscles;  the  inner  one,  the  thinner 
of  the  two,  separates  the>  Vastus  Internus 
from  the  Adductor  muscles.  Besides  these, 
there  are  numerous  smaller  septa,  separating 
the  individual  muscles,  and  inclosing  each 
in  a  distinct  sheath.  At  the  upper  and  inner 
part  of  the  thigh,  a  little  below  Poupart's 
ligament,  a  large  oval-shaped  aperture  is 
observed  after  the  superficial  fascia  has  been 
cleared  off:  it  transmits  the  internal  saphe- 
nous vein,  and  other  smaller  vessels,  and  is 
termed  the  saphenoits  opening.  In  order  more 
correctly  to  consider  the  mode  of  formation 
of  this  aperture,  the  fascia  lata  is  described 
as  consisting,  in  this  part  of  the  tlugh,  of 
two  portions,  an  iliac  portion,  and  a  pubio 
portion. 


ANTERIOR    FEMORAL    REGION.  407 

The  iliac  portiofi  is  all  that  part  of  the  fascia  lata  on  the  outer  side  of  the 
saphenous  opening.  It  is  attached,  externally,  to  the  crest  of  the  ilium,  and  its 
anterior  superior  spine,  to  the  whole  length  of  Poupart's  ligament,  as  far  inter- 
nally as  the  spine  of  the  pubes,  and  to  the  pectineal  line  in  conjunction  with 
Gim^bernat's  ligament.  From  the  spine  of  the  pubes,  it  is  reflected  downwards 
and  outwards,  forming  an  arched  margin,  the  superior  cornu,  or  outer  boundary 
of  the  saphenous  opening ;  this  margin  oyerlies,  and  is  adherent  to  the  anterior 
layer  of  the  sheath  of  the  femoral  vessels;  to  its  edge  is  attached  the  cribriform 
fascia,  and,  below,  it  is  continuous  with  the  pubic  portion  of  the  fascia  lata. 

The  pubic  portion  is  situated  at  the  inner  side  of  the  saphenous  opening ;  at 
the  lower  margin  of  this  aperture  it  is  continuous  with  the  iliac  portion ;  traced 
upwards,  it  is  seen  to  cover  the  surface  of  the  Pectineus  muscle,  and  passing 
behind  the  sheath  of  the  femoral  vessels,  to  which  it  is  closely  united,  is  con- 
tinuous with  the  sheath  of  the  Psoas  and  Iliacus  muscles,  and  is  finally  lost  in 
the  fibrous  capsule  of  the  hip-joint.  This  fascia  is  attached  above  to  the  pecti- 
neal line  in  front  of  the  insertion  of  the  aponeurosis  of  the  External  Oblique, 
and  internally  to  the  margin  of  the  pubic  arch.  From  this  description  it  may 
be  observed,  that  the  iliac  portion  of  the  fascia  lata  passes  in  front  of  the  femo- 
ral vessels,  and  the  pubic  portion  behind  them,  so  that  an  apparent  aperture 
exists  between  the  two,  through  which  the  internal  saphenous  joins  the  femoral 
veins.^ 

The  fascia  should  now  be  removed  from  the  surface  of  the  muscles.  This  may  be  cflFected  by 
pinching  it  up  between  the  forceps,  dividing  it,  and  separating  it  from  each  muscle  in  the  course 
of  its  fibres. 

The  Tensor  Vaginse  Femoris  is  a  short  flat  muscle,  situated  at  the  upper  and 
outer  side  of  the  thigh.  It  arises  from  the  anterior  part  of  the  outer  lip  of  the 
crest  of  the  ilium,  and  from  the  outer  surface  of  the  anterior  superior  spinous 
process,  between  the  Gluteus  Medius  a,nd  Sartorius.  The  muscle  passes  obliquely 
downwards,  and  a  little  backwards,  to  be  inserted  into  the  fascia  lata,  about 
one-fourth  down  the  outer  side  of  the  thigh. 

Relations.  By  its  superficial  surface,  with  the  fascia  lata  and  the  integument. 
By  its  deep  surface,  with  the  Gluteus  Medius,  Eectus  Femoris,  Vastus  Externus, 
and  the  ascending  branches  of  the  external  circumflex  artery.  By  its  anterior 
border,  with  the  Sartorius,  from  which  it  is  separated  below  by  a  triangular 
space,  in  which  is  seen  the  Eectus  Femoris.  By  its  posterior  border,  with  the 
Gluteus  Medius. 

The  Sartorius,  the  longest  muscle  in  the  body,  is  flat,  narrow,  and  ribbon - 
like:  it  arises  by  tendinous  fibres  from  the  anterior  superior  spinous  process 
of  the  ilium  and  upper  half  of  the  notch  below  it,  passes  obliquely  across  the 
upper  and  anterior  part  of  the  thigh,  from  the  outer  to  the  inner  side  of  the 
limb,  then  descends  vertically,  as  far  as  the  inner  side  of  the  knee,  passing 
behind  the  inner  condyle  of  the  femur,  and  terminates  in  a  tendon,  which 
curving  obliquely  forwards,  expands  into  a  broad  aponeurosis,  inserted  into  the 
upper  part  of  the  inner  surface  of  the  shaft  of  the  tibia,  nearly  as  far  forwards 
as  the  crest.  This  expansion  covers  the  insertion  of  the  tendons  of  the  Gracilis 
and  Semitendinosus,  with  which  it  is  partially  united,  a  synovial  bursa  being 
interposed  between  them.  An  offset  is  derived  from  this  aponeurosis,  which 
blends  with  the  fibrous  capsule  of  the  knee-joint,  and  another,  given  off  from 
its  lower  border,  blends  with  the  fascia  on  the  inner  side  of  the  leg.  The  rela- 
tions of  this  muscle  to  the  femoral  artery  should  be  carefully  examined,  as  its 
inner  border  forms  the  chief  guide  in  tying  the  artery.  In  the  upper  third  of 
the  thigh,  it  forms,  with  the  Adductor  Longus,  the  side  of  a  triangular  space, 
Scarpa's  triangle,  the  base  of  which,  turned  upwards,  is  formed  by  Poupart's 
ligament;  the  femoral  artery  passes  perpendicularly  through  the  middle  of  this 

'  These  parts  will  be  again  more  particularly  described  with  the  anatomy  of  Hernia. 


408  MUSCLES    AND    FASCIA. 

space  from  its  base  to  its  apex.  In  the  middle  third  of  the  thigh,  the  femoral 
artery  lies  first  along  the  inner  border,  and  then  behind  the  Sartorius. 

Relations.  By  its  superficial  surface^  with  the  fascia  lata  and  integument.  By 
its  deep  surface,  with  the  Iliacus,  Psoas,  Rectus,  Vastus  Internus,  anterior  crural 
nerve,  sheath  of  the  femoral  vessels,  Adductor  Longus,  Adductor  Magnus,  Gra- 
cilis, long  saphenous  nerve,  and  internal  lateral  ligament  of  the  knee-joint. 

The  Quadriceps  Extensor  includes  the  four  remaining  muscles  on  the  front 
of  the  thigh.  It  is  the  great  extensor  muscle  of  the  leg,  forming  a  large  fleshy 
mass,  which  covers  the  front  and  sides  of  the  femur,  being  united  below  into  a 
single  tendon,  attached  to  the  tibia,  and  above  subdividing  into  separate  por- 
tions, which  have  received  distinct  names.  Of  these,  one  occupying  the  middle 
of  the  thigh,  connected  above  with  the  ilium,  is  called  the  Rectus  Femoris,  from 
its  straight  course.  The  other  divisions  lie  in  immediate  connection  with  the 
shaft  of  the  femur,  which  they  cover  from  the  condyles  to  the  trochanters. 
The  portion  on  the  outer  side  of  the  femur  is  termed  the  Vastus  Externus;  that 
covering  the  inner  side,  the  Vastus  Internus;  and  that  covering  the  front  of  the 
femur,  the  Crureus.  The  two  latter  portions  are,  however,  so  intimately 
blended,  as  to  form  but  one  muscle. 

The  Rectus  Femoris  is  situated  in  the  middle  of  the  anterior  region  of  the 
thigh;  it  is  fusiform  in  shape,  and  its  fibres  are  arranged  in  a  bipenniform 
manner.  It  arises  by  two  tendons;  one,  the  straight  tendon,  from  the  anterior 
inferior  spinous  process  of  the  ilium ;  the  other  is  flattened,  and  curves  out- 
wards, to  be  attached  to  a  groove  above  the  brim  of  the  acetabulum;  this  is  the 
reflected  tendon  of  the  Rectus,  it  unites  with  the  straight  tendon  at  an  acute 
angle,  and  then  spreads  into  an  aponeurosis,  from  which  the  muscular  fibres 
arise.  The  muscle  terminates  in  a  broad  and  thick  aponeurosis,  which  occupies 
the  lower  two-thirds  of  its  posterior  surface,  and  gradually  becoming  narrowed 
into  a  flattened  tendon,  is  inserted  into  the  patella  in  common  with  the  Vasti 
and  Crureus. 

Relations.  By  its  superficial  surface,  with  the  anterior  fibres  of  the  Gluteus 
Medius,  the  Tensor  Vaginae  Femoris,  Sartorius,  and  the  Psoas  and  Iliacus ;  by 
its  lower  three-fourths,  with  the  fascia  lata.  By  its  posterior  surface,  with  the 
hip-joint,  the  external  circumflex  vessels,  and  the  Crureus  and  Vasti  muscles. 

The  three  remaining  muscles  have  been  described  collectively  by  some 
anatomists,  separate  from  the  Rectus,  under  the  name  of  the  Triceps  Extensor 
Cruris;  in  order  to  expose  them,  divide  the  Sartorius  and  Rectus  across  the 
middle,  and  turn  them  aside,  when  the  muscles  in  question  will  be  fully 
brought  into  view. 

The  Vastus  Externus  is  the  largest  part  of  the  Quadriceps  Extensor.  It  arises 
by  a  broad  aponeurosis,  which  is  attached  to  the  anterior  border  of  the  great 
trochanter,  to  a  horizontal  ridge  on  its  outer  surface,  to  a  rough  line  leading 
from  the  trochanter  major  to  the  linea  aspera,  and  to  the  whole  length  of  the 
outer  lip  of  the  linea  aspera;  this  aponeurosis  covers  the  upper  three-fourths 
of  the  muscle,  and  from  its  inner  surface  many  fibres  arise.  A  few  additional 
fibres  arise  from  the  tendon  of  the  Gluteus  Maximus,  and  from  the  external 
intermuscular  septum  between  the  Vastus  Externus,  and  short  head  of  the 
Biceps.  The  fibres  form  a  large  fleshy  mass,  which  is  attached  to  a  strong 
aponeurosis,  placed  on  the  under  surface  of  the  muscle  at  its  lowest  part ;  this 
becomes  contracted  and  thickened  into  a  flat  tendon,  which  is  inserted  into  the 
outer  part  of  the  upper  border  of  the  patella,  blending  with  the  great  extensor 
tendon. 

Relations.  By  its  superficial  surface,  with  the  Rectus,  the  Tensor  Vaginae 
Femorisr,  the  fascia  lata,  and  the  Gluteus  Maximus,  from  which  it  is  separated 
by  a  synovial  bursa.  By  its  deep  surface,  with  the  Crureus,  some  large  branches 
of  the  external  circumflex  artery  and  anterior  crural  nerve  being  interposed. 

The  Vastus  Internus  and  Crureus  are  so  inseparably  connected  together,  as  to 
form  but  one  muscle,  as  which  it  will  be  accordingly  described.     It  is  the  smallest 


ANTERIOR    FEMORAL    REGION.  409 

portion  of  the  Quadriceps  Extensor.  The  anterior  portion  of  it,  covered  by 
the  Rectus,  is  called  the  Crureus ;  the  internal  portion,  which  lies  immediately 
beneath  the  fascia  lata,  the  Vastus  Internus.  It  arises  by  an  aponeurosis,  which 
is  attached  to  the  lower  part  of  the  line  that  extends  from  the  inner  side  of  the 
neck  of  the  femur  to  the  linea  aspera,  from  the  whole  length  of  the  inner  lip  of 
the  linea  aspera,  and  internal  intermuscular  septum.  It  also  arises  from  nearly 
the  whole  of  the  internal,  anterior,  and  external  surfaces  of  t[ie  shaft  of  the 
femur,  limited,  above,  by  the  line  between  the  two  trochanters,  and  extending 
below,  to  within  the  lower  fourth  of  the  bone.  From  these  different  origins, 
the  fibres  converge  to  a  broad  aponeurosis,  which  covers  the  anterior  surface  of 
the  middle  portion  of  the  muscle  (the  Crureus),  and  the  deep  surface  of  the  inner 
division  of  the  muscle  (the  Vastus  Internus),  and  which  gradually  narrows 
down  to  its  insertion  into  the  patella,  where  it  blends  with  the  other  portions  of 
the  Quadriceps  Extensor. 

Relations.  By  its  stiperficial  surface,  with  the  Psoas  and  Iliacus,  the  .Rectus, 
Sartorius,  Pectineus,  Adductors,  and  fascia  lata,  femoral  vessels,  and  saphenous 
nerve.  By  its  deep  surface,  with  the  femur,  Subcrureus,  and  synovial  membrane 
of  the  knee-joint. 

The  student  will  observe  the  striking  analogy  that  exists  between  the  Quad- 
riceps Extensor  and  the  Triceps  muscle  in  the  upper  extremity.  So  close  is 
this  similarity,  that  M.  Cruveilhier  has  described  it  under  the  name  of  the  Triceps 
Femoralis.  Like  the  Triceps  Brachialis,  it  consists  of  three  distinct  divisions, 
or  heads ;  a  middle  or  long  head,  analogous  to  the  long  head  of  the  Triceps, 
attached  to  the  ilium,  and  two  other  portions  which  may  be  called  the  external 
and  internal  heads  of  the  Triceps  Femoralis.  These,  it  will  be  noticed,  are 
strictly  analogous  to  the  outer  and  inner  heads  of  the  Triceps  Brachialis. 

The  tendons  of  the  different  portions  of  the  Quadriceps  Extensor  unite  at  the 
lower  part  of  the  thigh,  so  as  to  form  a  single  strong  tendon,  which  is  inserted 
into  the  upper  part  of  the  patella.  More  properly,  the  patella  may  be  regarded 
as  a  sesamoid  bone,  developed  in  the  tendon  of  the  Quadriceps  ;  and  the  liga- 
mentum  patellar,  which  is  continued  from  the  lower  part  of  the  patella  to  the 
tuberosity  of  the  tibia,  as  the  proper  tendon  of  insertion  of  the  muscle.  A 
synovial  bursa  is  interposed  between  the  tendon  and  the  upper  part  of  the  tuber- 
osity of  the  tibia.  From  the  tendons  corresponding  to  the  Vasti,  a  fibrous  pro- 
longation is  derived,  which  is  attached  below  to  the  upper  extremities  of  the 
tibia  and  fibula,  and  which  serves  to  protect  the  knee-joint,  being  strengthened 
on  its  outer  side  by  the  fascia  lata. 

The  Subcrureus  is  a  small  muscle,  usually  distinct  from  the  Crureus,  but  occa- 
sionally blended  with  it,  which  arises  from  the  anterior  surface  of  the  lower 
part  of  the  shaft  of  the  femur,  and  is  inserted  into  the  upper  part  of  the  syno- 
vial pouch  that  extends  upwards  from  the  knee-joint  behind  the  patella.  It 
sometimes  consists  of  two  separate  muscular  bundles. 

Nerves.  The  Tensor  Vaginae  Femoris  is  supplied  by  the  superior  gluteal 
nerve;  the  other  muscles  of  this  region,  by  branches  from  the  anterior -crural. 

Actions.  The  Tensor  Vaginee  Femoris  is  a  tensor  of  the  fascia  lata ;  continuing 
its  action,  the  oblique  direction  of  its  fibres  enables  it  to  rotate  the  thigh  in- 
wards. In  the  erect  posture,  acting  from  below,  it  will  serve  to  steady  the 
pelvis  upon  the  head  of  the  femur.  The  Sartorius  flexes  the  leg  upon  the  thigh, 
and,  continuing  to  act,  flexes  the  thigh  upon  the  pelvis,  at  the  same  time  draw- 
ing the  limb  inwards,  so  as  to  cross  one  leg  over  the  other.  Taking  its  fixed 
point  from  the  leg,  it  flexes  the  pelvis  upon  the  thigh,  and,  if  one  muscle  acts, 
assists  in  rotating  the  pelvis.  The  Quadriceps  Extensor  extend's  the  leg  upon 
the  thigh.  Taking  its  fixed  point  from  the  leg,  as  in  standing,  this  muscle  will 
act  upon  the  femur,  supporting  it  perpendicularly  upon  the  head  of  the  tibia, 
and  thus  maintaining  the  entire  weight  of  the  body.  The  Rectus  muscle  assists 
the  Psoas  and  Iliacus,  in  supporting  the  pelvis  and  trunk  upon  the  femur,  or  in 
bendinor  it  forwards. 


410 


MUSCLES    AND    FASCIA 


Internal  Femoral  Region. 


Gracilis. 
Pectineus. 


255. — Deep  Muscles  of  the  Internal 
Femoral  Rearion. 


Adductor  Longus. 
Adductor  Brevis. 
Adductor  Magnus. 

Dissection.  These  muscles  are  at  once  exposed 
by  removing  the  fascia  from  the  forepart  and  inner 
side  of  the  thigh.  The  limb  should  be  abducted, 
so  as  to  render  the  muscles  tense,  and  easier  of  dis- 
section. 

The  Gracilis  (^\g^.  254,  257)  is  the  most 
superficial  muscle  on  the  inner  side  of  the 
thigh.  It  is  thin  and  flattened,  broad 
above,  narrow  and  tapering  below.  It 
arises  by  a  thin  aponeurosis  between  two 
and  three  inches  in  breadth,  from  the  in- 
ner margin  of  the  ramus  of  the  pubes  and 
ischium.  The  fibres  pass  vertically  down- 
wards, and  terminate  in  a  rounded  tendon 
which  passes  behind  the  internal  condyle 
of  the  femur,  and  curving  round  the  inner 
tuberosity  of  the  tibia,  becomes  flattened 
and  is  inserted  into  the  upper  part  of  the 
inner  surface  of  the  shaft  of  the  tibia, 
below  the  tuberosity.  The  tendon  of  this 
muscle  is  situated  immediately  above  that 
of  the  Semitendinosus,  and  beneath  the 
aponeurosis  of  the  Sartorius,  with  which 
it  is  in  part  blended.  As  it  passes  across 
the  internal  lateral  ligament  of  the  knee- 
joint,  it  is  separated  from  it  by  a  synovial 
bursa  common  to  it  and  the  Semitendinosus 
muscle. 

Relations.  By  its  superficial  surface^ 
with  the  fascia  lata  and  the  Sartorius  be- 
low ;  the  internal  saphenous  vein  crosses 
it  obliquely  near  its  lower  part,  lying 
superficial  to  the  fascia  lata.  By  its  deep 
surface,  with  the  three  Adductors,  and 
the  internal  lateral  ligament  of  the  knee- 
joint. 

The  Pectineus  (Fig.  254)  is  a  flat  quad- 
rangular muscle,  situated  at  the  anterior 
part  of  the  upper  and  inner  aspect  of  the 
thigh.  It  arises  from  the  linea  ilio-pecti- 
nea,  from  the  surface  of  bone  in  front  of 
it,  between  the  pectineal  eminence  and 
spine  of  the  pubes,  and  from  a  tendinous 
prolongation  of  Gimbernat's  ligament, 
which  is  attached  to  the  crest  of  the  pubes, 
and  is  continuous  with  the  fascia  covering 
the  outer  surface  of  the  muscle ;  the  fibres 
pass  downwards,  backwards,  and  outwards, 
to  be  inserted  into  a  rough  line  leading 
from  the  trochanter  minor  to  the  linea 
aspera. 

Rdatlons.  By  its  anterior  surface,  with 
the  pubic  portion  of  the  fascia  lata,  which 


INTERNAL    FEMORAL    REGION.  411 

separates  it  from  the  femoral  vessels  and  internal  saphenous  vein.  By  its  j^oste- 
rior  surface^  with  the  hip-joint,  the  Adductor  Brevis  and  Obturator  Externus 
muscles,  the  obturator  vessels' and  nerve  being  interposed.  By  its  outer  border, 
with  the  Psoas,  a  cellular  interval  separating  them,  upon  which  lies  the  femoral 
artery.     By  its  inner  border,  with  the  margin  of  the  Adductor  Longus. 

The  Adductor  Longus,  the  most  superficial  of  the  three  Adductors,  is  a  flat 
triangular  muscle,  lying  on  the  same  plane  at  the  Pectineus,  with  which  it  is 
often  blended  above.  It  arises  by  a  flat  narrow  tendon,  from  the  front  of  the 
pubes,  at  the  angle  of  junction  of  the  crest  with  the  symphysis ;  and  soon  ex- 
pands into  a  broad  fleshy  belly,  which,  passing  downwards,  backwards,  and  out- 
wards, is  inserted,  by  an  aponeurosis,  into  the  midddle  third  of  the  linea  aspera, 
between  the  Vastus  Internus  and  the  Adductor  Magnus. 

Relations.  By  its  anterior  surface,  with  the  fascia  lata,  and,  near  its  insertion, 
with  the  femoral  artery  and  vein.  By  lis  i^sterior  surface,  with  the  Adductor 
Brevis  and  Adductor  Magnus,  the  anterior  branches  of  the  obturator  vessels 
and  nerve,  and  with  the  profunda  artery  and  vein  near  its  insertion.  By  its 
outer  border,  with  the  Pectineus.     By  its  inner  border,  with  the  Gracilis. 

The  Pectineus  and  Adductor  Lonjrus  should  now  be  divided  near  their  origin,  and  turned 
downwards,  when  the  Adductor  Brevis  and  Obturator  Externus  will  be  exposed. 

The  Adductor  Brevis  is  situated  immediately  behind  the  two  preceding  muscles. 
It  is  somewhat  triangular  in  form,  and  arises  by  a  narrow  origin  from  the  outer 
surface  of  the  descending  ramus  of  the  pubes,  between  the  Gracilis  and  Obtu- 
rator Externus.  Its  fibres,  passing  backwards,  outwards,  and  downwards,  are 
inserted,  by  an  aponeurosis,  into  the  upper  part  of  the  linea  aspera,  immediately 
behind  the  Pectineus  and  upper  part  of  the  Adductor  Longus. 

Relations.  By  its  anterior  surface,  with  the  Pectineus,  Adductor  Longus,  and 
anterior  branches  of  the  obturator  vessels  and  nerve.  By  its  posterior  surface, 
■with  the  Adductor  Magnus,  and  posterior  branches  of  the  obturator  vessels  and 
nerve.  By  its  outer  border,  with  the  Obturator  Externus,  and  conjoined  tendon 
of  the  Psoas  and  Iliacus.  By  its  inner  border,  with  the  Gracilis  and  Adductor 
Magnus.  This  muscle  is  pierced,  near  its  insertion,  by  the  middle  perforating 
branch  of  the  profunda  artery. 

The  Adductor  Brevis  should  now  be  cut  away  near  its  origin,  and  turned  outwards,  when  the 
entire  extent  of  the  Adductor  Magnus  will  be  exposed. 

The  Adductor  Magnus  is  a  large  triangular  muscle,  forming  a  septum  between 
the  muscles  on  the  inner,  and  those  on  the  back  of  the  thigh.  It  arises  from  a 
small  part  of  the  descending  ramus  of  the  pubes,  from  the  ascending  ramus  of 
the  ischium,  and  from  the  outer  margin  and  under  surface  of  the  tuberosity  of 
the  ischium.  Those  fibres  which  arise  from  the  ramus  of  the  pubes  are  very 
short,  horizontal  in  direction,  and  are  inserted  into  the  rough  line  leading  from 
the  great  trochanter  to  the  linea  aspera,  internal  to  the  Gluteus  Maxim  us  ;  those 
from  the  ramus  of  the  ischium  are  directed  downwards  and  outwards  with 
different  degrees  of  obliquity,  to  be  inserted,  by  means  of  a  broad  aponeurosis, 
into  the  whole  length  of  the  linea  aspera  and  the  upper  part  of  its  internal 
bifurcation  below.  The  internal  portion  of  the  muscle,  consisting  principally 
of  those  fibres  which  arise  from  the  tuberosity  of  the  ischium,  forms  a  thick 
fleshy  mass  consisting  of  coarse  bundles  which  descend  almost  vertically,  and 
terminates  about  the  lower  third  of  the  thigh  in  a  rounded  tendon,  which  is 
inserted  into  the  tubercle  above  the  inner  condyle  of  the  femur,  being  connected 
by  a  fibrous  expansion  to  the  line  leading  upwards  from  the  tubercle  to  the 
linea  aspera.  Between  the  two  portions  of  the  muscle  an  angular  interval  is 
left,  tendinous  in  front,  fleshy  behind,  for  the  passage  of  the  femoral  vessel  into 
the  popliteal  space.  The  external  portion  of  the  muscle  is  pierced  by  four 
apertures :  the  three  superior,  for  the  three  superior  perforating  arteries ;  the 


412 


MUSCLES    AND    FASCIA. 


Fig 


256. — Dissection  of  Lower 
tremitj.    Posterior  View. 


Ex- 


fourth,  for  the  passage  of  the  profunda.  This  muscle  gives  off  an  aponeurosis, 
which  passes  in  front  of  the  femoral  vessels,  and  joins  with  the  Vastus  Internus. 
Relations.  By  its  anterior  surface,  with  the  Pectineus,  Adductor  Brevis,  Ad- 
ductor Longus  and  the  femoral  vessels.  By  its  posterior  surface,  with  the  great 
sciatic  nerve,  the  Gluteus  Maximus,  Biceps,  Semitendinosus,  and  Semimembra- 
nosus. By  its  superior  or  shortest  border,  it  lies  parallel  with  the  Quadratus 
Femoris.  By  its  internal  or  longest  border,  with  the  Gracilis,  Sartorius,  and  fascia 
lata.  By  its  external  or  attached  border,  it  is  inserted  into  the  femur  behind  the 
Adductor  Brevis  and  Adductor  Longus,  which  separate  it  from  the  Vastus 
Internus ;  and  in  front  of  the  Gluteus  Maximus  and  short  head  of  the  Biceps, 
which  separate  it  from  the  Vastus  Extern  us. 

Nerves.  All  the  muscles  of  this  group  are  supplied  by  the  obturator  nerve. 
The  Pectineus  receives  additional  branches  from  the  accessory  obturator  and 
anterior  crural ;  and  the  Adductor  Magnus  an  additional  branch  from  the  great 
sciatic. 

Actions.  The  Pectineus  and  three  Adductors  adduct  the  thigh  powerfully, 
they  are  especially  used  in  horse  exercise,  the  flanks  of  the  horse  being  grasped 
between  the  knees  by  the  action  of  these  muscles.  In  consequence  of  the 
obliquity  of  their  insertion  into  the  linea  aspera,  they  rotate  the  thigh  outwards, 
assisting  the  external  rotators,  and  when  the  limb  has  been  adducted,  they  draw 

it  inwards,  carrying  the  thigh  across  that  of 
the  opposite  side.  The  Pectineus  and  Adductor 
Brevis  and  Adductor  Longus  assist  the  Psoas 
and  Iliacus  in  flexing  the  thigh  upon  the 
pelvis.  In  progression,  also,  all  these  muscles 
assist  in  drawing  forwards  the  hinder  limb. 
The  Gracilis  assists  the  Sartorius  in  flexing 
the  leg  and  drawing  it  inwards ;  it  is  also  an 
Adductor  of  the  thigh.  If  the  lower  extremi- 
ties are  fixed,  these  muscles  may  take  their 
fixed  point  from  below  and  act  upon  the  pel- 
vis, serving  to  maintain  the  body  in  the  erect 
posture;  or,  if  their  action  is  continued,  to 
flex  the  pelvis  forwards  upon  the  femur. 

BACK  tf  THICn 

Gluteal  Kegion. 

Gluteus  Maximus.  Gemellus  Superior. 

Gluteus  Medius.  Obturator  Internus. 

Gluteus  Minimus.  Gemellus  Inferior. 

Pyriformis.  Obturator  Externus. 

Quadratus  Femoris. 

Dissection  (Fig.  256).  The  subject  should  be  turned 
on  its  face,  a  block  ])Iacod  beneath  the  pelvis  to  make 
the  buttocks  tense,  and  the  limbs  allowed  to  hang  over 
the  end  of  the  table,  with  the  foot  inverted,  and  the 
thigh  abducted.  Make  an  incision  through  the  integu- 
ment along  the  back  part  of  the  crest  of  the  ilium  and 
margin  of  the  sacrum  to  the  tip  of  the  coccyx,  and 
carry  a  second  incision  from  that  point  obliquely  down- 
wards and  outwards  to  the  outer  side  of  the  thigh,  four 
inches  below  the  great  trochanter.  The  portion  of  in- 
tegument included  between  these  incisions,  together 
with  the  superficial  fascia,  is  to  be  removed  in  the  direc- 
tion shown  in  the  figure,  when  the  Gluteus  Maximus 
and  the  dense  fascia  covering  the  Gluteus  Medius  will 
be  exposed. 

The  Gluteus  Maximus  (Fig.  257),  the  most  superficial  muscle  in  the  gluteal 
region,  is  a  very  broad  and  thick  fleshy  mass,  of  a  quadrilateral  shape,  which 


/  ,  Dissection  of 

GLUTEAL    REGION 


POPLITEAL  SPACe 


BACtC 


Lca 


S  .  aOLC  ^    FOOT 


GLUTEAL    REGION. 


413 


forms  the  prominence  of  the 
nates.     Its  large  size  is  one  of 
the  most  characteristic  points 
in    the    muscular    system   in 
man,  connected   as  it  is  with 
the  power  he  has  of  maintain- 
ing the  trunk  in  the  erect  pos- 
ture.    In  structure  the  muscle 
is   remarkably    coarse,   being 
made  up  of  muscular  fasciculi 
lying    parallel    with   one   an- 
other, and  collected   together 
into  large  bundles,  separated 
by  deep  cellular  intervals.    It 
arises  from  the  superior  curved 
line  of  the  ilium,  and  the  por- 
tion   of    bone    including   the 
crest,  immediately  behind  it ; 
from  the  posterior  surface  of 
the  last  piece  of  the  sacrum, 
the  side  of  the  coccyx,  and 
posterior  surface  of  the  great 
sacro-sciatic  and  posterior  sa- 
cro-iliac  ligaments.   The  fibres 
are  directed   obliquely  down- 
wards   and    outwards;    those 
forming  the  upper  and  larger 
portion   of   the   muscle  (after 
converging  somewhat)  termi- 
nate   in    a    thick    tendinous 
lamina,    which    passes   across 
the   great    trochanter,  and  is 
inserted    into    the   fascia   lata 
covering  the  outer  side  of  the 
thigh,    the    lower   portion   of 
the  muscle  being  inserted  into 
the  rough    line   leading  from 
the    great    trochanter   to   the 
linea  aspera  between  the  Vas- 
tus  Externus    and   Adductor 
Magnus. 

Three  synovial  hursse  are 
usually  found  separating  the 
under  surface  of  this  muscle 
from  the  eminences  which  it 
covers.  One  of  these,  of  large 
size,  and  generally  multilocu- 
lar,  separates  it  from  the  great 
trochanter,  A  second,  often 
wanting,  is  situated  on  the 
tuberosity  of  the  ischium.  A 
third  is  found  between  the 
tendon  of  this  muscle  and  the 
Vastus  Externus. 

Relations.  By  its  superficial 
surface^  Avith  a  thin  fascia, 
which    separates  it  from    the 


Muscles  of  the  Hip  and  Thigh. 


T'cnJons 


SCMI.TCNOINOSUS 

•  IMI-MCMORANOigi 


Striaa 


414  MUSCLES    AND    FASCIA. 

subcutaneous  tissue.  By  its  deep  surface^  from  above  downwards,  with  the 
ilium,  sacrum,  coccyx,  and  great  sacro-sciatic  ligament,  part  of  the  Gluteus 
Medius,  Pyriformis,  Gemelli,  Obturator  Internus,  Quadratus  Femoris,  the  tube- 
rosity of  the  ischium,  great  trochanter,  the  origin  of  the  Biceps,  Semitendinosus, 
Semimembranosus,  and  Adductor  Magnus  muscles.  The  gluteal  vessels  and 
superior  gluteal  nerve  are  seen  issuing  from  the  pelvis  above  the  Pyriformis 
muscle,  the  ischiatic  and  internal  pudic  vessels  and  nerves,  and  the  nerve  to 
the  Obturator  Internus  muscle  below  it.  Its  upper  harder  is  thin,  and  connected 
with  the  Gluteus  Medius  by  the  fascia  lata.  Its  hiver  border,  free  and  promi- 
nent, forms  the  fold  of  the  nates,  and  is  directed  towards  the  perineum. 

Dissection.  Now  divide  the  Gluteus  Maximus  near  its  origin,  by  a  vertical  incision  carried 
from  its  upper  to  its  lower  border;  a  cellular  interval  will  be  exposed,  separating  it  from  the 
Gluteus  Medius  and  external  rotator  muscles  beneath.  The  upper  portion  of  the  muscle  is  to 
be  altogether  detached,  and  the  lower  portion  turned  outwards  ;  the  loose  areolar  tissue  filling 
up  the  interspace  between  the  trochanter  major  and  tuberosity  of  the  ischium  being  removed, 
the  parts  already  enumerated  as  eiiposed  by  the  removal  of  this  muscle  will  be  seen. 

The  Gluteus  Medius  is  a  broad,  thick,  radiated  muscle,  situated  on  the  outer 
surface  of  the  pelvis.  Its  posterior  third  is  covered  by  the  Gluteus  Maximus; 
its  anterior  two-thirds  by  the  fascia  lata,  which  separates  it  from  the  integu- 
ment. It  arises  from  the  outer  surface  of  the  ilium,  between  the  superior  and 
middle  curved  lines,  and  from  the  outer  lip  of  that  portion  of  the  crest  which 
is  between  them;  it  also  arises  from  the  dense  fascia  covering  its  anterior  part. 
The  fibres  converge  to  a  strong  flattened  tendon,  which  is  inserted  into  the 
oblique  line  which  traverses  the  outer  surface  of  the  great  trochanter.  A 
synovial  bursa  separates  the  tendon  of  the  muscle  from  the  surface  of  the 
trochanter  in  front  of  its  insertion. 

Relations.  By  its  superficial  surface,  with  the  Gluteus  Maximus  behind,  the 
Tensor  Vaginae  Femoris,  and  deep  fascia  in  front.  By  its  deep  surface,  with  the 
Gluteus  Miniipius  and  the  gluteal  vessels  and  superior  gluteal  nerve.  Its  an- 
terior border  is  blended  with  the  Gluteus  Minimus.  Its  posterior  border  lies 
parallel  with  the  Pyriformis,  the  gluteal  vessels  intervening. 

This  muscle  should  now  be  divided  near  its  insertion  and  turned  upwards,  when  the  Gluteus 
Miuimus  will  be  exposed. 

The  Gluteus  Minimus,  the  smallest  of  the  three  glutei,  is  placed  immediately 
beneath  the  preceding.  It  is  fan-shaped,  arising  from  the  outer  surface  of  the 
ilium,  between  the  middle  and  inferior  curved  lines,  and  behind,  from  the  mar- 
gin of  the  great  sacro-sciatic  notch;  the  fibres  converge  to  the  deep  surface  of 
a  radiated  aponeurosis,  which,  terminating  in  a  tendon,  is  inserted  into  an  im- 
pression on  the  anterior  border  of  the  great  trochanter.  A  synovial  bursa  is 
interposed  between  the  tendon  and  the  great  trochanter. 

Relations.  By  its  superficial  surface,  with  the  Gluteus  Medius,  and  the  gluteal 
vessels  and  superior  gluteal  nerve.  By  its  deep  surface,  with  the  ilium,  the 
reflected  tendon  of  the  Rectus  Femoris,  and  ca'psular  ligament  of  the  hip-joint. 
Its  anterior  marrjin  is  blended  with  the  Gluteus  Medius.  lis  posterior  margin  is 
often  joined  with  the  tendon  of  the  Pyriformis. 

The  Pyriformis  is  a  flat  muscle,  pyramidal  in  shape,  lying  almost  parallel 
with  the  lower  margin  of  the  Gluteus  Minimus.  It  is  situated  partly  within 
the  pelvis  at  its  posterior  part,  and  partly  at  the  back  of  the  hip-joint.  It  arises 
from  the  front  of  the  sacrum  by  three  fleshy  digitations,  attached  to  the  portions 
of  bone  between  the  first,  second,  third,  and  fourth  anterior  sacral  foramina, 
and  also  from  the  grooves  leading  from  the  foramina:  a  few  fibres  also  arise 
from  the  margin  of  tlie  great  sacro-sciatic  foramen,  and  from  the  anterior  surface 
of  the  great  sacro-sciatic  ligament.  The  muscle  passes  out  of  the  pelvis  through 
the  great  sacro-sciatic  foramen,  the  upper  part  of  which  it  fills,  and  is  inserted 
by  a  rounded  tendon  into  the  upper  border  of  the  great  trochanter,  being  gene- 
rally blended  with  the  tendon  of  the  Obturator  Internus. 

Relations.     By  its  anterior  surface,  within  the  pelvis,  with  the  rectum  (espe- 


GLUTEAL    REGION.  415 

cially  on  the  left  side),  the  sacral  plexus  of  nerves,  and  the  internal  iliac  vessels ; 
external  to  the  pelvis^  with  the  os  innominatum  and  capsular  ligament  of  the  hip- 
joint.  By  lis,  posterior  surface^  within  the  pelvis,  with  the  sacrum;  and  external 
to  it^  with  the  Gluteus  Maximus.  By  its  upper  border,  with  the  Gluteus  Medius, 
from  which  it  is  separated  by  the  gluteal  vessels  and  superior  gluteal  nerve. 
By  its  lower  border,  with  the  Gemellus  Superior  and  Coccygeus;  the  sciatic 
vessels  and  nerves,  the  internal  pudic  vessels  and  nerve,  and  the  nerve  to  the 
Obturator  Internus,  passing  from  the  pelvis  in  the  interval  between  the  two 
muscles. 

Dissection.  The  next  muscle,  as  well  as  the  origiu  of  the  Pyriformis,  can  only  be  seen  when 
the  pelvis  is  divided,  and  the  viscera  removed.    ' 

The  Obturator  Membrane  is  a  dense  layer  of  interlacing  fibres,  which  completely 
closes  the  obturator  foramen,  except  at  its  upper  and  outer  part,  where  a  small 
oval  canal  is  left  for  the  obturator  vessels  and  nerve.  Each  obturator  muscle 
is  connected  with  this  membrane. 

The  Obturator  Internus,  like  the  preceding  muscle,  is  situated  partly  within 
the  cavity  of  the  pelvis,  partly  at  the  back  of  the  hip-joint.  It  arises  from  the 
inner  surface  of  the  anterior  and  external  wall  of  the  pelvis,  around  the  inner 
side  of  the  obturator  foramen,  being  attached  to  the  descending  ramus  of  the 
pubes,  and  the  ascending  ramus  of  the  ischium,  and  at  the  side  to  the  inner 
surface  of  the  body  of  the  ischium,  between  the  margin  of  the  o"bturator  foramen 
in  front,  the  great  sacro-sciatic  notch  behind,  and  the  brim  of  the  true  pelvis 
above.  It  also  arises  from  the  inner  surface  of  the  obturator  membrane  and 
from  the  tendinous  arch  which  completes  the  canal  for  the  passage  of  the  obtu- 
rator vessels  and  nerve.  The  fibres  are  directed  backwards  and  downwards, 
and  terminate  in  four  or  five  tendinous  bands,  which  are  found  on  its  deep 
surface ;  these  bands  are  reflected  at  a  right  angle  over  the  inner  surface  of  the 
tuberosity  of  the  ischium,  which  is  grooved  for  their  reception :  the  groove  is 
covered  with  cartilage,  and  lined  with  a  synovial  bursa.  The  muscle  leaves 
the  pelvis  by  the  lesser  sacro-sciatic  notch ;  and  the  tendinous  bands  unite  into 
a  single  flattened  tendon,  which  passes  horizontally  outwards,  and,  after  receiv- 
ing the  attachment  of  the  Gemelli,  is  inserted  into  the  upper  border  of  the  great 
trochanter  in  front  of  the  Pyriformis.  A  synovial  bursa,  narrow  and  elongated 
in  form,  is  usually  found  between  the  tendon  of  this  muscle  and  the  capsular 
ligament  of  the  hip :  it  occasionally  communicates  with  that  between  the  tendon 
and  the  tuberosity  of  the  ischium,  the  two  forming  a  single  sac. 

In  order  to  display  the  peculiar  appearances  presented  by  the  tendon  of  this  muscle,  it  must 
be  divided  near  its  insertion  and  reflected  outwards. 

Relations.  Within  the  pelvis,  this  muscle  is  in  relation,  by  its  anterior  surface, 
with  the  obturator  membrane  and  inner  surface  of  the  anterior  wall  of  the 
pelvis;  hy'iis  pjosterior  surface,  with  the  pelvic  and  obturator  fasciae,  which  sepa- 
rate it  from  the  Levator  Ani ;  and  it  is  crossed  by  the  internal  pudic  vessels  and 
nerve.  This  surface  forms  the  outer  boundary  of  the  ischio-rectal  fossa.  Ex- 
ternal to  the  pelvis,  it  is  covered  by  the  great  sciatic  nerve  and  Gluteus  Maximus, 
and  rests  on  the  back  part  of  the  hip-joint. 

The  Oemelli  are  two  small  muscular  fasciculi,  accessories  to  the  tendon  of  the 
Obturator  Internus,  which  is  received  into  a  groove  between  them.  They  are 
called  superior  and  inferior. 

The  Gemellus  Superior,  the  smaller  of  the  two,  arises  from  the  outer  surface 
of  the  spine  of  the  ischium,  and  passing  horizontally  outwards  becomes  blended 
with  the  upper  part  of  the  tendon  of  the  Obturator  Internus,  and  is  inserted 
with  it  into  the  upper  border  of  the  great  trochanter.  This  muscle  is  sometimes 
wanting. 

Relations.  By  its  superficial  surface,  with  the  Gluteus  Maximus  and  the  sciatic 
vessels  and  nerves.     By  its  deep  surface,  with  the  capsule  of  the  hip-joint.     By 


416  MUSCLES    AND    FASCIA. 

its  upper  border^  with  the  lower  margin  of  the  Pyriformis.  By  its  lower  border, 
with  the  tendon  of  the  Obturator  Internus. 

The  Gemellus  Inferior  arises  from  the  upper  part  of  the  outer  border  of  the 
tuberosity  of  the  ischium,  and  passing  horizontally  outwards,  is  blended  with 
the  lower  part  of  the  tendon  of  the  Obturator  Internus,  and  inserted  with  it 
into  the  upper  border  of  the  great  trochanter. 

Relations.  By  ila superficial  surface,  with  the  Grluteus  Maximus,  and  the  sciatic 
vessels  and  nerves.  By  its  deep  surface,  with  the  capsular  ligament  of  the  hip- 
joint.  By  its  upper  harder,  with  the  tendon  of  the  Obturator  Internus.  By 
its  lower  border,  with  the  tendon  of  the  Obturator  Externus  and  Quadratus 
Femoris. 

The  Quadratus  Femoris  is  a  short,  flat  muscle,  quadrilateral  in  shape  (lience 
its  name),  situated  between  the  Gemellus  Inferior  and  the  upper  margin  of  the 
Adductor  Magnus.  It  arises  from  the  outer  border  of  the  tuberosity  of  the 
ischium,  and  proceeding  horizontally  outwards,  is  inserted  into  the  upper  part 
of  the  linea  quadrati,  on  the  posterior  surface  of  the  trochanter  major.  A  syno- 
vial bursa  is  often  found  between  the  under  surface  of  this  muscle  and  the  lesser 
trochanter,  which  it  covers. 

Belations.  By  ils  posterior  surface,  with  the  Gluteus  Maximus  and  the  sciatic 
vessels  and  nerves.  By  its  anterior  surface,  with  the  tendon  of  the  Obturator 
Externus  and  trochanter  minor,  and  with  the  capsule  of  the  hip-joint.  By 
its  upper  border,  with  the  Gemellus  Inferior.  Its  lower  border  is  separated  from 
the  Adductor  Magnus  by  the  terminal  branches  of  the  internal  circumflex 
vessels. 

Dissection.  In  order  to  expose  the  next  muscle  (the  Obturator  Externus),  it  is  necessary  to 
remove  the  Psoas,  Iliacus,  Pectineus,  and  Adductor  Brevis  and  Adductor  Longus  muscles  from 
the  front  and  inner  side  of  the  thigh ;  and  the  Ghiteus  Maximus  and  Quadratas  Femoris  from 
the  back  part.  Its  dissection  should  consequently  be  postponed  until  the  muscles  of  the  anterior 
and  internal  femoral  regions  have  been  examined. 

The  Obturator  Externus  (Fig.  255)  is  a  flat  triangular  muscle,  which  covers 
the  outer  surface  of  the  anterior  wall  of  the  pelvis.  It  arises  from  the  margin 
of  bone  immediately  around  the  inner  side  of  the  obturator  foramen,  viz.,  from 
the  body  and  ramus  of  the  pubes,  and  the  ramus  of  the  ischium ;  it  also  arises 
from  the  inner  two-thirds  of  the  outer  surface  of  the  obturator  membrane,  and 
from  the  tendinous  arch  which  completes  the  canal  for  the  passage  of  the  obtu- 
rator vessels  and  nerves.  The  fibres  converging  pass  outwards  and  backwards, 
and  terminate  in  a  tendon  which  runs  across  the  back  part  of  the  hip-joint,  and 
is  inserted  into  the  digital  fossa  of  the  femur. 

Relations.  By  its  anterior  surface,  with  the  Psoas,  Iliacus,  Pectineus,  Adduc- 
tor Longus,  Adductor  Brevis,  and  Gracilis;  and  more  externally,  with  the  neck 
of  the  femur  and  capsule  of  the  hip-joint.  By  \is  posterior  surface,  with  the 
obturator  membrane  and  Quadratus  Femoris. 

Nerves.  The  Gluteus  Maximum  is  supplied  by  the  inferior  gluteal  nerve  and 
a  branch  from  the  sacral  plexus;  the  Gluteus  Medius  and  Gluteus  Minimus,  by 
the  superior  gluteal ;  the  Pyriformis,  Gemelli,  Obturator  Internus,  and  Quad- 
ratus Femoris,  by  branches  from  the  sacral  plexus,  and  the  Obturator  Exter- 
nus, by  the  obturator  nerve. 

Actions.  The  Glutei  muscles,  when  they  take  their  fixed  point  from  the 
pelvis,  are  all  abductors  of  tlie  thigh.  The  Gluteus  Maximus  and  tlie  posterior 
fibres  of  the  Gluteus  Medius,  rotate  the  thigh  outwards;  the  anterior  fibres  of 
the  Gluteus  Medius  and  the  Gluteus  Minimus  rotate  it  inwards.  The  Gluteus 
Maximus  serves  to  extend  the  femur,  and  the  Gluteus  Medius  and  Gluteus 
Minimus  draw  it  forwards.  The  Gluteus  Maximus  is  also  a  tensor  of  the  fascia 
lata.  Taking  their  fixed  point  from  the  femur,  the  Glutei  muscles  act  upon 
the  pelvis,  supporting  it  and  the  whole  trunk  upon  the  head  of  the  femur,  which 
ia  especially  obvious  in  standing  on  one  leg.  In  order  to  gain  the  erect  posture 
after  the  effort  of  stooping,  these  muscles  draw  the  pelvis  backwards,  assisted 


POSTERIOR    FEMORAL    REGION.  41T 

by  the  Biceps,  Semitendinosus,  and  Semimembranosus  muscles.  The  remain- 
ing muscles  are  powerful  rotators  of  the  thigh  outwards.  In  the  sitting  posture, 
w^hen  the  thigh  is  flexed  upon  the  pelvis,  their  action  as  rotators  ceases,  and 
they  become  abductors,  with  the  exception  of  the  Obturator  Externus,  which 
still  rotates  the  femur  outwards.  When  the  femur  is  fixed,  the  Pyriformis  and 
Obturator  muscles  serve  to  draw  the  pelvis  forwards  if  it  has  been  inclined 
backwards,  and  assist  in  steadying  it  upon  the  head  of  the  femur. 

Posterior  Femoral  Eegion. 
Biceps.  Semitendinosus.  Semimembranosus. 

Dissection  (Fig.  256).  Make  a  vertical  incision  along  the  middle  of  the  thigh,  from  the  lower 
fold  of  the  nates  to  about  three  inches  below  the  back  of  the  knee-joint,  and  there  connect  it 
with  a  transverse  incision,  carried  from  the  inner  to  the  outer  side  of  the  leg.  Make  a  third 
incision  transversely  at  the  junction  of  the  middle  with  the  lower  third  of  the  thigh.  The  in- 
tegument having  been  removed  from  the  back  of  the  knee,  and  the  boundaries  of  the  popliteal 
space  examined,  the  removal  of  the  integument  from  the  remaining  part  of  the  thigh  should  be 
continued,  when  the  fascia  and  muscles  of  this  region  will  be  exposed. 

The  Biceps  (Fig.  257)  is  a  large  muscle,  of  considerable  length,  situated  on 
the  posterior  and  outer  aspect  of  the  thigh.  It  arises  by  two  heads.  One,  the 
long  head,  arises  from  an  impression  at  the  upper  and  back  part  of  the  tube- 
rosity of  the  ischium,  by  a  tendon  common  to  it  and  the  Semitendinosus.  The 
femoral,  or  short  head,  arises  from  the  outer  lip  of  the  linea  aspera,  between 
the  Adductor  Magnus  and  Vastus  Externus,  extending  from  two  inches  below 
the  insertion  of  the  Gluteus  Maximu.s,  to  within  two  inches  of  the  outer  con- 
dyle ;  it  also  arises  from  the  external  intermuscular  septum.  The  fibres  of  the 
long  head  form  a  fusiform  belly,  which  passing  obliquely  downwards  and  a 
little  outwards,  terminate  in  an  aponeurosis  which  covers  the  posterior  surface 
of  the  muscle,  and  receives  the  fibres  of  the  short  head;  this  aponeurosis  be- 
comes gradually  contracted  into  a  tendon,  which  is  inserted  into  the  outer  side 
of  the  head  of  the  fibula.  At  its  insertion,  the  tendon  divides  into  two  por- 
tions, which  embrace  the  external  lateral  ligament  of  the  knee-joint,  a  strong 
prolongation  being  sent  forwards  to  the  outer  tuberosity  of  the  tibia,  which 
gives  off  an  expansion  to  the  fascia  of  the  leg.  The  tendon  of  this  muscle 
forms  the  outer  hamstring. 

Relations.  By  its  superficial  surface  wath  the  Gluteus  Maximus  above,  the 
fascia  lata  and  integument  in  the  rest  of  its  extent.  By  its  deep  surface,  with 
the  Semimembranosus,  Adductor  Magnus,  and  Vastus  Externus,  the  great 
sciatic  nerve,  popliteal  artery  and  vein,  and  near  its  insertion,  with  the  external 
head  of  the  Gastrocnemius,  Plantaris,  the  superior  external  articular  artery, 
and  the  external  popliteal  nerve. 

The  Sertiitendinosus,  remarkable  for  the  great  length  of  its  tendon,  is  situated 
at  the  posterior  and  inner  aspect  of  the  thigh.  It  arises  from  the  tuberosity 
of  the  ischium  by  a  tendon  common  to  it  and  the  long  head  of  the  Biceps;  it 
also  arises  from  an  aponeurosis  which  connects  the  adjacent  surfaces  of  the 
two  muscles  to  the  extent  of  about  three  inches  after  their  origin.  It  forms  a 
fusiform  muscle,  which,  passing  downwards  and  inwards,  terminates  a  little 
below  the  middle  of  the  thigh  in  a  long  round  tendon  which  lies  along  the" 
inner  side  of  the  popliteal  space,  then  curves  around  the  inner  tuberosity  of 
the  tibia,  and  is  inserted  into  the  upper  part  of  the  inner  surfoce  of  the  shaft 
of  that  bone,  nearly  as  far  forwards  as  its  anterior  border.  This  tendon  lies 
beneath  the  expansion  of  the  Sartorius,  and  below  that  of  the  Gracilis,  to 
which  it  is  united.  A  tendinous  intersection  is  usually  observed  about  the 
middle  of  the  muscle. 

Relations.  By  its  siqierficial  surface,  with  the  Gluteus  Maximus  and  fa.scia 
lata.  By  its  deep  surface,  with  the  Semimembranosus,  Adductor  Magnus,  inner 
head  of  the  Gastrocnemius,  and  internal  lateral  ligament  of  the  knee-joint. 

The  Semimembranosus,  so  called  from  the  membranous  expansion  on  its 
27 


418  MUSCLES    AND    FASCIA. 

anterior  and  posterior  surfaces,  is  situated  at  the  back  part  and  inner  side  of 
the  thigh.  It  arises  by  a  thick  tendon  from  the  upper  and  outer  part  of  the 
tuberosity  of  the  ischium,  above  and  to  the  outer  side  of  the  Biceps  and  Semi- 
tendinosus,  and  is  inserted  into  the  inner  and  back  part  of  the  inner  tuberosity 
of  the  tibia,  beneath  the  internal  lateral  ligament.  The  tendon  of  the  muscle 
at  its  origin  expands  into  an  aponeurosis,  which  covers  the  upper  part  of  its 
anterior  surface;  from  this  aponeurosis,  muscular  fibres  arise,  and  converge  to 
another  aponeurosis,  which  covers  the  lower  part  of  its  posterior  surface,  and 
this  contracts  into  the  tendon  of  insertion.  The  tendon  of  the  muscle  at  its 
insertion  divides  into  three  portions;  the  middle  portion  is  the  fasciculus  of 
insertion  into  the  back  part  of  the  inner  tuberosity ;  it  sends  down  an  expan- 
sion to  cover  the  Popliteus  muscle.  The  internal  portion  is  horizontal,  passing 
forwards  beneath  the  internal  lateral  ligament,  to  be  inserted  into  a  groove 
along  the  inner  side  of  the  lateral  tuberosity.  The  posterior  division  passes 
upwards  and  backwards,  to  be  inserted  into  the  back  part  of  the  outer  con- 
dyle of  the  femur,  forming  the  chief  part  of  the  posterior  ligament  of  the 
knee-joint. 

The  tendons  of  the  two  preceding  muscles,  with  those  of  the  Gracilis  and 
Sartorius,  form  the  inner  hamstring. 

Relations,  By  its  superficial  surface^  with  the  Semitendinosus,  Biceps,  and 
fascia  lata.  By  its  deep  surface^  with  the  popliteal  vessels,  Adductor  Magnus, 
and  inner  head  of  the  Gastrocnemius,  from  which  it  is  separated  by  a  synovial 
bursa.  By  its  inner  border,  with  the  Gracilis.  By  its  outer  border^  with  the 
great  sciatic  nerve,  and  its  internal  popliteal  branch. 

Nerves.     The  muscles  of  this  region  are  supplied  by  the  great  sciatic  nerve. 

Actions.  The  three  hamstring  muscles  flex  the  leg  upon  the  thigh.  When 
the  knee  is  semi-fixed,  the  Biceps,  in  consequence  of  its  oblique  direction 
downwards  and  outwards,  rotates  the  leg  slightly  outwards;  and  the  Semi- 
membranosus, in  consequence  of  its  oblique  direction,  rotates  the  leg  inwards, 
assisting  the  Popliteus.  Taking  their  fixed  point  from  below,  these  muscles 
serve  to  support  the  pelvis  upon  the  head  of  the  femur,  and  to  draw  the  trunk 
directly  backwards,  as  in  feats  of  strength,  when  the  body  is  thrown  backwards 
in  the  form  of  an  arch. 

Surgical  Anatomy.  The  tendons  of  these  muscles  occasionally  require  subcutaneous  division 
in  some  forms  of  spurious  anchylosis  of  the  knee-joint,  dependent  upon  permanent  contraction 
and  rigidity  of  the  flexor  muscles,  or  from  stifTcning  of  the  ligamentous  and  other  tissues  sur- 
rounding the  joint,  the  result  of  disease.  This  is  effected  by  putting  the  tendon  upon  the 
stretch,  and  inserting  a  narrow  sharp-pointed  knife  between  it  unci  the  skin  ;  the  cutting  edge 
being  then  turned  towards  the  tendon,  it  should  be  divided,  taking  care  that  the  wound  in  the 
skin  is  not  at  the  same  time  enlarged. 

Muscles  and  Fascia  op  the  Leg. 

Dissection  (Fig.  2.5.S).  The  knee  should  be  bent,  a  block  placed  beneath  it,  and  the  foot  kept 
Id  an  extended 'position ;  then  make  an  incision  through  the  integument  in  the  middle  line  of 
the  leg  to  the  ankle,  and  continue  it  along  the  dorsum  of  the  foot  to  the  toes.  Make  a  second 
incision  transversely  across  the  ankle,  and  a  third  in  the  same  direction  across  the  bases  of  the 
toes ;  remove  the  flaps  of  integument  included  between  these  incisions,  in  order  to  examine  the 
deep  fascia  of  the  leg. 

The /ascj'a  of  the  leg  forms  a  complete  investment  to  the  whole  of  this  region 
of  the  limb,  excepting  to  the  inner  surface  of  the  tibia.  It  is  continuous  above 
with  the  fascia  lata,  receiving  an  expansion  from  the  tendon  of  the  Biceps  on 
the  outer  side,  and  from  the  tendons  of  the  Sartorius,  Gracilis,  and  Semitendi- 
nosus on  the  inner  side;  in  front  it  blends  with  the  periosteum  covering  the 
tibia  and  fibula ;  below,  it  is  continuous  with  the  annular  ligaments  of  the  ankle. 
It  is  thick  and  dense  in  the  upper  and  anterior  part  of  the  leg,  and  gives 
attachment,  by  its  inner  surface,  to  the  Tibialis  Anticus  and  Extensor  Longus 
Digitorum  muscles ;  but  thinner  behind,  where  it  covers  the  Gastrocnemius 
and  Soleus  muscles.     Its  inner  surface  gives  off,  on  the  outer  side  of  the  leg, 


ANTERIOR    TIBIO-FIBULAR    REGION. 


419 


two  strong  intermuscular  septa,  which  inclose 
the  Peronei  muscles,  and  separate  them  from 
the  muscles  on  the  anterior  and  posterior  tibial 
regions,  and  several  smaller  and  more  slender 
processes,  which  inclose  the  individual  muscles 
in  each  region ;  at  the  same  time  a  broad  trans- 
verse intermuscular  septum  intervenes  between 
the  superficial  and  deep  muscles  in  the  poste- 
rior tibio-fibular  region. 

Now  remove  the  fascia  by  dividing'  it  in  the  same 
direction  as  the  integument,  excepting  opposite  the 
ankle,  where  it  should  be  loft  entire.  Commence  the 
removal  of  the  fascia  from  below,  opposite  the  tendons, 
and  detach  it  in  the  line  of  direction  of  the  muscular 
fibres. 

The  Muscles  of  the  Leg  may  be  subdivided 
into  three  groups :  Those  on  the  anterior,  those 
ou  the  posterior,  and  those  on  the  outer  side. 

Anterior  Tibio-fibular  Regiox. 

Tibialis  Antic  us. 
Extensor  Proprius  Pollicis. 
Extensor  Longus  Digitorum. 
Peroneus  Tertius. 

The  Tibialis  Anticus  is  situated  on  the  outer 
side  of  the  tibia ;  it  is  thick  and  fleshy  at  its 
upper  part,  tendinous  below.  It  arises  from 
the  outer  tuberosity  and  upper  two-thirds  of 
the  external  surface  of  the  shaft  of  the  tibia ; 
from  the  adjoining  part  of  the  interosseous 
membrane;  from  the  deep  fascia  of  the  leg; 
and  from  the  intermuscular  septum  between  it 
and  the  Extensor  Longus  Digitorum;  the  fibres 
pass  vertically  downwards,  and  terminate  in  a 
tendon,  which  is  apparent  on  the  anterior  sur- 
face of  the  muscle  at  the  lower  third  of  the  leg. 
After  passing  through  the  innermost  compart- 
ment of  the  anterior  annular  ligament,  it  is 
inserted  into  the  inner  and  unfler  surface  of  the 
internal  cuneiform  bone,  and  base  of  the  meta- 
tarsal bone  of  the  great  toe. 

Relat'ions.  By  its  anterior  surface^  with  the 
deep  fascia,  and  with  the  annular  ligament. 
By  its  posterior  surface,  with  the  interosseous 
membrane,  tibia,  ankle-joint,  and  inner  side  of 
the  tarsus ;  this  surface  also  overlaps  the  an- 
terior tibial  vessels  and  nerve  in  the  upper 
part  of  the  leg.  By  its  inner  surface^  with  the 
tibia.  By  its  outer  surface,  with  the  Extensor 
Longus  Digitorum,  and  Extensor  Proprius  Pol- 
licis, and  the  anterior  tibial  vessels  and  nerve. 

The  Extensor  Proprius  Pollicis  is  a  thin, 
elongated,  and  flattened  muscle,  situated  be- 
tween the  Tibialis  Anticus  and  Extensor 
Longus  Digitorum.  It  arises  from  the  anterior 
surface  of  the  fibula  for  about  the  middle  two- 


Fig.  258. — Muscles  of  the  Front  of 
the  Leg. 


f/Z 


tM\ 


\Tibi 


420  MUSCLES    AND    FASCIA. 

fourths  of  its  extent,  its  origin  being  internal  to  that  of  the  Extensor  Longus 
Digitorum;  it  also  arises  from  the  interosseous  membrane  to  a  similar  extent. 
The  fibres  pass  downwards,  and  terminate  in  a  tendon,  which  occupies  the  an- 
terior border  of  the  muscle,  passes  through  a  distinct  compartment  in  the 
annular  ligament,  crosses  the  anterior  tibial  vessels  near  the  bend  of  the  ankle, 
and  is  inserted  into  the  base  of  the  last  phalanx  of  the  great  toe.  Opposite  the 
metatarso-phalangeal  articulation,  the  tendon  gives  off  a  thin  prolongation  on 
each  side,  which  covers  the  surface  of  the  joint. 

Relations.  By  its  anterior  harder^  with  the  deep  fascia,  and  the  anterior  annular 
Kgament.  By  its  posterior  border^  with  the  interosseous  membrane,  fibula,  tibia, 
ankle-joint,  and  Extensor  Brevis  Digitorum.  By  its  outer  side,  with  the  Exten- 
sor Longus  Digitorum  above,  the  dorsalis  pedis  vessels  and  anterior  tibial 
nerve  below.  By  its  inner  side,  with  the  Tibialis  Anticus  and  the  anterior  tibial 
vessels  above. 

The  Extensor  Longus  Digitorum  is  an  elongated,  flattened,  semipenniform 
muscle,  situated  the  most  externally  of  all  the  muscles  on  the  forepart  of  the 
leg.  It  arises  from  the  outer  tuberosity  of  the  tibia ;  from  the  upper  three- 
fourths  of  the  anterior  surface  of  the  shaft  of  the  fibula  ;  from  the  interosseous 
membrane,  and  deep  fascia ;  and  from  the  intermuscular  septa  between  it  and 
the  Tibialis  Anticus  on  the  inner,  and  the  Peronei  on  the  outer  side.  The 
muscle  terminates  in  three  tendons,  which  pass  through  a  canal  in  the  annular 
ligament,  with  the  Peroneus  Tertius,  run  across  the  dorsum  of  the  foot,  and  are 
inserted  into  the  second  and  third  phalanges  of  the  four  "lesser  toes,  the  inner- 
most tendon  having  subdivided  into  two.  The  mode  in  which  the  tendons  are 
inserted  is  the  following:  Each  tendon  opposite  the  metatarso-phalangeal  articu- 
lation is  joined,  on  its  outer  side,  by  the  tendon  of  the  Extensor  Brevis  Digi- 
torum (except  the  fourth),  and  receives  a  fibrous  expansion  from  the  Interossei 
and  Lumbricales ;  it  then  spreads  into  a  broad  aponeurosis,  wliich  covers  the 
dorsal  surface  of  the  first  phalanx.  This  aponeurosis,  at  the  articulation  of  the 
first  with  the  second  phalanx,  divides  into  three  slips,  a  middle  one,  which  is 
inserted  into  the  base  of  the  second  phalanx ;  and  two  lateral  slips,  which,  after 
uniting  on  the  dorsal  surface  of  the  second  phalanx,  are  continued  onwards,  to 
be  inserted  into  the  base  of  the  third. 

Relations.  By  its  anterior  surface,  with  the  deep  fascia  and-  the  annular  liga- 
ment. By  its  posterior  surface,  with  the  fibula,  interosseous  membrane,  ankle- 
joint,  and  Extensor  Brevis  Digitorum.  By  its  inner  side,  with  the  Tibialis 
Anticus,  Extensor  Proprius  Pollicis,  and  anterior  tibial  vessels  and  nerve.  By 
its  outer  side,  with  the  Peroneus  Longus  and  Peroneus  Brevis. 

The  Peroneus  Tertius  is  a  part  of  the  Extensor  Longus  Digitorum,  and  might 
be  described  as  its  fifth  tendon.  The  fibres  belonging  to  this  tendon  arise  from 
the  lower  fourth  of  the  anterior  surface  of  the  fibula,  on  its  outer  side ;  from 
the  lower  part  of  the  interosseous  membrane;  and  from  an  intermuscular  septum 
between  the  Peroneus  Tertius  and  the  Peroneus  Brevis.  The  tendon,  after 
passing  through  the  same  canal  in  the  annular  ligament  as  the  Extensor  Longus 
Digitorum,  is  inserted  into  the  base  of  the  metatarsal  bone  of  the  little  toe,  on 
its  dorsal  surface.     This  muscle  is  sometimes  wanting. 

Nerves.     These  muscles  are  supplied  by  the  anterior  tibial  nerve. 

Actions.  The  Tibialis  Anticus  and  Peroneus  Tertius  are  the  direct  flexors  of 
the  tarsus  upon  the  leg ;  the  former  muscle,  from  the  obliquity  in  the  direction 
of  its  tendon,  raises  the  inner  border  of  the  foot ;  and  the  latter,  acting  with 
the  Peroneus  Brevis  and  Peroneus  Longus,  will  draw  the  outer  border  of  the 
foot  upwards,  and  the  sole  outwards.  The  Extensor  Longus  Digitorum  and 
Extensor  Proprius  Pollicis  extend  the  phalanges  of  the  toes,  and,  continuing 
their  action,  flex  the  tarsus  upon  the  leg.  Taking  their  fixed  point  from  below, 
in  the  erect  posture,  all  these  muscles  serve  to  fix  the  bones  of  the  leg  in  the 
perpendicular  position,  and  give  increased  strength  to  the  ankle-joint. 


POSTERIOR    TIBIO-FIBULAR    REGION". 


421 


Posterior  Tibio-fibular  Region. 

Dissection  (Fig.  256).  Make  a  vertical  incision  along  the  middle  line  of  the  back  of  the  leg, 
from  the  lower  part  of  the  popliteal  space  to  the  heel,  connecting  it  below  by  a  transverse  in- 
cision extending  between  the  two  malleoli ;  the  flaps  of  integument  being  removed,  the  fascia 
and  muscles  should  be  examined. 


259. — Muscles  of  the  Back  of  tho 
Leg.     Superficial  Layer. 


The  muscles  in  this  region  of  the  leg  are  Fig 
subdivided  into  two  layers,  superficial  and 
deep.  The  superficial  layer  constitutes  a 
powerful  muscular  mass,  forming  the  calf  of 
the  leg.  Their  large  size  is  one  of  the  most 
characteristic  features  of  the  muscular  appa- 
ratus in  man,  and  bears  a  direct  connection 
with  his  ordinary  attitude  and  mode  of  pro 
gression. 

Superficial  Layer. 

Gastrocnemius.  Soleus. 

Plantaris. 

The  Gastrocnemius  is  the  most  superficial 
muscle,  and  forms  the  greater  part  of  the 
calf.  It  arises  by  two  heads,  whicli  are  con- 
nected to  the  condyles  of  the  femur  by  two 
strong  flat  tendons.  The  inner  head,  the 
larger,  and  a  little  the  more  posterior,  arises 
from  a  depression  at  the  upper  and  back 
part  of  the  inner  condyle.  The  outer  head 
arises  from  the  upper  and  back  part  of  the 
external  condyle,  immediately  above  the 
origin  of  the  Popliteus.  Both  heads,  also, 
arise  by  a  few  tendinous  and  fleshy  fibres 
from  the  ridges  which  are  continued  upwards 
from  the  condyles  to  the  linea  aspera.  Each 
tendon  spreads  out  into  an  aponeurosis, 
which  covers  the  posterior  surface  of  that 
portion  of  the  muscle  to  which  it  belongs ; 
that  covering  the  inner  head  being  longer 
and  thicker  than  the  outer.  From  the  ante- 
rior surface  of  these  tendinous  expansions, 
muscular  fibres  are  given  off.  The  fibres  in 
the  median  line,  which  correspond  to  the 
accessory  portions  of  the  muscle  derived 
from  the  bifurcations  of  the  linea  aspera, 
unite  at  an  angle  upon  a  median  tendinous 
raphe  below ;  the  remaining  fibres  converge 
to  the  posterior  surface  of  an  aponeurosis 
whicli  covers  the  front  of  the  muscle,  and 
this,  gradually  contracting,  unites  with  the 
tendon  of  the  Soleus,  and  forms  with  it  the 
tendo  Achillis. 

Relations.  By  its  superficial  surface^  with 
the  fascia  of  the  leg,  which  separates  it  from 
the  external  saphenous  vein  and  nerve.  By 
its  deep  surface^  with  the  posterior  ligament  of  the  knee-joint,  the  Popliteus,  So- 
leus, Plantaris,  popliteal  vessels,  and  internal  popliteal  nerve.  The  tendon  of  the 
inner  head  corresponds  with  the  back  part  of  the  inner  condyle,  from  which  it 


422  MUSCLES    AND    FASCIA. 

is  separated  hy  a  synovial  bursa,  which,  in  some  cases,  communicates  with  the 
cavity  of  the  knee-joint.  The  tendon  of  the  outer  head  contains  a  sesamoid 
tibro-cartilage  (rarely  osseous),  where  it  plays  over  the  corresponding  outer 
condyle;  and  one  is  occasionally  found  in  the  tendon  of  the  inner  head. 

The  Gastrocnemius  should  be  divided  across,  just  below  its  origin,  and  turned  downwards,  Id 
order  to  expose  the  next  muscles. 

The  Soleus  is  a  broad  flat  muscle,  situated  immediately  beneath  the  preceding. 
It  has  received  its  name  from  its  resemblance  in  shape  to  a  sole-fish.  It  arises 
by  tendinous  fibres  from  the  back  part  ot  the  head  of  the  fibula,  and  from  the 
upper  half  of  the  posterior  surface  of  its  shaft ;  from  the  oblique  line  of  the 
tibia,  and  from  the  middle  third  of  its  internal  border;  some  fibres  also  arise 
from  a  tendinous  arch  placed  between  the  tibial  and  fibular  origins  of  the 
muscle,  and  beneath  which  the  posterior  tibial  vessels  and  nerve  pass.  The 
fibres  pass  backwards  to  an  aponeurosis  which  covers  the  posterior  surface  of 
the  muscle,  and  this,  gradually  becoming  thicker  and  narrower,  joins  with  the 
tendon  of  the  Gastrocnemius,  and  forms  with  it  the  tendo  Achillis. 

Belations.  By  its  superficial  surface^  with  the  Gastrocnemius  and  Plantaris. 
By  its  deep  surface,  with  the  Flexor  Longus  Digitorum,  Flexor  Longus  Pollicis, 
Tibialis  Posticus,  and  posterior  tibial  vessels  and  nerve,  from  which  it  is  sepa- 
rated by  the  transverse  intermuscular  septum  or  deep  fascia  of  the  leg. 

The  Tendo  Achillis,  the  common  tendon  of  the  Gastrocnemius  and  Soleus,  is 
the  thickest  and  strongest  tendon  in  the  body.  It  is  about  six  inches  in  length, 
and  formed  by  the  junction  of  the  aponeuroses  of  the  two  preceding  muscles. 
It  commences  about  the  middle  of  the  leg,  but  receives  fleshy  fibres  on  its  an- 
terior surface,  nearly  to  its  lower  end.  Gradually  becoming  contracted  below, 
it  is  inserted  into  the  lower  part  of  the  posterior  tuberosity  of  the  os  calcis, 
a  synovial  bursa  being  interposed  between  the  tendon  and  the  upper  part  of  the 
tuberosity.  The  tendon  spreads  out  somewhat  at  its  lower  end,  so  that  its  nar- 
rowest part  is  usually  about  an  inch  and  a  half  above  its  insertion.  The  tendon 
is  covered  by  the  fascia  and  the  integument,  and  is  separated  from  the  deep 
muscles  and  vessels  by  a  considerable  interval  filled  up  with  areolar  and 
adipose  tissue.  Along  its  outer  side,  but  superficial  to  it,  is  the  external  saphe- 
nous vein. 

The  Plantaris  is  an  extremely  diminutive  muscle,  placed  between  the  Gastroc- 
nemius and  Soleus,  and  remarkable  for  its  long  and  delicate  tendon.  It  arises 
from  the  lower  part  of  the  outer  bifurcation  of  the  linea  aspera,  and  from  the 
posterior  ligament  of  the  knee-joint.  It  forms  a  small  fusiform  belly,  about 
two  inches  in  length,  which  terminates  in  a  long  slender  tendon  which  crosses 
obliquely  between  the  two  muscles  of  the  calf,  and  running  along  the  inner 
border  of  the  tendo  Achillis,  is  inserted  with  it  into  the  posterior  part  of  the 
OS  calcis.  This  muscle  is  occasionally  double,  and  is  sometimes  wanting. 
Occasionally,  its  tendon  is  lost  in  the  internal  annular  ligament,  or  in  the  fascia 
of  the  leg. 

Nerves.     These  muscles  are  supplied  by  the  internal  popliteal  nerve. 

Actions.  The  muscles  of  the  calf  possess  considerable  power,  and  are  con- 
stantly called  into  use  in  standing,  walking,  dancing,  and  leaping;  hence  the 
large  size  they  usually  present.  In  walking,  these  muscles  draw  powerfully 
upon  the  os  calcis,  raising  the  heel,  and,  with  it,  the  entire  body,  from  the 
ground ;  the  body  being  thus  supported  on  the  raised  foot,  the  opposite  limb 
can  be  carried  forwards.  In  standing,  the  Soleus,  taking  its  fixed  point  from 
below,  steadies  the  leg  upon  the  foot,  and  prevents  the  body  from  falling  for- 
wards, to  which  there  is  a  constant  tendency  from  the  superincumbent  weight. 
The  Gastrocnemius,  acting  from  below,  serves  to  flex  the  femur  upon  the  tibia, 
assisted  by  the  Popliteus.  The  Plantaris  is  the  rudiment  of  a  large  muscle 
which  exists  in  some  of  the  lower  animals,  and  serves  as  a  tensor  of  the  plantar 
fascia. 


POSTERIOR    TIBIO-FIBULAR    REGION. 


423 


Popliteus. 

Flexor  Longus  Pollicis. 


Deep  Layer. 


Flexor  Longus  Digitorum. 
Tibialis  Posticus. 


Fig.  260.— Muscles  of  the 
Back  of  the  Leg.  Deep 
Layers. 


V'l^O,i. 


\  Canidule   /    ' 


Dissection.  Detach  the  Soleus  frora  its  attachment  to  the 
fibula  and  tibia,  and  turn  it  downwards  when  the  deep  layer  of 
muscles  is  exposed,  covered  by  the  deeji  fascia  of  the  leg. 

The  deep  fascia  of  the  leg  is  a  broad,  transverse,  in- 
termuscular septum,  interposed  between  the  super- 
ficial and  deep  muscles  in  the  posterior  tibio-fibular 
region.  On  each  side  it  is  connected  to  the  margins 
of  the  tibia  and  fibula.  Above,  where  it  covers  the 
Popliteus,  it  is  thick  and  dense,  and  receives  an  ex- 
pansion from  the  tendon  of  the  Semimembranosus;  it 
is  thinner  in  the  middle  of  the  leg  ;  but  below,  where 
it  covers  the  tendons  passing  behind  the  malleoli,  it 
is  thickened.  It  is  continued  onwards  in  the  interval 
between  the  ankle  and  the  heel,  where  it  covers  the 
vessels,  and  is  blended  with  the  internal  annular  liga- 
ment. 

This  fascia  should  now  be  removed,  commencing  frora  below 
opposite  the  tendons,  and  detaching  it  from  the  muscles  in  the 
direction  of  their  fibres. 

The  PopUtens  is  a  thin,  flat  triangular  muscle,  which 
forms  part  of  the  floor  of  the  popliteal  space,  and  is 
covered  by  a  tendinous  expansion,  derived  from  the 
Semimembranosus  muscle.  It  arises  by  a  strong  flat 
tendon,  about  an  inch  in  length,  from  a  deep  depres- 
sion on  the  outer  side  of  the  exteral  condyle  of  the 
femur,  and  from  the  posterior  ligament  of  the  knee- 
joint  ;  and  is  inserted  into  the  inner  two-thirds  of  the 
triangular  surface  above  the  oblique  line  on  the  pos- 
terior surface  of  the  shaft  of  the  tibia,  and  into  the 
tendinous  expansion  covering  the  surface  of  the 
muscle.  The  tendon  of  the  muscle  is  covered  by  that 
of  the  Biceps  and  the  external  lateral  ligament  of  the 
knee-joint;  it  grooves  the  outer  surface  of  the  exter- 
nal semilunar  cartilage,  and  is  invested  by  the  syno- 
vial membrane  of  the  knee-joint. 

Relations.  By  its  superjicial  surface,  with  the  fascia 
above  mentioned,  which  separates  it  from  the  Gastroc- 
nemius, Plantaris,  popliteal  vessels,  and  internal  pop- 
liteal nerve.  By  its  deep  surface^  with  the  superior 
tibio-fibular  articulation,  and  back  of  the  tibia. 

The  Flexor  Longus  Pollicis  is  situated  on  the  fibular 
side  of  the  leg,  and  is  the  most  superficial  and  largest 
of  the  three  next  muscles.  It  arises  from  the  lower 
two-thirds  of  the  internal  surface  of  the  shaft  of  the 
fibula,  with  the  exception  of  an  inch  at  its  lowest 
part ;  from  the  lower  part  of  the  interosseous  mem- 
brane ;  from  an  intermuscular  septum  between  it  and 
the  Peronei,  externally  ;  and  from  the  fascia  covering 
the  Tibialis  Posticus.  The  fibres  pass  obliquely 
downwards  and  backwards,  and  terminate  round  a 
tendon  which  occupies  nearly  the  whole  length  of  the  posterior  surface  of 
muscle.     This  tendon  passes  through  a  groove  on  the  posterior  surface  of 


the 
the 


424  MUSCLES    AND    FASCIA. 

tibia,  external  to  that  for  the  Tibialis  Posticus  and  Flexor  Longus  Digitorum ; 
it  then  passes  through  another  groove  on  the  posterior  extremity  of  the  astra- 
galus, and  along  a  third  groove,  beneath  the  tubercle  of  the  os  calcis,  into  the 
sole  of  the  foot,  where  it  runs  forwards  between  the  two  heads  of  the  Flexor 
Brevis  Pollicis,  and  is  inserted  into  the  base  of  the  last  phalanx  of  the  great 
toe.  The  grooves  in  the  astragalus  and  os  calcis  which  contain  the  tendon  of 
the  muscle,  are  converted  by  tendinous  fibres  into  distinct  canals,  lined  by 
synovial  membrane ;  and  as  the  tendon  crosses  the  sole  of  the  foot,  it  is  con- 
nected to  the  common  flexor  by  a  tendinous  slip. 

Relations.  By  its  superficial  surface^  with  the  Soleus  and  tendo  Achillis,  from 
which  it  is  separated  by  the  deep  fascia.  By  its  dep])  surface,  with  the  fibula, 
Tibialis  Posticus,  the  peroneal  vessels,  the  lower  part  of  the  interosseus  mem- 
brane, and  the  ankle-joint.  By  its  outer  border,  with  the  Peronei.  By  its  iniier 
border,  with  the  Tibialis  Posticus,  and  Flexor  Longus  Digitorum. 

The  Flexor  Longus  Digitorum  (Per/orans)  is  situated  on  the  tibial  side  of  the 
leg.  At  its  origin,  it  is  thin  and  pointed,  but  gradually  increases  in  size  as  it 
descends.  It  arises  from  the  posterior  surface  of  the  shaft  of  the  tibia,  imme- 
diately below  the  oblique  line,  to  within  three  inches  of  its  extremity,  internal 
to  the  tibial  origin  of  the  Tibialis  Posticus ;  some  fibres  also  arise  from  the 
intermuscular  septum  between  it  and  the  Tibialis  Posticus.  The  fibres  termi- 
nate in  a  tendon,  which  runs  nearly  the  whole  length  of  the  posterior  surface 
of  the  muscle.  This  tendon  passes,  behind  the  inner  malleolus,  in  a  groove, 
common  to  it  and  the  Tibialis  Posticus,  but  separated  from  the  latter  by  a 
fibrous  septum;  each  tendon  being  contained  in  a  special  sheath  lined  by  a 
separate  synovial  membrane.  It  then  passes  obliquely  forwards  and  outwards, 
beneath  the  arch  of  the  os  calcis,  into  the  sole  of  the  foot  (Fig.  262),  where, 
crossing  beneath  the  tendon  of  the  Flexor  Longus  Pollicis,  to  which  it  is  con- 
nected by  a  strong  tendinous  slip,  it  becomes  expanded,  is  joined  by  the  Flexor 
Accessorius,  and  finally  divides  into  four  tendons  which  are  inserted  into  the 
bases  of  the  last  phalanges  of  the  four  lesser  toes,  each  tendon  passing  through 
a  fissure  in  the  tendon  of  the  Flexor  Brevis  Digitorum,  opposite  the  middle  of 
the  first  phalanges. 

Relations.  In  the  leg:  by  its  superficial  surface,  with  the  Soleus,  and  the  pos- 
terior tibial  vessels  and  nerve,  from  which  it  is  separated  by  the  deep  fascia ; 
by  its  deep  surface,  with  the  tibia  and  Tibialis  Posticus.  In  the  foot,  it  is  covered 
by  the  Abductor  Pollicis,  and  Flexor  Brevis  Digitorum,  and  crosses  beneath 
the  Flexor  Longus  Pollicis. 

The  Tibialis  Posticus  lies  between  the  two  preceding  muscles,  and  is  the  most 
deeply  seated  of  all  the  muscles  in  the  leg.  It  commences  above,  by  two  pointed 
processes,  separated  by  an  angular  interval,  through  which  the  anterior  tibial 
vessels  pass  forwards  to  the  front  of  the  leg.  It  arises  from  the  whole  of  the 
posterior  surface  of  the  interosseous  membrane,  excepting  its  lowest  part,  from 
the  posterior  surface  of  the  shaft  of  the  tibia,  external  to  the  Flexor  Longus 
Digitorum,  between  the  commencement  of  the  oblique  line  above,  and  the 
middle  of  the  external  border  of  the  bone  below,  and  from  the  upper  two-thirds 
of  the  inner  surface  of  the  shaft  of  the  fibula;  some  fibres  also  arise  from  the 
deep  fascia,  and  from  the  intermuscular  septa,  separating  it  from  the  adjacent 
muscles  on  each  side.  This  muscle,  in  the  lower  fourth  of  the  leg,  passes  in 
front  of  the  Flexor  Longus  Digitorum,  terminates  in  a  tendon,  which  passes 
through  a  groove  behind  the  inner  malleolus,  with  the  tendon  of  that  muscle, 
but  inclosed  in  a  separate  sheath;  it  then  passes  through  another  sheath,  over 
the  internal  lateral  ligament,  and  beneath  the  calcaneo-scaphoid  articulation, 
and  is  inserted  into  the  tuberosity  of  the  scaphoid,  and  internal  cuneiform  bones. 
The  tendon  of  this  muscle  contains  a  sesamoid  bone,  near  its  insertion,  and  gives 
off'  fibrous  expansions,  one  of  which  passes  backwards  to  the  os  calcis,  others 
outwards  to  the  middle  and  external  cuneiform,  and  some  forwards  to  the  bases 
of  the  third  and  fourth  metatarsal  bones  (Fig.  263). 


FIBULAR    REGION.  425 

Relations.  By  its  superficial  surface^  with  the  Soleus,  and  Flexor  Longus 
Digitorum,  the  postfirior  tibial  vessels  and  nerve,  and  the  peroneal  vessels,  from 
which  it  is  separated  hy  the  deep  fascia.  By  its  deep  surface^  with  the  interos- 
seous ligament,  the  tibia,  fibula,  and  ankle-joint. 

Nerves.  The  Popliteus  is  supplied  by  the  internal  popliteal  nerve,  the  re- 
maining muscles  of  this  group  by  the  posterior  tibial  nerve. 

Actions.  The  Popliteus  assists  in  flexing  the  leg  upon  the  thigh;  when  the 
leg  is  flexed,  it  will  rotate  the  tibia  inwards.  The  Tibialis  Posticus  is  a  direct 
extensor  of  the  tarsus  upon  the  leg;  acting  in  conjunction  with  the  Tibialis 
Anticus,  it  turns  the  sole  of  the  foot  inwards,  antagonizing  the  Peroneus 
Longus,  which  turns  it  outwards.  The  Flexor  Longus  Digitorum  and  Flexor 
Longus  Pollicis  are  the  direct  flexors  of  the  phalanges,  and,  continuing  their 
action,  extend  the  foot  upon  the  leg;  they  assist  the  Gastrocnemius  and  Soleus 
in  extending  the  foot,  as  in  the  act  of  walking,  or  in  standing  on  tiptoe.  In 
consequence  of  the  oblique  direction  of  the  tendon  of  the  long  extensor,  the 
toes  would  be  drawn  inwards,  were  it  not  for  the  Flexor  Accessorius  muscle, 
which  is  inserted  into  the  outer  side  of  that  tendon,  and  draws  it  to  the  middle 
line  of  the  foot  during  its  action.  Taking  their  fixed  point  from  the  foot,  these 
muscles  serve  to  maintain  the  upright  posture,  by  steadying  the  tibia  and  fibula, 
perpendicularly,  upon  the  ankle-joint.  They  also  serve  to  raise  these  bones  from 
the  oblique  position  they  assume  in  the  stooping  posture. 

Fibulae  Eegion". 
Peroneus  Longus.  Peroneus  Brevis. 

Disnedion.  These  muscles  are  readily  exposed,  by  removing  the  fascia  covering  their  surface, 
from  below  upwards,  in  the  line  of  direction  of  their  fibres. 

The  Peroneus  Longus  is  situated  at  the  upper  part  of  the  outer  side  of  the  leg, 
and  is  the  more  superficial  of  the  two  muscles.  It  arises  from  the  head,  and 
upper  two-thirds  of  the  outer  surface  of  the  shaft  of  the  fibula,  from  the  deep 
fascia,  and  from  the  intermuscular  septa,  between  it  and  the  muscles  on  the 
front,  and  those  on  the  back  of  the  leg.  It  terminates  in  a  long  tendon,  which 
passes  behind  the  outer  malleolus,  in  a  groove,  common  to  it  and  the  Peroneus 
Brevis,  the  groove  being  converted  into  a  canal  by  .a  fibrous  band,  and  the  ten- 
dons invested  by  a  common  synovial  membrane;  it  is  then  reflected,  obliquely 
forwards,  across  the  outer  side  of  the  os  caicis,  being  contained  in  a  separate 
fibrous  sheath,  lined  by  a  prolongation  of  the  synovial  membrane  from  that 
which  lines  the  groove  behind  the  malleolus.  Having  reached  the  outer  side 
of  the  cuboid  bone,  it  runs  in  a  groove  on  the  under  surface  of  that  bone,  which 
is  converted  into  a  canal  by  the  long  calcaneo-cuboid  ligament,  and  is  lined  by 
a  synovial  membrane :  the  tendon  then  crosses,  obliquely,  the  sole  of  tlie  foot, 
and  is  inserted  into  the  outer  side  of  the  base  of  the  metatarsal  bone  of  the 
great  toe.  The  tendon  changes  its  direction  at  two  points,  first,  behind  the 
external  malleolus;  secondly,  on  the  outer  side  of  the  cuboid  bone:  in  both 
of  these  situations,  the  tendon  is  thickened,  and,  in  the  latter,  a  sesamoid  bone 
is  usually  developed  in  its  substance. 

Relations.  By  its  superficial  surf  ace,  with  the  fascia  and  integument;  by  its 
deep  surface,  with  the  fibula,  the  Peroneus  Brevis,  os  caicis  and  cuboid  bone; 
by  its  anterior  border,  with  an  intermuscular  septum,  which  intervenes  between 
it  and  the  Extensor  Longus  Digitorum;  by  its  posterior  border,  with  an  intermus- 
cular septum,  which  separates  it  from  the  Soleus  above,  and  the  Flexor  Longus 
Pollicis  below. 

The  Peroneus  Brevis  lies  beneath  the  Peroneus  Longus,  and  is  shorter  and 
smaller  than  it.  It  arises  from  the  middle  third  of  the  external  surface  of  the 
shaft  of  the  fibula,  internal  to  the  Peroneus  Longus ;  from  the  anterior  and 
posterior  borders  of  the  bone ;  and  from  the  intermuscular  septa  separating  it 
from  the  adjacent  muscles  on  the  front  and  back  part  of  the  leg.     The  fibres 


426  MUSCLES    AND    FASCIA. 

pass  vertically  downwards,  and  terminate  in  a  tendon,  which  runs  in  front  of 
that  of  the  preceding  muscle  through  the  same  groove,  behind  the  external 
malleolus,  being  contained  in  the  same  fibrous  sheath,  and  lubricated  by  the 
same  synovial  membrane;  it  then  passes  through  a  separate  sheath  on  the  outer 
side  of  the  os  calcis,  above  that  for  the  tendon  of  the  Peroneus  Longus,  and  is 
finally  inserted  into  the  base  of  the  metatarsal  bone  of  the  little  toe,  on  its  dorsal 
Eurface. 

Relations.  By  its  superficial  surface,  with  the  Peroneus  Longus  and  the  fascia 
of  the  leg  and  foot.  By  its  deep  surface,  with  the  fibula  and  outer  side  of  the 
OS  calcis. 

Nerves.  The  Peroneus  Longus  and  Peroneus  Brevis  are  supplied  by  the 
musculo-cutaneous  branch  of  the  external  popliteal  nerve. 

Actions.  The  Peroneus  Longus  and  Peroneus  Brevis  extend  the  foot  upon 
the  leg,  in  conjunction  with  the  Tibialis  Posticus,  antagonizing  the  Tibialis 
Anticus  and  Peroneus  Tertius,  which  are  flexors  of  the  foot.  The  Peroneus 
Longus  also  everts  the  sole  of  the  foot ;  hence  the  extreme  eversion  occasionally 
observed  in  fracture  of  the  lower  end  of  the  fibula,  where  that  bone  offers  no 
resistance  to  the  action  of  this  muscle.  Taking  their  fixed  point  below,  the 
Peroni  serve  to  steady  the  leg  upon  the  foot.  This  is  especially  the  case  in 
standing  upon  one  leg,  when  the  tendency  of  the  superincumbent  weight  is  to 
throw  the  leg  inwards:  the  Peroneus  Longus  overcomes  this  tendency,  by 
drawing  on  the  outer  side  of  the  leg,  and  thus  maintains  the  perpendicular 
direction  of  the  limb. 

Surgical  Anatomy.  The  student  should  now  consider  the  position  of  the  tendons  of  the 
various  muscles  of  the  leg,  their  relation  with  the  ankle-joint  and  surrounding  bloodvessels,  and 
especially  their  action  upon  the  foot,  as  their  rigidity  and  contraction  give  rise  to  one  or  the 
other  forms  of  deformity  known  as  club-foot.  'J'he  most  simple  and  common  deformity,  and  one 
that  is  rarely  if  ever  congenital,  is  the  talipes  equinu.s,  the  heel  being  raised  by  rigidity  and  con- 
traction of  the  Gastrocnemius  muscle,  and  the  patient  walking  upon  the  ball  of  the  foot.  In  the 
talipes  yariis,  which  is  the  more  common  congenital  form,  the  heel  is  .raised  by  the  tendo  Achillis, 
the  inner  border  of  the  foot  drawn  upwards  by  the  Tibialis  Anticus,  and  the  anterior  two-thirds 
of  the  foot  twisted  inwards  by  the  Tibialis  Posticus  and  Flexor  Longus  Digitorum,  the  patient 
walking  upon  the  outer  edge  of  the  foot,  and  in  severe  cases  upon  the  dorsum  and  outer  ankle. 
In  the  talipes  valgus,  the  outer  edge  of  the  foot  is  raised  by  the  Peronei  muscles,  and  the  patient 
walks  on  the  inner  ankle.  In  the  talipes  calcaneus,  the  toes  are  raised  by  the  e.\tensor  muscles, 
the  heel  is  depressed,  and  the  patient  walks  upon  it.  Other  varieties  of  deformity  are  met  with, 
as  the  talipes  equino-varus,  equino-valgus,  and  calcaneo-valgus,  whose  names  sufficiently  indicate 
their  nature.  Each  of  these  deformities  may  be  successfully  relieved  (after  other  remedies  fail) 
by  division  of  the  opposing  tendons  and  fascia ;  by  this  means,  the  foot  regains  the  proper  posi- 
tion, and  the  tendons  heal  by  the  organization  of  lymph  thrown  out  between  the  divided  ends. 
The  operation  is  easily  performed  by  putting  the  contracted  tendon  upon  the  stretch,  and 
dividing  it  by  means  of  a  narrow  sharp-pointed  knife  inserted  between  it  and  the  skin. 

Fascia  of  the  Foot. 

The  fibrous  bands  which  bind  down  the  tendons  in  front  of  and  behind  the  ankle  in  their 
passage  to  the  foot,  should  now  be  examined ;  they  are  termed  the  annular  ligaments,  and  are 
three  in  number,  anterior,  internal,  and  external. 

The  Anterior  Annular  Ligament  consists  of  a  superior  or  vertical  portion, 
which  binds  down  the  extensor  tendons  as  they  descend  on  the  front  of  the 
tibia  and  fibula;  and  an  inferior  or  horizontal  portion,  which  retains  them  in 
connection  with  the  tarsus,  the  two  portions  being  connected  by  a  thin  inter- 
vening layer  of  fascia.  The  vertical  portion  is  attached  externally  to  the  lower 
end  of  the  fibula,  internally  to  the  tibia,  and  above  is  continuous  with  the  fascia 
of  the  leg;  it  contains  two  separate  sheaths,  one  internally,  for  the  tendon  of 
the  Tibialis  Anticus;  one  externally,  for  the  tendons  of  the  p]xtensor  Longus 
Digitorum  and  Peroneus  Tertius,  the  tendon  of  the  Exten.sor  Proprius  Pollicis, 
and  the  anterior  tibial  vessels  and  nerve  pass  beneath  it,  but  without  any  dis- 
tinct sheath.  The  horizontal  portion  is  attached  externally  to  the  upper  surface 
of  the  OS  calcis,  in  front  of  the  depression  for  the  interosseous  ligament,  and 
iniernally  to  the  inner  malleolus  and  plantar  fascia:  it  contains  three  sheaths; 


FASCIA    OF    THE    FOOT.  427 

the  most  internal  for  the  tendon  of  the  Tibialis  Anticus,  the  next  in  order  for 
the  tendon  of  the  Extensor  Proprius  Pollicis,  and  the  most  external  for  the 
Extensor  Longus  Digitorum  and  Peroneus  Tertius :  the  anterior  tibial  vessels 
and  nerve  lie  altogether  beneath  it.  These  sheaths  are  lined  bj  separate 
synovial  membranes. 

The  Internal  Annular  Ligament  is  a  strong  fibrous  band,  which  extends  from 
the  inner  malleolus  above,  to  the  internal  margin  of  the  os  calcis  below,  con- 
verting a  series  of  bony  grooves  in  this  situation  into  osseo-fibrous  canals,  for 
the  passage  of  the  tendons  of  the  flexor  muscles  and  vessels  into  the  sole  of  the 
foot.  It  is  continuous  above  with  the  deep  fascia  of  the  leg,  below  with  the 
plantar  fascia  and  the  fibres  of  origin  of  the  Abductor  Pollicis  muscle.  The 
three  canals  which  it  forms  transmit  from  within  outwards,  first,  the  tendon  of 
the  Tibialis  Posticus ;  second,  the  tendon  of  the  Flexor  Longus  Digitorum,  then 
tlie  posterior  tibial  vessels  and  nerve,  which  run  through  a  broad  space  beneath 
the  ligament;  lastly,  in  a  canal  formed  partly  by  the  astragalus,  the  tendon  of 
the  Flexor  Longus  Pollicis.  Each  of  these  canals  is  lined  by  a  separate  syno- 
vial membrane. 

The  External  Annular  Ligament  extends  from  the  extremity  of  the  outer 
malleolus  to  the  outer  surface  of  the  os  calcis ;  it  binds  down  the  tendons  of  the 
Peronei  muscles  in  their  passage  beneath  the  outer  ankle.  The  two  tendons 
are  inclosed  in  one  synovial  sac. 

Dissection  of  the  Sole  of  the  Foot.  The  foot  should  be  placed  on  a  hijrh  block  with  the  sole 
uppermost,  and  fii-mly  secured  in  that  position.  Carry  an  incision  round  the  heel  and  alonj?  the 
inner  and  outer  borders  of  the  foot  to  the  great  and  little  toes.  This  incision  should  divide  the 
integument  and  thick  layer  of  granular  fat  beneath,  until  the  fascia  is  visible ;  the  skin  and  fat 
should  then  be  removed  from  the  fascia  in  a  direction  from  behind  forwards,  as  seen  in  Fig.  256. 

The  Plantar  Fa^cia^  the  densest  of  all  the  fibrous  membranes,  is  of  great 
strength,  and  consists  of  dense  pearly-white  glistening  fibres,  disposed,  for  the 
most  part,  longitudinally:  it  is  divided  into  a  central  and  two  lateral  portions. 

The  central  portion,  the  thickest,  is  narrow  behind  and  attached  to  the  inner 
tuberosity  of  the  os  calcis,  behind  the  origin  of  the  Flexor  Brevis  Digitorum, 
and  becoming  broader  and  thinner  in  front,  divides  opposite  the  middle  of  the 
metatarsal  bones  into  five  processes,  one  for  each  of  the  toes.  Each  of  these 
processes  divides  opposite  the  metatarso- phalangeal  articulation  into  two  slips, 
which  embrace  the  sides  of  the  flexor  tendons  of  the  toes,  and  are  inserted  into 
the  sides  of  the  metatarsal  bones,  and  into  the  transverse  metatarsal  ligament, 
thus  forming  a  series  of  arches  through  which  the  tendons  of  the  short  and 
long  flexors  pass  to  the  toes.  The  intervals  left  between  the  five  processes 
allow  the  digital  vessels  and  nerves,  and  the  tendons  of  the  Lumbricales  and 
Interossei  muscles  to  become-  superficial.  At  the  point  of  division  of  the  fascia 
into  processes  and  slips,  numerous  transverse  fibres  are  superadded,  which  serve 
to  increase  the  strength  of  the  fascia  at  this  part,  by  binding  the  processes  to- 
gether, and  connecting  them  with  the  integument.  The  central  portion  of  the 
plantar  fascia  is  continuous  with  the  lateral  portions  at  each  side,  and  sends 
upwards  into  the  foot,  at  their  point  of  junction,  two  strong  vertical  intermus- 
cular septa,  broader  in  front  than  behind,  which  separate  the  middle  from  the 
external  and  internal  plantar  group  of  muscles;  from  these  again  thinner  trans- 
verse septa  are  derived,  which  separate  the  various  layers  of  muscles  in  this 
region.  The  upper  surface  of  this  fascia  gives  .attachment  behind  to  the  Flexor 
Brevis  Digitorum  muscle. 

The  lateral  portions  of  the  plantar  fascia  are  thinner  than  the  central  piece,  and 
cover  the  sides  of  the  foot. 

The  outer  portion  covers  the  under  surface  of  the  Abductor  Minimi  Digiti ;  it 
is  thick  behind,  thin  in  front,  and  extends  from  the  os  calcis  forwards  to  the 
base  of  the  fifth  metatarsal  bone,  into  the  outer  side  of  which  it  is  iittached ;  it 
is  continuous  internally  with  the  middle  portion  of  the  plantar  fascia,  and 
externally  with  the  dorsal  fascia. 


428  MUSCLES    AND    FASCIA. 

The  inner  portion  is  very  tliin,  and  covers  the  Abductor  Pollicis  muscle;  it 
is  attached  behind  to  the  internal  annular  ligament,  and  is  continuous  around 
the  side  of  the  foot  with  the  dorsal  fascia,  and  externally  with  the  middle  por- 
tion of  the  plantar  fascia. 

MUSCLES  OF  THE  FOOT. 
These  are  found  in  two  regions:  1.  On  the  dorsum ;  2.  On  the  plantar  surface. 

1.  Dorsal  Region. 
Extensor  Brevis  Digitorum. 

The  Fascia  on  the  dorsum  of  the  foot  is  a  thin  membranous  layer,  continuous 
above  with  the  anterior  margin  of  the  annular  ligament;  it  becomes  gradually 
lost  opposite  the  heads  of  the  metatarsal  bones,  and  on  each  side  blends  with 
the  lateral  portions  of  the  plantar  fascia ;  it  forms  a  sheath  for  the  tendons 
placed  on  the  dorsum  of  the  foot.  On  the  removal  of  this  fascia,  the  muscles 
and  tendons  of  the  dorsal  region  of  the  foot  are  exposed. 

The  Extensor  Brevis  Digitorum  (Fig.  258)  is  a  broad  thin  muscle,  which  arises 
from  the  outer  side  of  the  os  calcis,  in  front  of  the  groove  for  the  Peroneus 
Brevis;  from  the  astragalo-calcanean  ligament;  and  from  the  horizontal  portion 
of  the  anterior  annular  ligament.  It  passes  obliquely  across  the  dorsum  of  the 
foot,  and  terminates  in  four  tendons.  The  innermost,  which  is  the  largest,  is 
inserted  into  the  first  phalanx  of  the  great  toe ;  the  other  three,  into  the  outer 
sides  of  the  long  extensor  tendons  of  the  second,  third,  and  fourth  toes. 

Relations.  By  its  superficial  surface^  with  the  fascia  of  the  foot,  the  tendons 
of  the  Extensor  Longus  Digitorum,  and  Extensor  Proprius  Pollicis.  By  its 
deep  surface,  with  the  tarsal  and  metatarsal  bones,  and  the  Dorsal  Interossei 
muscles. 

Nerves.     It  is  supplied  by  the  anterior  tibial  nerve. 

Actions.  The  Extensor  Brevis  Digitorum  is  an  accessory  to  the  long  Extensor, 
extending  the  phalanges  of  the  four  inner  toes,  but  acting  only  on  the  first 
phalanx  of  the  great  toe.  The  obliquity  of  its  direction  counteracts  the  oblique 
movement  given  to  the  toes  by  the  long  Extensor,  so  that,  both  muscles  acting 
together,  the  toes  are  evenly  extended. 

2.  Plantar  Eegion. 

The  muscles  in  the  plantar  region  of  the  foot  may  be  divided  into  three  groups, 
in  a  similar  manner  to  those  in  the  hand.  Those  of  the  internal  plantar  region 
are  connected  with  the  great  toe,  and  correspond  with  those  of  the  thumb ;  those 
of  the  external  plantar  region  are  connected  with  the  little  toe,  and  correspond 
with  those  of  the  little  finger;  and  those  of  the  middle  plantar  region  are  con- 
nected with  the  tendons  intervening  between  the  two  former  groups;  but  in 
order  to  facilitate  the  dissection  of  these  muscles,  it  will  be  found  more  con- 
venient to  divide  them  into  four  layers,  as  they  present  themselves,  in  the  order 
in  which  they  are  successively  exposed. 

First  Layer. 

Abductor  Pollicis.  Flexor  Brevis  Digitorum. 

Abductor  Minimi  Digiti. 

Dissection.  Remove  the  fascia  on  the  inner  and  outer  sides  of  the  foot,  commencing  in  front 
over  the  tendons,  and  proceeding  backwards.  The  central  portion  should  be  divided  transversely 
in  the  middle  of  the  foot,  and  the  two  flaps  dissected  forwards  and  backward.s. 

The  Abductor  Pollicis  lies  along  the  inner  border  of  the  foot.  It  arises  from 
the  inner  tuberosity  on  the  under  surface  of  the  os  calcis;  from  the  internal 
annular  ligament;  from  the  plantar  fascia;  and  from  the  intermuscular  septum 


PLANTAR    REGIOX. 


429 


261.— Muscles  of  the  Sole  of  the  Foot. 
First  Layer. 


between  it  and  the  Flexor  Brevis  Digitorum.  The  fibres  terminate  in  a  tendon, 
which  is  inserted,  together  with  the  innermost  tendon  of  the  Flexor  Brevis  PoUi- 
cis,  into  the  inner  side  of  the  base  of  the  first 
phalanx  of  the  great  toe.  It  is  supplied  bj 
the  internal  plantar  nerve. 

Relations.  By  its  superficial  surface^  with 
the  plantar  fascia.  By  its  deep  surface,  with 
the  Flexor  Brevis  Pollicis,  the  Flexor  Ac- 
cessorius,  and  the  tendons  of  the  Flexor 
Longus  Digitorum  and  Flexor  Longns  Polli- 
cis, the  Tibialis  Anticus  and  Tibialis  Posticus, 
the  plantar  vessels  and  nerves,  and  the  ar- 
ticulations of  the  tarsus. 

The  Flexor  Brevis  Digitorum  {Perforatus) 
lies  in  the  middle  of  the  sole  of  the  foot,  im- 
mediately beneath  the  plantar  fascia,  with 
which  it  is  firmly  united.  It  arises  by  a 
narrow  tendinous  process,  from  the  inner  tu- 
bercle of  the  OS  calcis  ;  from  the  central  part 
of  the  plantar  fascia;  and  from  the  inter- 
muscular septa  between  it  and  the  adjacent 
muscles.  It  passes  forwards,  and  divides  into 
four  tendons.  Opposite  the  middle  of  the 
first  phalanges  each  tendon  presents  a  longi- 
tudinal slit,  to  allow  of  the  passage  of  the 
corresponding  tendon  of  the  Flexor  Longus 
Digitorum  ;  the  two  portions  form  a  groove 
for  the  reception  of  that  tendon.  The  tendon 
of  the  short  Flexor  then  reunites  and  imme- 
diately divides  a  second  time  into  two  pro- 
cesses, which  are  inserted  into  the  sides  of 
the  second  phalanges.  The  mode  of  division 
of  the  tendons  of  the  Flexor  Brevis  Digi- 
torum and  their  insertion  into  the  phalanges, 
is  analogous  to  the  Flexor  Sublimis  in  the 
hand.  It  is  supplied  by  the  internal  plantar 
nerve. 

Relations.  By  its  superficial  surface^  with 
the  plantar  fascia.  By  its  deep  surface,  with 
the  Flexor  Accessorius,  the  Lumbricales,  the 
tendons  of  the  Flexor  Longus  Digitorum, 
and  the  external  plantar  vessels  and  nerve, 
from  which  it  is  separated  by  a  thin  layer  of 
fascia.  The  outer  and  inner  borders  are  sepa- 
rated from  the  adjacent  muscles  by  means  of  vertical  prolongations  of  the 
plantar  fascia. 

The  Abductor  Minimi  Digiti  lies  along  the  outer  border  of  the  foot.  It  arises, 
by  a  very  broad  origin,  from  the  outer  tuberosity  of  the  os  calcis,  from  the 
under  surface  of  the  os  calcis  in  front  of  the  tubercles,  from  the  plantar  fascia, 
and  the  intermuscular  septum  between  it  and  the  Flexor  Brevis  Digitorum.  Its 
tendon,  after  gliding  over  a  smooth  facet  on  the  under  surface  of  the  base  of 
the  fifth  metatarsal  bone,  is  inserted  with  the  short  flexor  of  the  little  toe,  into 
the  outer  side  of  the  base  of  the  first  phalanx  of  the  little  toe.  It  is  supplied 
by  the  external  plantar  nerve. 

Relations.  By  its  superficial  surface,  with  the  plantar  fascia.  By  its  deep 
surface^  with  the  Flexor  Accessorius,  the  Flexor  Brevis  Minimi  Digiti,  the  long 


430 


MUSCLES    AND    FASCIAE. 


plantar  ligament,  and  Peroneus  Longus.  On  its  inner  side  are  the  external 
plantar  vessels  and  nerve,  and  it  is  separated  from  the  Flexor  Brevis  Digitorum 
by  a  vertical  septum  of  fascia. 

Dissection.  The  muscles  of  the  superficial  layer  should  be  divided  at  their  origin,  by  insert- 
ing the  knife  beneath  each,  and  cutting  obliquely  backwards,  so  as  to  detach  them  from  the  bone ; 
they  should  then  be  drawn  forwards,  in  order  to  expose  the  second  layer,  but  not  cut  away  at 
their  insertion.  The  two  layers  are  separated  by  a  thin  membrane,  the  deep  plantar  fascia,  on 
the  remov;il  of  which  is  seen  the  tendon  ot  the  Flexor  Longus  Digitorum,  the  Flexor  Accea- 

sorius,the  Flexor  Longus  PoUicis,  and  the  Lura- 
bricales.  The  long  flexor  tendons  cross  each  other 
at  an  acute  angle,  the  Flexor  Longus  PoUicis  run- 
ning along  the  inner  side  of  the  foot,  on  a  plane 
superior  to  that  of  the  Flexor  Longus  Digitorum, 
the  direction  of  which  is  obliquely  outwards. 


262.— Muscles  of  the  Sole  of  the  Foot. 
Second  Layer. 


Second  Layer. 

Flexor  Accessorius. 
Lumbricales. 

The  Flexor  Accessorius  arises  by  two 
heads;  the  inner  or  larger,  which  is  mus- 
cular, being  attached  to  the  inner  concave 
surface  of  the  os  calcis,  and  to  the  cal- 
caneo-scaphoid  ligament;  the  outer  head, 
flat  and  tendinous,  to  the  under  surface  of 
the  OS  calcis,  in  front  of  its  outer  tuber- 
cle, and  to  the  long  plantar  ligament ;  the 
two  portions  join  at  an  acute  angle,  and 
are  inserted  into  the  outer  margin  and 
upper  and  under  surfaces  of  the  tendon  of 
the  Flexor  Longus  Digitorum,  forming  a 
kind  of  groove,  in  which  the  tendon  is 
lodged.  It  is  supplied  by  the  external 
plantar  nerve. 

Relations.  By  its  superficial  surface, 
with  the  muscles  of  the  superficial  layer, 
from  which  it  is  separated  by  the  external 
plantar  vessels  and  nerves.  By  its  deep 
surface,  with  the  os  calcis  and  long  cal- 
caneo-cuboid  ligament. 

The  ZwrnAncaZes  are  four  small  muscles, 
accessory  to   the  tendons  of  the  Flexor 
Longus  Digitorum ;  they  arise  from  the 
tendons  of  the  long  flexor,  as  far  back  as 
their  angle  of  division,  each  arising  from 
two   tendons,    except   the    internal    one. 
Each  muscle  terminates  in  a  tendon,  which 
passes  forwards  on  the  inner  side  of  each 
of  the  lesser  toes,  and  is  inserted  into  the 
expansion  of  the  long  Extensor  and  base 
of  the  second  phalanx  of  the  corresponding  toe.     The  two  internal  Lumbri- 
cales muscles  are  supplied  by  the  internal,  and  the  two  external  by  the  external 
plantar  nerve. 

Dissection.    The  flexor  tendons  should  be  divided  at  the  back  part  of  the  foot,  and  the  Flexoi 
AccesBorius  at  its  origin,  and  drawn  forwards,  in  order  to  expose  the  third  layer. 


PLANTAR    REGION. 


431 


Third  Layer. 


Flexor  Brevis  Pollicis. 
Adductor  Pollicis. 


Flexor  Brevis  Minimi  Digiti. 
Transversus  Pedis. 


Fiff.  263.— Muscles  of  the  Sole  of  the  Foot. 


The  Flexor  Brevis  Pollicis  arises,  by  a  pointed  tendinous  process,  from  the 
inner  border  of  the  cuboid  bone,  from  the  contiguous  portion  of  the  external 
cuneiform,  and  from  the  prolongation  of  the  tendon  of  the  Tibialis  Posticus, 
which  is  attached  to  that  bone.  The  muscle  divides,  in  front,  into  two  portions, 
which  are  inserted  into  the  inner  and  outer  sides  of  the  base  of  the  first  phalanx 
of  the  great  toe,  a  sesamoid  bone  being 
developed  in  each  tendon  at  its  insertion. 
The  inner  head  of  this  muscle  is  blended 
with  the  Abductor  Pollicis  previous  to 
its  insertion ;  the  outer  head,  with  the 
Adductor  Pollicis ;  and  the  tendon  of  the 
Flexor  Longus  Pollicis  lies  in  a  groove 
between  them. 

Relations.  By  its  superficial  surface, 
with  the  Abductor  Pollicis,  the  tendon 
of  the  Flexor  Longus  Pollicis  and  plantar 
fascia.  By  its  deep  surface,  with  the  ten- 
don of  the  Peroneus  Longus,  and  meta- 
tarsal bone  of  the  great  toe.  By  its 
inner  border,  with  the  Abductor  Pollicis. 
By  its  outer  border,  with  the  Adductor 
Pollicis. 

The  Adductor  Pollicis  is  a  large,  thick, 
fleshy  mass,  passing  obliquely  across  the 
foot,  and  occupying  the  hollow  space 
between  the  four  outer  metatarsal  bones. 
It  arises  from  the  tarsal  extremities  of 
the  second,  third,  and  fourth  metatarsal 
bones,  and  from  the  sheath  of  the  tendon 
of  the  Peroneus  Longus,  and  is  inserted, 
together  with  the  outer  head  of  the  Flexor 
Brevis  Pollicis,  into  the  outer  side  of  the 
base  of  the  first  phalanx  of  the  great  too. 

The  Flexor  Brevis  Minimi  Digiti  lies 
on  the  metatarsal  bone  of  the  little  toe, 
and  much  resembles  one  of  the  interossei. 
It  arises  from  the  base  of  the  metatarsal 
bone  of  the  little  toe,  and  from  the  sheath 
of  the  Peroneus  Longus;  its  tendon  is 
inserted  into  the  base  of  the  first  phalanx 
of  the  little  toe,  on  its  outer  side. 

Relations.  By  its  superficial  surface, 
with  the  plantar  fascia  and  tendon  of  the 
Abductor  Minimi  Digiti.  By  its  deep 
surface,  with  the  fifth  metatarsal  bone. 

The  Transversus  Pedis  is  a  narrow,  fiat,  muscular  fasciculus,  stretched  trans- 
versely across  the  heads  of  the  metatarsal  bones,  between  them  and  the  flexor 
tendons.  It  arises  from  the  under  surface  of  the  head  of  the  fifth  metatarsal 
bone,  and  from  the  transverse  ligament  of  the  metatarsus;  and  is  inserted  into 
the  outer  side  of  the  first  phalanx  of  the  great  toe;  its  fibres  being  blended  with 
the  tendon  of  insertion  of  the  Adductor  Pollicis. 


43'^ 
Fig. 


SURGICAL    ANATOMY. 


264. 


-The  Dorsal  Intcrossei. 
Left  Foot. 


Fig.  265.— The  PLintar  Intcrossei. 
Left  Foot. 


Nerves.  The  Flexor  Brevis  Pollicis  is  supplied 
by  the  internal  plantar  nerve,  and  sometimes 
(according  to  Meckel)  receives  a  branch  from  the 
external  plantar.  The  other  three  muscles  of 
this  layer  are  supplied  by  the  external  plantar 
nerve. 

Relations.  By  its  under  surface,  with  the  ten- 
dons of  the  long  and  short  Flexors  and  Lumbri- 
cales.     By  its  u]p;per  surface,  with  the  Intcrossei. 

Fourth  Layer. 
The  Intcrossei. 

The  Intcrossei  muscles  in  the  foot  are  similar 
to  those  in  the  hand,  with  this  exception,  that 
they  are  grouped  around  the  middle  line  of  the 
second  toe,  instead  of  the  middle  line  of  the  whole 
member,  as  in  the  hand.  They  are  seven  in  num- 
ber, and  consist  of  two  groups,  dorsal  and  plantar. 

The  Dorsal  Interossei,  four  in  number,  are  situ- 
ated between  the  metatarsal  bones.  They  are 
bipenniform  muscles,  arising  by  two  heads  from 
the  adjacent  sides  of  the  metatarsal  bones  between 
which  they  are  placed ;  their  tendons  are  inserted 
into  the  bases  of  the  first  phalanges,  and  into  the 
aponeurosis  of  the  common  extensor  tendon.  In 
the  angular  interval  left  between  each  muscle  at 
its  posterior  extremity,  the  perforating  arteries 
pass  to  the  dorsum  of  the  foot ;  except  in  the  first 
Interosseous  muscle,  where  tlie  interval  allows 
the  passage  of  the  communicating  branch  of  the 
dorsalis  pedis  artery.  The  first  Dorsal  Interos- 
seous rauscle  is  inserted  into  the  inner  side  of  the 
second  toe ;  the  other  three  are  inserted  into  the 
outer  sides  of  the  second,  third,  and  fourth  toes. 
They  are  all  adductors  from  the  middle  line  of 
the  second  toe. 

The  Plantar  Interossei,  three  in  number,  lie  be- 
neath, rather  than  between,  the  metatarsal  bones. 
They  are  single  muscles,  and  are  each  connected 
with  but  one  metatarsal  bone.  They  arise  from 
the  base  and  inner  sides  of  the  shaft,  of  the  third, 
fourth,  and  fifth  metatarsal  bones,  and  are  inserted 
into  the  inner  sides  of  the  bases  of  the  first  pha- 
langes of  the  same  toes,  and  into  the  aponeurosis 
of  the  common  extensor  tendon.  These  muscles 
are  all  adductors  towards  the  middle  line  of  the 
second  toe. 

All  the  Interossei  muscles  are  supplied  by  the 
external  plantar  nerve. 


SURGICAL  ANATOMY. 

The  student  shonld  now  consider  the  effects  produced  by  the  action  of  the  various  muscles  in 
fractures  of  the  bones  of  iho  h)wer  extremity.  The  more  common  forms  of  fracture  are  selected 
for  illustration  and  description. 


•I 


OF    THE    MUSCLES    OF    THE    LOWER    EXTREMITY.       433 


Fracture  of  the  neck  of  the 
femar  intemalto  thecapsp/- 
lar  ligament  (Fig.  266)  is  a 
very  common  accident,  aild 
is  most  frequently  caused 
by  indirect  violence,  such 
as  slipping  off  the  edge  of 
the  kerbstone,  the  impetus 
and  weight  of  the  body 
falling  upon  the  neck  of 
the  bone.  It  usually  oc- 
curs in  females,  and  sel- 
dom under  fifty  years  of 
age.  At  this  period  of  life, 
the  cancellous  tissue  of  the 
neck  of  the  bone  not  un- 
frequently  is  atrophied,  be- 
coming soft  and  infiltrated 
with  fatty  matter ;  the  com- 
pact tissue  is  partially  ab- 
sorbed :  hence  the  bone 
is  more  brittle,  and  more 
liable  to  fracture.  The  cha- 
racteristic marks  of  this  ac- 
cident are  slight  shortening 
of  the  limb,  and  eversion  of 
the  foot,  neither  of  which 
symptoms  occur,  however, 
in  some  cases,  until  some 
time  after  the  injury.  The 
eversion  is  caused  by  the 
combined  action  of  the  external  rotator  muscles,  as  well  as 
by  the  Psoas  and  Iliacus,  Pectineus,  Adductors,  and  Glutei 
muscles.  'J'he  shortening  is  produced  by  the  action  of  the 
Glutei,  and  by  the  Kectus  Femoris  in  front,  and  the  Biceps, 
Semitendinosus,  and  Semimembranosus  behind. 

Fracture  of  the  femur  just  below  the  trochanters  (Fig.  267) 
is  an  accident  of  not  unfrequent  occurrence,  and  is  at- 
tended with  great  displacement,  producing  considerable 
deformity.  The  upper  fragment,  the  portion  chiefly  dis- 
placed, is  tilted  forwards  almost  at  right  angles  with  the 
pelvis,  by  the  combined  action  of  the  Psoas  and  Iliacus  ; 
and,  at  the  same  time,  everted  and  drawn  outwards  by 
the  e.\ternal  rotator  and  Glutei  muscles,  causing  a  marked 
prominence  at  the  upper  and  outer  side  of  the  thigh,  and 
much  pain  from  the  bruising  and  laceration  of  the  muscles. 
The  limb  is  shortened,  in  consequence  of  the  lower  frag- 
ment being  drawn  upwards  by  the  Rectus  in  front,  and 
the  Biceps,  Semimembranosus,  and  Semitendinosus  behind ; 
and,  at  the  same  time,  everted,  and  the  upper  end  thrown 
outwards,  the  lower  inwards,  by  the  Pectineus  and  Ad- 
ductor muscles.  This  fracture  may  be  reduced  in  two 
different  methods :  either  by  direct  relaxation  of  all  the 
opposing  muscles,  to  effect  which  the  limb  should  be  placed 
on  a  double  inclined  plane  ;  or  by  overcoming  the  contrac- 
tion of  the  muscles,  by  continued  extension,  which  may  be 
effected  by  means  of  the  long  splint. 

Oblique  fracture  of  the  femur  immediately  above  the  con- 
dyle (Fig.  2GS)  is  a  formidable  injury,  and  attended  with 
considerable  displacement.  On  examination  of  the  limb, 
the  lower  fragment  may  be  felt  deep  in  the  popliteal  space, 
being  drawn  backwards  by  the  Gastrocnemius,  Soleus,  and 
Plantaris  muscles ;  and  upwards  by  the  posterior  femoral 
and  Rectus  muscles.  The  pointed  end  of  the  upper  frag- 
ment is  drawn  inwards  by  the  Pectineus  and  Adductor 
muscles,  and  tilted  forwards  by  the  Psoas  and  Iliacus, 
piercing  the  Rectus  muscle,  and,  occasionally,  the  integu- 
ment. Relaxation  of  these  muscles,  and  direct  approxi- 
mation of  the  broken  fragments  is  effected  by  placing  the 
limb    on  a  double  inclined  plane.     The  greatest  care  is 

28 


Fig.  266.— Fracture  of  the  Neck  of  the  Femur  within  the 
Capsular  Ligament. 


PTRirenMii 


s    surtmsK 

OBTURATOR     INTCRNUa 


■  iNFcmon 

OBTUKATOII    EXTERNU* 


QUAOAATUt     rXMOKI* 


Fis:. 


267. — Fracture  of  the  Femur 
below  the  Trochanters. 


434 


SURGICAL    ANATOMY. 


requisite  in  keeping  the  pointed  extremity  of  the  upper  fragment  in  proper  position ;  other- 
wise, after  union  of  the  fracture,  the  power  of  extension  of  the  limb  is  partially  destroyed, 
from  the  Rectus  muscle  being  held  down  by  the  fractured  end  of  the  bone,  and  from  the  patella, 
when  elevated,  being  drawn  upwards  against  the  projecting  fragment. 

Fig.  268.— Fracture  of  the  Femur  above  the  Condyles.     Fig.  269.— Fracture  of  the  Patella. 


Fracture  of  the  patella  (Fig.  269)  may  be  produced  by  muscular  action,  or  by  direct 
violence.  When  produced  by  muscular  action,  it  occurs  thus :  a  person  in  danger  of  falling 
forwards,  attempts    to   recover   himself  by  throwing   the  body  backwards,  and    the  violent 

action  of  the  Quadriceps  Extensor  upon  the  pa 


Fig.  270.— Oblique  Fracture  of  the  Shaft 
of  the  'J'ibia. 


tella  snaps  that  bone  transversely  across.  The 
upper  fragment  is  drawn  up  the  thigh  by  the 
Quadriceps  Extensor,  the  lower  fragment  being 
retained  in  its  position  by  the  ligamentura 
patellae;  the  extent  of  separation  of  the  two 
fragments  depending  upon  the  degree  of  lacera- 
tion of  the  ligamentous  structures  around  the 
bone.  The  patient  is  totally  unable  to  straighten 
the  limb  ;  the  prominence  of  the  patella  is  lost ; 
and  a  marked  but  varying  interval  can  be  felt 
between  the  fragments.  The  treatment  consists 
in  relaxing  the  opposing  muscles,  which  may  be 
effected  by  raising  the  trunk,  and  slightly  ele- 
vating the  limb,  which  should  be  kept  in  a 
straight  position.  Union  is  usually  ligamentous. 
In  fracture  from  direct  violence,  the  bone  is 
generally  comminuted,  or  fractured  obliquely  or 
perpendicularly. 

Obli(iuc  fracture  of  the  shaft  of  the  tibia 
(Fig.  270)  usually  occurs  at  the  lower  fourth  of 
the  bone,  this  being  the  narrowest  and  weakest 
part,  and  is  usually  accompanied  with  fracture 
of  the  fibula.  If  the  fracture  has  taken  place 
obliquely  from  above,  downwards,  and  forwards, 
the  fragments  ride  over  one  another,  the  lower 
fragments  being  drawn  backwards  and  upwards 
by  the  powerful  action  of  the  muscles  of  the  calf; 
the  pointed  extremity  of  the  upper  fragment  pro- 
jects forwards  immediately  beneath  the  integu- 
ment, often  protruding  through  it,  and  rendering 
the  fracture  a  compound  one.  If  the  direction 
of  the  fracture  is  the  reverse  of  that  shown  in 
the  figure,  the  pointed  extremity  of  the  lower 
fragment  projects  forwards,  riding  upon  the  lower 
end  of  the  upper  one.  By  bending  the  knee, 
which  relaxes  the  opposingmusclcs,  and  making- 


OF    THE    MUSCLES    OF    THE    LOWER    EXTREMITY.     435 


extension  from  the  knee  and  ankle,  the  fragments  may  be  brought  into  apposition.  It  is  often 
nc'ceessary;  however,  in  compound  fracture,  to  remove  a  portion  of  the  projecting  bone  with  the 
saw  before  complete  adaptation  can  be  effected. 

Fracture  of  the  fibula,  with  displace- 
ment of  the  tibia   (Fig.  271),  commonly         271.— Fracture  of  the  Fibula,  with  displacement 
known  as  "  Pott's  Fracture,"  is  one   of  of  the  Tibial.—"  Pott's  Fracture." 

the  most  frequent  injuries  of  the  ankle- 
joint.  The  end  of  the  tibia  is  displaced 
from  the  corresponding  surface  of  the 
astragalus  ;  the  internal  lateral  ligament 
is  ruptured;  and  the  inner  malleolus 
projects  inwards  beneath  the  integu- 
ment, which  is  tightly  stretched  over 
it,  and  in  danger  of  bursting.  The 
fibula  is  broken,  usually  from  two  to 
three  inches  above  the  ankle,  and  occa- 
sionally that  portion  of  the  tibia  with 
which  it  is  more  directly  connected  be- 
low ;  the  foot  is  everted  by  the  action 
of  the  Peroneus  Longus,  its  inner  border 
resting  upon  the  ground,  and,  at  the 
same  time,  the  heel  is  drawn  up  by 
the  muscles  of  the  calf.  'J'his  injury 
may  be  at  once  reduced  by  flexing  the 
leg  at  right  angles  with  the  thigh, 
which  relaxes  all  the  opposing  muscles, 
and  by  making  slight  extension  from  the 
knee  and  ankle. 


On  the  Descriptive  Anatomy  of  the  Muscles,  refer  to  Cruveilhier's  "Anatomic  Descriptive;" 
,"  Trait6  de  Myologie  et  d'Angeiologie,"  by  F.  G.  Thiele,  Encyclopedic  Anatomique,  Paris, 
1843 ;  and  Henle's  "  Handbuch  der  Systematischen  Anatomic,"  before  referred  to. 


Of  the  Arteries. 

The  Arteries  are  cylindrical  tubular  vessels,  whicli  serve  to  convey  blood 
from  both  ventricles  of  tbe  heart  to  every  part  of  the  body.  These  vessels  were 
named  arteries  (a^p,  air]  ttiptiv,  to  contain)^  from  the  belief  entertained  by  the 
ancients  that  they  contained  air.  To  Galen  is  due  the  honor  of  refuting  this 
opinion ;  he  showed  that  these  vessels,  though  for  the  most  part  empty  after 
death,  contain  blood  in  the  living  body. 

The  pulmonary  artery,  which  arises  from  the  right  ventricle  of  the  heart, 
carries  venous  blood  directly  into  the  lungs,  whence  it  is  returned  by  the  pul- 
monary veins  into  the  left  auricle.  This  constitutes  the  lesser  or  pulmonic 
circulation.  The  great  artery  which  arises  from  the  left  ventricle,  the  aorta, 
conveys  arterial  blood  to  the  body  generally  ;  whence  it  is  brought  back  to  the 
right  side  of  the  heart  by  means  of  the  veins.  This*  constitutes  the  greater  or 
systemic  circulation. 

The  distribution  of  the  systemic  arteries  is  like  a  highly  ramified  tree,  the 
common  trunk  of  which,  formed  by  the  aorta,  commences  at  the  left  ventricle 
of  the  heart,  the  smallest  ramifications  corresponding  to  the  circumference  of 
the  body  and  the  contained  organs.  The  arteries  are  found  in  nearly  every 
part  of  the  body,  with  the  exception  of  the  hairs,  nails,  epidermis,  cartilages, 
and  cornea ;  and  the  larger  trunks  usually  occupy  the  most  protected  situations, 
Tunning,  in  the  limbs,  along  the  flexor  side,  where  they  are  less  exposed  to 
injury. 

There  is  considerable  variation  in  the  mode  of  division  of  the  arteries ;  occa- 
sionally a  short  trunk  subdivides  into  several  branches  at  the  same  point,  as  we 
observe  in  the  coeliac  and  thyroid  axes;  or  the  vessel  may  give  off  several 
branches  in  succession,  and  still  continue  as  the  main  trunk,  as  is  seen  in  the 
arteries  of  the  limbs;  but  the  usual  division  is  dichotomous,  as,  for  instance,  the 
aorta  dividing  into  the  two  common  iliacs;  and  the  common  carotid,  into  the 
external  and  internal. 

The  branches  of  arteries  arise  at  very  variable  angles ;  some,  as  the  superior 
intercostal  arteries  from  the  aorta,  arise  at  an  obtuse  angle;  others,  as  the  lum- 
bar arteries,  at  a  right  angle ;  or,  as  the  spermatic,  at  an  acute  angle.  An  artery 
from  which  a  branch  is  given  off,  is  smaller  in  size,  but  retains  a  uniform 
diameter  until  a  second  branch  is  derived  from  it.  A  branch  of  an  artery  is 
smaller  than  the  trunk  from  whicli  it  arises;  but  if  an  artery  divides  into  two 
branches,  the  combined  area  of  the  two  vessels  is,  in  nearly  every  instance, 
somewhat  greater  than  that  of  the  trunk ;  and  the  combined  area  of  all  the 
arterial  branches  greatly  exceeds  the  area  of  the  aorta ;  so  that  the  arteries 
collectively  may  be  regarded  as  a  cone,  the  apex  of  which  corresponds  to  the 
aorta;  the  base,  to  the  capillary  system. 

The  arteries,  in  their  distribution,  communicate  freely  with  one  another, 
forming  what  is  called  an  anastomosis  (dm,  beiiveen ;  otd/io,  moiith),  or  inoscula- 
tion :  and  this  communication  is  very  free  between  the  large,  as  well  as  between 
the  smaller  branches.  The  anastomoses  between  trunks  of  equal  size  are  found 
where  great  freedom  and  activity  of  the  circulation  are  requisite,  as  in  the  bruin  ; 
here  the  two  vertebral  arteries  unite  to  form  the  basilar,  and  the  two  internal 
carotid  arteries  are  connected  by  a  short  communicating  trunk  ;  it  is  also  found 
in  the  abdomen,  the  intestinal  arteries  having  very  free  anastomoses  between 
their  larger  branches.  In  the  limbs,  the  anastomoses  are  most  frequent  and  of 
largest  size  around  the  joints;  the  branches  of  an  artery  above  freely  iiio.scu- 

436 


THE    AORTA.  437 

lating  with  branches  from  the  vessels  below ;  these  anastomoses  are  of  considerable 
interest  to  the  surgeon,  as  it  is  by  their  enlargement  that  a  collateral  circulation 
is  established  after  the  application  of  a  ligature  to  an  artery  for  the  cure  of 
aneurism.  The  smaller  branches  of  arteries  anastomose  more  frequently  than 
the  larger :  and  between  the  smallest  twigs,  these  inosculations  become  so 
numerous  as  to  constitute  a  close  network  that  pervades  nearly  every  tissue  of 
the  body. 

Throughout  the  body  generally,  the  larger  arterial  branches  pursue  a  per- 
fectly straight  course ;  but  in  certain  situations  they  are  tortuous.  Thus,  the 
facial  artery  in  its  course  over  the  face,  and  the  arteries  of  the  lips,  are  ex- 
tremely tortuous  in  their  course,  to  accommodate  themselves  to  the  movements 
of  the  parts.  The  uterine  arteries  are  also  tortuous,  to  accommodate  them- 
selves to  the  increase  of  size  which  the  organ  undergoes  during  pregnancy. 
Again,  the  internal  carotid  and  vertebral  arteries,  previous  to  their  entering  the 
cavity  of  the  skull,  describe  a  series  of  curves,  which  are  evidently  intended  to 
diminish  the  velocity  of  the  current  of  blood,  by  increasing  the  extent  of  sur- 
face over  which  it  moves,  and  adding  to  the  amount  of  impediment  which  is 
produced  by  friction. 

The  arteries  are  dense  in  structure,  of  considerable  strength,  highly  elastic, 
and,  when  divided,  they  preserve,  although  empty,  their  cylindrical  form. 

The  minute  structure  of  these  vessels  is  described  in  the  Introduction. 

In  the  description  of  the  arteries,  we  shall  first  consider  the  efferent  trunk  of 
the  systemic  circulation,  the  aorta,  and  its  branches;  and  then  the  efferent 
trunk  of  the  pulmonic  circulation,  the  pulmonary  artery. 

The  Aorta. 

The  Aorta  (aop*^;  arteria  magna)  is  the  main  trunk  of  a  series  of  vessels, 
which,  arising  from  the  heart,  convey  the  red  oxygenated  blood  to  every  part 
of  the  body  for  its  nutrition.  This  vessel  commences  at  the  upper  part  of  the 
left  ventricle,  and,  after  ascending  for  a  short  distance,  arches  backwards  to 
the  left  side,  over  the  root  of  the  left  lung,  descends  within  the  thorax  on  the 
left  side  of  the  vertebral  column,  passes  through  the  aortic  opening  in  the 
Diaphragm,  and  entering  the  abdominal  cavity,  terminates,  considerably  dimin- 
ished in  size,  opposite  the  fourth  lumbar  vertebra,  where  it  divides  into  the 
right  and  left  common  iliac  arteries.  Hence  its  subdivision  into  the  arch  of  the 
aorta,  the  thoracic  aorta,  and  the  abdominal  aorta,  from  the  direction  or  position 
of  its  parts. 

Arch  of  the  Aorta. 

Dissection.  In  order  to  examine  the  arch  of  the  aorta,  open  the  thorax,  by  dividing  the 
cartilages  of  the  ribs  on  each  side  of  the  sternum,  raising  this  bone  from  below  upwards,  and 
then  sawing  through  the  sternum  on  a  level  with  its  articulation  with  the  clavicle.  By  this 
means,  the  relations  of  the  large  vessels  to  the  upper  border  of  the  sternum  and  root  of  the  neck 
are  kept  in  view. 

The  Arch  of  the  Aorta  extends  from  the  origin  of  the  vessel  at  the  upper 
part  of  the  left  ventricle  to  the  lower  border  of  the  body  of  the  fourth  dorsal 
vertebra.  At  its  commencement,  it  ascends  behind  the  sternum,  obliquely 
upwards  and  forwards  towards  the  right  side,  and  opposite  the  upper  border  of 
the  second  costal  cartilage  of  the  right  side,  passes  transversely  from  right  to 
left,  and  from  before  backwards,  to  the  left  side  of  the  third  dorsal  vertebra ;  it 
then  descends  upon  the  left  side  of  the  body  of  the  fourth  dorsal  vertebra,  at 
the  lower  border  of  which  it  takes  the  name  of  thoracic  aorta.  The  arch  of 
the  aorta  describes  a  curve,  the  convexity  of  which  is  directed  upwards  and  to 
the  right  side ;  and  it  is  subdivided,  at  the  points  where  it  changes  its  direction, 
so  as  to  be  described  in  three  portions,  the  ascending,  transverse,  and  descending 
portions  of  the  arch  of  the  aorta. 


438 


ARTERIES. 


Ascending  Part  of  the  Arch. 

The  Ascending  Portion  of  the  Arch,  of  the  Aorta  is  about  two  inches  in 
length.  It  commences  at  the  upper  part  of  the  left  ventricle,  in  front  of  the 
left  auriculo- ventricular  orifice,  and  opposite  the  middle  of  the  sternum  on  a 
line  with  its  junction  to  the  third  costal  cartilage  ;  it  passes  obliquely  upwards 
in  the  direction  of  the  heart's  axis,  to  the  right  side,  as  high  as  the  upper  border 
of  the  second  costal  cartilage,  describing  a  slight  curve  in  its  course,  and  being 
situated,  when  distended,  about  a  quarter  of  an  inch  behind  the  posterior  sur- 
face of  the  sternum.     A  little  above  its  commencement,  it  is  somewhat  enlarged, 

Fig.  272. — The  Arch  of  the  Aorta  and  its  Branches. 


tttVaytu 
Bteiirr$)ft  laryngeal 


IfftTajut 


Fig.  llZ.Flan  rf iLBraTuJtei 


■'Ltjl  Ctnaarg 


and  presents  three  small  dilatations,  called  the  sinuses  of  the  aorta  (sinuses  of  Val- 
salva), opposite  to  which  are  attached  the  three  semilunar  valves,  which  serve 
the  purpose  of  preventing  any  regurgitation  of  blood  into  the  cavity  of  the 
ventricle.  A  section  of  the  aorta  opposite  this  part  has  a  somewhat  triangular 
figure ;  but  below  the  attachment  of  the  valves  it  is  circular.  This  portion  of 
the  arch  is  contained  in  the  cavity  of  the  pericardium,  and,  together  with  the 
pulmonary  artery,  is  invested  in  a  tube  of  serous  membrane,  continued  on  to 
them  from  the  surface  of  the  heart. 


ARCH    OF    AORTA. 


439 


Relations,  The  ascending  part  of  the  arch  is  covered  at  its  commencement 
by  the  trunk  of  the  pulmonary  artery  and  the  right  auricular  appendix,  and, 
higher  up,  is  separated  from  the  sternum  by  the  pericardium,  some  loose  areolar 
tissue,  and  the  remains  of  the  thymus  gland ;  behind,  it  rests  upon  the  right 
pulmonary  vessels  and  root  of  the  right  lung.  On  the  right  side,  it  is  in  relation 
with  the  superior  vena  cava  and  right  auricle ;  on  the  left  side,  with  the  pulmo- 
nary artery. 

Plan  of  the  Relations  of  the  Ascending  Paet  of  the  Arch. 

In  Front. 
Pulmonary  artery. 
Right  auricular  appendix. 
Pericardium. 
Eemains  of  thymus  gland. 


Eight  side. 
Superior  cava. 
Eight  auricle. 


Left  side. 
Pulmonary  artery. 


Behind. 
Right  pulmonary  vessels. 
Root  of  right  lung. 

Transverse  Part  of  the  Arch. 

The  second  or  Transverse  Portion  of  the  Arch  commences  at  the  upper  border 
of  the  second  costo-sternal  articulation  of  the  right  side  in  front,  and  passes 
from  right  to  left,  and  from  before  backwards,  to  the  left  side  of  the  second 
dorsal  vertebra  behind.  Its  upper  border  is  usually  about  an  inch  below  the 
upper  margin  of  the  sternum. 

Relations.  Its  anterior  surface  is  covered  by  the  left  pleura  and  lung,  and 
crossed  towards  the  left  side  by  the  left  pneumogastric  and  phrenic  nerves,  and 
cardiac  branches  of  the  sympathetic.  Its  posterior  surface  lies  on  the  trachea, 
just  above  its  bifurcation,  on  the  great  cardiac  plexus,  the  oesophagus,  thoracic 
duct,  and  left  recurrent  laryngeal  nerve.  Its  upper  border  is  in  relation  with  the 
left  innominate  vein ;  and  from  its  upper  part  are  given  off'  the  innominate,  left 
carotid,  and  left  subclavian  arteries.  Its  lower  border  is  in  relation  with  the 
bifurcation  of  the  pulmonary  artery,  and  the  remains  of  the  ductus  arteriosus, 
which  is  connected  with  the  left  division  of  that  vessel;  the  left  recurrent 
laryngeal  nerve  winds  round  it  from  before  backwards,  whilst  the  left  bronchus 
passes  below  it. 

Plan  of  the  Relations  of  the  Transverse  Part  of  the  Arch. 

Above. 
Left  innominata  vein. 
Arteria  innominata. 
Left  carotid. 
Left  subclavian. 


In  front. 
Left  pleura  and  lung. 
Left  pneumogastric  nerve. 
Left  phrenic  nerve. 
Cardiac  nerves. 


Behind. 
Trachea. 
Cardiac  plexus. 
CEsophagus. 
Thoracic  duct. 
Left  recurrent  nerve. 


Beloxi). 
Bifurcation  of  pulmonary  artery. 
Remains  of  ductus  arteriosus. 
Left  recurrent  nerve. 
Left  bronchus. 


440  ARTERIES.  <»  ■ 

Descending  Part  of  the  Arch. 

The  Descending  Portion  of  the  Arch  has  a  straight  directiorf,  inclining  down- 
wards on  the  left  side  of  the  body  of  the  fourth  dorsal  vertebra,  at  the  lower 
border  of  which  it  takes  the  name  of  thoracic  aorta. 

Belalions.  Its  anterior  surface  is  covered  by  the  pleura  and  root  of  the  left 
lung;  behind,  it  lies  on  the  left  side  of  the  body  of  the  fourth  dorsal  vertebra. 
On  its  right  side  are  the  oesophagus  and  thoracic  duct ;  on  its  left  side  it  is  covered 
by  the  pleura. 

Plan  of  the  Relatiions  of  the  Descending  Part  of  the  Arcei. 

In  Front. 
Pleura. 
Root  of  left  lung. 


■       Riaht  side.  Arch  of  AortaA  ^^^  ««'^e. 

(Esophagus.  I    Descending  Pleura. 

Thoracic  duct. 


Behind. 
Left  side  of  body  of  fourth  dorsal  vertebra. 

The  ascending,  transverse,  and  descending  portions  of  the  arch  vary  in  posi- 
tion according  to  the  movements  of  respiration,  being  lowered,  together  with 
the  trachea,  bronchi,  and  pulmonary  vessels,  during  inspiration  by  the  descent 
of  the  Diaphragm,  and  elevated  during  expiration,  when  the  Diaphragm  ascends. 
These  movements  are  greater  in  the  ascending  than  the  transverse,  and  in  the 
latter  than  the  descending  part. 

Peculiarities.  The  height  to  which  the  aorta  rises  in  the  chest  is  usually  about  an  inch  below 
the  upper  border  of  the  sternum ;  but  it  may  ascend  nearly  to  the  top  of  that  bone.  Occasion- 
ally it  is  found  an  inch  and  a  half,  more  rarely,  three  inches  below  this  point. 

In  Direction.  Sometimes  the  aorta  aretes  over  the  root  of  the  right  instead  of  the  left  lung, 
as  in  birds,  and  passes  down  on  the  right  side  of  the  spine.  In  such  cases  all  the  viscera  of  the 
thoracic  and  abdominal  cavities  are  transposed.  Less  frequently,  the  aorta,  after  arching  over 
the  root  of  the  right  lung,  is  directed  to  its  usual  position  on  the  left  side  of  the  spine,  this  pecu- 
liarity not  being  accompanied  by  .any  transposition  of  the  viscera. 

In  Conformation.  The  aorta  occasionally  divides,  as  in  some  quadrupeds,  into  an  ascending 
and  a  descending  trunk,  the  former  of  which  is  directed  vertically  upwards,  and  subdivides  into 
three  branches,  to  supply  the  head  and  upper  extremities.  Sometimes  the  aorta  subdivides  soon 
after  its  origin  into  two  branches,  which  soon  reunite.  In  one  of  these  cases,  the  OBSopliugus 
and  trachea  were  found  to  pass  through  the  interval  left  by  their  division ;  this  is  the  normal 
condition  of  the  vessels  in  tne  reptilia. 

Surgical  Anatomy.  Of  all  the  vessels  of  the  arterial  system,  the  aorta,  and  more  especially 
its  arch,  is  most  frequently  the  seat  of  disease ;  hence  it  is  important  to  consider  some  of  the 
consequences  that  may  ensue  from  aneurism  of  this  part. 

It  will  be  remembered,  that  the  ascending  part  of  tlie  arch  is  contained  in  the  pericardium, 
just  behind  the  sternum,  being  crossed  at  its  commencement  by  the  pulmonary  artery  and  right 
auricular  appendix,  and  having  the  root  of  the  right  lung  behind,  the  vena  cava  on  the  right  side, 
and  the  pulmonary  artery  and  left  auricle  on  the  left  side. 

Aneurism  of  the  ascending  aorta,  in  the  situation  of  the  aortic  sinuses,  in  the  great  majority 
of  cases,  affects  the  right  coronary  sinus ;  this  is  mainly  owing  to  the  fact  that  the  regurgitation 
of  blood  upon  the  sinuses  takes  place  chiefly  on  the  right  anterior  aspect  of  the  vessel.  As  the 
aneurismal  sac  enlarges,  it  may  compress  any  or  all  of  the  structures  in  immediate  proximity  with 
it.  but  chiefly  projects  towards  the  right  anterior  side  ;  and,  consequently,  interferes  mainly  with 
those  structures  that  have  a  corresponding  relation  with  the  vessel.  In  the  majority  of  cases,  it 
bursts  in  the  cavity  of  the  pericardium,  the  "patient  suddenly  drops  down  dead,  and,  upon  a  post- 
mortem examination,  the  pericardial  sac  is  found  full  of  blood ;  or  it  may  compress  the  right 
auricle,  or  the  pulmonary  artery,  and  adjoining  part  of  the  right  ventricle,  and  open  into  one  or 
the  other  of  these  parts,  or  may  press  upon  the  superior  cava. 

Aneurism  of  the  ascending  aorta,  originating  above  the  sinuses,  most  frequently  implicates  the 
right  anterior  wall  of  the  vessel ;  this  is  probably  mainly  owing  to  the  blood  being  impelled 


ARCH    OF    AORTA.  441 

against  this  part.  The  direction  of  the  aneurism  is  also  chiefly  towards  the  right  of  the  median 
line.  If  it  attains  a  large  size  and  projects  forwards,  it  may  absorb  the  sternum  and  the  carti- 
lages of  the  ribs,  usually  on  the  right  side,  and  appear  as  a  pulsating  tumor  on  the  front  of  the 
chest,  just  below  the  mani»brium  ;  or  it  may  burst  into  the  pericardium,  or  may  compress,  or 
open  into,  the  right  lung,  the  trachea,  bronchi,  or  oesophagus. 

Regarding  the  transverse  part  of  the  arch,  the  student  is  reminded  that  the  vessel  lies  on  the 
trachea,  the  oesophagus,  and  thoracic  duct ;  that  the  recurrent  laryngeal  nerve  winds  around  it ; 
and  that  from  its  upper  part  are  given  off"  three  large  trunks,  which  supply  the  head,  neck,  and 
upper  extremities.  Now  an  aneurismal  tumor  taking  origin  from  the  posterior  part  or  right 
aspect  of  the  vessel,  its  most  usual  site,  may  press  upon  the  trachea,  impede  the  breathing,  or 
produce  cough,  htemoptysis,  or  stridulous  breathing,  or  it  may  ultimately  burst  into  that  tube, 
producing  fatal  hemorrhage.  Again,  its  pressure  on  the  laryngeal  nerves  may  give  rise  to  symp- 
toms which  so  accurately  resemble  those  of  laryngitis,  that  the  operation  of  tracheotomy  has  in 
some  cases  been  resorted  to,  from  the  supposition  that  disease  existed  in  the  larynx  ;  or  it  may 
press  upon  the  thoracic  duct,  and  destroy  life  by  inanition ;  or  it  may  involve  the  oesophagus, 
producing  dysphagia ;  or  may  burst  into  the  oesophagus,  when  fatal  hemorrhage  will  occur. 
Again,  the  innominate  artery,  or  the  left  carotid,  or  subclavian,  may  be  so  obstructed  by  clots, 
as  to  produce  a  weakness,  or  even  a  disappearance,  of  the  pulse  in  one  or  the  other  wrist ;  or 
the  tumor  may  present  itself  at  or  above  the  manubrium,  generally  either  in  the  median  line, 
or  to  the  right  of  the  sternum,  and  may  simulate  an  aneurism  of  one  of  the  arteries  of  the  neck. 

Aneurism  affecting  the  descending  part  of  the  arch  is  usually  directed  backwards  and  to  the 
left  side,  causing  absorption  of  the  vertebrae  and  corresponding  ribs  ;  or  it  may  press  upon  the 
trachea,  left  bronchus,  oesophagus,  and  the  right  and  left  lungs,  generally  the  latter.  When 
rupture  of  the  sac  occurs,  it  usually  takes  place  into  the  left  pleural  cavity  ;  less  frequently  into 
the  left  bronchus,  the  right  pleura,  or  into  the  substance  of  the  lungs  or  trachea.  In  this  form 
of  aneurism,  pain  is  almost  a  constant  and  characteristic  symptom,  referred  to  either  the  back 
or  chest,  and  usually  radiating  from  the  spine  around  the  left  side.  This  symptom  depends  upon 
the  aneurismal  sac  compressing  the  intercostal  nerves  against  the  bone. 

Branches  of  the  Arch  op  the  Aorta.    (Figs.  272,  273.) 

The  branches  given  off  from  the  arch  of  the  aorta  are  five  in  number ;  two 
of  small  size  from  the  ascending  portion,  the  right  and  left  coronary ;  and  three 
of  large  size  from  the  transverse  portion,  the  innominate  artery,  the  left  carotid, 
and  the  left  subclavian. 

Peculiarities.  Position  of  the  Branches. — The  branches,  instead  of  arising  from  the  highest 
part  of  the  arch  (their  usual  position),  may  be  moved  more  to  the  right,  arising  from  the  com- 
mencement of  the  transverse  or  upper  part  of  the  ascending  portion ;  or  the  distance  from  one 
another  at  their  origin  may  be  increased  or  diminished,  the  most  frequent  change  in  this  respect 
being  the  approximation  of  the  left  carotid  towards  the  innominate  artery. 

The  Number  of  the  primary  branches  may  be  reduced  to  two :  the  left  carotid  arising  from 
the  innominate  artery;  or  (more  rarely),  the  carotid  and  subclavian  arteries  of  the  leftside 
arising  from  a  left  innominate  artery.  But  the  number  may  be  increased  to  four,  from  the  right 
carotid  and  subclavian  arteries  arising  directly  from  the  aorta,  the  innominate  being  absent.  In 
most  of  these  latter  cases,  the  right  subclavian  has  been  found  to  arise  from  the  left  end  of  the 
arch;  in  other  cases,  it  was  the  second  or  third  branch  given  off  instead  of  the  first.  Lastly, 
the  number  of  trunks  from  the  arch  may  be  increased  to  five  or  six  ;  in  these  instances,  the  ex- 
ternal and  internal  carotids  arose  separately  from  the  arch,  the  common  carotid  being  absent  on 
one  or  both  sides. 

Number  usual,  Arrangement  different.  When  the  aorta  arches  over  to  the  right  side,  the 
three  branches  have  an  arrangement  the  reverse  of  what  is  usual,  the  innomjnate  supplying  the 
left  side ;  and  the  carotid  and  subclavian  (which  arises  separately)  the  right  side.  In  other 
cases,  where  the  aorta  takes  its  usual  course,  the  two  carotids  may  be  joined  in  a  common 
trunk,  and  the  subclavians  arise  separately  from  the  arch,  the  right  subclavian  generally  arising 
from  the  left  end  of  the  arch. 

Secondary  Branches  sometimes  arise  from  the  arch ;  most  commonly  such  a  secondary  branch 
is  the  left  vertebral,  which  usually  takes  origin  between  the  left  carotid  and  left  subclavian,  or 
beyond  them.  Sometimes,  a  thyroid  branch  is  derived  from  the  arch,  or  the  right  internal  mam- 
mary, or  left  vertebral,  or,  more  rarely,  both  vertebrals. 

The  Coronary  Arteries. 

The  Coronary  Arteries  supply  the  heart ;  they  are  two  in  number,  right  and 
left,  arising  near  the  commencement  of  the  aorta  immediately  above  the  free 
margin  of  the  semilunar  valves. 

The  Right  Coronary  Artery^  about  the  size  of  a  crow's  quill,  arises  from  the 
aorta  immediately  above  the  free  margin  of  the  right  semihinar  valve,  between 
the  pulmonary  artery  and  the  appendix  of  the  right  auricle.     It  passes  for- 


iifi  ARTERIES. 

wards  to  the  right  side,  in  the  groove  between  the  right  auricle  and  ventricle; 
and  curving  around  the  right  border  of  the  heart,  runs  along  its  posterior  sur- 
face as  far  as  the  posterior  interventricular  groove,  where  it  divides  into  two 
branches,  one  of  which  continues  onwards  in  the  groove  between  the  left  auricle 
and  ventricle,  and  anastomoses  with  the  left  coronary ;  the  other  descends 
along  the  posterior  interventricular  furrow,  supplying  branches  to  both  ven- 
tricles and  to  the  septum,  and  anastomosing  at  the  apex  of  the  heart  with  the 
descending  branch  of  the  left  coronary. 

This  vessel  sends  a  large  branch  -along  the  thin  margin  of  the  right  ventricle 
to  the  apex,  and  numerous  small  branches  to  the  right  auricle  and  ventricle, 
and  the  commencement  of  the  pulmonary  artery. 

The  Left  Coronary,  smaller  than  the  former,  arises  immediately  above  the  free 
edge  of  the  left  semilunar  valve,  a  little  higher  than  the  right ;  it  passes  for- 
wards between  the  pulmonary  artery  and  the  left  appendix  auriculae,  and  descends 
obliquely  towards  the  anterior  interventricular  groove,  where  it  divides  into 
two  branches.  Of  these,  one  passes  transversely  outwards  in  the  left  auriculo- 
ventricular  groove,  and  winds  around  the  left  border  of  the  heart  to  its  poste- 
rior surface,  where  it  anastomoses  with  the  superior  branch  of  the  right  coro- 
nary ;  the  other  descends  along  the  anterior  interventricular  groove  to  the 
apex  of  the  heart,  where  it  anastomoses  with  the  descending  branch  of  the  right 
coronary.  The  left  coronary  supplies  the  left  auricle  and  its  appendix,  both 
ventricles,  and  numerous  small  branches  to  the  pulmonary  artery,  and  com- 
mencement of  the  aorta. 

Peculiarities.  These  vessels  occasionally  arise  by  a  common  trunk,  or  their  number  may  be 
increased  to  three ;  the  additional  branch  being  of  small  size.  More  rarely,  there  are  two  additional 
branches. 

Aeteria  Tnnominata. 

The  Innominate  Artery  is  the  largest  branch  given  off  from  the  arch  of  the 
aorta.  It  arises  from  the  commencement  of  the  transverse  portion  in  front  of 
the  left  carotid,  and,  ascending  obliquely  to  the  upper  border  of  the  right 
sterno-clavicular  articulation,  divides  into  the  right  carotid  and  subclavian 
arteries.     This  vessel  varies  from  an  inch  and  a  half  to  two  inches  in  length. 

Relations.  In  front,  it  is  separated  from  the  first  bone  of  the  sternum  by  the 
Sterno-hyoid  and  Sterno-thyroid  muscles,  the  remains  of  the  thymus  gland, 
and  by  the  left  innominate  and  right  inferior  thyroid  veins  which  cross  its  root. 
Behind,  it  lies  upon  the  trachea,  which  it  crosses  obliquely.  On  the  right  side 
is  the  right  vena  innominata,  right  pneumogastric  nerve,  and  the  pleura ;  and 
on  the  left  side^  the  remains  of  the  thymus  gland,  and  origin  of  the  left  carotid 
aitery. 

Plan  op  the  Relations  of  the  Innominate  Artery. 

In  front. 
Sternum. 

Sterno-hyoid  and  Sterno-thyroid  muscles. 
Remains  of  thymus  pland. 
Left  innominate  and  inferior  thyroid  veins. 
Inferior  cervical  cardiac  branch  from  right  pneumogastric  nerve. 

Right  side.  f  \  Leftside 

Right  vona  innominata.  /  i„„„n,inate  \  Remains  of  thymus. 

Right  pneumogastric  nerve.  \      Artery.      )  ^^^^  carotid. 


Pleura. 


Behind. 
Truchca. 


Peculiarities  in  'point  of  division.    When  the  bifurcation  of  the  Innominate  artery  varies  from 
the  point  above  mentioned,  it  sometimes  ascends  a  considerable  distance  above  the  sternal  end  of 


INNOMINATE;    COMMON    CAROTID.  443 

the  clavicle  ;  less  frequently  it  divides  below  it.  In  the  former  class  of  cases,  its  length  may  ex- 
ceed two  inches  ;  and,  in  the  latter,  be  reduced  to  an  inch  or  less.  These  are  points  of  consider- 
able interest  for  the  surgeon  to  remember  in  connection  with  the  operation  of  tying  this  vessel. 

Branches.  The  arteria  innominata  occasionally  supplies  a  thyroid  branch  (middle  thyroid 
artery),  which  ascends  along  the  front  of  the  trachea  to  the  thyroid  gland ;  and  sometimes,  a 
thymic  or  bronchial  branch.  The  left  carotid  is  frequently  joined  with  the  innominate  artery  at 
its  origin.  Sometimes,  there  is  no  innominate  artery,  the  right  subclavian  arising  directly  from 
the  arch  of  the  aorta. 

Position.  When  the  aorta  ai-ches  over  to  the  right  side,  the  innominate  is  directed  to  the  left 
side  of  the  neck  instead  of  the  right. 

Collateral  circuUition.  Allan  Burns  demonstrated,  on  the  dead  subject,  the  possibility  of  the 
establishment  of  the  collateral  circulation  after  ligature  of  the  innominate  artery,  by  tying  and 
dividing  that  artery,  after  which,  he  says,  "  Even  coarse  injection  impelled  into  the  aorta,  passed 
freely  by  the  anastomosing  branches  into  the  arteries  of  the  right  arm,  filling  them  and  all  the 
vessels  of  the  head  completely."  {Surgical  Anatomy  of  the  Head  and  Neck,  page  62.)  The 
branches  by  which  this  circulation  would  be  carried  on  are  very  numerous ;  thus,  all  the  com- 
munications across  the  middle  line  between  the  branches  of  the  carotid  arteries  of  opposite  sides 
would  be  available  for  the  supply  of  blood  to  the  right  side  of  the  head  and  neck ;  while  the 
anastomosis  between  the  superior  intercostal  of  the  subclavian  and  the  first  aortic  intercostal 
(see  ivfra  on  the  collateral  circulation  after  obliteration  of  the  thoracic  aorta),  would  bring  the 
blood,  by  a  free  and  direct  course,  into  the  right  subclavian :  the  numerous  connections,  also, 
between  the  lower  intercostal  arteries,  and  the  branches  of  the  axillary  and  internal  mammary 
arteries  would,  doubtless,  assist  in  the  supply  of  blood  to  the  right  arm,  while  the  epigastric, 
from  the  external  iliac,  would  by  means  of  its  anastomosis  with  the  internal  mammary,  compen- 
sate for  any  deficiency  in  the  vascularity  of  the  wall  of  the  chest. 

Surgical  Anatomy.  Although  the  operation  of  tying  the  innominate  artery  has  been  per- 
formed by  several  surgeons,  for  aneurism  of  the  right  subclavian  extending  inwards  as  far  as  the 
Scalenus,  in  only  one  instance  has  it  been  attended  with  success.'  Mott's  patient,  however,  on 
whom  the  operation  was  first  performed,  lived  nearly  four  weeks,  and  Uraefe's  more  than  two 
months.  The  main  obstacles  to  the  operation  are,  as  the  student  will  perceive  from  his  dissec- 
tion of  this  vessel,  the  deep  situation  of  the  artery  behind  and  beneath  the  sternum,  and  the 
number  of  important  structures  which  surround  it  in  every  part. 

In  order  to  apply  a  ligature  to  this  vessel,  the  patient  is  to  be  placed  upon  his  back,  with  the 
shoulders  raised,  and  the  head  bent  a  little  backwards,  so  as  to  draw  out  the  artery  from  behind 
the  sternum  into  the  neck.  An  incision  two  inches  long  is  then  made  along  the  anterior  border 
of  the  Sterno-mastoid  muscle,  terminating  at  the  sternal  end  of  the  clavicle.  From  this  point,  a 
second  incision  is  carried  about  the  same  length  along  the  upper  border  of  the  clavicle.  The 
skin  is  then  dissected  back,  and  the  Platysma  divided  on  a  director :  the  sternal  end  of  the 
Sterno-mastoid  is  now  brought  into  view,  and  a  director  being  passed  beneath  it,  and  close  to  its 
under  surface,  so  as  to  avoid  any  small  vessels,  the  muscle  is  to  be  divided  transversely  through- 
out the  greater  part  of  its  attachment.  By  pressing  aside  any  loose  cellular  tissue  or  vessels 
that  may  now  appear,  the  Sterno-hyoid  and  Sterno-thyroid  muscles  will  be  exposed,  and  must  be 
divided,  a  director  being  previously  passed  beneath  them.  The  inferior  thyroid  veins  now  come 
into  view,  and  must  be  carefully  drawn  either  upwards  or  downwards,  by  means  of  a  blunt  hook. 
On  no  account  should  these  vessels  be  divided,  as  it  would  add  much  to  the  difficulty  of  the 
operation,  and  endanger  its  ultimate  success.  After  tearing  through  a  strong  fibro-cellular 
lamina,  the  right  carotid  is  brought  into  view,  and  being  traced  downwards,  the  arteria  innomi- 
nata is  arrived  at.  The  left  vena  innominata  should  now  be  depressed,  the  right  vena  innomi- 
nata, the  internal  jugular  vein,  and  pneumogastric  nerve  drawn  to  the  right  side;  and  a  curved 
aneurism  needle  may  then  be  passed  around  the  vessel,  close  to  its  surface,  and  in  a  direction 
from  below  upwards  and  inwards  ;  care  being  taken  to  avoid  the  right  pleural  sac,  the  trachea, 
and  cardiac  nerves.  The  ligature  should  be  applied  to  the  artery  as  high  as.  possible,  in  order  to 
allow  room  between  it  and  the  aorta  for  the  formation  of  a  coagulum.  The  importance  of  avoid- 
ing the  thyroid  plexus  of  veins  during  the  primary  steps  of  the  operation,  and  the  pleural  sac 
whilst  including  the  vessel  in  the  ligature,  should  be  most  carefully  borne  in  mind,  since  secondary 
hemorrhage  or  pleurisy  have  been  the  cause  of  death  in  all  the  cases  hitherto  operated  on. 

Common  Carotid  Arteries. 

The  Common  Carotid  Arteries,  although  occupying  a  nearly  similar  position 
in  the  neck,  dijffer  in  position,  and,  consequently,  in  their  relations  at  their 
origin.  The  right  carotid  arises  from  the  arteria  innominata,  behind  the  right 
sterno-clavicular  articulation ;  the  left  from  the  highest  part  of  the  arch  of  the 
aorta.     The  left  carotid  is,  consequently,  longer  and  placed  more  deeply  in  the 

'  The  operation  was  performed  by  Dr.  Srayth.  of  New  Orleans :  see  the  New  Sydenham  So- 
ciety's "Biennial  Retrospect,"  for  1865-1866,  page  346. 


444  ARTERIES. 

thorax.  It  will,  therefore,  be  more  convenient  to  describe  first  the  course  and 
relations  of  that  portion  of  the  left  carotid  which  intervenes  between  the  arch 
of  the  aorta  and  the  left  sterno-clavicular  articulations  (see  Fig.  272). 

The  left  carotid  within  the  thorax  ascends  obliquely  outwards  from  the  arch 
of  the  aorta  to  the  root  of  the  neck.  In  front,  it  is  separated  from  the  first 
piece  of  the  sternum  by  the  Sterno-hyoid  and  Sterno-thyroid  muscles,  the  left 
innominate  vein,  and  the  remains  of  the  thymus  gland;  behind,  it  lies  on  the 
trachea,  oesophagus,  and  thoracic  duct.  Internally,  it  is  in  relation  with  the 
arteria  innominata ;  externally^  with  the  left  pnemogastrio  nerve,  and  left  sub- 
clavian artery. 

Plan  op  the  Relations  of  the  Left  Common  Carotid. 
Thoracic  Portion. 

Jn  Front. 

Sternmn. 

Sterno-hyoid  and  Sterno-thyroid  muscles. 

Left  innominate  vein. 

Bemains  of  thymus  gland. 

J.  „  /Left  CommonX  Externally. 

Intemally.  ^t"'"^.     )        Left  pneumojjastric  nerve. 

Arteria  umommata.  \     Thoradc     /        Left  subclavian  artery. 


Behind. 
Trachea, 
ttlsophagus. 
Thoracic  duct. 

In  the  neck,  the  two  common  carotids  resemble  each  other  so  closely,  that 
one  description  will  apply  to  both.  Each  vessel  passes  obliquely  upwards, 
from  behind  the  sterno-clavicular  articulation,  to  a  level  with  the  upper  border 
of  the  thyroid  cartilage,  where  it  divides  into  the  external  and  internal  carotid ; 
these  names  being  derived  from  the  distribution  of  the  arteries  to  the  external 
parts  of  the  head  and  face,  and  to  the  internal  parts  of  the  cranium  respectively. 
The  course  of  the  common  carotid  is  indicated  by  a  line  drawn  from  the  sternal 
end  of  the  clavicle  below,  to  a  point  midway  between  the  angle  of  the  jaw  and 
the  mastgid  process  above. 

At  the  lower  part  of  the  neck  the  two  common  carotid  arteries  are  separated 
from  each  other  by  a  very  small  interval,  which  contains  the  trachea;  but  at 
the  upper  part,  the  thyroid  body,  the  larynx  and  pharynx  project  forwards 
between  the  two  vessels,  and  give  the  appearance  of  their  being  placed  further 
back  in  that  situation.  The  common  carotid  artery  is  contained  in  a  sheath, 
derived  from  the  deep  cervical  fascia,  which  also  incloses  the  internal  jugular 
vein  and  pneumogastric  nerve,  the  vein  lying  on  the  outer  side  of  the  artery, 
and  the  nerve  between  the  artery  and  vein,  on  a  plane  posterior  to  both.  On 
opening  the  sheath,  these  three  structures  are  seen  to  be  separated  from  one 
another,  each  being  inclosed  in  a  separate  fibrous  investment. 

Relations.  At  the  lower  part  of  the  neck  the  common  carotid  artery  is  very 
deeply  seated,  being  covered  by  the  superficial  fascia,  Platysma,  and  deep  fascia, 
the  Sterno-mastoid,  Sterno-hyoid,  and  Sterno-thyroid  muscles,  and  by  the  Omo- 
hyoid opposite  the  cricoid  cartilage ;  but  in  the  upper  part  of  its  course,  near 
its  termination,  it  is  more  superficial,  being  covered  merely  by  the  integument, 
the  superficial  fascia,  Platysma,  and  deep  fascia,  and  inner  margin  of  the  Sterno- 
mastoid,  and  is  contained  in  a  triangular  space,  bounded  behind  by  the  Sterno- 
mastoid,  above  by  the  posterior  belly  of  the  Digastric,  and  below  by  the  anterior 
belly  of  the  Omo-hyoid.     This  part  of  the  artery  is  crossed  obliquely  from 


COMMON    CAROTID. 


446 


within  outwards  by  the  sterno-mastoid  artery ;  it  is  also  crossed  by  the  fascial, 
lingual,  and  superior  thyroid  veins,  which  terminate  in  the  internal  jugular, 
and  descending  on  its  sheath  in  front,  is  seen  the  descendens  noni  nerve,  this 
filament  being  joined  with  branches  from  the  cervical  nerves,  which  cross  the 
vessel   from  without  inwards.     Sometimes  the  descendens  noni  is  contained 

Fig.  274. — Surgical  Anatomy  of  the  Arteries  of  the  Neck.    Right  Side. 


within  the  sheath.  The  middle  thyroid  vein  crosses  the  artery  about  its  middle, 
and  the  anterior  jugular  vein  below.  Behind^  the  artery  lies  in  front  of  the 
cervical  portion  of  the  spine,  resting  first  an  the  Longus  Colli  muscle,  then  on 
the  Rectus  Anticus  Major,  from  which  it  is  separated  by  the  sympathetic  nerve. 
The  recurrent  laryngeal  nerve  and  inferior  thyroid  artery  cross  behind  the 
vessel  at  its  lower  part.  Internally,  it  is  in  relation  with  the  trachea  and 
thyroid  gland,  the  inferior  thyroid  artery  and  recurrent  laryngeal  nerve  being 


446  ARTERIES. 

interposed ;  higher  up,  with  the  larynx  and  pharynx.     On  its  outer  side  are 
placed  the  internal  jugular  vein  and  pneumogastric  nerve. 

At  the  lower  part  of  the  neck,  the  internal  jugular  vein  on  the  right  side 
diverges  from  the  artery,  but  on  the  left  side  it  approaches  it,  and  often  crosses 
its  lower  part.  This  is  an  important  fact  to  bear  in  mind  during  the  perform- 
ance of  any  operation  on  the  lower  part  of  the  left  common  carotid  artery. 

Plan  of  the  Relations  of  the  Common  Carotid  Artery. 

Infront. 
Integument  and  fascia.  Omo-hyoid. 

Platysma.  Descendens  noni  nerve. 

Sterno-mastoid.  Sterno-mastoid  artery. 

Sterno-hyoid.  I'hyroid,  lingual,  and  facial  veins. 

Sterno-tuyroid.  Anterior  jugular  vein. 

©Internally. 
Trachea. 
Thyroid  gland. 
Recurrent  laryngeal  nerve. 
Inferior  thyroid  artery. 
Larynx. 
Pharynx. 

Behind. 
Longus  Colli.  Sympathetic  nerve. 

Eectus  Anticus  Major,  Inferior  thyroid  artery. 

Recurrent  laryngeal  nerve. 

Peculiarities  as  to  Origin.  The  right  common  carotid  may  arise  above  or  below  its  usual 
point,  the  upper  border  of  the  sterno-clavicular  articulation.  This  variation  occurs  in  one  out 
of  about  eight  cases  and  a  half,  and  the  origin  is  more  frequently  above  than  below  the  usual 
point ;  or  the  artery  may  arise  as  a  separate  branch  from  the  arch  of  the  aorta,  or  in  conjunction 
with  the  left  carotid.  The  left  common  carotid  varies  more  frequently  in  its  origin  than  the 
right.  In  the  majority  of  abnormal  cases  it  arises  with  the  innominate  artery,  or  if  the  innomi- 
nate artery  is  absent,  the  two  carotids  arise  usually  by  a  single  trunk.  The  left  carotid  has  a 
tendency  towards  the  right  side  of  the  arch  of  the  aorta,  being  occasionally  the  first  branch 
given  off  from  the  transverse  portion.  It  rarely  joins  with  the  left  subclavian,  except  in  cases 
of  transposition  of  the  arch. 

Pecidiarities  as  to  Point  of  Division.  The  most  important  peculiarities  of  this  vessel,  in  a 
surgical  point  of  view,  relate  to  its  place  of  division  in  the  neck.  In  the  majority  of  abnormal 
cases,  this  occurs  higher  than  usual,  the  artery  dividing  into  two  branches  opposite  the  hyoid 
bone,  or  even  higher ;  more  rarely,  it  occurs  below  its  usual  place  opposite  the  middle  of  the 
larynx,  or  the  lower  body  of  the  cricoid  cartilage ;  and  one  case  is  related  by  Morgagni,  where 
the  common  carotid,  only  an  inch  and  a  half  in  length,  divided  at  the  root  of  the  neck.  Very 
rarely,  the  common  carotid  ascends  in  the  neck  without  any  subdivision,  the  internal  carotid 
bein^  wanting;  and  in  two  cases,  the  common  carotid  has  been  found  to  be  absent,  the  external 
and  internal  carotids  arising  directly  from  the  arch  of  the  aorta.  This  peculiarity  existed  on 
both  sides  in  one  subject,  on  one  side  in  the  other. 

Occasional  Branches.  The  common  carotid  usually  gives  off  no  branches  ;  but  it  occasionally 
gives  origin  to  the  superior  thyroid,  or  a  laryngeal  branch,  the  inferior  thyroid,  or,  more  rarely, 
the  vertebral  artery. 

Surgical  Anatomy.  The  operation  of  tying  the  common  carotid  artery  may  be  necessary  in  a 
wound  of  that  vessel  or  its  branches,  in  an  aneurism,  or  in  a  case  of  pulsating  tumor  of  the  orbit 
or  skull.  If  the  wound  involves  the  trunk  of  the  common  carotid,  it  will  be  necessary  to  tie  the 
artery  above  and  below  the  wounded  part.  But  in  cases  of  aneurism,  or  where  one  of  the 
branches  of  the  common  carotid  is  wounded  in  an  inaccessible  situation,  it  may  be  judged  neces- 
sary to  tie  the  trunk.  In  such  cases,  the  whole  of  the  artery  is  accessible,  and  any  part  may  be 
tied,  except  close  to  either  end.  When  the  case  is  such  as  to  allow  of  a  choice  being  made,  the 
lower  part  of  the  carotid  should  never  be  selected  as  the  spot  upon  which  to  place  a  ligature,  for 
not  only  is  the  artery  in  this  situation  placed  very  deeply  in  the  neck,  but  it  is  covered  by  three 
layers  of  muscles,  and  on  the  left  side  the  jugular  vein,  in  the  great  majority  of  cases,  passes 
obliquely  in  front  of  it.  Neither  should  the  upper  end  be  selected,  for  here  the  superior  thyroid, 
lingual,  and  facial  veins  would  give  rise  to  very  considerable  difficulty  in  the  application  of  a 
ligature.  The  point  most  favorable  for  the  operation  is  opposite  the  lower  part  of  the  larynx, 
and  here  a  ligature  may  be  applied  on  the  vessel,  either  above  or  below  the  point  where  it  is 
crossed  by  the  Omo-hyoid  muscle.  In  the  former  situation  the  artery  is  most  accessible,  and  it 
may  be  tied  there  in  cases  of  wounds,  or  aneurism  of  any  of  the  large  branches  of  the  carotid; 


EXTERNAL    CAROTID.  447 

whilst  in  cases  of  aneurism  of  the  upper  part  of  the  carotid,  that  part  of  the  vessel  may  be 
selected  which  is  below  the  Orao-hyoid.  It  occasionally  happens  that  the  carotid  artery  bifur- 
cates below  its  usual  position  :  if  the  artery  be  exposed  at  its  point  of  bifurcation,  both  divisions 
of  the  vessel  should  be  tied  near  their  origin,  in  preference  to  tying  the  trunk  of  the  artery  near 
its  termination  ;  and  if,  in  consequence  of  the  entire  absence  of  the  common  carotid,  or  from  its 
early  division,  two  arteries,  the  external  and  internal  carotids,  are  met  with,  the  ligature  should 
be  placed  on  that  vessel  which  is  found  on  compression  to  be  connected  with  the  disease. 

In  this  operation,  the  direction  of  the  vessel  and  the  inner  margin  of  the  JSterno-mastoid  are 
the  chief  guides  to  its  performance. 

To  tie  the  Common  Carotid,  above  the  Omo-hyoid.  The  patient  should  be  placed  on  his  back 
with  the  head  thrown  back  ;  an  incision  is  to  be  made,  three  inches  Joug,  in  the  direction  of  the 
anterior  border  of  the  Sterno-mastoid,  from  a  little  below  the  angle  of  the  jaw  to  a  level  with 
the  cricoid  cartilage  ;  after  dividing  the  integument,  superficial  fascia,  and  Platysma,  the  deep 
fascia  must  be  cut  through  on  a  director,  so  as  to  avoid  wounding  numerous  small  veins  that  are 
usually  found  beneath.  The  head  may  now  be  brought  forwards  so  as  to  relax  the  parts  some- 
what, and  the  margins  of  the  wound  held  asunder  by  copper  spatulae.  The  descendens  noni  nerve 
is  now  exposed,  and  must  be  avoided,  and  the  sheath  of  the  vessel  having  been  raised  by  forceps, 
is  to  be  opened  over  the  artery  to  a  small  extent  at  its  inner  side.  The  internal  jugular  vein  may 
now  present  itself  alternately  distended  and  relaxed  ;  this  should  be  compressed  both  above  and 
below,  and  drawn  outwards,  in  order  to  facilitate  the  operation.  The  aneurism  needle  is  now 
passed  from  the  outside,  care  being  taken  to  keep  the  needle  in  close  contact  with  the  artery, 
and  thus  avoid  the  risk  of  injuring  the  jugular  vein,  or  including  the  vagus  nerve.  Before  the 
ligature  is  tied,  it  should  be  ascertained  that  nothing  but  the  artery  is  included  in  it. 

To  tie  the  Common  Carotid,  beloio  the  Omo-hyoid.  The  patient  should  be  placed  in  the  same 
position  as  above  mentioned.  An  incision  about  three  inches  in  length  is  to  be  made,  parallel 
with  the  inner  edge  of  the  Sterno-mastoid,  commencing  on  a  level  with  the  cricoid  cartilage. 
The  inner  border  of  the  Sterno-mastoid  having  been  exposed,  the  sterno-mastoid  artery  and  a 
large  vein,  the  middle  thyroid,  will  be  seen,  and  must  be  carefully  avoided  ;  the  Sterno-mastoid  is 
to  be  drawn  outwards,  and  the  Sterno-hyoid  and  thyroid  muscles  inwards.  The  deep  fascia  must 
now  be  divided  below  the  Omo-hyoid  muscle,  and  the  sheath  having  been  exposed,  must  be 
opened,  care  being  taken  to  avoid  the  descendens  noni,  which  here  runs  on  the  inner  or  tracheal 
side.  The  jugular  vein  and  vagus  nerve  being  then  pressed  to  the  outer  side,  the  needle  must  be 
passed  round  the  artery  from  without  inwards,  great  care  being  taken  to  avoid  the  inferioi 
thyroid  artery,  the  recurrent  laryngeal,  and  sympathetic  nerves  which  lie  behind  it. 

Collateral  Circulation.  After  ligature  of  the  common  carotid,  the  collateral  circulation  can 
be  perfectly  established,  by  the  free  communication  which  exists  between  the  carotid  arteries  of 
opposite  sides,  both  without  and  within  the  cranium — and  by  enlargement  of  the  branches  of  the 
subclavian  artery  on  the  side  corresponding  to  that  on  which  the  vessel  has  been  tied,  the  chief 
communication  outside  the  skull  taking  place  between  the  superior  and  inferior  thyroid  arteries, 
and  the  profunda  cervicis,  and  arteria  princeps  cervicis  of  the  occipital ;  the  vertebral  taking 
the  place  of  the  internal  carotid  within  the  cranium. 

Sir  A.  Cooper  had  an  opportunity  of  dissecting,  thirteen  years  after  the  operation,  the  case  in 
which  he  first  successfully  tied  the  common  carotid  (the  second  case  in  which  the  operation  had 
been  performed).  Guy's  HoKpital  Reports,  i.  h6.  The  injection,  however,  does  not  seem  to  have 
been  a  successful  one.  It  showed  merely  that  the  arteries  at  the  base  of  the  brain  (circle  of 
Willis)  were  much  enlarged  on  the  side  of  the  tied  artery,  the  basilar  artery  on  that  side  having 
been  one  of  the  chief  means  of  restoring  the  circulation,  and  that  the  anastomosis  between  the 
branches  of  the  external  carotid  on  the  affected  side  and  those  of  the  same  artery  on  the  sound 
side  was  free,  so  that  the  external  carotid  was  pervious  throughout. 

External  Carotid  Artery. 

The  External  Carotid  Artery  (Fig.  274)  arises  opposite  the  upper  border  of 
the  thyroid  cartilage,  and  taking  a  slightly  curved  course,  ascends  upwards  and 
forwards,  and  then  inclines  backwards,  to  the  space  between  the  neck  of  the 
condyle  of  the  lower  jaw,  and  the  external  meatus,  where  it  divides  into  the 
temporal  and  internal  maxillary  arteries.  It  rapidly  diminishes  in  size  in  its 
course  up  the  neck,  owing  to  the  number  and  large  size  of  the  branches  given 
off  from  it.  In  the  child,  it  is  somewhat  smaller  than  the  internal  carotid;  but 
in  the  adult,  the  two  vessels  are  of  nearly  equal  size.  At  its  commencement, 
this  artery  is  more  superficial,  and  placed  nearer  the  middle  line  than  the  inter- 
nal carotid,  and  is  contained  in  the  triangular  space  bounded  by  the  Sterno- 
mastoid  behind,  the  Omo-hyoid  below,  and  the  posterior  belly  of  the  Digastric 
and  Stylo-hyoid  above ;  it  is  covered  by  the  skin,  Platysma,  deep  fascia,  and 


448 


ARTERIES. 


anterior  margin  of  the  Sterno-mastoid,  crossed  by  the  hypoglossal  nerve,  and 
by  the  lingual  and  facial  veins ;  it  is  afterwards  crossed  by  the  Digastric  and 
Stylo-hyoid  muscles,  and  higher  up  passes  deeply  into  the  substance  of  the 
parotid  gland,  where  it  lies  beneath  the  facial  nerve  and  the  junction  of  the 
temporal  and  internal  maxillary  veins. 

Internally  is  the  hyoid  bone,  the  wall  of  the  pharynx,  and  the  ramus  of  the 
jaw,  from  which  it  is  separated  by  a  portion  of  the  parotid  gland. 

Behind  it,  near  its  origin,  is  the  superior  laryngeal  nerve ;  and  higher  up,  it 
is  separated  from  the  internal  carotid  by  the  Stylo-gl-ossus  and  Stylo-pharyngeus 
muscles,  the  glosso-pharyngeal  nerve,  and  part  of  the  parotid  gland. 

Plan  of  the  Relations  of  the  External  Carotid. 


In  front. 

Behind. 

Integument,  superficial  fascia, 
Platysma  and  deep  fascia. 

/^       ^ 

Superior  laryngeal  nerve, 

/               \ 

Stylo-glossus. 

Hypoglossal  nerve. 

Extfirnal 

Stylo-pharyngeus. 

Lingual  and  facial  veins. 

Carotid. 

Glosso-pharyngeul  nerve. 

Digastric  and  Stylo-hyoid  muscles. 

V      J 

Parotid  gland. 

Parotid  gland,  with  facial  nerve  and 

V  y 

temporo-maxillary  vein  in  its  sub- 

stance. 

I 


II 


Internally. 
Hyoid  bone. 
Pharynx. 
Parotid  gland. 
Ramus  of  jaw. 

Surgical  Anatomy.  The  application  of  a  ligature  to  the  external  carotid  may  be  required'ln 
cases  of  wounds  of  this  vessel,  or  of  its  branches  when  these  cannot  be  tied,  and  in  some  cases 
of  pulsating  tumor  of  the  scalp  or  face  ;  the  operation,  however,  is  very  rarely  performed,  liga- 
ture of  the  common  carotid  being  preferable,  on  account  of  the  number  of  branches  given  oflF 
from  the  external.  To  tie  this  vessel  near  its  origin,  below  the  point  where  it  is  crossed  by  the 
Digastric,  an  incision  about  three  inches  in  length  should  be  made  along  the  margin  of  the  Sterno- 
mastoid,  from  the  angle  of  the  jaw  to  the  cricoid  cartilage,  as  in  the  operation  for  tying  the 
common  carotid.  'I'o  tie  the  vessel  above  the  Digastric,  between  it  and  the  parotid  gland,  an 
incision  should  be  made  from  the  lobe  of  the  ear  to  the  great  cornu  of  the  os  hyoidcs,  dividing 
successfully  the  skin,  Platysma,  and  fascia.  By  separatimg  the  posterior  belly  of  the  Digastric 
and  Stylo-hyoid  muscles  which  are  seen  at  the  lower  part  of  the  wound,  from  the  parotid  gland, 
the  vessel  will  be  exposed,  and  a  ligature  may  be  applied  to  it.  The  circulation  is  at  once  re-  Jl 
established  by  the  free  communication  between  most  of  the  large  branches  of  the  artery  (facial  ll 
lingual,  superior  thyroid,  occipital)  and  the  corresponding  arteries  of  the  opposite  side,  aud  by 
the  free  anastomosis  of  the  facial  with  branches  from  the  internal  carotid,  of  the  occipital  with 
branches  of  the  subclavian,  etc. 

Branches,  The  external  carotid  artery  gives  off  eight  branches,  which,  for 
convenience  of  description,  may  be  divided  into  four  sets.  (See  Fig.  275,  Plan 
of  the  branches.) 

Anterior.  Posterior.  Ascending. 

Superior  thyroid.  Occipital.  Ascending  pha 

Lingual.  Posterior  aurjcular.        ryngeal. 
Facial. 

The  student  is  here  reminded  that  many  variations  are  met  with  in  the  num- 
ber, origin,  and  course  of  these  branches  in  different  subjects ;  but  the  above 
arrangement  is  that  which  is  found  in  the  great  majority  of  cases. 

The  Sujyerior  Thyroid  Artery  (Figs.  274  and  279)  is  the  first  branch  given  off 
from  the  external  carotid,  being  derived  from  that  vessel  just  below  the  great 
cornu  of  the  hyoid  bone.  At  its  commencement,  it  is  quite  superficial,  being 
covered  by  the  integument,  fascia,  and  Platysma,  and  is  contained  in  the  trian- 
gular space  bounded  by  the  Sterno-mastoid,  Digastric,  and  Omo-hyoid  muscles. 
After  running  upwards  and  inwards  for  a  short  distance,  it  curves  downwards 
and  forwards  in  an  arched  and  tortuous  manner  to  the  upper  part  of  the  thyroid 
gland,  passing  beneath  the  Omo-hyoid,  Sterno-hyoid,  and  Sterno-thyroid  mus- 


Terminal. 
Temporal. 
Internal  maxillaryT' 


SUPERIOR    THYROID;    LINGUAL.  449 

cles;  and  distributes  numerous  braaches  to  the  anterior  surface  of  tlie  gland, 
anastomosing  with  its  fellow  of  the  opposite  side,  and  with  the  inferior  thyroid 
arteries.  Besides  the  arteries  distributed  to  the  muscles  and  the  substance  of 
the  gland,  the  branches  of  the  superior  thyroid  are  the  following : — • 

Hyoid.  Superior  Laryngeal. 

Superficial  descending  branch  (Sterno-mastoid.)      Crico-thyroid. 

The  hyoid  is  a  small  branch  which  runs  along  the  lower  border  of.'  the  os 
hyoides,  beneath  the  Thyro-hyoid  muscle;  after  supplying  the  muscles  con- 
nected to  that  bone,  it  forms  an  arch,  by  anastomosing  with  the  vessel  of  the 
opposite  side. 

The  stiperficial  descending  branch  runs  downwards  and  outwards  across  the 
sheath  of  the  common  carotid  artery,  and  supplies  the  Sterno-mastoid  and 
neighboring  muscles  and  integument.  It  is  of  importance  that  the  situation 
of  this  vessel  be  remembered,  in  the  operation  for  tying  the  common  carotid 
artery.  There  is  often  a  distinct  branch  from  the  external  carotid  distributed 
to  the  Sterno-mastoid  muscle. 

The  superior  laryngeal,,  larger  than  either  of  the  preceding,  accompanies  the 
superior  laryngeal  nerve,  beneath  the  Thyro-hyoid  muscle;  it  pierces  the 
thyro-hyoid  membrane,  and  supplies  the  muscles,  mucous  membrane,  and 
glands  of  the  larynx  and  epiglottis,  anastomosing  with  the  branch  from  the 
opposite  side. 

The  crico-thyroid  (inferior  laryngeal)  is  a  small  branch  which  runs  transversely 
across  the  crico-thyroid  membrane,  communicating  with  the  artery  of  the  op- 
posite side.  The  position  of  this  vessel  should  be  remembered,  as  it  may  prove 
the  source  of  troublesome  hemorrhage  during  the  operation  of  laryngotomy. 

Surgical  Anatomy  The  superior  thyroid,  or  some  of  its  branches,  are  often  divided  in  cases 
of  cut  throat,  giving  rise  to  considerable  hemorrhage.  In  such  cases,  the  artery  should  be 
secured,  the  wound  being  enlarged  for  that  purpose,  if  necessary.  The  operation  may  be  easily 
performed,  the  position  of  the  artery  being  very  superficial,  and  the  only  structures  of  imports 
ance  covering  it  being  a  few  small  veins.  The  operation  of  tying  the  superior  thyroid  artery, 
in  bronchocele,  has  been  performed  in  numerous  instances  with  partial  or  temporary  success. 
When,  however,  the  collateral  circulation  between  this  vessel  and  the  artery  of  the  opposite  side 
and  the  inferior  thyroid,  is  completely  re-established,  the  tumour  usually  regains  its  former  size. 

The  Lingual  Artery  (Fig.  279)  arises  from  the  external  carotid  between  the 
superior  thyroid  and  facial ;  it  runs  obliquely  upwards  and  inwards  to  the  great 
cornu  of  the  hyoid  bone,  then  passes  horizontally  forwards  parallel  with  the 
great  cornu,  and,  ascending  perpendicularly  to  the  under  surface  of  the  tongue, 
turns  forwards  on  its  under  surface  as  far  as  the  tip  of  that  organ,  under  the 
name  of  the  ranine  artery. 

Relations.  Its  first,  or  oblique  portion,  is  superficial,  being  contained  in  the 
triangular  space  already  described,  resting  upon  the  Middle  Constrictor  of  the 
pharynx,  and  covered  by  the  Platysma  and  fascia  of  the  neck.  Its  second,  or 
horizontal  portion,  also  lies  upon  the  Middle  Constrictor,  being  covered  at  first 
by  the  tendon  of  the  digastric  and  the  Stylo-hyoid  muscle,  and  afterwards  by 
the  Hyo-glossus,  the  latter  muscle  separating  it  from  the  hypoglossal  nerve. 
Its  third,  or  ascending  portion,  lies  between  the  Hyo-glossus  and  Genio-hyo- 
glossus  muscles.  The  fourth,  or  terminal  part,  under  the  name  of  the  ranine, 
runs  along  the  under  surface  of  the  tongue  to  its  tip;  it  is  very  superficial, 
being  covered  only  by  the  mucous  membrane,  and  rests  on  the  Lingualis  on 
the  outer  side  of  the  Genio-hyo-glossus.  The  hypoglossal  nerve  lies  nearly 
parallel  with  the  lingual  artery,  separated  from  it,  in  the  second  part  of  its 
course,  by  the  Hyo-glossus  muscle. 

The  branches  of  the  lingual  artery  are,  the 

Hyoid.  Sublingual. 

Dorsalis  Linguae.  Ranine. 

The  hyoid  branch  runs  along  the  upper  border  of  the  hyoid  bone,  supply- 


450 


ARTERIES. 


ing  the  muscles  attached  to  it,  and  anastomosing  with  its  fellow  of  the  opposite 
side. 

The  dorsalis  linguae  (Fig.  279)  arises  from  the  lingual  artery  beneath  the  Hyo- 
glossus  muscle  (which,  in  the  figure,  has  been  partly  cut  away,  to  show  the 
vessel) ;  ascending  to  the  dorsum  of  the  tongue,  it  supplies  the  mucous  mem- 
brane, the  tonsil,  soft  palate,  and  epiglottis ;  anastomosing  with  its  fellow  from 
the  opposite  side. 

The  sublingual,  which  may  be  described  as  a  branch  of  bifurcation  of  the 
lingual  artery,  arises  at  the  anterior  margin  of  the  Hyo-glossus  muscle,  and, 
running  forwards  and  outwards  beneath  the  Mylo-hyoid  to  the  sublingual 
gland,  supplies  its  substance,  giving  branches  to  the  Mylo-hyoid  and  neighbor- 
ing muscles,  the  mucous  membrane  of  the  mouth  and  gums. 

Fig.  276.— The  Arteries  of  the  Face  and  Scalp.' 


The  ranine  maybe  regarded  as  the  other  branch  of  bifurcation,  or,  as  is  more 
usual,  as  the  continuation  of  the  lingual  artery ;  it  runs  along  the  under  surface 
of  the  tongue,  resting  on  the  Lingualis,  and  covered  by  the  mucous  mem- 
brane of  the  mouth ;  it  lies  on  the  outer  side  of  the  Genio-hyo-glossus,  and  is 
covered  by  the  llyo-glossus  and  Stylo-glossus,  accompanied  by  the  gustatory 
nerve.  On  arriving  at  the  tip  of  the  tongue,  it  anastomoses  with  the  artery 
of  the  opposite  side.  These  vessels  in  the  mouth  are  placed  one  on  each  side 
of  the  fraenum. 

Surgical  Anatomy.    The  lingual  artery  may  be  divided  near  its  origin  in  cases  of  cut  throat, 

'  The  muscular  tisane  of  the  lips  must  bo  supposed  to  have  been  cut  away,  in  order  to  show 
the  course  of  the  coronary  arteries. 


FACIAL.  461 

a  coraplication  that  not  unfrequently  happens  in  this  class  of  wounds,  or  severe  hemorrhage 
which  cannot  be  restrained  by  ordinary  means,  may  ensue  from  a  wound,  or  deep  ulcer,  of  the 
tongue.  In  the  former  case.'the  primary  wound  may  be  enlarged  if  necessary,  and  the  bleeding 
vessel  secured.  In  the  latter  case,  it  has  been  suggested  that  the  lingual  artery  should  be  tied  near 
its  origin.  Ligature  of  the  lingual  artery  is  also  occasionally  practised,  as  a  palliative  measure,  in 
cases  of  tumor  of  the  tongue,  in  order  to  check  the  progress  of  the  disease.  The  operation  is  a 
difiBcult  one,  on  account  of  the  depth  of  the  artery,  the  of  number  important  parts  by  which  it  is 
surrounded,  the  loose  and  yielding  nature  of  the  parts  upon  which  it  is  supported,  and  its  occa- 
sional irregularity  of  origin.  An  incision  is  to  be  made;  about  two  and  a  half  inches  in  length, 
running  obliquely  downwards  and  backwards,  and  having  its  centre  opposite  the  point  of  the 
great  cornu  of  the  hyoid  bone,  which  is  the  guide  to  the  artery.  The  parts  being  gradually 
dissected,  the  hypoglossal  nerve  will  first  come  into  view,  and  then  the  artery  must  be  carefully 
sought  for  among  the  loose  tissue  at  the  bottom  of  the  wound,  care  being  taken  not  to  open  the 
pharynx.  Large  veins,  the  internal  jugular  or  some  of  its  branches,  may  be  met  with,  and  prove 
a  source  of  embarrassment. 

Troublesome  hemorrhage  may  occur  in  the  division  of  the  fraenum  in  children,  if  the  ranine 
artery,  which  lies  on  each  side  of  it,  is  cut  through.  The  student  should  remember  that  the 
operation  is  always  to  be  performed  with  a  pair  of  blunt-pointed  scissors,  and  the  mucous  mem- 
brane only  is  to  be  divided  by  a  very  superficial  cut,  which  cannot  endanger  any  vessel.  The 
scissors,  also,  should  be  directed  away  from  the  tongue.  Any  fuither  liberation  of  the  tongue, 
which  may  be  necessary,  can  be  effected  by  tearing. 

The  Facial  Artery  (Fig.  276)  arises  a  little  above  the  lingual,  and  ascends 
obliquely  forwards  and  upwards,  beneath  the  body  of  the  lower  jaw,  to  the 
submaxillary  gland,  in  which  it  is  imbedded ;  this  may  be  called  the  cervical 
part  of  the  artery.  It  then  curves  upwards  over  the  body  of  the  jaw  at  the 
anterior  inferior  angle  of  the  Masseter  muscle,  ascends  forwards  and  upwards 
across  the  cheek  to  the  angle  of  the  mouth,  passes  up  along  the  side  of  the 
nose,  and  terminates  at  the  inner  canthus  of  the  eye,  under  the  name  of  the 
angular  artery.  This  vessel,  both  in  the  neck,  and  on  the  face,  is  remarkably 
tortuous ;  in  the  former  situation,  to  accommodate  itself  to  the  movements  of 
the  pharynx  in  deglutition ;  and  in  the  latter,  to  the  movements  of  the  jaw,  and 
the  lips  and  cheeks. 

Relations.  In  the  neck,  its  origin  is  superficial,  being  covered  by  the  integu- 
ment, Platysma,  and  fascia;  it  then  passes  beneath  the  Digastric  and  Stylo- 
hyoid muscles,  and  the  submaxillary  gland.  On  the  face,  where  it  passes  over 
the  body  of  the  lower  jaw,  it  is  comparatively  superficial,  lying  immediately 
beneath  the  Platysma.  In  this  situation,  its  pulsation  may  be  distinctly  felt, 
and  compression  of  the  vessel  effectually  made  against  the  bone.  In  its  course 
over  the  face,  it  is  covered  by  the  integument,  the  fat  of  the  cheek,  and,  near 
the  angle  of  the  mouth,  by  the  Platysma  and  Zygomatic  muscles.  It  rests  on 
the  Buccinator,  the  Levator  Anguli  Oris,  and  the  Levator  Labii  Superioris 
Alaeque  Nasi.  It  is  accompanied  by  the  facial  vein  throughout  its  entire  course; 
the  vein  is  not  tortuous  like  the  artery,  and,  on  the  face,  is  separated  from  that 
vessel  by  a  considerable  interval.  The  branches  of  the  facial  nerve  cross  the 
artery,  and  the  infra-orbital  nerve  lies  beneath  it. 

The  branches  of  this  vessel  may  be  divided  into  two  sets,  those  given  off 
below  the  jaw  (cervical),  and  those  on  the  face  (facial). 

Cervical  Branches.  Facial  Branches. 

Inferior  or  Ascending  Palatine.  Muscular. 

Tonsillar.  Inferior  Labial. 

Submaxillary  Inferior  Coronary., 

Submental.  Superior  Coronary. 

Lateralis  Nasi. 
Angular. 

The  inferior  or  ascending  palatine  (Fig.  279)  passes  up  between  the  Stylo- 
glossus and  Stylo-pharyngeus  to  the  outer  side  of  the  pharynx.  After  sup- 
plying those  muscles,  the  tonsil,  and  Eustachian  tube,  it  divides,  near  the 
Levator  Palati,  into  two  branches;  one  follows  the  course  of  the  Tensor  Palati, 
and  supplies  the  soft  palate  and  the  palatine  glands ;  the  other  passes  to  the 


452  ARTERIES. 

tonsil,  which  it  supplies,  anastomosing  with  the  tonsillar  artery.  These  vessels 
inosculate  with  the  posterior  palatine  branch  of  the  internal  maxillary  artery. 

The  tonsillar  branch  (Fig.  279)  passes  up  along  the  side  of  the  pharynx,  and, 
perforating  the  Superior  Constrictor,  ramifies  in  the  substance  of  the  tonsil  and 
root  of  the  tongue. 

The  submaxillary  consists  of  three  or  four  large  branches,  which  supply  the 
submaxillary  gland,  some  being  prolonged  to  the  neighboring  muscles,  lym- 
phatic glands,  and  integument. 

The  suhmental,  the  largest  of  the  cervical  branches,  is  given  oflf  from  the 
facial  artery,  just  as  that  vessel  quits  the  submaxillary  gland ;  it  runs  forwards 
upon  the  Mylo-hyoid  muscle,  just  below  the  body  of  the  jaV,  and  beneath  the 
Digastric ;  after  supplying  the  muscles  attached  to  the  jaw,  and  anastomosing 
with  the  sublingual  artery,  it  arrives  at  the  symphysis  of  the  chin,  where  it 
divides  into  a  superficial  and  a  deep  branch  ;  the  former  turns  round  the  chin, 
and,  passing  between  the  integument  and  Depressor  Labii  Inferioris,  supplies 
both,  and  anastomoses  with  the  inferior  labial.  The  deep  branch  passes  beneath 
the  latter  muscle  and  the  bone,  supplies  the  lip,  and  anastomoses  with  the  in- 
ferior labial  and  mental  arteries. 

The  muscular  branches  are  distributed  to  the  Internal  Pterygoid,  Masseter, 
and  Buccinator. 

The  inferior  labial  passes  beneath  the  Depressor  Anguli  Oris,  to  supply  the 
muscles  and  integument  of  the  lower  lip,  anastomosing  with  the  inferior  coro- 
nary and  submental  branches  of  the  facial,  and  with  the  mental  branch  of  the 
inferior  dental  artery. 

The  inferior  coronary  is  derived  from  the  facial  artery  near  the  angle  of  the 
mouth  ;  it  passes  upwards  and  inwards  beneath  the  Depressor  Anguli  Oris,  and, 
penetrating  the  Orbicularis  muscle,  runs  in  a  tortuous  course  along  the  edge  of 
the  lower  lip  between  this  muscle  and  the  mucous  membrane,  inosculating  with 
the  artery  of  the  opposite  side.  This  artery  supplies  the  labial  glands,  the 
mucous  membrane,  and  muscles  of  the  lower  lip ;  and  anastomoses  with  the 
inferior  labial  and  mental  branch  of  the  inferior  dental  artery. 

The  superior  coronary  is  larger,  and  more  tortuous  in  its  course  than  the  pre- 
ceding. It  follows  the  same  course  along  the  edge  of  the  upper  lip,  lying  be- 
tween the  mucous  membrane  and  the  Orbicularis,  and  anastomoses  with  the 
artery  of  the  opposite  side.  It  supplies  the  textures  of  the  upper  lip,  and  gives 
off  in  its  course  two  or  three  vessels  which  ascend  to  the  nose.  One,  named 
the  artery  of  the  septum,  ramifies  on  the  septum  of  the  nares  as  far  as  the  point 
of  the  nose ;  another  supplies  the  ala  of  the  nose. 

The  lateralis  nasi  is  derived  from  the  facial,  as  that  vessel  is  ascending  along 
the  side  of  the  nose  ;  it  supplies  the  ala  and  dorsum  of  the  nose,  anastomosing 
with  its  fellow,  the  nasal  branch  of  the  ophthalmic,  the  artery  of  the  septum, 
and  the  infra-orbital. 

The  angular  artery  is  the  termination  of  the  trunk  of  the  facial ;  it  ascends 
to  the  inner  angle  of  the  orbit,  accompanied  by  a  large  vein,  the  angular;  it 
distributes  some  branches  on  the  cheek  which  anastomose  with  the  infra-orbital, 
and,  after  supplying  the  lachrymal  sac,  and  Orbicularis  muscle,  terminates  by 
anastomosing  with  the  nasal  branch  of  the  ophthalmic  artery. 

The  anastomoses  of  the  facial  artery  are  very  numerous,  not  only  with  the 
vessels  of  the  opposite  side,  but  with  other  vessels  from  different  sources ;  viz., 
with  the  sublingual  branch  of  the  lingual,  with  the  mental  branch  of  the  infe- 
rior dental  as  it  emerges  from  the  mental  foramen,  with  the  ascending  pharyn- 
geal and  posterior  palatine,  and  with  the  ophthalmic,  a  branch  of  the  internal 
carotid;  it  also  inosculates  with  the  transverse  facial,  and  with  the  infraorbital. 

Peculiarities.  The  facial  artery  not  unfrequently  arises  by  a  common  trunk  with  the  lingual. 
This  vessel  also  is  subject  to  some  variations  in  its  size,  ana  in  the  extent  to  which  it  supplies 
\be  face.    It  occasionally  terminates  as  the  submental,  and  not  unfrequently  supplies  the  face 


OCCIPITAL.  453 

only  as  high  as  the  angle  of  the  mouth  or  nose.    The  deficiency  is  then  supplied  by  enlargement 
of  one  of  the  neighboring  arteries. 

Surgical  Anatomy.^  The  passage  of  the  facial  artery  over  the  body  of  the  jaw  would  appear 
to  afford  a  favorable  position  for  the  application  of  pressure  in  cases  of  hemorrhage  from  the 
lips,  the  result  either  of  an  accidental  wound,  or  from  an  operation  ;  but  its  application  is  useless, 
except  for  a  very  short  time,  on  account  of  the  free  communication  of  this  vessel  with  its  fellow, 
and  with  numerous  branches  from  different  sources.  In  a  wound  involving  the  lip,  it  is  better  to 
seize  the  part  between  the  fingers,  and  evert  it,  when  the  bleeding  vessel  may  be  at  once  secured 
with  a  tenaculum.  In  order  to  prevent  hemorrhage  in  cases  of  excision,  or  in  the  removal  of 
diseased  growths  from  the  part,  the  lip  should  be  compressed  on  each  side  between  the  finger 
and  thumb,  whilst  the  surgeon  excises  the  diseased  part.  In  order  to  stop  hemorrhage  where 
the  lip  has  been  divided  in  an  operation,  it  is  necessary  in  uniting  the  edges  of  the  wound,  to  pass 
the  sutures  through  the  cut  edges,  almost  as  deep  as  its  mucous  surface ;  by  these  means,  not 
only  are  the  cut  surfaces  more  neatly  and  securely  adapted  to  each  other,  but  the  possibility  of 
hemorrhage  is  prevented  by  including  in  the  suture  the  divided  artery.  If  the  suture  is,  on  the 
contrary,  passed  through  merely  the  cutaneous  portion  of  the  wound,  hemorrhage  occurs  into 
the  cavity  of  the  mouth.  The  student  should,  lastly,  observe  the  relation  of  the  angular  artery 
to  the  lachrymal  sac,  and  it  will  be  seen  that,  as  the  vessel  passes  up  along  the  inner  margin  of 
the  orbit  it  ascends  on  its  nasal  side.  In  operating  for  fistula  lachrymalis,  the  sac  should  always 
be  opened  on  its  outer  side,  in  order  that  this  vessel  may  be  avoided. 

The  Occipital  Artery  (Fig.  276)  arises  from  the  posterior  part  of  the  external 
carotid,  opposite  the  facial,  near  the  lower  margin  of  the  Digastric  muscle.  At 
its  origin,  it  is  covered  by  the  posterior  belly  of  the  Digastric  and  Stylo-hyoid 
muscles,  and  part  of  the  parotid  gland,  the  hypoglossal  nerve  winding  around 
it  from  behind  forwards ;  higher  up,  it  passes  across  the  internal  carotid  artery, 
the  internal  jugular  vein,  and  the  pneumogastric  and  spinal  accessory  nerves; 
it  then  ascends  to  the  interval  between  the  transverse  process  of  the  atlas,  4ind 
the  mastoid  process  of  the  temporal  bone,  and  passes  horizontally  backwards, 
grooving  the  surface  of  the  latter  bone,  being  covered  by  the  Sterno-mastoid, 
Splenius,  Digastric,  and  Trachelo-mastoid  muscles,  and  resting  upon  the  Com- 
{)lexus,  Superior  Oblique,  and  Eectus  Posticus  Major  muscles ;  it  then  ascends 
vertically  upwards,  piercing  the  cranial  attachment  of  the  Trapezius,  and  passes 
in  a  tortuous  course  over  the  occiput,  as  high  as  the  vertex,  where  it  divides 
into  numerous  branches. 

The  branches  given  off  from  this  vessel  are, 

Muscular.  Inferior  Meningeal. 

Auricular.  Arteria  Princeps  Cervicis. 

The  muscular  branches  supply  the  Digastric,  Stylo-hyoid,  Sterno-mastoid, 
Splenius,  and  Trachelo-mastoid  muscles.  The  branch  distributed  to  the  Sterno- 
mastoid  is  of  large  size. 

The  auricular  branch  supplies  the  back  part  of  the  concha. 

The  meningeal  branch  ascends  with  the  internal  jugular  vein,  and  enters  the 
skull  through  the  foramen  lacerum  poster! us,  to  supply  the  dura  mater  in  the 
posterior  fossa. 

The  arteria  princeps  cervicis  (Fig.  279)  is  a  large  branch  which  descends  along 
the  back  part  of  the  neck,  and  divides  into  a  superficial  and  deep  branch.  The 
former  runs  beneath  the  Splenius,  giving  off  branches  which  perforate  that 
muscle  to  supply  the  Trapezius,  anastomosing  with  the  superficial  cervical 
artery :  the  latter  passes  beneath  the  Complexus,  between  it  and  the  Semispi- 
nalis  Colli,  and  anastomoses  with  the  vertebral,  and  deep  cervical  branch  of  the 
superior  intercostal.  The  anastomosis  between  these  vessels  serves  mainly  to 
establish  the  collateral  circulation  after  ligature  of  the  carotid  or  subclavian 
artery. 

The  cranial  branches  of  the  occipital  artery  are  distributed  upon  the  occiput; 
they  are  very  tortuous,  and  lie  between  the  integument  and  Occipito-frontalis, 
anastomosing  with  the  artery  of  the  opposite  side,  the  posterior  auricular,  and 
temporal  arteries.  They  supply  the  back  part  of  the  Occipito-frontalis  muscle, 
the  integument  and  pericranium,  and  one  or  two  branches  occasionally  pass 
through  the  parietal  or  mastoid  foramina,  to  supply  the  dura  mater. 


454  ARTERIES. 

The  Posterior  Auricular  Artery  (Fig.  276)  is  a  small  vessel  whicH  arises  from 
the  external  carotid,  above  the  Digastric  and  Stjlo-hyoid  muscles,  opposite  the 
apex  of  the  styloid  process.  It  ascends,  under  cover  of  the  parotid  gland,  to 
the  groove  between  the  cartilage  of  the  ear  and  the  mastoid  process,  immediately 
above  which  it  divides  into  two  branches,  an  anterior,  passing  forwards  to  anas- 
tomose with  the  posterior  division  of  the  temporal ;  and  a  posterior,  communi- 
cating with  the  occipital.  Just  before  arriving  at  the  mastoid  process,  this 
artery  is  crossed  by  the  portio  dura,  and  has  beneath  it  the  spinal  accessory 
nerve. 

Besides  several  small  branches  to  the  Digastric,  Stylo-hyoid,  and  Sterno- 
mastoid  muscles,  and  to  the  parotid  gland,  this  vessel  gives  oft*  two  branches, 

Stylo-mastoid.  Auricular. 

The  stylo-mastoid  .branch  enters  the  stylo-mastoid  foramen,  and  supplies  the 
tympanum,  mastoid  cells,  and  semicircular  canals.  In  the  young  subject,  a 
branch  from  this  vessel  forms,  with  the  tympanic  "branch  from  the  internal 
maxillary,  a  vascular  circle,  which  surrounds  the  auditory  meatus,  and  from 
which  delicate  vessels  ramify  on  the  membrana  tympani. 

The  auricular  branch  is  distributed  to  the  back  ])art  of  the  cartilage  of  the  ear, 
upon  which  it  ramifies  minutely,  some  branches  curving  round  the  margin  of 
the  fibro-cartilage,  others  perforating  it',  to  supply  its  anterior  surface. 

^he  Ascending  Pharyngeal  Artery  (Fig.  279),  the  smallest  branch  of  the  external 
carotid,  is  a  long  slender  vessel,  deeply  seated  in  the  neck,  beneath  the  other 
branches  of  the  external  carotid  and  the  Stylo-pharyngeus  muscle.  It  arises 
from  the  back  part  of  the  external  carotid,  near  the  commencement  of  that  vessel, 
and  ascends  vertically  between  the  internal  carotid  and  the  side  of  the  pharynx, 
to  the  under  surface  of  the  base  of  the  skull,  lying  on  the  Rectus  Capitis  Anti 
cus  Major.  Its  branches  may  be  subdivided  into  three  sets :  1.  Those  directed 
outwards  to  supply  muscles  and  nerves.  '2.  Those  directed  inwards  to  the 
pharynx.     8.  Meningeal  branches. 

The  external  branches  are  numerous  small  vessels,  which  supply  the  Recti 
Antici  muscles,  the  sympathetic,  hypoglossal  and  pneumogastric  nerves,  and 
the  lymphatic  glands  of  the  neck,  anastomosing  with  the  ascending  cervical 
artery. 

The  pharyngeal  branches  are  three  or  four  in  number.  Two  of  these  descend 
to  supply  the  Middle  and  Inferior  Constrictors  and  the  Stylo-pharyngeus,  rami- 
fying in  their  substance  and  in  the  mucous  membrane  lining  them.  The  largest 
of  the  pharyngeal  branches  passes  inwards,  running  upon  the  Superior  Con- 
strictor, and  sends  ramifications  to  the  soft  palate,  Eustachian  tube,  and  tonsil, 
which  take  the  place  of  the  ascending  palatine  branch  of  the  facial  artery,  Avhen 
that  vessel  is  of  small  size. 

The  meningeal  branches  consist  of  several  small  vessels,  which  pass  through 
foramina  in  the  base  of  the  skull,  to  supply  the  dura  mater.  One,  the  posterior 
meningeal,  enters  the  cranium  through  the  foramen  lacerum  posterius  with  the 
internal  jugular  vein.  A  second  passes  through  the  foramen  lacerum  medium  ; 
and  occasionally  a  third  through  the  anterior  condyloid  foramen.  They  are  all 
distributed  to  the  dura  mater. 

The  Temporal  Artery  (Fig.  276),  the  smaller  of  the  two  terminal  branches  of 
the  external  carotid,  appears,  from  its  direction,  to  be  the  continuation  of  that 
vessel.  It  commences  in  the  substance  of  the  parotid  gland,  in  the  interspace 
between  the  neck  of  the  condyle  of  the  lower  jaw  and  the  external  meatus, 
crosses  over  the  root  of  the  zygoma,  immediately  beneath  the  integument,  and 
divides  about  two  inches  above  the  zygomatic  arch  into  two  branches,  an  ante- 
rior and  a  posterior. 

The  anterior  teynporal  inclines  forwards  over  the  forehead,  supplying  the 
muscles,  integument,  and  pericranium  in  this  region,  and  anastomoses  with  the 


INTERNAL    MAXILLARY.  458 

supraorbital  and  frontal  arteries,  its  branches  being  directed  from  before  back- 
wards. 

The  posterior  temporal,  larger  than  the  anterior,  curves  upwards  and  back- 
wards along  the  side  of  the  head,  lying  above  the  temporal  fascia,  and  inoscu- 
lates with  its  fellow  of  the  opposite  side,  and  with  the  posterior  auricular  and 
occipital  arteries. 

The  temporal  artery,  as  it  crosses  the  zygoma,  is  covered  by  the  Attrahens 
Aurem  muscle,  and  by  a  dense  fascia  given  off  from  the  parotid  gland;  it  is  also 
usually  crossed  by  one  or  two  veins,  and  accompanied  by  branches  of  the  fascial 
and  auriculo-temporal  nerves.  Besides  some  twigs  to  the  parotid  gland,  the 
articulation  of  the  jaw,  and  the  Masseter  muscle,  its  branches  are  the 

Transverse  Facial.  Middle  Temporal. 

Anterior  Auricular. 

The  transverse  facial  is  given  off  from  the  temporal  before  that  vessel  quits 
the  parotid  gland;  running  forwards  through  its  substance,  it  passes  transversely 
across  the  face,  between  Steno's  duct  and  the  lower  border  of  the  zygoma,  and 
divides  on  the  side  of  the  face  into  numerous  branches,  which  supply  the  parotid 
gland,  the  Masseter  muscle,  and  the  integument,  anastomosing  with  the  facial 
and  infraorbital  arteries.  This  vessel  rests  on  the  Masseter,  and  is  accompanied 
by  one  or  two  branches  of  the  facial  nerve.  It  is  sometimes  a  branch  of  the 
external  carotid. 

The  middle  temporal  artery  arises  immediately  above  the  zygomatic  arch,  and 
perforating  the  temporal  fascia,  supplies  the  Temporal  muscle,  anastomosing 
with  the  deep  temporal  branches  of  the  internal  maxillary.  It  occasionally 
gives  off  an  orbital  branch,  which  runs  along  the  upper  border  of  the  zygoma, 
between  the  two  layers  of  the  temporal  fascia,  to  the  outer  angle  of  the  orbit. 
This  branch  supplies  the  Orbicularis,  and  anastomoses  with  the  lachrymal  and 
palpebral  branches  of  the  ophthalmic  artery. 

The  anterior  aiiricular  branches  are  distributed  to  the  anterior  portion  of  the 
pinna,  the  lobule,  and  part  of  the  external  meatus,  anastomosing  with  branches 
of  the  posterior  auricular. 

Surgical  Anatomy.  It  occasionally  happens  that  the  surgeon  is  called  npon  to  perform  the 
operation  of  arteriotomy  upon  this  vessel  in  cases  of  inflammation  of  the  eye  or  brain.  Under 
these  circumstances,  the  anterior  branch  is  the  one  usually  selected.  If  the  student  will  con- 
sider the  relations  of  the  trunk  of  this  vessel,  as  it  crosses  the  zygomatic  arch,  with  the  surround- 
ing structures,  he  will  observe  that  it  is  covered  by  a  thick  and  dense  fascia,  crossed  by  one  or 
two  veins,  and  accompanied  by  branches  of  the  fascial  and  temporo-auricular  nerves.  Bleeding 
should  not  be  performed  in  this  situation,  as  much  difficulty  may  arise  from  the  dense  fascia 
over  the  vessel  preventing  a  free  flow  of  blood,  and  considerable  pressure  is  recjuisite  afterwards 
to  repress  the  hemorrhage.  Again,  a  varicose  aneurism  may  be  formed  by  the  accidental  open- 
ing of  one  of  the  veins  in  front  of  the  artery  ;  or  severe  neuralgic  pain  may  arise  from  the  opera- 
tion implicating  one  of  the  nervous  filaments  in  the  neighborhood. 

The  anterior  branch  is,  on  the  contrary,  subcutaneous,  is  a  large  vessel,  and  as  readily  com- 
pressed as  any  other  portion  of  the  artery;  it  should  consequently  always  be  selected  for  the 
operation. 

The  Internal  Maxillary  (Fig.  277),  the  larger  of  the  two  terminal  branches  of 
the  external  carotid,  passes  inwards,  at  right  angles  from  that  vessel,  to  the 
inner  side  of  the  neck  of  the  condyle  of  the  lower  jaw,  to  supply  the  deep  struc- 
tures of  the  face.  At  its  origin,  it  is  imbedded  in  the  substance  of  the  parotid 
gland,  being  on  a  level  with  the  lower  extremity  of  the  lobe  of  the  ear. 

In  the  first  part  of  its  course  (maxillary  portion),  the  artery  passes  horizon- 
tally forwards  and  inwards,  between  the  ramus  of  the  jaw  and  the  internal 
lateral  ligament.  The  artery  here  lies  parallel  with  the  auriculo-temporal 
nerve ;  it  crosses  the  inferior  dental  nerve,  and  lies  beneath  the  narrow  portion 
of  the  External  Pterygoid  muscle. 

In  the  second  part  of  its  course  (pterygoid  portion),  it  runs  obliquely  for- 
wards and  upwards  upon  the  outer  surface  of  the  External  Pterygoid  muscle, 


456 


ARTERIES. 


being  covered  by  the  ramus  of  the  lower  jaw,  and  lower  part  of  the  Temporal 
muscle. 

In  the  third  part  of  its  course  (spheno-maxillary  portion),  it  approaches  the 
superior  maxillary  bone,  and  enters  the  spheno-maxillary  fossa,  in  the  interval 
between  the  processes  of  origin  of  the  External  Pterygoid,  where  it  lies  in  rela- 
tion with  Meckel's  ganglion,  and  gives  off  its  terminal  branches. 

Fig.  277. — The  Internal  Maxillary  Artery,  and  its  Branches, 


Imeittn 


Fig.  278.   flan  ef  the  Branches 

Dufi 

MUJ/t  Minlvgtal 

Htntnffif  Parva' 

Tyti/iajtic- 

Ji^McT  Stntal- 


Pectdiarities.  Occasionally,  this  artery  passes  between  the  two  Pterygoid  muscles.  The 
vessel  in  this  case  passes  forwards  to  the  interval  between  the  processes  of  origin  of  the  External 
Pterygoid,  in  order  to  reach  the  maxillary  bone.  Sometimes  the  vessel  escapes  from  beneath 
the  External  Pterygoid  by  perforating  the  middle  of  that  muscle. 

The  branches  of  this  vessel  may  be  divided  into  three  groups,  corresponding 
with  its  three  divisions. 

1.  Branches  from  the  Maxillary  Portion. 

Small  Meningeal. 
Inferior  Dental. 


Tympanic, 
Middle  Meningeal. 


The  tympanic  branch  passes  upwards  behind  the  articulation  of  the  lower  jaw, 
enters  the  tympanum  through  the  fissure  of  Glaser,  supplies  tlie  Laxator  Tym- 
pani,  and  ramifies  upon  the  membrana  tympani,  anastomosing  with  the  stylo- 
mastoid and  Vidian  arteries. 

The  middle  meningeal  is  the  largest  of  the  branches  which  supply  the  dura 
mater.     It  arises  from  the  internal  maxillary  between  the  internal  lateral  liga- 


INTERNAL    MAXILLARY.  457 

ment  and  the  neck  of  the  jaw,  and  passes  vertically  upwards  to  the  foramen 
spinosum  of  the  sphenoid  bone.  On  entering  the  cranium,  it  divides  into  two 
branches,  anterior  and  posterior.  The  anterior  branch,  the  larger,  crosses  the 
great  ala  of  the  sphenoid,  and  reaches  the  groove,  or  canal,  in  the  anterior 
inferior  angle  of  the  parietal  bone ;  it  then  divides  into  branches,  which  spread 
out  between  the  dura  mater  and  internal  surface  of  the  cranium,  some  passing 
upwards  over  the  parietal  bone  as  far  as  the  vertex,  and  others  backwards  to 
the  occipital  bone.  The  posterior  branch  crosses  the  squamous  portion  of  the 
temporal,  and  on  the  inner  surface  of  the  parietal  bone  divides  into  branches, 
which  supply  the  posterior  part  of  the  dura  mater  and  cranium.  The  branches 
of  this  vessel  are  distributed  partly  to  the  dura  mater,  but  chiefly  to  the  bones; 
they  anastomose  with  the  arteries  of  the  opposite  side,  and  with  the  anterior 
and  posterior  meningeal. 

The  middle  meningeal,  on  entering  the  cranium,  gives  off  the  following  col- 
lateral branches  :  1.  Numerous  small  vessels  to  the  ganglion  of  the  fifth  nerve, 
and  to  the  dura  mater  in  this  situation.  2.  A  branch  to  the  facial  nerve,  which 
enters  the  hiatus  Fallopii,  supplies  the  facial  nerve,  and  anastomoses  with  the 
stylo-mastoid  branch  of  the  posterior  auricular  artery.  3.  Orbital  branches, 
which  pass  through  the  sphenoidal  fissure,  or  through  separate  canals  in  the 
great  wing  of  the  sphenoid,  to  anastomose  with  the  lachrymal  or  other  branches 
of  the  ophthalmic  artery.  4.  Temporal  branches,  which  pass  through  foramina 
in  the  great  wing  of  the  sphenoid,  and  anastomose  in  the  temporal  fossa  with 
the  deep  temporal  arteries. 

The  small  meningeal  is  sometimes  derived  from  the  preceding.  It  enters  the 
skull  through  the  foramen  ovale,  and  supplies  the  Casserian  ganglion  and  dura 
mater.  Before  entering  the  cranium,  it  gives  off  a  branch  to  the  nasal  fossa 
and  soft  palate. 

The  inferior  dental  descends  with  the  dental  nerve,  to  the  foramen  on  the 
inner  side  of  the  ramus  of  the  jaw.  It  runs  along  the  dental  canal  in  the  sub- 
stance of  the  bone,  accompanied  by  the  nerve,  and  opposite  the  first  bicuspid 
tooth  divides  into  two  branches,  incisor  and  mental :  the  former  is  continued 
forwards  beneath  the  incisor  teeth  as  far  as  the  symphysis,  where  it  anastomoses 
with  the  artery  of  the  opposite  side;  the  mental  branch  escapes  with  the  nerve 
at  the  mental  foramen,  supplies  the  structures  composing  the  chin,  and  anasto- 
moses with  the  submental,  inferior  labial,  and  inferior  coronary  arteries.  As 
the  dental  artery  enters  the  foramen,  it  gives  off  a  mylo-hyoid  branch,  which 
runs  in  the  mylo-hyoid  groove,  and  ramifies  on  the  under  surface  of  the  Mylo- 
hyoid muscle.  The  dental  and  incisor  arteries,  during  their  course  through 
the  substance  of  the  bone,  give  off  a  few  twigs,  which  are  lost  in  the  cancellous 
tissue,  and  a  series  of  branches  which  correspond  in  number  to  the  roots  of 
the  teeth ;  these  enter  the  minute  apertures  at  the  extremities  of  the  fangs,  and 
supply  the  pulp  of  the  teeth. 

2.  Branches  of  the  Second,  or  Pterygoid  Portion. 

Deep  Temporal.  Masseteric. 

Pterygoid.  Buccal. 

These  branches  are  distributed,  as  their  names  imply,  to  the  muscles  in  the"" 
maxillary  region. 

The  deep  temporal  branches^  two  in  number,  anterior  and  posterior,  each 
occupy  that  part  of  the  temporal  fossa  indicated  by  its  name.  Ascending  be- 
tween the  Temporal  muscle  and  pericranium,  they  supply  that  muscle,  and 
anastomose  with  the  other  temporal  arteries;  the  anterior  branch  communi- 
cating with  the  lachrymal  through  small  branches,  which  perforate  the  malar 
bone. 

The  pterygoid  branches^  irregular  in  their  number  and  origin,  supply  the 
Pterygoid  muscles. 


458  SURGICAL    ANATOMY. 

The  masseteric  is  a  small  branch  which  passes  outwards  above  the  sigmoid 
notch  of  the  lower  jaw,  to  the  deep  surface  of  the  Masseter.  It  supplies  that 
muscle,  and  anastomoses  with  the  masseteric  branches  of  the-  facial  and  with 
the  transverse  facial  artery. 

The  buccal  is  a  small  branch  which  runs  obliquely  forwards  between  the 
Internal  Pterygoid  and  the  ramus  of  the  jaw,  to  the  outer  surface  of  the  Buc- 
cinator, to  which  it  is  distributed,  anastomosing  with  branches  of  the  facial 
artery. 

S.  Branches  of  the  Third,  or  Spheno-maxillary  Portion. 

Alveolar.  Vidian. 

Infraorbital.  Pterygo-palatine. 

Posterior  or  Descending  Palatine.  Nasal  or  Spheno-palatine. 

The  alveolar  is  given  off  from  the  internal  maxillary  by  a  common  branch 
with  the  infraorbital,  and  just  as  the  trunk  of  the  vessel  is  passing  into  the 
spheno-maxillary  fossa.  Descending  upon  the  tuberosity  of  the  superior  max- 
illary bone,  it  divides  into  numerous  branches;  one,  the  superior  dental,  larger 
than  the  rest,  supplies  the  molar  and  bicuspid  teeth,  its  branches  entering  the 
foramina  in  the  alveolar  process;  some  branches  pierce  the  bone  to  supply  the 
lining  of  the  antrum,  and  others  are  continued  forwards  on  the  alveolar  process 
to  supply  the  gums. 

The  infraorbital  appears,  from  its  direction,  to  be  the  continuation  of  the 
trunk  of  the  internal  maxillary.  It  arises  from  that  vessel  by  a  common  trunk 
with  the  preceding  branch,  and  runs  along  the  infraorbital  canal  with  the 
superior  maxillary  nerve,  emerging  upon  the  face  at  the  infraorbital  foramen, 
beneath  the  Levator  Labii  Superioris.  Whilst  contained  in  the  canal,  it  gives 
off  branches  which  ascend  into  the  orbit,  and  supply  the  Inferior  Rectus  and 
Inferior  Oblique  muscles,  and  the  lachrymal  gland.  Other  branches  descend 
through  canals  in  the  bone,  to  supply  the  mucous  membrane  of  the  antrum, 
and  the  front  teeth  of  the  upper  jaw.  On  the  face,  it  supplies  the  lachrymal 
sac,  and  inner  angle  of  the  orbit,  anastomosing  with  the  facial  artery  and  nasal 
branch  of  the  ophthalmic ;  and  other  branches  descend  beneath  the  elevator  of 
the  upper  lip,  and  anastomose  with  the  transverse  facial  and  buccal  branches. 

The  four  remaining  branches  arise  from  that  portion  of  the  internal  maxillary 
which  is  contained  in  the  spheno-maxillary  fossa. 

The  descending  palatine  passes  down  along  the  posterior  palatine  canal  with 
the  posterior  palatine  branches  of  Meckel's  ganglion,  and  emerging  from  the 
posterior  palatine  foramen,  runs  forwards  in  a  groove  on  the  inner  side  of  the 
alveolar  border  of  the  hard  palate,  to  be  distributed  to  the  gums,  the  mucous 
membrane  of  the  hard  palate,  and  palatine  glands.  Whilst  it  is  contained  in 
the  palatine  canal,  it  gives  off"  branches,  which  descend  in  the  accessory  pala- 
tine canals  to  supply  the  soft  palate,  anastomosing  with  the  ascending  palatine 
artery ;  and  anteriorly  it  terminates  in  a  small  vessel,  which  ascends  in  the  an- 
terior palatine  canal,  and  anastomoses  with  the  artery  of  the  septum,  a  branch 
of  the  spheno-palatine. 

The  Vidian  branch  passes  backwards  along  the  Vidian  canal  with  the  Vidian 
nerve.  It  is  distributed  to  the  upper  part  of  the  pharynx  and  Eustachian  tube, 
sending  a  small  branch  into  the  tympanum. 

The  2^i^'>'y[/o  palatine  is  also  a  very  small  branch,  which  passes  backwards 
through  the  pterygo-palatine  canal  with  the  pharyngeal  nerve,  and  is  distri- 
buted to  the  upper  part  of  the  pharynx  and  Eustachian  tube. 

The  nasal  or  spheno-palatine  passes  through  the  spheno-palatine  foramen  into 
the  cavity  of  the  nose,  at  the  back  part  of  the  superior  meatus,  and  divides 
into  two  branches;  one  internal,  the  artery  of  the  septum,  passes  obliquely 
downwards  and  forwards  along  the  septum  nasi,  supplies  the  mucous  mem- 


OF  THE  TRIANGLES  OF  THE  NECK.        45» 

brane,  and  anastomoses  in  front  with  the  ascending  branch  of  the  descending 
palatine.  The  external  branches,  two  or  three  in  number,  supply  the  mucous 
membrane  covering  the  lateral  wall  of  the  nose,  the  antrum,  and  the  ethmoid 
and  sphenoid  cells. 

SuKGiCAL  Anatomy  of  the  Triangles  of  the  Neck. 

The  student  having  considered  the  relative  anatomy  of  the  large  arteries  of 
the  neck  and  their  branches,  and  the  relations  they  bear  to  the  veins  and  nerves, 
should  now  examine  these  structures  collectively,  as  they  present  themselves  in 
certain  regions  of  the  neck,  in  each  of  which  important  operations  are  being 
constantly  performed. 

For  this  purpose,  the  Sterno-mastoid,  or  any  other  muscles  that  have  been 
divided  in  the  dissection  of  the  vessels,  should  be  replaced  in  their  normal  posi- 
tion ;  the  head  should  be  supported  by  placing  a  block  at  the  back  of  the  neck, 
and  the  face  turned  to  the  side  opposite  to  that  which  is  being  examined. 

The  side  of  the  neck  presents  a  somewhat  quadrilateral  outline,  limited, 
above,  by  the  lower  border  of  the  body  of  the  jaw,  and  an  imaginary  line  ex- 
tending from  the  angle  of  the  jaw  to  the  mastoid  process ;  below,  by  the  promi- 
nent upper  border  of  the  clavicle ;  in  front,  by  the  median  line  of  the  neck ; 
behind,  by  the  anterior  margin  of  the  Trapezius  muscle.  This  space  is  subdi- 
vided into  two  large  triangles  by  the  Sterno-mastoid  muscle,  which  passes 
obliquely  across  the  neck,  from  the  sternum  and  clavicle,  below,  to  the  mastoid 
process,  above.  The  triangular  space  in  front  of  this  muscle  is  called  the  ante- 
rior triangle;  and  that  behind  it,  i\iQ  posterior  triangle. 

Anterior  Triangular  Space. 

The  Anterior  Triangle  is  limited,  in  front,  by  a  line  extending  from  the  chin 
to  the  sternum;  behind,  by  the  anterior  margin  of  the  Sterno-mastoid;  its  base, 
directed  upwards,  is  formed  by  the  lower  border  of  the  body  of  the  jaw,  and  a 
line  extending  from  the  angle  of  the  jaw  to  the  mastoid  process ;  its  apex  is 
below,  at  the  sternum.  This  space  is  covered  by  the  integument,  superficial 
fascia,  Platysma,  and  deep  fascia ;  it  is  crossed  by  branches  of  the  fascial  and 
superficial  cervical  nerves,  and  is  subdivided  into  three  smaller  triangles  by 
the  Digastric  muscle,  above,  and  the  anterior  belly  of  the  Omo-hyoid,  below. 
These  smaller  triangles  are  named  from  below  upwards,  the  inferior  carotid, 
the  superior  carotid,  and  the  submaxillary  triangle. 

The  Inferior  Carotid  Triangle  is  limited,  in  front,  by  the  median  line  of  the 
neck ;  behind,  by  the  anterior  margin  of  the  Sterno-mastoid ;  above,  by  the 
anterior  belly  of  the  Omo-hyoid ;  and  is  covered  by  the  integument,  superficial 
fascia,  Platysma,  and  deep  fascia;  ramifying  between  which  is  seen  the  descend- 
ing branch  of  the  superficial  cervical  nerve.  Beneath  these  superficial  struc- 
tures, are  the  Sterno-hyoid  and  Sterno-thyroid  muscles,  which,  together  with 
the  anterior  margin  of  the  Sterno-mastoid,  conceal  the  lower  part  of  the  common 
carotid  artery.' 

This  vessel  is  inclosed  within  its  sheath,  together  with  the  internal  jugular 
vein,  and  pneumogastric  nerve;  the  vein  lying  on  the  outer  side  of  the  artery 
on  the  right  side  of  the  neck,  but  overlapping  it,  or  passing  directly  across  it  on 
the  left  side :  the  nerve  lying  between  the  artery  and  vein,  on  a  plane  posterior 
to  both.     In  front  of  the  sheath  are  a  few  filaments  descending  from  the  loop 

'  Therefore  the  carotid  artery  and  jugular  vein  are  not,  strictly  speaking,  contained  in  this 
triangle,  since  they  are  covered  by  the  Sterno-mastoid  muscle,  that  is  to  say,  lie  behind  the 
anterior  border  of  that  muscle,  which  forms  the  posterior  border  of  the  triangle.  But  as  they  lie 
very  close  to  the  structures  which  are  really  contained  in  the  triangle,  and  whose  position  it  is 
essential  to  remember  in  operating  on  this  part  of  the  artery,  it  has  seemed  expedient  to  study 
the  relations  of  all  these  parts  together. 


460  SURGICAL    ANATOMY. 

of  communication  between  the  descendens  and  communicans  noni ;  behind  the 
sheath  are  seen  the  inferior  thyroid  artery,  the  recurrent  laryngeal  nerve,  and 
the  sympathetic  nerve ;  and  on  its  inner  side,  the  trachea,  the  thyroid  gland, 
much  more  prominent  in  the  female  than  in  the  male,  and  the  lower  part  of  the 
larynx.  By  cutting  into  the  upper  part  of  this  space,  and  slightly  displacing 
the  Sterno-mastoid  muscle,  the  common  carotid  artery  may  be  tied  below  the 
Omo-hyoid  muscle. 

The  Superior  Carotid  Triangle  is  bounded,  behind,  by  the  Sterno-mastoid ; 
below,  by  the  anterior  belly  of  the  Omo-hyoid ;  and  above,  by  the  posterior 
belly  of  the  Digastric  muscle.  Its  floor  is  formed  by  parts  of  the  Thyro-hyoid, 
Hyo-glossus,  and  the  Inferior  and  Middle  Constrictor  muscles  of  the  pharynx; 
and  it  is  covered  by  the  integument,  superficial  fascia,  Platysma,  and  deep 
fascia ;  ramifying  between  which,  are  branches  of  the  fascial  and  superficial 
cervical  nerves.  This  space  contains  the  upper  part  of  the  common  carotid 
artery,  which  bifurcates  opposite  the  upper  border  of  the  thyroid  cartilage  into 
the  external  and  internal  carotid.  These  vessels  are  occasionally  somewhat 
concealed  from  view  by  the  anterior  margin  of  the  Sterno-mastoid  muscle, 
which  overlaps  them.  The  external  and  internal  carotids  lie  side  by  side,  the 
external  being  the  most  anterior  of  the  two.  The  following  branches  of  the 
external  carotid  are  also  met  with  in  this  space :  the  superior  thyroid,  running 
forwards  and  downwards ;  the  lingual  directly  forwards ;  the  fascial,  forwards 
and  upwards;  the  occipital,  backwards;  and  the  ascending  pharyngeal  directly 
upwards  on  the  inner  side  of  the  internal  carotid.  The  veins  met  with  are : 
the  internal  jugular,  which  lies  on  the  outer  side  of  the  common  and  internal 
carotid  arteries ;  and  veins  corresponding  to  the  above-mentioned  branches  of 
the  external  carotid,  viz.,  the  superior  thyroid,  the  lingual,  fascial,  ascending 
pharyngeal,  and  sometimes  the  occipital ;  all  of  which  accompany  their  corres- 
ponding arteries,  and  terminate  in  the  internal  jugular.  The  nerves  in  this  space 
are  the  following :  In  front  of  the  sheath  of  the  common  carotid  is  the  descendens 
noni.  The  hypoglossal  nerve  crosses  both  carotids  above,  curving  round  the 
occipital  artery  at  its  origin.  Within  the  sheath,  between  the  artery  and  vein, 
and  behind  both,  is  the  pneumogastric  nerve ;  behind  the  sheath,  the  sympa- 
thetic. On  the  outer  side  of  the  vessels,  the  spinal  accessory  nerve  runs  for  a 
short  distance  before  it  pierces  the  Sterno-mastoid  muscle ;  and  on  the  inner 
side  of  the  internal  carotid,  just  below  the  hyoid  bone,  maybe  seen  the  superior 
laryngeal  nerve ;  and  still  more  inferiorly,  the  external  laryngeal  nerve.  The 
upper  part  of  the  larynx  and  lower  part  of  the  pharynx  are  also  found  in  the 
front  part  of  this  space. 

The  Submaxillary  Triangle  corresponds  to  the  part  of  the  neck  immediately 
beneath  the  body  of  the  jaw.  It  is  bounded,  above,  by  the  lower  border  of  the 
body  of  the  jaw,  the  parotid  gland,  and  mastoid  process ;  behind,  by  the  poste- 
rior belly  of  the  Digastric  and  Stylo-hyoid  muscles ;  in  front,  by  the  middle 
line  of  the  neck.  The  floor  of  this  space  is  formed  by  the  anterior  belly  of  the 
Digastric,  the  Mylo-hyoid,  and  Hyo-glossus  muscles ;  and  it  is  covered  by  the 
integument,  superficial  fascia,  Platysma,  and  deep  fascia;  ramifying  between 
which  are  branches  of  the  facial  and  ascending  filaments  of  the  superficial 
cervical  nerve.  This  space  contains,  in  front,  the  submaxillary  gland,  imbedded 
in  the  substance  of  which  are  the  facial  artery  and  vein,  and  their  glandular 
branches ;  beneath  this  gland,  on  the  surface  of  tlie  Mylo-hyoid  muscle,  is  the 
submental  artery,  and  the  mylo-hyoid  artery  and  nerve.  The  back  part  of  this 
space  is  separated  from  the  front  part  by  the  stylo-maxillary  ligament ;  it  con- 
tains the  external  carotid  artery,  ascending  deeply  in  the  substance  of  the  parotid 
gland ;  this  vessel  here  lies  in  front  of,  and  superficial  to,  the  internal  carotid, 
being  crossed  by  the  facial  nerve,  and  gives  oft"  in  its  course  the  posterior  auri- 
cular, temporal,  and  internal  maxillary  branches;  more  deeply  is  the  internal 
carotid,  the  intern&l  jugular  vein,  and  the  pneumogastric  nerve,  separated  from 


OF  THE  TRIANGLES  OF  THE  NECK.        461 

the  external  carotid  by  the  Stylo-glossus  and  Stylo-pharjngeus  muscles,  and 
the  glosso-pharyngeal  nerve.' 

Posterior  Triangular  Space. 

The  Posterior  Triangular  Space  is  bounded,  in  front  by  the  Sterno-mastoid 
muscle ;  behind,  by  the  anterior  margin  of  the  Trapezius :  its  base  corresponds 
to  the  upper  border  of  the  clavicle ;  its  apex,  to  the  occiput.  This  space  is 
crossed,  about  an  inch  above  the  clavicle,  by  the  posterior  belly  of  the  Omo- 
hyoid, which  divides  it  unequally  into  two,  an  upper  or  occipital,  and  a  lower 
or  subclavian  triangle. 

The  Occipital^  the  larger  of  the  two  posterior  triangles,  is  bounded,  in  front, 
by  the  Sterno- mastoid  ;  behind,  by  the  Trapezius;  below,  by  the  Omo-hyoid. 
Its  floor  is  formed  from  above  downwards  by  the  Splenius,  Levator  Anguli 
Scapulae,  and  the  Middle  and  Posterior  Scaleni  muscles.  It  is  covered  by  the 
integument,  the  Platysma  below,  the  superficial  and  deep  fascice ;  and  crossed, 
above,  by  the  ascending  branches  of  the  cervical  plexus ;  the  spinal  accessory 
nerve  is  directed  obliquely  across  the  space  from  the  Sterno-mastoid,  which  it 
pierces,  to  the  under  surface  of  the  Trapezius ;  below,  the  descending  branches 
of  the  cervical  plexus  and  the  transversalis  colli  artery  and  vein  cross  the  space. 
A  chain  of  lymphatic  glands  is  also  found  running  along  the  posterior  border 
of  the  Sterno-mastoid,  from  the  mastoid  process  to  the  root  of  the  neck. 

The  Subclavian,  the  smaller  of  the  two  posterior  triangles,  is  bounded,  above, 
by  the  posterior  belly  of  the  Omo-hyoid ;  below,  by  the  clavicle ;  its  base, 
directed  forwards,  being  formed  by  the  Sterno-mastoid.  The  size  of  this  space 
varies  according  to  the  extent  of  attachment  of  the  clavicular  portion  of  the 
Sterno-mastoid  and  Trapezius  muscles,  and  also  according  to  the  height  at  which 
the  Omo-hyoid  crosses  the  neck  above  the  clavicle.  The  height  also  of  this 
space  varies  much,  according  to  the  position  of  the  arm,  being  much  diminished 
by  raising  the  limb,  on  account  of  the  ascent  of  the  clavicle,  and  increased  by 
drawing  the  arm  downwards,  when  that  bone  is  depressed.  This  space  is  covered 
by  the  integument,  superficial  and  deep  fascia ;  and  crossed  by  the  descending 
branches  of  the  cervical  plexus.  Just  above  the  level  of  the  clavicle,  the  third 
portion  of  the  subclavian  artery  curves  outwards  and  downwards  from  the 
outer  margin  of  the  Scalenus  Anticus,  across  the  first  rib  to  the  axilla.  Some- 
times this  vessel  rises  as  high  as  an  inch  and  a  half  above  the  clavicle,  or  to 
any  point  intermediate  between  this  and  the  usual  level.  Occasionally,  it 
passes  in  front  of  the  Scalenus  Anticus,  or  pierces  the  fibres  of  that  muscle. 
The  subclavian  vein  lies  behind  the  clavicle,  and  is  usually  not  seen  in  this 
space  ;  but  it  occasionally  rises  as  high  up  as  the  artery,  and  has  even  been  seen 
to  pass  with  that  vessel  behind  the  Scalenus  Anticus.  The  brachial  plexus  of 
nerves  lies  above  the  artery,  and  in  close  contact  with  it.  Passing  transversely 
across  the  clavicular  margin  of  the  space  are  the  suprascapular  vessels ;  and 
traversing  its  upper  angle  in  the  same  direction,  the  transverse  cervical  vessels. 
The  external  jugular  vein  runs  vertically  downwards  behind  the  posterior 
border  of  the  Sterno-mastoid,  to  terminate  in  the  subclavian  vein;  it  receives 
the  transverse  cervical  and  suprascapular  veins,  which  occasionally  form  a  plexus 
in  front  of  the  artery,  and  a  small  vein  which  crosses  the  •clavicle  from  the  ce- 
phalic. The  small  nerve  to  the  Subclavius  also  crosses  this  "triangle  about  its 
middle.     A  lymphatic  gland  is  also  found  in  the  space. 

Internal  Carotid  Artery. 
The  Internal  Carotid  Artery  commences  at  the  bifurcation  of  the  common 

'  The  same  remark  will  apply  to  this  triangle  as  was  made  about  the  inferior  carotid  triangle. 
The  structures  enumerated,  as  contained  in  the  back  part  of  the  space,  lie,  strictly  speaking, 
beneath  the  muscles  which  form  the  posterior  boundary  of  the  triangle  ;  but  as  it  is  very  import- 
ant to  bear  in  mind  their  close  relation  to  the  parotid  gland  and  its  boundaries  (on  account  of 
the  frequency  of  surgical  operations  ou  this  gland)  all  these  parts  are  spoken  of  together. 


4G2 


ARTERIES. 


carotid,  opposite  the  upper  border  of  the  thyroid  cartilage,  and  runs  perpen- 
dicularly upwards,  in  front  of  the  transverse  processes  of  the  three  upper  cervical 
vertebrae,  to  the  carotid  foramen  in  the  petrous  portion  of  the  temporal  bone. 
After  ascending  in  it  for  a  short  distance,  it  passes  forwards  and  inwards  through 
the  <;arotid  canal,  and,  -again  ascending  a  little  by  the  side  of  the  sella  Turcica, 
curves  upwards  by  the  anterior  clinoid  process,  where  it  pierces  the  dura  mater, 
and  divides  into  its  terminal  branches. 


279. — The  Internal  Carotid  and  Vertebral  Arteries.    Eight  Side. 


ItfMrticJ*^' 


This  vessel  supplies  the  anterior  part  of  the  brain,  the  eye,  and  its  appen- 
dages. Its  size  in  the  adult,  is  equal  to  that  of  the  external  carotid.  In  the 
child,  it  is  larger  than  tliat  vessel.     It  is  remarkable  for  the  number  of  curva- 


Al 


INTERNAL    CAROTID.  463 

tures  that  it  presents  in  different  parts  of  its  course.  In  its  cervical  portion  it 
occasionally  presents  one  or  two  flexures  near  the  base  of  the  skull,  whilst 
through  the  rest  of  its  extent  it  describes  a  double  curvature  which  resembles 
the  italic  letter  /  placed  horizontally  X-  These  curvatures  most  probably 
diminish  the  velocity  of  the  current  of  blood,  by  increasing  the  extent  of  sur- 
face over  which  it  moves,  and  adding  to  the  amount  of  impediment  produced 
from  friction.  In  considering  the  courses  and  relations  of  this  vessel,  it  may  be 
conveniently  divided  into  four  portions,  a  cervical,  petrous,  cavernous,  and 
cerebral. 

Cervical  Portion.  This  portion  of  the  internal  carotid  is  superficial  at  its  com- 
mencement, being  contained  in  the  superior  carotid  triangle,  and  lying  on  the 
same  level  as  the  external  carotid,  but  behind  that  artery,  overlapped  by  the 
Sterno-mastoid,  and  covered  by  the  Platysma,  deep  fascia,  and  integument ;  it 
then  passes  beneath  the  parotid  gland,  being  crossed  by  the  hypoglossal  nerve, 
the  Digastric  and  Stylo-hyoid  muscles,  and  the  external  carotid  and  occipital 
arteries.  Higher  up,  it  is  separated  from  the  external  carotid  by  the  Stylo-glos- 
sus  and  Stylo-pharyngeus  muscles,  the  glosso-pharyngeal  nerve,  and  pharyngeal 
branch  of  the  vagus.  It  is  in  relation,  hehind^  with  the  Rectus  Anticus  Major, 
the  superior  cervical  ganglion  of  the  sympathetic,  and  superior  laryngeal  nerve ; 
externally^  with  the  internal  jugular  vein,  and  pneumogastric  nerve;  internally^ 
with  the  pharynx,  tonsil,  and  ascending  pharyngeal  artery. 

Petrous  Portion.  When  the  internal  carotid  artery  enters  the  canal  in  the 
petrous  portion  of  the  temporal  bone,  it  first  ascends  a  short  distance,  then 
curves  forwards  and  inwards,  and  again  ascends  as  it  leaves  the  canal  to  enter 
the  cavity  of  the  skull.  In  this  canal,  the  artery  lies  at  first  anterior  to  the 
tympanum,  from  which  it  is  separated  by  a  thin  bony  lamella,  which  is  cribri- 
form in  the  young  subject,  and  often  absorbed  in  old  age.  It  is  separated  from 
the  bony  wall  of  the  carotid  canal  by  a  prolongation  of  dura  mater,  and  is  sur- 
rounded by  filaments  of  the  carotid  plexus. 

Cavei^nous  Portion.  The  internal  carotid  artery,  in  this  part  of  its  course,  at 
first  ascends  to  the  posterior  clinoid  process,  then  passes  forwards  by  the  side 
of  the  body  of  the  sphenoid  bone,  being  situated  on  the  inner  wall  of  the 
cavernous  sinus,  in  relation,  externally,  with  the  sixth  nerve,  and  covered  by 
the  lining  membrane  of  the  sinus.  The  third,  fourth,  and  ophthalmic  nerves 
are  placed  on  the  outer  wall  of  the  sinus,  being  separated  from  its  cavity  by  the 
lining  membrane. 

Cerebral  Portion.  On  the  inner  side  of  the  anterior  clinoid  process  the  inter- 
nal carotid  curves  upwards,  perforates  the  dura  mater  bounding  the  sinus,  and 
is  received  into  a  sheath  of  the  arachnoid.  This  portion  of  the  artery  is  on 
the  outer  side  of  the  optic  nerve ;  it  lies  at  the  inner  extremity  of  the  fissure 
of  Sylvius,  having  the  third  nerve  externally. 

Plan  of  the  Relations  of  the  Internal  Carotid  Artery  in  the  Neck. 

In  front. 
Skin,  superficial  and  deep  fasciae. 
Parotid  gland. 

Stylo-glossus  and  Stylo-ph;iryngeus  muscles. 
^  .  Glosso-pharyngeal  nerve. 

Externally.  /  \  p.      Internally. 

Internal  jugular  vein.  (      ^^'^^f  Pharynx. 

Pneumogastric  nerve.  \     Ky'     j  Ascending  pharyngeal  artery. 

Behind. 
Rectus  Anticus  Major, 
Sympathetic. 
Superior  laryngeal  nerve. 


4G4  ■  ARTERIES. 

Peculiarities.  The  length  of  the  internal  carotid  varies  according  to  the  length  of  the  neck, 
and  also  according  to  the  point  of  bifurcation  of  the  common  carotid.  Its  origin  sometimes 
takes  place  from  the  arch  of  the  aorta ;  in  such  rare  instances,  this  vessel  has  been  found  to  be 
placed  nearer  the  middle  line  of  the  neck  than  the  external  carotid,  as  far  upwards  as  the  larynx, 
when  the  latter  vessel  crossed  the  internal  carotid.  The  course  of  the  vessel,  instead  of  being 
straight,  may  be  very  tortuous.  A  few  instances  are  recorded  in  which  this  vessel  was  altogether 
absent:  in  one  of  these  the  common  carotid  passed  up  the  neck,  and  gave  off  the  usual  branches 
of  the  external  carotid :  the  cranial  portion  of  the  internal  carotid  being  replaced  by  two 
branches  of  the  internal  maxillary,  which  entered  the  skull  through  the  foramen  rotundum  and 
foramen  ovale,  and  joined  to  form  a  single  vessel. 

Surgical  Anatomy,  The  cervical  part  of  the  internal  carotid  is  sometimes  wounded  by  a  stab 
or  gunshot  wound  in  the  neck,  or  even  occasionally  by  a  stab  from  within  the  mouth,  as  when  a 
person  receives  a  thrust  from  the  end  of  a  parasol,  or  falls  down  with  a  tobacco-pipe  in  his 
mouth.  In  such  cases  a  ligature  should  be  applied  to  the  common  carotid.  The  relation  of  the 
internal  carotid  with  the  tonsil  should  be  especially  remembered,  as  instances  have  occurred  in 
which  the  artery  has  been  wounded  during  the  operation  of  scarifying  the  tonsil,  and  fatal 
hemorrhage  has  supervened. 

The  branches  given  off  from  the  internal  carotid  are: — 

From  the  Petrous  Portion     .     Tympanic. 

{Arteriae  receptaculi.^ 
Anterior  meningeal. 
Ophthalmic. 


Anterior  cerebral. 

From  the  Cerebral  Portion    ^  r>    .     •  '     •     .  • 

I  rosterior  communicating. 


\ 


1^  Anterior  choroid 

The  cervical  portion  of  the  internal  carotid  gives  off  no  branches. 

The  tympanic  is  a  small  branch  which  enters  the  cavity  of  the  tympanum, 
through  a  minute  foramen  in  the  carotid  canal,  and  anastomoses  with  the  tym- 
panic branch  of  the  internal  maxillary,  and  with  the  stylo-mastoid  artery. 

The  arterise  receptacuU  are  numerous  small  vessels,  derived  from  the  internal 
carotid  in  the  cavernous  sinus ;  they  supply  the  pituitary  body,  the  Casserian 
ganglion,  and  the  walls  of  the  cavernous  and  inferior  petrosal  sinuses.     One 
of  these  branches,  distributed  to  the  dura  mater,  is  called  the  anterior  meningeal ;    -^ 
it  anastomoses  with  the  middle  meningeal.  Il 

The  Ophthalmic  Artery  arises  from  the  internal  carotid,  just  as  that  vessel  is 
emerging  from  the  cavernous  sinus,  on  the  inner  side  of  the  anterior  clinoid 
process,  and  enters  the  orbit  through  the  optic  foramen,  below  and  on  the  outer 
side  of  the  optic  nerve.  It  then  passes  across  the  nerve,  to  the  inner  wall  of 
the  orbit,  and  thence  horizontally  forwards,  beneath  the  lower  border  of  the 
Superior  Oblique  muscle  to  the  inner  angle  of  the  eye,  where  it  divides  into 
two  terminal  branches,  the  frontal,  and  nasal. 

Branches.  The  branches  of  this  vessel  may  be  divided  into  an  orbital  group, 
which  are  distributed  to  the  orbit  and  surrounding  parts ;  and  an  ocular  group, 
which  supply  the  muscles  and  globe  of  the  eye. 

Orbital  Group.  Ocular  Group, 

Lachrymal.  Muscular. 

Supraorbital.  Anterior  ciliary. 

Posterior  ethmoidal.  Short  ciliary. 

Anterior  ethmoidal.  Long  ciliary. 

Palpebral.  Arteria  centralis  retinae. 
Frontal. 
Nasal. 

The  lachrymal  is  the  first,  and  one  of  the  largest  branches,  derived  from  the 
ophthalmic,  arising  close  to  the  optic  foramen ;  not  unfrequently  it  is  given  off 
from  the  artery  before  it  enters  the  orbit.  It  accompanies  the  lachrymal  nerve 
along  the  upper  border  of  the  External  Rectus  muscle,  and  is  distributed  to 


I 


^ 


OPHTHALMIC. 


465 


the  lachrymal  gland.  Its  terminal  branches,  escaping  from  the  gland,  are  dis- 
tributed to  the  upper  eyelid  and  conjunctiva,  anastomosing  with  the  palpebral 
arteries.  The  lachrymal  artery  gives  off  one  or  two  malar  branches ;  one  of 
which  passes  through  a  foramen  in  the  malar  bone  to  reach  the  temporal  fossa, 

Fig.  280. — The  Ophthalmic  Artery  and  its  Branches,  the  Eoof  of  the  Orbit  having  been  removed. 

Kami  V  P"'j'f"'^      ^ 

f   n,     ^         Jnmtnl  Snpra  OrJi'feiJ 


^    AMUrior  J^moiSar 


r»>ttTiM'  ^^"ijr—uJu^ 


llti^alvUa 


I  Caratii 


and  anastomoses  with  the  deep  temporal  arteries.  The  other  appears  on  the 
cheek,  and  anastomoses  Avith  the  transverse  facial.  A  branch  is  also  sent  back- 
wards, through  the  sphenoidal  fissure,  to  the  dura  mater,  which  anastomoses 
with  a  branch  of  the  middle  meningeal  artery. 

Peculiarities.  The  lachrymal  artery  is  sometimes  derived  from  one  of  the  anterior  branches 
of  the  middle  meningeal  artery. 

The  supraorbital  artery,  the  largest  branch  of  the  ophthalmic,  arises  from  that 
vessel  above  the  optic  nerve.  Ascending  so  as  to  rise  above  all  the  muscles 
of  the  orbit,  it  passes  forwards,  with  the  frontal  nerve,  between  the  periosteum 
and  Levator  Palpebrte ;  and  passing  through  the  supraorbital  foramen,  divides 
into  a  superficial  and  deep  branch,  which  supply  the  muscles  and  integument 
of  the  forehead  and  pericranium,  anastomosing  with  the  temporal,  angular 
branch  of  the  facial,  and  the  artery  of  the  opposite  side.  This  artery  in  the 
orbit  supplies  the  Superior  Rectus  and  the  Levator  Palpebrae,  sends  a  branch 
inwards,  across  the  pulley  of  the  Superior  Oblique  muscle,  to  supply  "the  parts 
at  the  inner  canthus ;  and  at  the  supraorbital  foramen,  frequently  transmits  a 
branch  to  the  diploe. 

The  ethmoidal  branches  are  two  in  number ;  posterior  and  anterior.  The 
former,  which  is  the  smaller,  passes  through  the  posterior  ethmoidal  foramen, 
supplies  the  posterior  ethmoidal  cells,  and  entering  the  cranium,  gives  off  a 
meningeal  branch,  which  supplies  the  adjacent  dura  mater,  and  nasal  branches, 
which  descend  into  the  nose  through  apertures  in  the  cribriform  plate,  anasto- 
mosing with  branches  of  the  spheno-palatine.  The  anterior  ethmoidal  artery 
accompanies  the  nasal  nerve  through  the  anterior  ethmoidal  foramen,  supplies 
30 


4G6 


AKTEIUKS, 


tlio  niitorior  ethmoidal  cells  and  frontal  sinuses,  and  entering  the  cranium, 
divides  into  a  meningeal  branch,  which  supplies  the  adjacent  dura  mater,  and 
n  nasal  branch,  which  descends  into  the  nose,  through  an  aperture  in  the  crib- 
riform plate. 

The  palpebral  arteries^  two  in  number,  superior  and  inferior,  arise  from  the 
ophthalmic,  opposite  the  pulley  of  the  Superior  Oblique  muscle;  they  encircle 

Fig.  281.— The  Arteries  of  the  Base  of  the  Brain.    The  Ripht  Half  of  the  Cerebellum  and  Pons 

have  bocu  removed. 


the  eyelids  near  their  free  margin,  forming  a  superior  and  an  inferior  arch, 
whicli  lie  between  the  Orbicularis  muscle  and  tarsal  cartilages;  the  superior 


^1 


OF    THE    BRAIN.  WJ 

palpebral,  inosculating  at  the  outer  angle  of  the  orbit  with  the  orbital  branch 
of  the  temporal  artery,  the  inferior  palpebral  with  the  orbital  branch  of  the 
infraorbital  artery,  at  the  inner  side  of  the  lid.  From  this  anastomosis,  a 
branch  passes  to  the  nasal  duct,  ramifying  in  its  mucous  membrane,  as  far  as 
the  inferior  meatus. 

The  frorvtal  artery^  one  of  the  terminal  branches  of  the  ophthalmic,  passes  from 
the  orbit  at  its  inner  angje,  and  ascending  on  the  forehead,  supplies  the  muscles, 
integument,  and  pericranium,  anastomosing  with  the  supraorbital  artery. 

The  iiasal  arttry^  the  other  terminal  branch  of  the  ophthalmic,  emerges  from 
the  orbit  above  the  tendo  oculi,  and,  after  giving  a  branch  to  the  lachrymal 
-^ac,  divides  into  two,  one  of  which  anastomoses  with  the  angular  artery,  the 
other  branch,  the  dorsalis  nasi,  runs  along  the  dorsum  of  the  nose,  supplies  its 
entire  surface,  and  anastomoses  with  the  artery  of  the  opposite  side. 

The  ciliary  arteries  are  divisible  into  three  groups,  the  short,  long,  and  ante- 
rior. The  short  ciliary  arteries,  from  twelve  to  fifteen  in  number,  arise  from  the 
ophthalmic,  or  some  of  its  branches ;  they  surround  the  optic  nerve  as  they 
pass  forwards  to  the  posterior  part  of  the  eyeball,  pierce  the  sclerotic  coat 
around  the  entrance  of  the  nerve,  and  supply  the  choroid  coat  and  ciliary  pro- 
cesses. The  long  ciliary  arteries,  two  in  number,  also  pierce  the  posterior  part 
of  the  sclerotic,  and  run  forwards,  along  each  side  of  the  eyeball,  between  the 
sclerotic  and  choroid,  to  the  ciliary  ligament,  where  they  divide  into  two 
branches ;  these  form  an  arterial  circle  around  the  circumference  of  the  iris, 
from  which  numerous  radiating  branches  pass  forwards,  in  its  substance,  to  its 
free  margin,  where  they  form  a  second  arterial  circle  around  its  pupillary  mar- 
gin. The  anterior  ciliary  arteries  are  derived  from  the  muscular  branches :  they 
pierce  the  sclerotic  a  short  distance  from  the  cornea,  and  terminate  in  the  great 
arterial  circle  of  the  iris. 

The  arteria  centralis  retinae  is  one  of  the  smallest  branches  of  the  ophthalmic 
artery.  It  arises  near  the  optic  foramen,  pierces  the  optic  nerve  obliquely,  and 
runs  forwards,  in  the  centre  of  its  substance,  to  the  retina,  in  which  its  branches 
are  distributed  as  far  forwards  as  the  ciliary  processes.  In  the  human  foetus,  a 
small  vessel  passes  forwards,  through  the  vitreous  humor,  to  the  posterior  surface 
of  the  capsule  of  the  lens. 

The  jmiscular  branches,  two  in  number,  superior  and  inferior,  supply  the  mus- 
cles of  the  eyeball.  The  superior,  the  smaller,  often  wanting,  supplies  the 
Levator  Palpebrse,  Superior  Eectus,  and  Superior  Oblique.  The  inferior,  more 
constant  in  its  existence,  passes  forwards,  between  the  optic  nerve  and  Inferior 
Eectus,  and  is  distributed  to  the  External  and  Inferior  Eecti,  and  Inferior 
Oblique.     This  vessel  gives  off  most  of  the  anterior  ciliarj-  arteries. 

The  Cerebral  Branches  of  the  internal  carotid  are,  the  anterior  cerebral,  the 
middle  cerebral,  the  posterior  communicating,  and  the  anterior  choroid. 

The  anterior  cerebral  arises  from  the  internal  carotid,  at  the  inner  extremitv 
of  the  fissure  of  Sylvius.  It  passes  forwards  in  the  great  longitudinal  fissure 
between  the  two  anterior  lobes  of  the  brain,  being  connected,  soon  after  its 
origin,  with  the  vessel  of  the  opposite  side  by  a  short  anastomosing  trunk,  about 
two  lines  in  length,  the  anterior  communicating.  The  two  anterior  cerebral 
arteries,  lying  side  by  side,  curve  round  the  anterior  border  of  the  corpus  cal- 
losum,  and  run  along  its  upper  surface  to  its  posterior  part,  where  they  ter- 
minate by  anastomosing  with  the  posterior  cerebral  arteries.  They  supply  the 
olfactory  and  optic  nerves,  the  under  surface  of  the  anterior  lobes,  the  third 
ventricle,  the  anterior  perforated  space,  the  corpus  callosum,  and  the  inferior 
surface  of  the  hemispheres. 

The  anterior  communicating  artery  is  a  short  branch,  about  two  lines  in  length, 
but  of  moderate  size,  connecting  together  the  two  anterior  cerebral  arteries 
across  the  longitudinal  fissure.  Sometimes  this  vessel  is  wanting,  the  two  ar- 
teries joining  together  to  form  a  single  trunk,  which  afterwards  subdivides.  Or 
the  vessel  may  be  wholly  or  partially  subdivided  into  two;  frequently,  it  is 
longer  and  smaller  than  usual. 


468  ARTERIES. 

The  middle  cerebral  artery^  the  largest  branch  of  the  internal  carotid,  passes 
obliquely  outwards  along  the  fissure  of  Sylvius,  within  which  it  divides  into 
three  branches  ;  an  interior,  which  supplies  the  pia  mater,  investing  the  surface 
of  the  anterior  lobe;  a  posterior,  which  supplies  the  middle  lobe;  and  a  median 
branch,  which  supplies  the  small  lobe  at  the  outer  extremity  of  the  Sylvian  fis- 
sure. Near  its  origin,  this  vessel  gives  ojff  numerous  small  branches,  which 
enter  the  substantia  perforata,  to  be  distributed  to  the  corpus  striatum. 

The  posterior  communicating  artery  arises  from  the  back  part  of  the  internal 
carotid,  runs  directly  backwards,  and  anastomoses  with  the  posterior  cerebral,  a 
branch  of  the  basilar.  This  artery  varies  considerably  in  size,  being  sometimes 
small,  and  occasionally  so  large  that  the  posterior  cerebral  may  be  considered 
as  arising  from  the  internal  carotid  rather  than  from  the  basilar.  It  is  frequently 
larger  on  one  side  than  on  the  other  side. 

The  anterior  choroid  is  a  small  but  constant  branch  which  arises  from  the  back 
part  of  the  internal  carotid,  near  the  posterior  communicating  artery.  Passing 
backwards  and  outwards,  it  enters  the  descending  horn  of  the  lateral  ventricle, 
beneath  the  edge  of  the  middle  lobe  of  the  brain.  It  is  distributed  to  the  hip- 
pocampus major,  corpus  fimbriatum,  and  choroid  plexus. 

ARTERIES  OF  THE  UPPER  EXTREMITY. 

The  artery  which  supplies  the  upper  extremity,  continues  as  a  single  trunk 
from  its  commencement,  as  far  as  the  elbow ;  but  difi'erent  portions  of  it  have 
received  different  names,  according  to  the  region  through  which  it  passes.  That 
part  of  the  vessel  which  extends  from  its  origin,  as  far  as  the  outer  border  of 
the  first  rib,  is  termed  the  Subclavian  ;  beyond  this  point  to  the  lower  border  of 
the  axilla,  it  is  termed  the  Axillary ;  and  from  the  lower  margin  of  the  axillary 
space  to  the  bend  of  the  elbow,  it  is  termed  Brachial ;  here  the  single  trunk  ter- 
minates by  dividing  into  two  branches,  the  Radial  and  Ulnar,  an  arrangement 
precisely  similar  to  what  occurs  in  the  lower  limb. 


J 


Subclavian  Artkries. 

The  Subclavian  Artery  on  the  right  side  arises  from  the  arteria  innominata^ 
opposite  the  right  sterno-clavicular  articulation  ;  on  the  left  side  it  arises  from 
the  arch  of  the  aorta.  It  follows,  therefore,  that  these  two  vessels  must,  in  the 
first  part  of  their  course,  differ  in  their  length,  their  direction,  and  in  their  re- 
lation with  neighboring  parts. 

In  order  to  facilitate  the  description  of  these  vessels,  more  especially  in  a 
surgical  point  of  view,  each  subclavian  artery  has  been  divided  into  three  parts. 
The  first  portion,  on  the  right  side,  ascends  obliquely  outwards,  from  the  origin 
of  the  vessel  to  the  inner  border  of  the  Scalenus  Anticus.  On  the  left  side  it 
ascends  perpendicularly,  to  gain  the  inner  border  of  that  muscle.  The  second 
part  passes  outwards,  behind  the  Scalenus  Anticus ;  and  the  third  part  passes 
from  the  outer  margin  of  that  muscle,  beneath  the  clavicle,  to  the  lower  border 
of  the  first  rib,  where  it  becomes  the  axillary  artery.  The  first  portions  of  these 
two  vessels  differ  so  much  in  their  course,  and  in  their  relation  with  neighboring 
parts,  that  they  will  be  described  separately.  The  second  and-  third  parts  are 
precisely  alike  on  both  sides. 

First  Part  or  the  Right  Subclavian  Artery.    (Figs.  272,  274.) 

The  riglit  subclavian  artery  arises  from  the  arteria  innominata,  opposite  the 
right  sterno-clavicular  articulation,  passes  upwards  and  outwards  across  the 
root  of  the  neck,  and  terminates  at  tne  inner  margin  of  the  Scalenus  Anticus 
muscle.  In  this  part  of  its  course,  it  ascends  a  little  above  the  clavicle,  the  ex- 
tent to  which  it  does  so  varying  in  different  cases.  It  is  covered,  in  front,  by 
the  integument,  superficial  fascia,  Platysma,  deep  fascia,  the  clavicular  origin  of 
the  Sterno-mastoid,  the  Sterno-hyoid,  and  Sterno-thyroid  muscles,  and  another 


SUBCLAVIAN.  469 

layer  of  the  deep  fascia.  It  is  crossed  by  the  internal  jugular  and  vertebral 
veins,  and  by  the  pneumogastric,  the  cardiac  branches  of  the  sympathetic,  and 
phrenic  nerves.  Beneath^  the  artery  is  invested  by  the  pleura,  and  behind,  it  is 
separated  by  a  cellular  interval  from  the  Longus  Colli,  the  transverse  process 
of  the  seventh  cervical  vertebra,  and  the  sympathetic ;  the  recurrent  laryngeal 
nerve  winding  around  the  lower  and  back  part  of  the  vessel.  The  subclavian 
vein  lies  below  the  subclavian  artery,  immediately  behind  the  clavicle. 

Plan"  of  Relations  of  Fiest  Portion  of  Right  Subclavian  Artery. 

In  front. 
Clavicular  origin  of  Sterno-mastoid. 
Sterno-hyoid  and  Sterno-thyroid. 
Internal  jugular  and  vertebral  veins. 
Pneumogastric,  cardiac  and  phrenic  nerves. 


Right     \  Beneath. 

'^:P   ]  Pleura. 

yFlrst  portion. 


Behind. 
Recurrent  laryngeal  nerve. 
Sympathetic. 
Longus  Colli. 
Transverse  process  of  seventh  cervical  vertebra. 

First  Part  of  the  Left  Subclavian  Artery.    (Fig.  272.) 

The  left  subclavian  artery  arises  from  the  end  of  the  transverse  portion  of 
the  arch  of  the  aorta,  opposite  the  second  dorsal  vertebra,  and  ascends  to  the 
inner  margin  of  the  first  rib,  behind  the  insertion  of  the  Scalenus  anticus  muscle. 
This  vessel  is,  therefore,  longer  than  the  right,  situated  more  deeply  in  the 
cavity  of  the  chest,  and  directed  almost  vertically  upwards,  instead  of  arching 
outwards  like  the  vessel  of  the  opposite  side. 

It  is  in  relation,  in  front,  with  the  pleura,  the  left  lung,  the  pneumogastric, 
phrenic,  and  cardiac  nerves,  which  lie  parallel  with  it,  the  left  carotid  artery, 
left  internal  jugular  and  innominate  veins,  and  is  covered  by  the  Sterno-thyroid, 
Sterno-hyoid,  and  Sterno-mastoid  muscles ;  behind,  it  is  in  relation  with  the 
oesophagus,  thoracic  duct,  inferior  cervical  ganglion  of  the  sympathetic,  Longus 
Colli,  and  vertebral  column.  To  its  inner  side  are  the  oesophagus,  trachea  and 
thoracic  duct ;  to  its  outer  side,  the  pleura. 

Plan  of  Relations  of  First  Portion  of  Left  Subclavian  Artery. 

In  f runt. 
Pleura  and  left  lung. 

Pneumogastric,  cardiac,  and  phrenic  nerves. 
*■  Left  carotid  artery. 

Left  internal  jugular  and  innominate  veins, 
Sterno-thyroid,  Sterno-hyoid,  and  Sterno-mastoid  muscles. 

Inner  side. 
CEsophagus.  /  Snbc'iavian  \  Outer  side. 

Trachea.  (      Aneiy.      ]        ,  Pleura. 

Thoracic  duct. 

Behind. 
(Esophagus  and  thoracic  duct. 
Inferior  cervical  ganglion  of  sympathetic. 
Longus  Colli  and  vertebral  column. 


470  ARTERIES. 

Second  and  Third  Parts  op  the  Subclavian  Artery.    (Fig.  274.) 

The  second  portion  of  the  subclavian  artery  lies  behind  the  Scalenus  Anti- 
cus  muscle;  it  is  very  short,  and  forms  the  highest  part  of  the  arch  described 
by  that  vessel. 

Relations.  It  is  covered,  in  front,  by  the  integument,  Platysma,  Sterno-mas- 
toid,  cervical  fascia,  and  by  the  phrenic  nerve,  which  is  separated  from  the 
artery  by  the  Scalenus  Anticus  muscle.  Behind,  it  is  in  relation  with  the  Middle 
Scalenus.  Ahove,  with  the  brachial  plexus  of  nerves.  Below,  with  the  pleura. 
The  subclavian  vein  lies  below  and  in  front  of  the  artery,  separated  from  it  by 
the  Scalenus  Anticus. 

Plan  of  Relations  of  Second  Portion  of  Subclavian  Artery. 

In  front. 
Scalenus  Anticus. 
Phrenic  nerve. 
Subclavian  vein. 


Ahnve.  /        Artery.        \  lielnw. 

Bracliial  Piexns.  1  Second  portion.)  Pkura. 


Behind. 
Pleura  and  Middle  Scalenus. 

The  third  portion  of  the  subclavian  artery  passes  downwards  and  outwards 
from  the  outer  margin  of  the  Scalenus  Anticus  to  the  lower  border  of  the  first 
rib,  where  it  becomes  the  axillary  artery.  This  portion  of  the  vessel  is  the 
most  superficial,  and  is  contained  in  a  triangular  space,  the  base  of  which  is 
formed  in  front  by  the  Anterior  Scalenus,  and  the  two  sides  by  the  Omo-hyoid 
above  and  the  clavicle  below. 

Relatione.  It  is  covered,  in  front,  by  the  integument,  the  superficial  fascia, 
the  platysma,  deep  fascia ;  and  by  the  clavicle,  the  Subclavius  muscle,  and  the 
suprascapular  artery  and  vein;  the  clavicular  descending  branches  of  the  cer- 
vical plexus  and  the  nerve  to  the  Subclavius  pass  vertically  downwards  in  front 
of  the  artery.  The  external  jugular  vein  crosses  it  at  its  inner  side,  and  receives 
the  suprascapular  and  transverse  cervical  veins,  which  occasionally  form  a 
plexus  in  front  of  it.  The  subclavian  vein  is  below  the  artery,  lying  close 
Dehind  the  clavicle.  Behind,  it  lies  on  the  Middle  Scalenus  muscle.  Above  it, 
and  to  its  outer  side,  is  the  brachial  plexus,  and  Omo-hyoid  muscle.  Below,  it 
rests  on  the  outer  surface  of  the  first  rib. 

Plan  of  Relations  of  Third  Portion  of  Subclavian  Artery. 

In/ront. 
Cervical  fascia. 

External  jufrnlar,  suprascapular,  and  transverse  cervical  veins. 
Pescendinp:  branches  of  cervical  plexus. 
Subclavius  muscle,  suprascapular  artery,  and  clavicle. 


Abi)Ve.  I    Snbdnvlun    \  BeloV). 

Brachial  plexus.  Lk'^""''';.  F'«st  rib. 

_  .*,  I  Third  nmrlmt       / 

Omo-hyoiu. 


Bell  ind. 
Scalenus  Medius. 

Peculiarities.    The  subclavian  arteries  vary  in  iheir  origin,  their  course,  and  the  heiprht  to 
^bich  they  rise  in  the  neck. 


il 

II 


1 


SUBCLAVIAN.  471 

The  origin  of  the  right  subclavian  from  the  innominate  takes  place,  in  some  cases,  above  the 
sterno-clavicular  articulation ;  and  occasionally,  but  less  frequently,  in  the  cavity  of  the  thorax, 
below  that  joint.  Or  the  artery  may  arise  as  a  separate  trunk  from  the  arch  of  the  aorta,  la 
such  cases  it  may  be  either  the  first,  second,  third,  or  even  the  last  branch  derived  from  that 
vessel :  in  the  majority  of  cases,  it  is  the  first  or  last,  rarely  the  second  or  third.  AVhen  it  is  the 
first  branch,  it  occupies  the  ordinary  position  of  the  innominate  artery  ;  when  the  second  or  third, 
it  gains  its  usual  position  by  passing  behind  the  right  carotid  ;  and  when  the  hist  branch,  it  arises 
from  the  left  extremity  of  the  arch,  at  its  upper  or  back  part,  and  passes  obliquely  towards  the 
right  side,  usually  behind  the  oesophagus  and  right  carotid,  sometimes  between  the  oesophagus 
and  trachea,  to  the  upper  border  of  the  first  rib,  whence  it  follows  its  ordinary  course.  In  very 
rare  instances,  this  vessel  arises  from  the  thoracic  aorta,  as  low  down  as  the  fourth  dorsal  verte- 
bra. Occasionally  it  perforates  the  Anterior  Scalenus ;  more  rarely  it  passes  in  front  of  that 
muscle;  sometimes  the  subclavian  vein  passes  with  the  artery  behind  the  Scalenus.  The  artery 
sometimes  ascends  as  high  as  an  inch  and  a  half  above  the  clavicle,  or  to  any  intermediate  point 
between  this  and  the  upper  border  of  the  bone,  the  right  subclavian  usually  ascending  higher 
than  the  left. 

The  left  subclavian  is  occasionally  joined  at  its  origin  with  the  left  carotid. 

Surgical  Anatomy.  The  relations  of  the  subclavian  arteries  of  the  two  sides  having  been 
examined,  the  student  should  direct  his  attention  to  consider  the  best  position  in  which  com- 
pression of  the  vessel  may  be  effected,  or  in  what  situation  a  ligature  may  be  best  applied  in 
cases  of  aneurism  or  wounds. 

Compression  of  the  subclavian  arterT/ is  required  in  cases  of  operations  about  the  shoulder, 
in  the  axilla,  or  at  the  upper  part  of  the  arm  ;  and  the  student  will  observe  that  there  is  only 
one  situation  in  which  it  can  be  effectually  applied,  viz.,  where  the  artery  passes  across  the  outer 
surface  of  the  first  rib.  In  order  to  compress  the  vessel  in  this  situation,  the  shoulder  should  be 
depressed,  and  the  surgeon,  grasping  the  side  of  the  neck,  may  press  with  his  thumb  in  the  hollow 
behind  the  clavicle  downwards  against  the  rib ;  if  from  any  cause  the  shoulder  cannot  be  suffi- 
ciently depressed,  pressure  may  be  made  from  before  backwards,  so  as  to  compress  the  artery 
against  the  Middle  Scalenus  and  transverse  process  of  the  seventh  cervical  vertebra.  In  appro- 
priate cases,  a  preliminary  incision  may  be  made  through  the  cervical  fascia,  and  the  finger  may 
be  pressed  down  directly  upon  the  artery. 

Ligature  of  the  subclavian  artery  may  be  required  in  cases  of  wounds,  or  of  aneurism  in  the 
axilla ;  and  the  third  part  of  the  artery  is  that  which  is  most  favorable  for  an  operation,  on 
account  of  its  being  comparatively  superficial,  and  most  remote  from  the  origin  of  the  large 
branches.  In  those  cases  where  the  clavicle  is  not  displaced,  this  operation  may  be  per- 
formed with  comparative  facility;  but  where  the  clavicle  is  pushed  up  b-y  a  large  aneurismal 
tumor  in  the  axilla,  the  artery  is  placed  at  a  great  depth  from  the  surface,  which  materially  in- 
creases the  difficulty  of  the  operation.  Under  these  circumstances,  it  becomes  a  matter  of 
importance  to  consider  the  height  to  which  this  vessel  reaches  above  the  bone.  In  ordinary 
cases,  its  arch  is  about  half  an  inch  above  the  clavicle,  occasionally  as  high  as  an  inch  and  a 
half,  and  sometimes  so  low  as  to  be  on  a  level  with  its  upper  border.  If  the  clavicle  is  displaced, 
these  variations  will  necessarily  make  the  operation  more  or  less  difficult,  according  as  the  vessel 
is  more  or  less  accessible. 

The  chief  points  in  the  operation  of  tying  the  third  portion  of  the  subclavian  artery  are  as 
follows :  the  patient  being  placed  on  a  table  in  the  horizontal  position,  and  the  shoulder  de- 
pressed as  much  as  possible,  the  integument  should  be  drawn  downwards  upon  the  clavicle,  and 
an  incision  made  through  it  upon  that  bone  from  the  anterior  border  of  the  Trapezius  to  the 
posterior  border  of  the  Sterno-uuistoid,  to  which  may  be  added  a  short  vertical  incision  meeting 
the  centre  of  the  preceding ;  the  Platysma  and  cervical  fascia  should  be  divided  upon  a  director, 
and  if  the  interval  between  the  Trapezius  and  Sterno-mastoid  muscles  be  insufficient  tor  the  per- 
formance of  the  operation,  a  portion  oF  one  or  both  may  l)e  divided.  The  external  jugular  vein 
will  now  be  seen  towards  the  inner  side  of  the  wound  :  this  and  the  suprascapular  and  trans- 
verse cervical  veins  which  terminate  in  it  should  be  held  aside,  and  if  divided,  both  ends  should 
be  tied :  the  suprascapular  artery  should  be  avoided,  and  the  Omo-hyoid  muscle  must  now  be 
looked  for,  and  held  aside  if  necessary.  In  the  space  beneath  this  muscle,  careful  search  must 
be  made  for  the  vessel ;  the  deep  fascia  having  been  divided  with  the  finger-nail  or  silver  scalpel, 
the  outer  margin  of  the  Scalenus  must  be  felt  for,  and  the  finger  being  guided  by  it  to  the  tirst 
rib,  the  pulsation  of  the  subclavian  artery  will  be  felt  as  it  passes  over  the  rib.  The  aneurism 
needle  may  then  be  passed  around  the  vessel  from  before  backwards,  by  which  means  the  vein 
will  be  avoided,  care  being  taken  not  to  include  a  branch  of  the  brachial  plexus  instead  of  the 
artery  in  the  ligature.  If  the  clavicle  is  so  raised  by  the  tumor  that  the  application  of  the  liga- 
ture cannot  be  effected  in  this  situation,  the  artery  may  be  tied  above  the  first  rib.  or  even  behind 
the  Scalenus  muscle  ;  the  difficulties  of  the  operation  in  such  a  case  will  l)e  materially  increased, 
on  account  of  the  greater  depth  of  the  artery,  and  the  alteration  in  position  of  the  surrounding 
parts. 

The  second  part  of  the  subclavian  artery,  from  being  that  portion  which  rises  highest  in  the 
neck,  has  been  considered  favorable  for  the  application  of  the  ligature,  when  it  is  difficult  to  tie 
the  artery  in  the  third  part  of  its  course.  There  are,  however,  many  objections  to  the  operation 
in  this  situation.  It  is  necessary  to  divide  the  Scalenus  Anticus  muscle,  upon  which  lies  the 
phrenic  nerve,  and  at  the  inner  side  of  which  is  situated  the  internal  jugular  vein;  and  a  wound 


472 


ARTERIES. 


of  either  of  thcpe  structures  might  lead  to  the  most  dangerous  consequences.  Again,  the  artery- 
is  in  contact,  below,  with  the  pleura,  which  must  also  be  avoided  ;  and,  lastly,  the  proximity  of 
so  many  of  its  larger  branches  arising  internal  to  this  point,  must  be  a  still  further  objection  to 
the  operation.  If,  however,  it  has  been  determined  to  perform  the  operation  in  this  situation, 
it  should  be  remembered  that  it  occasionally  happens  that  the  artery  passes  in  front  of  the 
Scaleus  Anticus,  or  through  the  fibres  of  that  muscle ;  and  that  the  vein  sometimes  passes  with 
the  artery  behind  the  Scalenus  Amicus. 

In  those  cases  of  aneurism  of  the  axillary  or  subclavian  artery  which  encroach  upon  the  outer 
portion  of  the  Scalenus  muscle  to  such  an  extent  that  a  ligature  cannot  be  applied  in  that  situa- 
tion, it  may  be  deemed  advisable,  as  a  last  resource,  to  tie  the  first  portion  of  the  subclavian 
artery.  On  the  left  side,  this  operation  is  almost  impracticable;  the  gretit  depth  of  the  artery 
from  the  surface,  its  intimate  relation  with  the  pleura,  and  its  close  proximity  to  so  many  import- 
ant veins  and  nerves,  present  a  series  of  difiSculties  which  it  is  next  to  impopsihle  to  overcome.' 
On  the  right  side,  the  operation  is  practicable,  and  has  been  performed,  though  not  with  success. 
The  main  objection  to  tne  operation-in  this  situation  is  the  smallness  of  the  interval  which  usually 
exists  between  the  commencement  of  the  vessel,  and  the  origin  of  the  nearest  branch.  This 
operation  may  be  performer!  in  the  following  manner:  The  patient  being  placed  on  the  table  in 
the  horizontal  position,  with  the  neck  extended,  an  incision  should  be  made  parallel  with  the 
inner  part  of  the  chivicle,  and  a  second  along  the  inner  border  of  the  Sterno-mastoid,  meeting 
the  former  at  an  angle.  The  sternal  attachment  of  the  Sterno-mastoid  may  now  be  divided  on 
a  director,  and  turned  outwards;  a  few  small  arteries  and  veins,  and  occasionally  the  anterior 
jugular,  must  be  avoided,  and  the  Sterno-hyoid  and  Sterno-thyroid  muscles  divided  in  the  same 
manner  as  the  preceding  muscle.  After  tearing  through  the  deep  fascia  witli  the  finger-nail,  the 
internal  jugular  vein  will  be  seen  crossing  the  subclavian  artery ;  this  should  be  pressed  aside, 
and  the  artery  secured  by  passing  the  needle  from  below  upwards,  by  which  the  pleura  is  more 
efifectually  avoided.  The  exact  position  of  the  vagus  nerve,  the  recurrent  laryngeal,  the  phrenic 
and  sympathetic  nerves  should  be  remembered,  and  the  ligature  should  be  applied  near  the 
origin  of  the  vertebral,  in  order  to  afford  as  much  room  as  possible  for  the  formation  of  a  coagu- 
lum  between  the  ligature  and  the  origin  of  the  vessel.  It  should  be  remembered,  that  the  right 
subclavian  artery  is  occasionally  deeply  placed  in  the  first  part  of  its  course,  when  it  ari.«es  from 
the  left  side  of  the  aortic  arch,  and  passes  in  such  cases  behind  the  oesophagus,  or  between  it 
and  the  trachea. 

Collateral  Circulation. — After  ligature  of  the  third  part  of  the  subclavian  artery,  the  collateral 
circulation  is  mainly  established  by  three  sets  of  vessels,  thus  described  in  a  dissection  : — 

"  1.  A  posterior  set,  consisting  of  the  suprascapular  and  posterior  scapular  branches  of  the 
subclavian,  which  anastomosed  with  the  infrascapular  from  the  axillary. 

"2.  An  internal  set  produced  by  the  connection  of  the  internal  mammary  on  the  one  hand, 
with  the  short  and  long  thoracic  arteries,  and  the  infrascapular  on  the  other. 

'•  3.  A  middle  or  axillary  set,  which  consisted  of  a  number  of  small  vessels  derived  from  branches 
of  the  subclavian,  above  ;  and  passing  through  the  axilla,  to  terminate  either  in  the  main  trunk, 
or  some  of  the  branches  of  the  axillary,  below.    This  last  set  presented  most  conspicuously  the 

fteculiar  character  of  newly-formed,  or,  rather,  di- 
ated  arteries,"  being  excessively  tortuous,  and 
forming  a  complete  plexus. 

"  The  chief  agent  in  the  restoration  of  the  axil- 
lary artery  below  the  tumor,  was  the  infrascapular 
artery,  which  communicated  most  freely  with  the 
internal  mammary,  suprascapular,  and  posterior 
scapular  branches  of  the  subclavian,  from  all  of 
which  it  received  so  great  an  influx  of  blood  as  to 
dilate  it  to  three  times  its  natural  size."^ 

Branches  of  the  Subclavian  Artery. 

These  are  four  in  number.  Three  ari.s- 
ing  from  the  first  portion  of  the  vessel,  the 
vertebral,  the  internal  mammary,  and  the 
thyroid  axis;  and  one  from  the  second 
portion,  the  superior  intercostal.  The  ver- 
tebral arises  from  the  upper  and  back  part 
of  the  first  portion  of  the  artery ;  the  thyroid  axis  from  the  front,  and  the  in- 
ternal mammary  from  the  under  part  of  this  vessel.     The  superior  intercostal 

'  The  operation  was,  however,  performed  in  Now  York,  by  Dr.  J.  K.  Rodgers,  and  the  case  is 
very  briefly  mentioned  in  Mott's  Translation  of  Volpeau.  vol.  ii.  p.  365. 

'  (7iii/'s  JIoHpifdl  Rrports,  vol.  i.  1H3G.  Case  of  axillary  aneurism,  in  which  Mr.  Aston  Key 
had  tied  the  subclavian  artery  on  the  outer  edge  of  the  Scalenus  muscle,  twelve  years  previ- 
oufly. 


Fig.  282.— Plan  of  the  Branches  of  the 
Bight  Subclavian  Artery. 


VERTEBRAL.  473 

is  given  off  from  the  upper  and  back  part  of  the  second  portion  of  the  artery. 
On  the  left  side,  the  second  portion  usually  gives  off  no  branch,  the  superior 
intercostal  arising  at  the  inner  side  of  the  Scalenus  Anticus.  On  both  sides  of 
the  body,  the  first  three  branches  arise  close  together  at  the  inner  margin  of 
the  Scalenus  Anticus;  in  the  majority  of  cases,  a  free  interval  of  half  an  inch 
to  an  inch  existing  between  the  commencement  of  the  artery  and  the  origin  of 
the  nearest  branch ;  in  a  smaller  number  of  cases,  an  interval  of  more  than  an 
inch  exists,  never  exceeding  an  inch  and  three-quarters.  In  a  very  few  in- 
stances, the  interval  has  been  found  less  than  half  an  inch. 

The.  Vertebral  Artery  (Fig.  279)  is  generally  the  first  and  largest  branch  of 
the  subclavian ;  it  arises  from  the  upper  and  back  part  of  the  first  portion  of 
the  vessel,  and,  passing  upwards,  enters  the  foramen  in  the  transverse  process 
of  the  sixth  cervical  vertebra,  and  ascends  through  the  foramina  in  the  trans- 
verse processes  of  all  the  vertebrae  above  this.  Above  the  upper  border  of 
the  axis,  it  inclines  outwards  and  upwards  to  the  foramen  in  the  transverse 
process  of  the  atlas,  through  which  it  passes ;  it  then  winds  backwards  behind 
its  articular  process,  runs  in  a  deep  groove  on  the  surface  of  the  posterior  arch 
of  this  bone,  and,  piercing  the  posterior  occipito-atloid  ligament  and  dura  mater, 
enters  the  skull  through  the  foramen  magnum.  It  then  passes  in  front  of  the 
medulla  oblongata,  and  unites  with  the  vessel  of  the  opposite  side  at  the  lower 
border  of  the  pons  Varolii,  to  form  the  basilar  artery. 

At  its  origin,  it  is  situated  behind  the  internal  jugular  vein,  and  inferior 
thyroid  artery;  and,  near  the  spine,  lies  between  the  Longus  Colli  and  Scalenus 
Anticus  muscles,  having  the  thoracic  duct  in  front  of  it  on  the  left  side.  Within 
the  foramina  formed  by  the  transverse  processes  of  the  vertebrae,  it  is  accom- 
panied by  a  plexus  of  nerves  from  the  sympathetic,  and  lies  between  the  ver- 
tebral vein,  which  is  in  front,  and  the  cervical  nerves,  which  issue  from  the 
intervertebral  foramina  behind  it.  Whilst  winding  round  the  articular  process 
of  the  atlas,  it  is  contained  in  a  triangular  space  formed  by  the  Eectus  Posticus 
Major,  the  Superior  and  the  Inferior  Oblique  muscles;  and  is  covered  by  the 
Rectus  Posticus  Major  and  Complexus.  Within  the  skull,  as  it  winds  round 
the  medulla  oblongata,  it  is  placed  between  the  hypoglossal  nerve  and  the  an- 
terior root  of  the  suboccipital  nerve. 

Branches.  These  may  be  divided  into  two  sets,  those  given  off  in  the  neck, 
and  those  within  the  cra'nium. 

Cervical  Branches.  Cranial  Branches. 

Lateral  spinal.  Posterior  meningeal. 

Muscular.  Anterior  spinal. 

Posterior  spinal. 

Inferior  cerebellar. 

The  lateral  spinal  branches  enter  the  spinal  canal  through  the  intervertebral 
foramina,  each  dividing  into  two  branches.  Of  these,  one  passes  along  the 
roots  of  the  nerves  to  supply  the  spinal  cord  and  its  membranes,  anastomosing 
with  the  other  spinal  arteries ;  the  other  is  distributed  to  the  posterior  surface 
of  the  bodies  of  the  vertebrae. 

Muscular  branches  are  given  off  to  the  deep  muscles  of  the  neck,  where  the 
vertebral  artery  curves  round  the  articular  process  of  the  atlas.  They  anas- 
tomose with  the  occipital  and  deep  cervical  arteries. 

The  posterior  meningeal  are  one  or  two  small  branches  given  off  from  the 
vertebral  opposite  the  foramen  magnum.  They  ramify  between  the  bone  and 
dura  mater  in  the  cerebellar  fossae,  and  supply  the  falx  cerebelli. 

The  anterior  spinal  is  a  small  branch,  larger  than  the  posterior  spinal,  which 
arises  near  the  termination  of  the  vertebral,  and  unites  with  its  fellow  of  the 
opposite  side  in  front  of  the  medulla  oblongata.  The  single  trunk,  thus  formed, 
descends  a  short  distance  on  the  front  of  the  spinal  cord,  and  joins  with  a  sue- 


474  ARTERIES. 

cession  of  small  branches,  which  enter  the  spinal  canal  through  some  of  the 
intervertebral  foramina;  these  branches  are  derived  from  the  vertebral  and 
ascending  cervical  in  the  neck ;  from  the  intercostal,  in  the  dorsal  region ;  and 
from  the  lumbar,  ilio-lumbar,  and  lateral  sacral  arteries  in  the  lower  part  of 
the  spine.  They  unite,  by  means  of  ascending  and  descending  branches,  to 
form  a  single  anterior  median  artery,  which  extends  as  far  as  the  lower  part  of 
the  spinal  cord.  This  vessel  is  placed  beneath  the  pia  mater  along  the  anterior 
median  fissure;  it  supplies  that  membrane  and  the  substance  of  the  cord,  and 
sends  off  branches  at  its  lower  part,  to  be  distributed  to  the  cauda  equina. 

The  posterior  spinal  arises  from  the  vertebral,  at  the  side  of  the  medulla 
oblongata;  passing  backwards  to  the  posterior  aspect  of  the  spinal  cord,  it 
descends  on  either  side,  lying  behind  the  posterior  roots  of  the  spinal  nerves; 
and  is  reinforced  by  a  succession  of  small  branches,  which  enter  the  spinal 
canal  through  the  intervertebral  foramina,  and  by  which  it  is  continued  to  the 
lower  part  of  the  cord,  and  to  the  cauda  equina.  Branches  from  these  vessels 
form  a  free  anastomosis  round  the  posterior  roots  of  the  spinal  nerves,  and 
communicate,  by  means  of  very  tortuous  transverse  branches,  with  the  vessel 
of  the  opposite  side.  At  its  commencement,  it  gives  off'  an  ascending  branch, 
which  terminates  on  the  side  of  the  fourth  ventricle. 

The  inferior  cerebellar  artery  (Fig.  281),  the  largest  branch  of  the  vertebral, 
winds  backwards  round  the  upper  part  of  the  medulla  oblongata,  passing  be- 
tween the  origin  of  the  spinal  accessory  and  pneumogastric  nerves,  over  the 
restiform  body,  to  the  under  surface  of  the  cerebellum,  where  it  divides  into 
two  branches;  an  internal  one,  which  is  continued  backwards  to  the  notch  be- 
tween the  two  hemispheres  of  the  cerebellum ;  and  an  external  one,  which 
supplies  the  under  surface  of  the  cerebellum,  as  far  as  its  outer  border,  where 
it  anastomoses  with  the  superior  cerebellar.  Branches  from  this  artery  supply 
the  choroid  plexus  of  the  fourth  ventricle. 

The  Basilar  Artery,  so  named  from  its  position  at  the  base  of  the  skull,  is  a 
single  trunk,  formed  by  the  junction  of  the  two  vertebral  arteries;  it  extends 
from  the  posterior  to  the  anterior  border  of  the  pons  Varolii,  where  it  divides 
into  two  terminal  branches,  the  posterior  cerebral  arteries.  Its  branches  are, 
on  each  side,  the  following : — 

Transverse.  Superior  cerebellar. 

Anterior  cerebellar.  Posterior  cerebral. 

The  transverse  branches  supply  the  pons  Varolii  and  adjacent  parts  of  t! 
brain ;  one  accompanies  the  auditory  nerve  into  the  internal  auditory  meatus ; 
and  another,  of  larger  size,  passes  along  the  crus  cerebelli,  to  be  distributed  to 
the  anterior  border  of  the  under  surface  of  the  cerebellum.  It  is  called  the 
anterior  {inferior)  cerebellar  artery. 

The  superior  cerebellar  arteries  arise  near  the  termination  of  the  basilar.  They 
wind  round  the  crus  cerebri,  close  \o  the  fourth  nerve,  and  arriving  at  the  upper 
surface  of  the  cerebellum,  divide  into  branches,  which  ramify  in  the  pia  mater, 
and  anastomose  with  the  inferior  cerebellar.  Several  branches  are  given  to 
tlie  pineal  gland,  and  also  to  the  velum  interpositum. 

The  posterior  cerebral  arteries,  the  two  terminal  branches  of  the  basilar,  are 
larger  than  the  preceding,  from  which  they  are  separated  near  their  origin  by 
the  third  nerves.  Winding  round  the  crus  cerebri,  they  pass  to  the  under  sur- 
face of  the  posterior  lobes  of  the  cerebrum,  which  they  supply,  anastomosing 
with  the  anterior  and  middle  cerebral  arteries.  Near  their  origin,  the}'  receive 
the  posterior  communicating  arteries  from  the  internal  carotid,  and  give  off" 
numerous  branches,  which  enter  the  posterior  perforated  space.  They  also 
give  off  a  branch,  the  posterior  choroid,  which  supplies  the  velum  interpositum 
and  choroid  plexus,  entering  the  interior  of  the  brain  beneath  the  posterior 
border  of  the  corpus  callosum. 

Circle  of  Willis.     The  remarkable  anastomosis  which  exists   between  the 


THYROID    AXIS    AND    BRANCHES.  475 

brandies  of  the  internal  carotid  and  vertebral  arteries  at  the  base  of  the  brain, 
constitutes  the  circle  of  Willis.  It  is  formed,  in  front,  by  the  anterior  cerebral 
and  anterior  communicating  arteries ;  on  each  side,  by  the  trunk  of  the  internal 
carotid,  and  the  posterior  communicating;  behind,  by  the  posterior  cerebral, 
and  point  of  the  basilar.  It  is  by  this  anastomosis  that  the  cerebral  circula- 
tion is  equalized,  and  provision  made  for  effectually  carrying  it  on  if  one  or 
more  of  the  branches  are  obliterated.  The  parts  of  the  brain  included  within 
this  arterial  circle  are,  the  lamina  cinerea,  the  commissure  of  the  optic  nerves, 
the  infundibulum,  the  tuber  cinereum,  the  corpora  albicantia,  and  the  pars  per- 
forata postica. 

The  Thyroid  Axis  (Fig.  274)  is  a  short  thick  trunk,  which  arises  from  the 
fore  part  of  the  first  portion  of  the  subclavian  artery,  close  to  the  inner  side 
of  the  Scalenus  Anticus  muscle,  and  divides,  almost  immediately  after  its 
origin,  into  three  branches,  the  inferior  thyroid,  suprascapular,  and  trans versalis 
colli. 

The  Inferior  Thyroid  Artery  passes  upwards,  in  a  serpentine  course,  behind 
the  sheath  of  the  common  carotid  vessel  and  sympathetic  nerve  (the  middle 
cervical  ganglion  resting  upon  it),  and  is  distributed  to  the  under  surface  of  the 
thyroid  gland,  anastomosing  with  the  superior  thyroid,  and  with  the  correspond- 
ing artery  of  the  opposite  side.     Its  branches  are  the 

Laryngeal.  CEsophageal. 

Tracheal.  Ascending  cervical. 

The  laryngealhrawdk  ascends  upon  the  trachea  to  the  back  part  of  the  larynx, 
and  supplies  the  muscles  and  the  mucous  membrane  of  this  part. 

The  tracheal  branches  are  distributed  upon  the  trachea,  anastomosing  below 
with  the  bronchial  arteries. 

The  oesophageal  branches  are  distributed  to  the  oesophagus. 

The  ascending  cervical  is  a  small  branch  which  arises  from  the  inferior 
thyroid,  just  where  that  vessel  is  passing  behind  the  common  carotid  artery, 
and  runs  up  the  neck  in  the  interval  between  the  Scalenus  Anticus  and  Rectus 
Anticus  Major.  It  gives  branches  to  the  muscles  of  the  neck,  which  commu- 
nicate with  those  sent  out  from  the  vertebral,  and  sends  one  or  two  through 
the  intervertebral  foramina,  along  the  cervical  nerves,  to  supply  the  bodies  of 
the  vertebraB,  the  spinal  cord,  and  its  membranes. 

The  Suprascapular  Artery^  smaller  than  the  transversalis  colli,  passes  obliquely 
from  within  outwards,  across  the  root  of  the  neck.  It  at  first  lies  on  the  lower 
part  of  the  Scalenus  Anticus,  being  covered  by  the  Sterno-mastoid;  it  then 
crosses  the  subclavian  artery,  and  runs  outwards  behind  and  parallel  with  the 
clavicle  and  Subclavius  muscle,  and  beneath  the  posterior  belly  of  the  Omo- 
hyoid, to  the  superior  border  of  the  scapula,  where  it  passes  over  the  transverse 
ligament  of  the  scapula  to  the  supraspinous  fossa.  In  this  situation  it  lies 
close  to  the  bone,  and  ramifies  between  it  and  the  Supraspinatus  muscle,  to 
which  it  is  mainly  distributed,  giving  off"  a  communicating  branch,  which  crosses 
the  neck  of  the  scapula,  to  reach  the  infraspinous  fossa,  where  it  anastomoses 
with  the  dorsal  branch  of  the  subscapular  artery.  Besides  distributing  branches 
to  the  Sterno-mastoid,  and  neighboring  muscles,  it  gives  off'  a  supra-acromial 
branch,  which,  piercing  the  Trapezius  muscle,  supplies  the  cutaneous  surface  of 
the  acromion,  anastomosing  with  the  acromial  thoracic  artery.  As  the  artery 
passes  across  the  suprascapular  notch,  a  branch  descends  into  the  subscapular 
fossa,  ramifies  beneath  that  muscle,  and  anastomoses  with  the  posterior  and 
subscapular  arteries.     It  also  supplies  the  shoulder-joint. 

The  Transversalis  Colli  passes  transversely  outwards,  across  the  upper  part  of 
the  subclavian  triangle,  to  the  anterior  margin  of  the  Trapezius  muscle,  beneath 
which  it  divides  into  two  branches,  the  superficial  cervical,  and  the  posterior 
scapular.  In  its  passage  across  the  neck,  it  crosses  in  front  of  the  Scaleni 
muscles  and  the  brachial  plexus,  between  the  divisions  of  which  it  sometimci 


47; 


ARTERIES. 


passes,  and  is  covered  by  the  Platysma,  Sterno-mastoid,  Omo-liyoid,  and  Tra- 
pezius muscles. 

The  suj^erjicial  cervical  ascends  beneath  the  anterior  margin  of  the  Trapezius, 
distributing  branches  to  it,  and  to  the  neighboring  muscles  and  glands  in  the 
neck. 

The  posterior  scapular,  the  continuation  of  the  transversalis  colli,  passes  be- 
neath the  Levator  Anguli  Scapulae  to  the  superior  angle  of  the  scapula,  and 
descends  along  the  posterior  border  of  that  bone  as  far  as  the  inferior  angle, 
where  it  anastomoses  with  the  subscapular  branch  of  the  axillary.     In  its 

Fig.  283. — The  Scapular  and  Circumflex  Arteries. 

BfUricT  Seafiitltf 


Sufirt  Ste^ular 


Acremial  BTarch 
tf  Theraeito-  Acrcmiclit 


course  it  is  covered  by  the  Rhomboid  muscles,  supplying  these,  the  Latissimus 
Dorsi  and  Trapezius,  and  anastomosing  with  the  suprascapular  and  subscapular 
arteries,  and  with  the  posterior  branches  of  some  of  the  intercostal  arteries. 

Peculiarities.  The  superficial  cervical  frequently  arises  as  a  separate  branch  from  the  thyroid 
axis  ;  and  the  posterior  scapular,  from  the  third,  more  rarely  from  the  second,  part  of  the  subclavian. 

The  Internal  Mammary  arises  from  the  under  surface  of  the  first  portion  of 
the  subclavian  artery,  opposite  the  thyroid  axis.  It  descends  behind  the  cla- 
vicle, to  the  inner  surface  of  the  anterior  wall  of  the  chest,  resting  upon  the 
costal  cartilages,  a  short  distance  from  the  margin  of  the  sternum;  and,  at  the 
interval  between  the  sixth  and  seventh  cartilages,  divides  into  two  branches,  the 
musculo-phrenic,  and  superior  epigastric. 

At  its  origin,  it  is  covered  by  the  internal  jugular  and  subclavian  veins,  and 
crossed  by  the  phrenic  nerve.  In  the  upper  part  of  the  thorax,  it  lies  upon 
the  costal  cartilages,  and  Internal  Intercostal  muscles  in  front,  and  is  covered 
by  the  pleura  behind.  At  the  lower  part  of  the  thorax,  the  Triangularis  Sterui 
separates  the  artery  from  the  pleura.  It  is  accompanied  by  two  veins,  which 
join  at  the  upper  part  of  the  thorax  into  a  single  trunk. 

The  branches  of  the  internal  mammary  are 

Comes  Nervi  Phrcnici  (Superior  Phrenic).  Anterior  Intercostal. 

Mediastinal.  Perforating. 

Pericardiac.  Musculo-phrenic. 

Sternal.  Superior  epigastric. 

The  comes  nervi  phrenici  {superior  phrenic),  is  a  long  slender  branch,  which 
accompanies  the  phrenic  nerve,  between  the  pleura  and  pericardium,  to  the 


INTERNAL    MAMMARY.  477 

DiapTiragm,  to  which  it  is  distributed ;  anastomosing  -vvitli  the  other  phrenic 
arteries  from  the  internal  mammary,  and  abdominal  aorta. 

The  mediastinal  branches  are  small  vessels,  which  are  distributed  to  the  areolar 
tissue  in  the  anterior  mediastinum,  and  the  remains  of  the  thymus  gland. 

The  pericardiac  branches  supply  the  upper  part  of  the  pericardium,  the  lower 
part  receiving  branches  from  the  musculo-phrenic  artery.  Some  sternal  branches 
are  distributed  to  the  Triangularis  Sterni,  and  both  surfaces  of  the  sternum. 

The  anterior  intercostal  arteries  supply  the  five  or  six  upper  intercostal  spaces. 
The  branch  corresponding  to  each  space  passes  outwards,  and  soon  divides  into 
two,  which  run  along  the  opposite  borders  of  the  ribs,  and  inosculate  with  the 
intercostal  arteries  from  the  aorta.  They  are  at  first  situated  between  the 
pleura  and  the  Internal  Intercostal  muscles,  and  then  between  the  two  layers 
of  those  muscles.  They  supply  the  Intercostal  and  Pectoral  muscles,  and  the 
mammary  gland. 

The  perforating  arteries  correspond  to  the  five  or  six  upper  intercostal  spaces. 
They  arise  from  the  internal  mammary,  pass  forwards  through  the  intercostal 
spaces,  and  curving  outwards,  supply  the  Pectoralis  Major,  and  the  integument. 
Those  which  correspond  to  the  first  three  spaces,  are  distributed  to  the  mam- 
mary gland.     In  females,  during  lactation,  these  branches  are  of  large  size. 

The  musculo-phrenic  artery  is  directed  obliquely  downwards  and  outwards, 
behind  the  cartilages  of  the  false  ribs,  perforating  the  Diaphragm  at  the  eighth 
or  ninth  rib,  and  terminating,  considerably  reduced  in  size,  opposite  the  last 
intercostal  space.  It  gives  off  anterior  intercostal  arteries  to  each  of  the  inter- 
costal spaces  across  which  it  passes ;  these  diminish  in  size  as  the  spaces  de- 
crease in  length,  and  are  distributed  in  a  manner  precisely  similar  to  the 
anterior  intercostals  from  the  internal  mammary.  The  musculo-phrenic  also 
gives  branches  backwards  to  the  Diaphragm,  and  downwards  to  the  abdominal 
muscles. 

The  superior  epigastric  continues  in  the  original  direction  of  the  internal 
mammary,  descends  behind  the  Rectus  muscle,  and  perforating  its  sheath, 
divides  into  branches  which  supply  the  Rectus,  anastomosing  with  the  epi- 
gastric artery  from  the  external  iliac.  Some  vessels  perforate  the  sheath  of  the 
Rectus,  and  supply  the  muscles  of  the  abdomen  and  the  integument,  and  a  small 
branch  which  passes  inwards  upon  the  side  of  the  ensiform  appendix,  anasto- 
moses in  front  of  that  cartilage  with  the  artery  of  the  opposite  side. 

The  Superior  Intercostal  (Fig.  279)  arises  from  the  upper  and  back  part  of  the 
subclavian  artery,  behind  the  Anterior  Scalenus  on  the  right  side,  and  to  the 
inner  side  of  the  muscle  on  the  left  side.  Passing  backwards,  it  gives  off'  the 
deep  cervical  branch,  and  then  descends  behind  the  pleura  in  front  of  the  necks 
of  the  first  two  ribs,  and  inosculates  with  the  first  aortic  intercostal.  In  the 
first  intercostal  space,  it  gives  off  a  branch  which  is  distributed  in  a  manner 
similar  to  the  distribution  of  the  aortic  intercostals.  The  branch  of  the  second 
intercostal  space  usually  joins  with  one  from  the  first  aortic  intercostal.  Each 
intercostal  gives  oft'  a  branch  of  the  posterior  spinal  muscles,  and  a  small  one, 
which  passes  through  the  corresponding  intervertebral  foramen  to  the  spinal 
cord  and  its  membranes. 

The  deep  cervical  branch  [profunda  cervicis)  arises,  in  most  cases,  from  the 
superior  intercostal,  and  is  analogous  to  the  posterior  branch  of  an  aortic  inter- 
costal artery.  Passing  backwards,  between  the  transverse  process  of  the 
seventh  cervical  vertebra  and  the  first  rib,  it  runs  up  the  back  part  of  the  neck, 
between  the  Complexus  and  Semispinalis  Colli  muscles,  as  high  as  the  axis, 
supplying  these  and  adjacent  muscles,  and  anastomosing  with  the  arteria 
princeps  cervicis  of  the  occipital,  and  with  branches  which  pass  outwards  from 
the  vertebral. 


4T8 


ARTP]IIIES. 


Surgical  Anatomy  of  the  Axilla. 

The  Axilla  is  a  pyramidal  space,  situated  between  the  upper  and  lateral  part 
of  the  chest,  and  the  inner  side  of  the  arm. 

Boundaries.  Its  apex,  which  is  directed  upwards  towards  the  root  of  the 
neck,  corresponds  to  the  interval  between  the  two  Scaleni  on  the  first  rib. 
The  base,  directed  downwards,  is  formed  bj  the  integument,  and  a  thick  layer 
of  fascia,  extending  between  the  lower  border  of  the  Pectoralis  Major  in  front, 
and  the  lower  border  of  the  Latissimus  Dorsi  behind ;  it  is  broad  internally,  at 
the  chest,  but  narrow  and  pointed  externally,  at  the  arm.  The  anterior  boundary 
is  formed  by  the  Pectoralis  Major  and  Pectoralis  Minor  muscles,  the  former 
covering  the  whole  of  the  anterior  wall  of  the  axilla,  the  latter  covering  only 
its  central  part.  The  posterior  boundary^  which  extends  somewhat  lower  than 
the  anterior,  is  formed  by  the  Subscapularis  above,  the  Teres  Major  and  Latis- 
simus Dorsi  below.  On  the  inner  side  are  the  first  four  ribs  with  their  corres- 
ponding Intercostal  muscles,  and  part  of  the  Serratus  Magnus.  On  the  outer 
side,  where  the  anterior  and  posterior  boundaries  converge,  the  space  is  narrow, 
and  bounded  by  the  humerus,  the  Coraco-brachialis  and  Biceps  muscles. 

Fig.  284. — The  Axillary  Artery,  and  its  Branches, 


Contents.  This  space  contains  the  axillary  vessels,  and  brachial  plexus  o1 
nerves,  with  their  branches,  some  branches  of  the  intercostal  nerves,  and  a  large 
number  of  lym|)hatic  glands,  all  connected  together  by  a  quantity  of  fat  and 
loose  areolar  tissue. 

Their  Position.  The  axillary  artery  and  vein,  with  the  brachial  plexus  of 
nerves,  extend  obliquely  along  the  outer  boundary  of  the  axillary  space,  from 
its  apex  to  its  base,  and  are  placed  much  nearer  the  anterior  than  the  posterior 
wall,  the  vein  lying  to  the  inner  or  thoracic  side  of  the  artery,  and  altogether 
concealing  it.     At  the  fore  part  of  the  axillary  space,  in  contact  with  the  Pec- 


AXILLARY.  479 

toral  muscles,  are  the  thoracic  branches  of  the  axillary  artery,  and  along  the 
anterior  margin  of  the  axilla  the  long  thoracic  artery  extends  to  the  side  of  the 
chest.  At  the  back  part,  in  contact  with  the  lower  margin  of  the  Subscapularis 
muscle,  are  the  subscapular  vessels  and  nerves;  winding  around  the  lower 
border  of  this  muscle,  is  the  dorsalis  scapulee  artery  and  veins;  and  towards  the 
outer  extremity  of  the  muscle,  the  posterior  circumflex  vessels  and  the  circum- 
flex nerve  are  seen  curving  backwards  to  the  shoulder. 

Along  the  inner  or  thoracic  side  no  vessel  of  any  importance  exists,  the  upper 
part  of  the  space  being  crossed  merely  by  a  few  small  branches  from  the  supe- 
rior thoracic  artery.  There  are  some  important  nerves,  however,  in  this  situa- 
tion, viz.,  the  posterior  thoracic  or  external  respiratory  nerve,  descending  on 
the  surface  of  the  Serratus  Magnus,  to  which  it  is  distributed;  and  perforating 
the  upper  and  anterior  part  of  this  wall,  the  intercosto-humeral  nerve  or  nerves, 
passing  across  the  axilla  to  the  inner  side  of  the  arm. 

The  cavity  of  the  axilla  is  filled  by  a  quantity  of  loose  areolar  tissue,  a  large 
number  of  small  arteries  and  veins,  all  of  which  are,  however,  of  inconsider- 
able size,  and  numerous  lymphatic  glands;  these  are  from  ten  to  twelve  in 
number,  and -situated  chiefly  on  the  thoracic  side,  and  lower  and  back  part  of 
this  space. 

The  student  should  attentively  consider  the  relation  of  the  vessels  and  nerver 
in  the  several  parts  of  the  axilla ;  for  it  not  unfrequently  happens  that  the 
surgeon  is  called  upon  to  extirpate  diseased  glands,  or  to  remove  a  tumor  from 
this  situation.  In  performing  such  an  operation,  it  will  be  necessary  to  proceed 
with  much  caution  in  the  direction  of  the  outer  wall  and  apex  of  the  space,  as 
here  the  axillary  vessels  will  be  in  danger  of  being  wounded.  Towards  the 
posterior  wall,  it  will  be  necessary  to  avoid  the  subscapular,  dorsalis  scapulge, 
and  posterior  circumflex  vessels,  and,  along  the  anterior  wall,  the  thoracic 
branches.  Ifc  is  only  along  the  inner  or  thoracic  wall,  and  in  the  centre  of  the 
axillary  cavity,  that  there  are  no  vessels  of  any  importance ;  a  fortunate  cir- 
cumstance, for  it  is  in  this  situation  more  especially  that  tumors  requiring  re- 
moval arc  usually  situated. 

The  Axillary  Artery. 

The  Axillary  Artery,  the  continuation  of  the  subclavian,  commences  at  the 
lower  border  of  the  first  rib,  and  terminates  at  the  lower  border  of  the  tendons 
of  the  Latissimus  Dorsi  and  Teres  Major  muscles,  where  it  takes  the  name  of 
brachial.  Its  direction  varies  with  the  position  of  the  limb ;  when  the  arm  lies 
by  the  side  of  the  chest,  the  vessel  forms  a  gentle  curve,  the  convexity  being 
upwards  and  outwards :  when  it  is  directed  at  right  angles  with  the  trunk,  the 
vessel  is  nearly  straight ;  and  when  it  is  elevated  still  higher,  the  artery  describes 
a  curve,  the  concavity  of  which  is  directed  upwards.  At  its  commencement 
the  artery  is  very  deeply  situated,  but  near  its  termination  is  superficial,  being 
covered  only  by  the  skin  and  fascia.  The  description  of  the  relations  of  this 
vessel  is  facilitated  by  its  division  into  three  portions,  the  first  portion  being 
that  above  the  Pectoralis  Minor ;  the  second  portion,  behind ;  and  the  third, 
below  that  muscle. 

The^irs^  portion  of  the  axillary  artery  is  in  relation,  in  front^  with  the  clavi- 
cular portion  of  the  Pectoralis  Major,  the  costo-coracoid  membrane,  the  Sub- 
clavius,  and  the  cephalic  vein ;  behind,  with  the  first  intercostal  space,  the  corre- 
sponding Intercostal  muscle,  the  first  serration  of  the  Serratus  Magnus,  and  the 
posterior  thoracic  nerve  ;  on  its  outer  side  with  the  brachial  plexus,  from  which 
it  is  separated  by  a  little  cellular  interval ;  on  its  inner,  or  thoracic  side,  with 
the  axillary  vein. 


480  ARTERIES. 

Relations  of  First  Portion  of  the  Axillary  Artery. 

In  front. 
Pectoralis  Major, 
Costo-coracoid  membrane. 
Subclavius. 
Cephalic  vein. 


Outer  side.  (    AxUiary     \  Inner  side. 

Brachial  plexus.  Artery.  Axillary  vein. 


Behind. 
First  intercostal  space,  and  Intercostal  muscle. 
First  serration  of  Serratus  Magnus. 
Posterior  thoracic  nerve. 

The  second  portion  of  the  axillary  artery  lies  behind  the  Pectoralis  Minor.  It 
is  covered,  in  front,  by  the  Pectoralis  Major  and  Minor  muscles ;  behind,  it  is 
separated  from  the  Subscapularis  by  a  cellular  interval ;  on  the  inner  side  is  the 
axillary  vein.  The  brachial  plexus  of  nerves  surrounds  the  artery,  and  sepa- 
rates it  from  direct  contact  with  the  vein  and  adjacent  muscles. 

Relations  of  the  Second  Portion  of  the  Axillary  Artery. 

In  front, 
Pectoralis  Major  and  Pectoralis  Minor. 


Outer  side.  *       [      Artery^     ]  Inner  side. 

Outer  cord  of  plexus.  Isocmd  pi.rtiou.j  Axillary  vein. 

Inner  cord  of  plexus. 

Beh  ind. 
Subscapularis. 
Posterior  cord  of  plexus. 

The  third  portion  of  the  axillary  artery  lies  below  the  Pectoralis  Minor.  It 
is  in  relation,  in  front,  with  the  lower  part  of  the  Pectoralis  Major  above,  being 
covered  only  by  the  integument  and  fascia  below ;  behind,  with  the  lower  part  of 
the  Subscapularis,  and  the  tendons  of  the Latissimus  Dorsi  and  Teres  Major;  on 
its  outer  side,  with  the  Coraco-brachialis ;  on  its  inner,  or  thoracic  side,  with  the 
axillary  vein.  The  nerves  of  the  brachial  plexus  bear  the  following  relation 
to  the  artery  in  this  part  of  its  course ;  on  the  outer  side  is  the  median  nerve, 
and  the  musculo-cutaneous  for  a  short  distance  ;  on  the  inner  side,  the  ulnar,  the 
internal,  and  lesser  internal  cutaneous  nerves ;  and  behind,  the  musculo  spiral, 
and  circumflex,  the  latter  extending  only  to  the  lower  border  of  the  Subscapu- 
laris muscle. 

Relations  of  the  Third  Portion  of  the  Axillary  Artery. 

In  front. 
Intepumcnt  and  fascia. 
Pectoralis  Major. 

Outer  side.  /^  \^  Inner  side. 

Coraco-brachialis.  /     Axillary    \  Ulnar  nerve. 

Median  nerve.  (       Artery.  Internal  cntaneous  nerves. 

Musculo-cutaneous  nerve.  V '""'  »*""'""■/  Axillary  vein. 

Behind. 
Subscapularis. 

Tendons  of  Latissimus  Dorsi,  and  Teres  Major. 
Musculo-spiraU  and  circumflex  nerves. 


I 


AXILLARY.  481 

Peculiarities.  The  axillary  artery,  in  about  one  case  out  of  every  ten,  gives  off  a  large  branch, 
which  forms  either  one  of  the  arteries  of  the  forearm,  or  a  large  muscular  trunk.  In  the  first 
set  of  cases,  this  artery  is  most  frequently  the  radial  (L  in  33),  sonietimes  the  ulnar  (1  in  72 1, 
and,  very  rarely,  the  interosseous  (1  in  506).  In  the  second  set  of  cases,  the  trunk  has  been 
found  to  give  origin  to  the  subscapular,  circumflex,  and  profunda  arteries  of  the  arm.  Some- 
times, only  one  of  the  circumflex,  or  one  of  the  profunda  arteries,  arose  from  the  trunk.  In  these 
cases,  the  brachial  plexus  surrounded  the  trunk  of  the  branches,  and  not  the  main  vessel. 

Surgical  Anatomy.  The  student  having  carefully  examined  the  relations  of  the  axillary  ar- 
tery in  its  various  parts,  should  now  consider  in  what'  situation  compression  of  this  vessel  may 
be  most  easily  effected,  and  the  best  position  for  the  application  of  a  ligature  to  it  when  necessary. 

Compression  of  the  vessel  is  required  in  the  removal  of  tumors,  or  in  amputation  of  the  upper 
part  of  the  arm ;  and  the  only  situation  in  which  this  can  be  effectually  made,  is  in  the  lower 
part  of  its  course ;  by  pressing  on  it  in  this  situation  from  within  outwards  against  the  humerus, 
the  circulation  may  be  effectually  suspended. 

The  application  of  a  ligature  to  the  axillary  artery  may  be  required  in  cases  of  aneurism  of 
the  upper  part  of  the  brachial ;  and  there  are  only  two  situations  in  which  it  can  be  secured,  viz., 
in  the  first  and  in  the  third  parts  of  its  course  ;  for  the  axillary  artery  at  its  central  part  is  so 
deeply  seated,  and,  at  the  same  time,  so  closely  surrounded  with  large  nervous  trunks,  that  the 
application  of  a  ligature  to  it  in  that  situation  would  be  almost  impracticable. 

In  the  third  part  of  its  course,  the  operation  is  most  simple,  and  may  be  performed  in  the 
following  manner :  The  patient  being  placed  on  a  bed,  and  the  arm  separated  from  the  side,  with 
the  hand  supinated,  the  head  of  the  humerus  is  felt  for,  and  an  incision  made  through  the  integu- 
ment over  it,  about  two  inches  in  length,  a  little  nearer  to  the  anterior  than  the  posterior  fold  of 
the  axilla.  After  carefully  dissecting  through  the  areolar  tissue  and  fascia,  the  median  nerve 
and  axillary  vein  are  exposed  ;  the  former  having  been  displaced  to  the  outer,  and  the  latter  to 
the  inner  side  of  the  arm,  the  elbow  being  at  the  same  time  bent,  so  as  to  relax  the  structures, 
and  facilitate  their  separation,  the  ligature  may  be  passed  round  the  artery  from  the  ulnar  to  the 
radial  side.  This  portion  of  the  artery  is  occasionally  crossed  by  a  muscular  slip  derived  from 
the  Latissimus  Dorsi,  which  may  mislead  the  surgeon  during  an  operation.  The  occasional 
existence  of  this  muscular  fasciculus  was  spoken  of  in  the  description  of  the  muscles.  It  may 
easily  be  recognized  by  the  transverse  direction  of  its  fibres. 

Tha  first  portion  of  the  axillary  artery  may  be  tied,  in  cases  of  aneurism  encroaching  so  far 
upwards  that  a  ligature  cannot  be  applied  in  the  lower  part  of  its  course.  Notwithstanding  that 
this  operation  has  been  performed  in  some  few  cases,  and  with  success,  its  performance  is  attended 
with  much  difiiculty  and  danger.  The  student  will  remark  that  in  this  situation,  it  would  be 
necessary  to  divide  a  thick  muscle,  and  after  separating  the  costo-coracoid  membrane,  the  artery 
would  be  exposed  at  the  bottom  of  a  more  or  less  deep  space,  with  the  cephalic  and  axillary  veins 
in  such  relation  with  it  as  must  render  the  application  of  a  ligature  to  this  part  of  the  vessel 
particularly  hazardous.  Under  such  circumstances  it  is  an  easier,  and,  at  the  same  time,  more 
advisable  operation,  to  tie  the  subclavian  artery  in  the  third  part  of  its  course. 

In  a  case  of  wound  of  the  vessel,  the  general  practice  of  cutting  down  upon,  and  tying  it  above 
and  below  the  wounded  point,  should  be  adopted  in  all  cases. 

Collateral  circulation  after  ligature  of  the  axillary  artery.  If  the  artery  be  tied  above  the 
origin  of  the  acromial  thoracic,  the  collateral  circulation  will  be  carried  on  by  the  same  branches 
as  after  the  ligature  of  the  subclavian ;  if  at  the  lower  point,  between  the  acromial  thoracic  and 
subscapular  arteries,  the  latter  vessel,  by  its  free  anastomoses  with  the  other  scapular  arteries, 
branches  of  the  subclavian,  will  become  the  chief  agent  in  carrying  on  the  circulation,  to  which 
the  long  thoracic,  if  it  be  below  the  ligature,  will  materially  contribute,  by  its  anastomoses  with 
the  intercostal  and  internal  mammary  arteries.  If  the  point  included  in  the  ligature  be  below 
the  origin  of  the  subscapular  artery,  the  anastomoses  are  less  free.  The  chief  agents  in  restoring 
the  circulation  will  be  the  posterior  circumflex,  by  its  anastomoses  with  the  suprascapular  anil 
acromial  thoracic,  and  the  communications  between  the  subscapular  and  superior  profunda, 
which  will  be  afterwards  referred  to  as  performing  the  same  office  after  ligature  of  the  brachial. 
The  cases  in  which  the  operation  has  been  performed  are  few  in  number,  and  no  published 
account  of  dissection  of  the  collateral  circulation  appears  to  exist. 

The  branches  of  the  axillary  artery  are — 

From  1st  Fart      \  Superior  thoracic. 

(  Acromial  thoracic. 
From  2d  Fart      ]  Thoracica  longa. 

(  ihoracica  alans. 

{Subscapular. 
Anterior  circumflex. 
Posterior  circumflex. 

The  superior  thoracic  is  a  small  artery,  which  arises  from  the  axillary  sepa- 
rately, or  by  a  common  trunk  with  the  acromial  thoracic.     Running  forwards 
and  inwards  along  the  upper  border  of  the  Pectoralis  Minor,  it  passes  between 
31 


482  ARTERIES. 

it  and  the  Pectoralis  Major  to  the  side  of  the  chest.  It  supplies  these  muscles, 
and  the  parietes  of  the  thorax,  anastomosing  with  the  internal  mammary  and 
intercostal  arteries. 

The  acromial  thoracic  is  a  short  trunk,  which  arises  from  the  fore  part  of  the 
axillary  artery.  Projecting  forwards  to  the  upper  border  of  the  Pectoralis 
Minor,  it  divides  into  three  sets  of  branches,  thoracic,  acromial,  and  descending. 
The  thoracic  branches,  two  or  three  in  number,  are  distributed  to  the  Serratus 
Magnus,  and  Pectoral  muscles,  anastomosing  with  the  intercostal  branches  of 
the  internal  mammary.  The  acromial  branches  are  directed  outwards  towards 
the  acromion,  supplying  the  Deltoid  muscle,  and  anastomosing,  on  the  surface 
of  the  acromion,  with  the  suprascapular  and  posterior  circumflex  arteries.  The 
descending  branch  passes  in  the  interspace  between  the  Pectoralis  Major  and 
Deltoid,  accompanying  the  cephalic  vein,  and  supplying  both  muscles. 

The  long  thoracic  passes  downwards  and  inwards  along  the  lower  border  of 
the  Pectoralis  Minor  to  the  side  of  the  chest,  supplying  the  Serratus  Magnus, 
the  Pectoral  muscles,  and  mammary  gland,  and  sending  branches  across  the 
axilla  to  the  axillary  glands  and  Subscapularis,  which  anastomose  with  the 
internal  mammary  and  intercostal  arteries. 

The  ihoracica  alaris  is  a  small  branch,  which  supplies  the  glands  and  areolar 
tissue  of  the  axilla.  Its  place  is  frequently  supplied  by  branches  from  some 
of  the  other  thoracic  arteries. 

The  suhscapiilar,  the  largest  branch  of  the  axillary  artery,  arises  opposite  the 
lower  border  of  the  Subscapularis  muscle,  and  passes  downwards  and  backwards 
along  its  lower  margin  to  the  inferior  angle  of  the  scapula,  where  it  anastomoses 
with  the  posterior  scapula,  a  branch  of  the  subclavian.  It  distributes  branches 
to  the  Subscapularis,  Serratus  Magnus,  Teres  Major,  and  Latissimus  Dorsi  mus- 
cles, and  gives  off,  about  an  inch  and  a  half  from  its  origin,  a  large  branch,  the 
dorsalis  scapulae,  which  curves  round  the  inferior  border  of  the  scapula,  leaving 
the  axilla  in  the  interspace  between  the  Teres  Minor  above,  the  Teres  Major 
below,  and  the  long  head  of  the  Triceps  in  front.  Three  branches,  or  sets  of 
branches,  arise  from  the  dorsalis  scapulae ;  the  first  enters  the  subscapular  fossa, 
beneath  the  Subscapularis,  which  it  supplies,  anastomosing  with  the  subscapular 
and  suprascapular  arteries ;  the  second,  the  trunk  of  the  artery  {dorsalis  scapulse) 
turns  round  the  axillary  border  of  the  scapula,  and  enters  the  infraspinous  fossa-, 
where  it  anastomoses  with  the  suprascapular  and  posterior  scapular  arteries 
and  a  third,  or  median  branch,  is  continued  along  the  axillary  border  of  the 
scapula,  between  the  Teres  Major  and  Teres  Minor,  and,  at  the  dorsal  surface 
of  the  inferior  angle  of  the  bone,  anastomoses  with  the  posterior  scapular. 

The  circumflex  arteries  wind  round  the  neck  of  the  humerus.     The  jx^sterio 
circumflex  (Fig.  283),  the  larger  of  the  two,  arises  from  the  back  part  of  the 
axillary,  opposite  the  lower  border  of  the  Subscapularis  muscle,  and,  passing 
backwards  with  the  circumflex  veins  and  nerve,  through  the  quadrangular  space 
bounded  by  the  Teres  Major  and  Teres  Minor,  the  scapular  head  of  the  Triceps 
and  the  humerus,  winds  round  the  neck  of  that  bone,  and  is  distributed  to  the 
Deltoid  muscle  and  shoulder-joint,  anastomosing  with  the  anterior  circumflex, 
suprascapular  and  acromial  thoracic  arteries.    The  anterior  circumflex  (Figs.  283, 
284),  considerably  smaller  than  the  preceding,  arises  just  below  that  vessel,  from 
the  outer  side  of  the  axillary  artery.     It  passes  horizontally  outwards,  beneath 
the  Coraco-braohialis  and  short  head  of  the  Biceps,  lying  upon  the  forepart  of 
the  neck  of  the  humerus,  and,  on  reaching  the  bicipital  groove,  gives  off  au__ 
ascending  branch,  which  passes  upwards  along  the  groove,  to  supply  the  headHi 
of  the  bone  and  the  shoulder-joint.     The  trunk  of  the  vessel  is  then  continued"" 
outwards  beneath  the  Deltoid,  which  it  supplies,  and  anastomoses  with  the 
posterior  circumflex,  and  acromial  thoracic  arteries. 


3 

I 


BRACHIAL. 


483 


Brachial  Artery.    (Fig.  285.) 


Fig.  285. — The  Surgical  Anatomy  of  the  Brachial 
Artery. 


The  Brachial  Artery  commences  at 
the  lower  margin  of  the  tendon  of  the 
Teres  Major,  and  passing  down  the 
inner  and  anterior  aspect  of  the  arm, 
terminates  about  half  an  inch  below 
the  bend  of  the  elbow,  where  it 
divides  into  the  radial  and  ulnar 
arteries. 

The  direction  of  this  vessel  is 
marked  by  a  line  drawn  from  the 
outer  side  of  the  axillary  space  be- 
tween the  folds  of  the  axilla,  to  a 
point  midway  between  the  condyles 
of  the  humerus,  which  corresponds  to 
the  depression  along  the  inner  border 
of  the  Coraco-brachialis  and  Biceps 
muscles.  In  the  upper  part  of  its 
course,  the  artery  lies  internal  to  the 
humerus ;  but  below,  it  is  in  front  of 
that  bone. 

Relations,  This  artery  is  superficial 
throughout  its  entire  extent,  being 
covered,  infront^  by  the  integument, 
the  superficial  and  deep  fascia ;  the 
bicipital  fascia  separates  it  opposite 
the  elbow  from  the  median  basilic 
vein  ;  the  median  nerve  crosses  it  at 
its  middle;  and  the  basilic  vein  lies 
in  the  line  of  the  artery,  but  separated 
from  it  by  the  fascia,  in  the  lower  half 
of  its  course.  Behind,  it  is  separated 
from  the  inner  side  of  the  humerus 
above,  by  the  long  and  inner  heads 
of  the  Triceps,  the  musculo-spiral 
nerve  and  superior  profunda  artery 
intervening;  and  from  the  front  of  the 
bone  below,  by  the  insertion  of  the 
Coraco-brachialis  muscle,  and  by  the 
Brachialis  Anticus.  By  its  outer  side, 
it  is  in  relation  with  the  commence- 
ment of  the  median  nerve,  and  the 
Coraco-brachialis  and  Biceps  muscles, 
which  slightly  overlap  the  artery.  By  its  inner  side,  its  upper  half  is  in  relation 
with  the  internal  cutaneous  and  ulnar  nerves,  its  lower  half  with  the  median 
nerve.  It  is  accompanied  by  two  vense  comites,  which  lie  in  close  contact  with 
tlue  artery,  being  connected  together  at  intervals  by  short  transverse  communi- 
cating branches. 


(Inferior 
XTrtrfuauA 


AtuutoTtvo  tica 
Magiut 


484  ARTERIES. 


Plan  of  the  Relations  of  the  Brachial  Artery. 

In  front. 
Integument  and  fasciae. 
Bicipital  fascia,  median  basilic  vein. 
Median  nerve. 


Outer  side. 

/              \ 

Inner  side. 

Median  nerve. 

/       Brachial      \ 

Internal  cutaneous  and  ulnar  nerve, 

Coraco-brachialis. 

\        Artery.        1 

Median  nerve. 

Biceps. 

V      / 

Behind. 
Triceps. 

"Musculo-spiral  nerve. 
Superior  profunda  artery. 
Coraco-brachialis. 
Brachialis  Anticus. 

Bend  of  the  Elbow. 

At  the  bend  of  the  elbow,  the  brachial  artery  sinks  deeply  into  a  triangular 
interval,  the  base  of  which  is  directed  upwards  towards  the  humerus,  and  the 
sides  of  which  are  bounded,  externally,  by  the  Supinator  Longus,  internally, 
by  the  Pronator  Radii  Teres;  its  floor  is  formed  by  the  Brachialis  Anticus,  and 
Supinator  Brevis.  This  space  contains  the  brachial  artery,  with  its  accom- 
panying veins ;  the  radial  and  ulnar  arteries;  the  median  and  musculo-spiral 
nerves;  and  the  tendon  of  the  Biceps.  The  brachial  artery  occupies  the  middle 
line  of  this  space,  and  divides  opposite  the  coronoid  process  of  the  ulna  into 
the  radial  and  ulnar  arteries;  it  is  covered,  in  front,  by  the  integument,  the 
superficial  fascia,  and  the  median  basilic  vein,  the  vein  being  separated  from 
direct  contact  with  the  artery  by  the  bicipital  fascia.  Behind,  it  lies  on  the 
Brachialis  Anticus,  which  separates  it  from  the  elbow-joint.  The  median  nerve 
lies  on  the  inner  side  of  the  artery,  but  separated  from  it  below  by  an  interval 
of  half  an  inch.  The  tendon  of  the  Biceps  lies  to  the  outer  side  of  the  space, 
and  the  musculo-spiral  nerve  still  more  externally,  lying  upon  the  Supinator 
Brevis,  and  partly  concealed  by  the  Supinator  Longus. 

P ecidiarities  of  the  Artery  as  regards  its  Course.  The  brachial  artery,  accompanied  by  the 
median  nerve,  may  leave  the  inner  border  of  the  Biceps,  and  descend  towards  the  inner  condyle 
of  the  humerus,  where  it  usually  curves  round  a  prominence  of  bone,  to  which  it  is  connected  by 
a  fibrous  band ;  it  then  inclines  outwards,  beneath  or  through  the  substance  of  the  Pronator  Teres 
muscle,  to  the  bend  of  the  elbow.  This  variation  bears  considerable  analogy  with  the  normal 
condition  of  the  artery  in  some  of  the  carnivora :  it  has  been  referred  to,  above,  in  the  description 
of  the  humerus. 

As  regards  its  Division.  Occasionally  the  artery  is  divided  for  a  short  distance  at  its  upper 
part  into  two  trunks,  which  are  united  above  and  below.  A  similar  peculiarity  occurs  ia  the 
main  vessel  of  the  lower  limb. 

The  point  of  bifurcation  may  be  above  or  below  the  usual  point,  the  former  condition  being  by 
far  the  most  frecjucnt.  Out  of  481  examinations  recorded  by  Mr.  Quain,  some  made  on  the 
right,  and  some  on  the  left  side  of  the  body,  in  38(1  the  artery  bifurcated  in  its  normal  position. 
In  one  case  only  was  the  place  of  division  lower  than  usual,  being  two  or  three  inches  below  the 
elbow-joint.  "In  94  cases  out  of  481,  or  about  one  in  5^,  there  were  two  arteries  instead  of  one 
in  some  part,  or  in  the  whole  of  the  arm. 

There  appears,  however,  to  be  no  correspondence  between  the  arteries  of  the  two  arms,  with 
respect  to  their  irregular  division;  for  in  si.\ty-one  bodies  it  occurred  on  one  side  only  in  forty- 
throe  ;  on  both  sides,  in  different  positions,  in  thirteen  ;  on  both  sides,  in  the  same  position,  in  five. 

The  point  of  bifurcation  takes  place  at  different  parts  of  the  arm,  being  most  frequent  in  tho 
upper  part,  less  so  in  the  lower  part,  and  least  so  in  the  middle,  the  most  usual  point  for  tho 
application  of  a  ligature;  under  any  of  these  circumstances,  two  large  arteries  would  be  found 
in  the  arm  instead  of  one.  The  most  frecjuent  (in  three  out  of  four)  of  these  peculiarities  is  the 
high  division  of  the  radial.  That  artery  often  arises  from  the  inner  side  of  the  brachial,  and  runs 
pi'rallel  with  the  main  trunk  to  the  elbow,  where  it  crosses  it,  lying  beneath  the  fascia;  or  it  may 
perforate  the  fascia,  and  pass  over  the  artery  immediately  beneath  the  integument. 


SURGICAL    ANATOMY    OF    BRACHIAL    ARTERY.        485 

The  ulnar  sometimes  arises  from  the  brachial  high  up,  and  then  occasionally  leaves  that  vessel 
at  the  lower  part  of  the  arm,  and  descends  towards  the  inner  condyle.  In  the  forearm,  it  gene- 
rally lies  beneath  the  deep  fascia,  superficial  to  the  flexor  muscles ;  occasionally  between  the 
integument  and  deep  fascia,  and  very  rarely  beneath  the  flexor  muscles. 

The  interosseous  artery  sometimes  arises  from  the  upper  part  of  the  brachial  or  axillary  ;  as 
it  passes  down  the  arm,  it  lies  behind  the  main  trunk,  and,  at  the  bend  of  the  elbow,  regains  its 
usual  position. 

In  some  cases  of  high  division  of  the  radial,  the  remaining  trunk  (ulnar-interosseous)  occa- 
sionally passes,  together  with  the  median  nerve,  along  the  inner  margin  of  the  arm  to  the  inner 
condyle,  and  then  passing  from  within  outwards,  beneath  or  through  the  Pronator  Teres,  regains 
its  usual  position  at  the  bend  of  the  elbow. 

Occasionally,  the  two  arteries  representing  the  brachial  are  connected  at  the  bend  of  the  elbow 
by  a  short  transverse  branch,  and  are  even  sometimes  reunited. 

Sometimes,  long  slender  vessels,  vasa  abtrrantia,  connect  the  brachial  or  axillary  arteries 
with  one  of  the  arteries  of  the  forearm,  or  a  branch  from  them.  These  vessels  usually  join  the 
radial. 

Varieties  in  Muscular  Relations.^  The  brachial  artery  is  occasionally  concealed  in  some  part 
of  its  course,  by  muscular  or  tendinous  slips  derived  from  various  sources.  In  the  upper  third 
of  the  arm,  the  brachial  vessels  and  median  nerve  have  been  seen  concealed  to  the  extent  of  three 
inches,  by  a  muscular  layer  of  considerable  thickness,  derived  from  the  Coraco-brachialis,  ■which 
passed  round  to  the  inner  side  of  the  vessel,  and  joined  the  internal  head  of  the  Triceps.  In  the 
lower  half  of  the  arm  the  artery  is  occasionally  concealed  by  a  broad  thin  head  to  the  Bicepa 
muscle.  A  narrow  fleshy  slip  from  the  Biceps  has  been  seen  to  cross  the  artery,  concealing  it 
lor  an  inch  and  a  half,  its  tendon  ending  in  the  aponeurosis  covering  the  Pronator  Teres.  A 
muscular  and  tendinous  slip  has  been  seen  to  arise  from  the  external  bicipital  ridge  by  a  long 
tendon,  cross  obliquely  behind  the  long  tendon  of  the  Biceps,  and  end  in  a  fleshy  belly,  which 
appears  on  the  inner  side  of  the  arm  between  the  Biceps  and  Coraco-brachialis,  passes  down 
along  the  inner  edge  of  the  former,  and  crosses  the  artery  very  obliquely,  so  as  to  lie  in  front  of 
it  three  inches,  and,  finally,  gives  rise  to  a  narrow  flattened  tendon,  which  is  inserted  into  the 
aponeurosis  over  the  Pronator  Teres.  A  tendinous  slip,  arising  from  the  deep  part  of  the  ten- 
don of  the  Pectoralis  Major,  has  been  seen  to  cross  the  artery  obliquely  at  or  below  the  Coraco- 
brachialis,  and  join  the  intermuscular  septum  above  the  inner  condyle.  The  Brachialis  Anticus 
not  unfrequently  projects  at  the  outer  side  of  the  artery,  and  occasionally  overlaps  it,  sending 
inwards,  across  the  artery,  an  aponeurosis  which  binds  the  vessel  down  upon  the  Brachialis  An- 
ticus. Sometimes,  a  fleshy  slip  from  the  muscle  covers  the  vessel,  in  one  case  to  the  extent  of 
three  inches.  In  some  cases  of  high  origin  of  the  Pronator  Teres,  an  aponeurosis  extends  from 
it  to  join  the  Brachialis  Anticus  external  to  the  artery;  a  kind  of  arch  being  thus  formed  under 
which  the  principal  artery  and  median  nerve  pass,  so  as  to  be  concealed  for  half  an  inch  above 
the  transverse  level  of  the  condyle. 

Surgical  Anatomy.  Compression  of  the  brachial  artery  is  required  in  cases  of  amputation 
and  some  other  operations  in  the  arm  and  forearm  ;  and  it  will  be  observed,  that  it  may  be 
eSbcted  in  almost  any  part  of  the  course  of  the  artery.  If  pressure  is  made  in  the  upper  part 
of  the  limb,  it  should  be  directed  from  within  outwards,  and  if  in  the  lower  part,  from  before 
backwards,  as  the  artery  lies  on  the  inner  side  of  the  humerus  above,  and  in  front  of  it  below. 
The  most  favorable  situation  is  near  the  insertion  of  the  Coraco-brachialis. 

The  application  of  a  ligature  to  the  brachial  artery  may  be  required  in  cases  of  wounds  of  the 
vessel,  and  in  some  cases  of  wound  of  the  palmar  arch.  It  is  also  sometimes  necessary  in  cases 
of  aneurism  of  the  brachial,  the  radial,  ulnar,  or  interosseous  arteries.  The  artery  may  be  se- 
cured in  any  part  of  its  course.  The  chief  guides  in  determining  its  position  are  the  surface- 
<  markings  produced  by  the  inner  margin  of  the  Coraco-brachialis  and  Biceps,  the  known  course 
of  the  vessel,  and  its  pulsation,  which  should  be  carefully  felt  for  before  any  operation  is  per- 
formed, as  the  vessel  occasionally  deviates  from  its  usual  position  in  the  arm.  In  whatever 
situation  the  operation  is  performed,  great  care  is  necessary,  on  account  of  the  extreme  thinness 
of  the  parts  covering  the  artery,  and  the  intimate  connection  which  the  vessel  has  throughout  its 
whole  course  with  important  nerves  and  veins.  Sometimes  a  thin  layer  of  muscular  fibre  is  met. 
with  concealing  the  artery  ;  if  such  is  the  case,  it  must  be  cut  across,  in  order  to  expose  the  vessel. 

In  the  upper  third  of  the  arm  the  artery  may  be  exposed  in  the  following  manner:  the  patient 
being  placed  horizontally  upon  a  table,  the  affected  limb  should  be  raised  from  the  side,  and  the 
hand  supinated.  An  incision  about  two  inches  in  length  should  be  made  on  the  ulnar  side  of 
tlie  Coraco-brachialis  muscle,  and  the  subjacent  fascia  cautiously  divided,  so  as  to  avoid  wound- 
ing the  internal  cutaneous  nerve  or  basilic  vein,  which  sometimes  run  on  the  surface  of  the  artery 
as  high  as  the  axilla.  The  fascia  having  been  divided,  it  should  be  remembered,  that  the  ulnar 
and  internal  cutaneous  nerves  lie  on  the  inner  side  of  the  artery,  the  median  on  the  outer  side, 
the  latter  nerve  being  occasionally  superficial  to  the  artery  in  this  situation,  and  that  the  venae 
comites  are  also  in  relation  with  the  vessel,  one  on  either  side.  These  being  carefully  f<eparated, 
the  aneurism  needle  should  be  passed  round  the  artery  from  the  ulnar  to  the  radial  side. 

If  two  arteries  are  present  in  the  arm,  in  consequence  of  a  high  division,  they  are  usually 


See  Struthers's  Avatomical  and  Physiological  Observations. 


486  ARTERIES. 

placed  side  by  side  ;  and  if  they  are  exposed  in  an  operation,  the  surgeon  should  endeavor  to 
ascertain,  by  alternately  pressing  on  each  vessel,  which  of  the  two  communicates  with  the 
wound  or  aneurism,  when  a  ligature  may  be  applied  accordingly  ;  or  if  pulsation  or  hemorrhage 
ceases  only  when  both  vessels  are  compressed,  botii  vessels  may  be  tied,  as  it  may  be  concluded 
that  the  two  communicate  above  the  seat  of  disease,  or  are  reunited. 

It  should  also  be  remembered,  that  two  arteries  may  be  present  in  the  arm  in  a  case  of  high 
division,  and  that  one  of  these  may  be  found  along  the  inner  intermuscular  septum,  in  a  line 
towards  the  inner  condyle  of  the  humerus,  or  in  the  usual  position  of  the  brachial,  but  deeply 
placed  beneath  the  common  trunk  :  a  knowledge  of  these  facts  will  suggest  the  precautions 
necessary  in  every  case,  and  indicate  the  measures  to  be  adopted  when  anamolies  are  met  with. 

In  the  middle  of  the  arm  the  brachial  artery  may  be  exposed  by  making  an  incision  along  the 
inner  margin  of  the  Biceps  muscle.  'I'he  forearm  being  bent  so  as  to  relax  the  muscle,  it  should 
be  drawn  slightly  aside,  and  the  fascia  being  carefully  divided,  the  median  nerve  will  be  exposed 
lying  upon  the  artery  (sometimes  beneath) ;  this  being  drawn  inwards  and  the  muscle  outwards, 
the  artery  should  be  separated  from  its  accompanying  veins  and  secured.  In  this  situation  the 
inferior  profunda  may  be  mistaken  for  the  main  trunk,  especially  if  enlarged,  from  the  collateral 
circulation  having  become  established  ;  this  may  be  avoided  by  directing  the  incision  externally 
towards  the  Biceps  rather  than  inwards  or  backwards  towards  the  Triceps. 

The  lower  part  of  the  brachial  artery  is  of  extreme  interest  in  a  surgical  point  of  view,  on 
account  of  the  relation  which  it  bears  to  the  veins  most  commonly  opened  in  venesection.  Of 
these  vessels,  the  median  basilic  is  the  largest  and  most  prominent,  and,  consequently,  the  one 
usually  selected  for  the  operation.  It  should  be  remembered,  that  this  vein  runs  parallel  with  the 
brachial  artery,  from  which  it  is  separated  by  the  bicipital  fascia,  and  that  in  no  case  should  this 
vessel  be  selected  for  venesection,  except  in  a  part  which  is  not  in  contact  with  the  artery. 

Collateral  Circulation.  After  the  application  of  a  ligature  to  the  brachial  artery  in  the 
upper  third  of  the  arm,  the  circulation  is  carried  on  by  branches  from  the  circumflex  and  sub- 
scapular arteries,  anastomosing  with  ascending  branches  from  the  superior  profunda  If  the 
brachial  is  tied  below  the  origin  of  the  profunda  arteries  the  circulation  is  maintained  by  the 
branches  of  the  profunda?,  anastomosing  with  the  recurrent  radial,  ulnar,  and  interosseous  arteries. 
In  two  cases  described  by  Mr.  South,'  in  which  the  brachial  artery  had  been  tied  some  time  pre- 
viously, in  one  "  a  long  portion  of  the  artery  had  been  obliterated,  and  sets  of  vessels  are  descend- 
ing on  either  side  from  above  the  obliteration,  to  be  received  into  others  which  ascend  in  a  similar 
manner  from  below  it.  In  the  other,  the  obliteration  is  less  extensive,  and  a  single  curved  artery 
about  as  big  as  a  crow-quill  passes  from  the  upper  to  the  lower  open  part  of  the  artery." 

The  branches  of  the  brachial  artery  are  the 

Superior  profunda.  Inferior  profunda. 

Nutrient  artery.  Anastomotica  magna. 

Muscular. 

The  superior  profunda  arises  from  the  inner  and  back  part  of  the  brachial, 
opposite  the  lower  border  of  the  Teres  Major,  and  passes  backwards  to  tiie  in- 
terval between  the  outer  and  inner  heads  of  the  Triceps  muscle,  accompanied 
by  the  musculo-spiral  nerve ;  it  winds  round  the  back  part  of  the  shaft  of  the 
humerus  in  the  spiral  groove,  between  the  Triceps  and  the  bone,  and  descends 
on  the  outer  side  of  the  arm  to  the  space  between  the  Brachialis  Anticus  and 
Supinator  Longus,  as  far  as  the  elbow,  where  it  anastomoses  with  the  recurrent 
branch  of  the  radial  artery.  It  supplies  the  Deltoid,  Coraco-brachialis,  and. 
Triceps  muscles,  and  whilst  in  the  groove  between  the  Triceps  and  the  bone,  it 
gives  off  the  posterior  articular  artery,  which  descends  perpendicularly  between 
the  Triceps  and  the  bone,  to  the  back  part  of  the  elbow-joint,  where  it  anasto- 
moses with  the  interosseous  recurrent  branch,  and,  on  the  inner  side  of  the  arm, 
with  the  posterior  ulnar  recurrent,  and  with  the  anastomotica  magna  or  inferior 
profunda  (Fig.  288). 

The  nutrient  ar^en/of  the  shaft  of  the  humerus  arises  from  the  brachial,  about 
the  middle  of  the  arm.     Passing  downwards,  it  enters  the  nutrient  canal  of  _. 
that  bone,  near  the  insertion  of  the  Coraco-brachialis  muscle.  H 

The  inferior  profunda^  of  small  size,  arises  from  the  brachial,  a  little  below 
the  middle  of  the  arm ;  piercing  the  internal  intermuscular  sejitum,  it  descends 
on  the  surface  of  the  inner  head  of  the  Triceps  muscle,  to  the  space  between  the  M 

'  Chelius's  Surgery,  vol.  ii.  pp.  254.  See  also  White's  engraving  referred  to  by  Mr.  South,  of 
the  anastomosing  branches  after  ligature  of  the  brachial,  in  White's  Cases  in  Surgery.  Porta 
also  gives  a  case  (with  drawings)  of  the  circulation  after  ligature  of  both  brachial  and  radial.— 
AUerazioni  Patologiche  delle  Arlerie. 


RADIAL. 


487 


BaOaI  Rt«itrrrtn 


inner  condyle  and  olecranon,  accompanied  bj  the  ulnar  nerve,  and  terminates 
by  anastomosing  with  the  posterior  ulnar  recurrent,  and  anastomotica  magna. 

The  anastomotica  magna  arises  from  the  brachial,  about  two  inches  above  the 
elbow-joint.     It  passes  trans- 
versely    inwards      upon     the       ^io*  286. — The  Surp:ical  Anatomy  of  the  Radial  and 
Brachialis  Anticus,  and  pierc-  U'"^'"  ^>-teries. 

ing  the  internal  intermuscular 
septum,  winds  round  the  back 
part  of  the  humerus  between 
the  Triceps  and  the  bone, 
forming  an  arch  above  the 
olecranon  fossa,  by  its  junc- 
tion with  the  posterior  articu- 
lar branch  of  the  superior 
profunda.  As  this  vessel  lies 
on  the  Brachialis  Anticus,  an 
offset  passes  between  the  in- 
ternal condyle  and  olecranon, 
which  anastomoses  with  the 
inferior  profunda  and  poste- 
rior ulnar  recurrent  arteries. 
Other  branches  ascend  to  join 
the  inferior  profunda;  and 
some  descend  in  front  of  the 
inner  condyle,  to  anastomose 
with  the  anterior  ulnar  re- 
current. 

The  muscular  are  three  or 
four  large  branches,  which 
are  distributed  to  the  muscles 
in  the  course  of  the  artery. 
They  supply  the  Coraco- 
brachialis,  Biceps,  and  Brachi- 
alis Anticus  muscles. 

Radial  Artery. 

The  Radial  Artery  appears, 
from  its  direction,  to  be  the 
continuation  of  the  brachial, 
but,  in  size,  it  is  smaller  than 
the  ulnar.  It  commences  at 
the  bifurcation  of  the  brachial, 
just  below  the  bend  of  the 
elbow,  and  passes  along  the 
radial  side  of  the  forearm  to 
the  wrist ;  it  then  winds  back- 
wards, round  the  outer  side 
of  the  carpus,  beneath  the  ex- 
tensor tendons  of  the  thumb, 
and,  finally,  passes  forwards 
between  the  two  heads  of  the 
first  Dorsal  Interosseous  mus- 
cle, into  the  palm  of  the  hand, 
where  it  crosses  the  metacar- 
pal bones  to  the  ulnar  border 
of  the  hand,  to  form  the  deep 


-JDry/  hxLnaA  if  PTjtfW 


SuperfieiaUt  Vila 


488 


ARTERIES. 


palmar  arch.  At  its  termination,  it  inosculates  witli  the  deep  branch  of  the 
ulnar  artery.  The  relations  of  this  vessel  may  thus  be  conveniently  divided 
into  three  parts,  viz.,  in  front  of  the  forearm,  at  the  back  of  the  wrist,  and  in 
the  hand. 

Relations.  In  the  forearm,  this  vessel  extends  from  opposite  the  neck  of  the 
radius,  to  the  fore-part  of  the  styloid  process,  being  placed  to  the  inner  side  of 
the  shaft  of  the  bone,  above,  and  in  front  of  it  below.  It  is  superficial  throughout 
its  entire  extent,  being  covered  by  the  integument,  the  superficial  and  deep  fascia, 
and  slightly  overlapped  above  by  the  Supinator  Longus.  In  its  course  down- 
wards, it  lies  upon  the  tendon  of  the  Biceps,  the  Supinator  Brevis,  the  Pronator 
Radii  Teres,  the  radial  origin  of  the  Flexor  Sublimis  Digitorum,  the  Flexor 
Longus  Pollicis,  the  Pronator  Quadratus,  and  the  lower  extremity  of  the  radius. 
In  the  upper  third  of  its  course,  it  lies  between  the  Supinator  Longus  and  the 
Pronator  Radii  Teres;  in  its  lower  two-thirds,  between  the  tendons  of  the 
Supinator  Longus  and  the  Flexor  Carpi  Radialis.  The  radial  nerve  lies  along 
the  outer  side  of  the  artery,  in  the  middle  third  of  its  course;  and  some  fila- 
ments of  the  musculo-cutaneous  nerve,  after  piercing  the  deep  fascia,  run  along 
the  lower  part  of  the  artery  as  it  winds  round  the  wrist.  The  vessel  is  accom- 
panied by  venae  comites  throughout  its  whole  course. 

Plan  of  the  Relations  of  the  Radial  Artery  in  the  Forearm. 

In  front. 

Integument — superficial  and  deep  fasciae. 

Supinator  Longus. 


Inner  side. 
Pronator  Radii  Teres. 
Flexor  Carpi  Radialis. 


Outer  side. 
Supinator  Longus. 
Radial  nerve  (middle  third). 


Behind. 
Tendon  of  Biceps. 
Supinator  Brevis. 
Pronator  Radii  Teres. 
Flexor  Sublimis  Digitorum. 
Flexor  Longus  Pollicis. 
Pronator  Quadratus. 
Radius. 

At  the  wrist,  as  it  winds  round  the  outer  side  of  the  carpus,  from  the  styloid 
process  to  the  first  interosseous  space,  it  lies  upon  the  external  lateral  ligament, 
being  covered  by  the  extensor  tendons  of  the  thumb,  subcutaneous  veins,  some 
filaments  of  the  radial  nerve,  and  the  integument.  It  is  accompanied  by  two 
veins,  and  a  filament  of  the  musculo-cutaneous  nerve. 

In  the  hand,  it  passes  from  the  upper  end  of  the  finst  interosseous  space,  be- 
tween the  heads  of  the  Abductor  Indicis  or  first  Dorsal  Interosseous  muscle 
transversely  across  the  palm,  to  the  base  of  the  metacarpal  bone  of  the  little 
finger,  where  it  inosculates  witli  the  communicating  branch  from  the  ulnar 
artery,  forming  the  deep  palmar  arch.  It  lies  upon  the  carpal  extremities  of 
the  metacarpal  bones  and  the  Interossei  muscles,  being  covered  by  the  flexor 
tendons  of  the  fingers,  the  Lumbricales,  the  muscles  of  the  little  finger,  and 
the  Flexor  Brevis  Pollicis,  and  is  accompanied  by  the  deep  branch  of  the  ulnar 
nerve. 

rccuUnrifipH.  The  origin  of  the  radial  artery  varies  in  the  proportion  nearly  of  one  in  eipht 
cases.  In  one  case  iho  origin  was  lower  than  usual.  In  the  other  cases,  the  upper  part  of  the 
brachial  was  a  more  freciuent  source  of  oriijin  than  the  axillary.  The  variations  in  the  position 
of  this  vessel  in  the  arm.  and  at  the  bond  of  the  elbow,  have' been  already  mentioned.  In  the 
forearm  it  deviates  less  frecjuently  from  its  position  than  the  ulnar.  It'has  been  found  lying 
over  the  fascia,  instead  of  beneath  it.  It  has  also  been  observed  on  the  surface  of  the  Supina- 
tor Longus.  instead  of  along  its  inner  border:  and  in  turning  round  the  wrist,  it  has  been  seen 
lying  over,  instead  of  beneath,  the  extensor  tendons. 


BRANCHES    OF    RADIAL.  489 

Surgical  Anatomy.  The  operation  of  tying  the  radial  artery  is  required  in  cases  of  wounds 
either  of  its  trunk,  or  of  some  of  its  branches,  or  for  aneurism ;  and  it  will  be  observed,  that  the 
vessel  may  be  easily  exposed  in  any  part  of  its  course  through  the  forearm.  The  operation  in 
the  middle  or  inferior  third  of  the  forearm  is  easily  performed ;  but  in  the  upper  third,  near  the 
elbow,  it  is  attended  with  some  difficulty,  from  the  greater  depth  of  the  vessel,  and  from  its 
being  overlapped  by  the  Supinator  Longus  aud  Pronator  Teres  muscles. 

To  tie  the  artery  in  the  upper  third,  an  incision  three  inches  in  length  should  be  made  through 
the  integument,  from  the  bend  of  the  elbow  obliquely  downwards  and  outwards,  on  the  radial 
side  of  the  forearm,  avoiding  the  branches  of  the  median  vein ;  the  fascia  of  the  arm  being 
divided,  and  the  Supinator  I^ongus  drawn  a  little  outwards,  the  artery  will  be  exposed.  'J'he 
vena?  comites  should  be  carefully  separated  from  the  vessel,  and  the  ligature  passed  from  the 
radial  to  the  ulnar  side. 

In  the  middle  third  of  the  forearm  the  artery  may  be  exposed  by  making  an  incision  of  similar 
length  on  the  inner  margin  of  the  Supinator  Longus.  In  this  situation,  the  radial  nerve  lies  in 
close  relation  with  the  outer  side  of  the  artery,  and  should,  as  well  as  the  veins,  be  carefully 
avoided. 

In  the  lower  third,  the  artery  is  easily  secured  by  dividing  the  integument  and  fascise  in  the 
interval  between  the  tendons  of  the  Supinator  Longus  and  Flexor  Carpi  Radialis  muscles. 

The  branches  of  the  radial  artery  may  be  divided  into  three  groups,  corres- 
ponding with  the  three  regions  in  which  the  vessel  is  situated: — 


TEadial  recurrent. 
In  the  J  Muscular. 
Forearm.  J  Superficialis  volse. 
Anterior  carpal. 

Hand, 


Wrist. 

Princeps  pollicis. 
Radialis  indicis. 
Perforating. 
Interosseous. 


'  Posterior  carpal. 
Metacarpal. 
Dorsales  pollicis. 
Dorsalis  indicis. 


The  radial  recurrent  is  given  off  immediately  below  the  elbow.  It  ascends 
between  the  branches  of  the  musculo-spiral  nerve,  lying  on  the  Supinator  Brevis, 
and  then  between  the  Supinator  Longas  and  Brachialis  Anticus,  supplying  these 
muscles  and  the  elbow-joint,  and  anastomosing  with  the  terminal  branches  of  the 
superior  profunda. 

The  muscular  branches  are  distributed  to  the  muscles  on  the  radial  side  of  the 
forearm. 

The  superficialis  volse  arises  from  the  radial  artery,  just  where  this  vessel  is 
about  to  wind  round  the  wrist.  Running  forward's,  it  passes  between  the  mus- 
cles of  the  thumb,  which  it  supplies,  and  sometimes  anastomoses  with  the  termi- 
nation of  the  ulnar  artery,  completing  the  superficial  palmar  arch.  This  vessel 
varies  considerably  in  size,  usually  it  is  very  small,  and  terminates  in  the  mus- 
cles of  the  thumb;  sometimes  it  is  as  large  as  the  continuation  of  the  radial. 

The  carpal  branches  supply  the  joints  of  the  wrist.  The  anterior  carpal  is  a 
small  vessel  which  arises  from  the  radial  artery  near  the  lower  border  of  the 
Pronator  Quadratus,  and  running  inwards  in  front  of  the  radius,  anastomoses 
with  the  anterior  carpal  branch  of  the  ulnar  artery.  From  the  arch  thus  formed, 
branches  descend  to  supply  the  articulations  of  the  wrist. 

^\iQ  posterior  carpal  is  a  small  vessel  which  arises  from  the  radial  .artery  be- 
neath the  extensor  tendons  of  the  thumb;  crossing  the  carpus  transversely  tc 
tlie  inner  border  of  the  hand,  it  anastomoses  with  the  posterior  carpal  branch 
of  the  ulnar.  It  sends  branches  upwards,  which  anastomose  with  the  termina- 
tion of  the  anterior  interosseous  artery ;  other  branches  descend  to  the  meta- 
carpal spaces;  they  are  the  dorsal  interosseous  arteries  for  the  third  and  fourth 
interosseous  spaces;  they  anastomose  with  the  posterior  perforating  branches 
from  the  deep  palmar  arch. 

The  metacarpal  {first  dorsal  inter'osseous  branch)  arises  beneath  the  extensor 
tendons  of  the  thumb,  sometimes  with  the  posterior  carpal  artery;  running  for- 
wards on  the  second  dorsal  interosseous  muscle,  it  communicates,  behind,  with 
the  corresponding  perforating  branch  of  the  deep  palmar  arch;  and,  in  front. 


490 


ARTERIES. 


inosculates  with  the  digital  branch  of  the  suy)erficial  palmar  arch,  and  supplies 
the  adjoining  sides  of  the  index  and  middle  fingers. 

The  dorsaks  pollicis  are  two  small  vessels  which  run  along  the  sides  of  the 
dorsal  aspect  of  the  thumb.  They  arise  separately,  or  occasionally  by  a  com- 
mon trunk,  near  the  base  of  the  first  metacarpal  bone. 

The  dorsalis  indicis^  also  a  small  branch,  runs  along  the  radial  side  of  the  back 
of  the  index  finger,  sending  a  few  branches  to  the  Abductor  Indicis. 

The  princeps  pollicis  arises  from  the  radial  just  as  it  turns  inwards  to  the  deep 
part  of  the  hand;  it  descends  between  the  Abductor  Indicis  and  Adductor  Pol- 
licis, along  the  ulnar  side  of  the  metacarpal  bone  of  the  thumb,  to  the  base  of 
the  first  phalanx,  where  it  divides  into  two  branches,  which  run  along  the  sides 

of  the  palmar  aspect  of  the  thumb, 


Fig.  287. — Ulnar  and  Radial  Arteries.  Deep  View. 


RaJia/ 
JUeitrre»t 


Awhiiar  Vinar 
Itieurreiit 


■rotftrur  VlfUtr 
Jttfttm$t* 


erp  I  ranch  "J'  Ulnar 


and  form  an  arch  on  the  under  sur- 
face of  the  last  phalanx,  from  which 
branches  are  distributed  to  the  in- 
tegument and  cellular  membrane  of 
the  thumb. 

The  radialis  indicis  arises  close  to 
the  preceding,  descends  between  the 
Abductor  Indicis  and  Adductor  Pol 
licis,  and  runs  along  the  radial  side 
of  the  index  finger  to  its  extremity, 
where  it  anastomoses  with  the  col- 
lateral digital  artery  from  the  super- 
ficial palmar  arch.  At  the  lower 
border  of  the  Adductor  Pollicis,  this 
vessel  anastomoses  with  the  princeps 

Eollicis,  and  gives  a  communicating 
ranch   to  the    superficial    palmar 
arch. 

The  perforating  arteries,  three  in 
number,  pass  backwards  between 
the  heads  of  the  last  three  Dorsal 
Interossei  muscles,  to  inosculate  with 
the  dorsal  interosseous  arteries. 

The  palmar  inter osseotis,  three  or 
four  in  number,  are  branches  of  the 
deep  palmar  arch;  they  run  for- 
wards upon  the  Interossei  muscles, 
and  anastomose  at  the  clefts  of  the 
fingers  with  the  digital  branches 
of  the  superficial  arch. 

Ulnar  Artery. 

Tlie  Ulnar  Artery,  the  larger  of 
the  two  subdivisions  of  the  brachial, 
commences  a  little  below  the  bend 
of  the  elbow,  and  crosses  the  inner 
side  of  the  forearm  obliquely  in- 
wards, to  the  commencement  of  its 
lower  half;  it  then  runs  along  its 
ulnar  border  to  the  wrist,  crosses 
the  annular  ligament  on  the  radial 
side  of  the  pisiform  bone,  and  passes 
across  the  palm  of  the  hand,  forming 


SUPERFICIAL    PALMAR    ARCH.  491 

the  superficial  palmar  arch,  which  sometimes  terminates  by  inosculating  with 
the  superficialis  volse. 

Relations  in  the  Forearm.  In  its  upper  half,  it  is  deeply  seated,  being  covered 
by  all  the  superficial  flexor  muscles,  excepting  the  Flexor  Carpi  Ulnaris;  it  is 
crossed  by  the  median  nerve,  which  lies  to  its  inner  side  for  about  an  inch,  and 
it  lies  upon  the  Brachialis  Anticus  and  Flexor  Profundus  Digitorum  muscles. 
In  the  lovjer  half  of  the  forearm,  it  lies  upon  the  Flexor  Profundus,  being 
covered  by  the  integument,  the  superficial  and  deep  fascia,  and  is  placed 
between  the  Flexor  Carpi  Ulnaris  and  Flexor  Sublimis  Digitorum  muscles.  It 
is  accompanied  by  two  venae  comites ;  the  ulnar  nerve  lies  on  its  inner  side  for 
the  lower  two-thirds  of  its  extent,  and  a  small  branch  from  the  nerve  descends 
on  the  lower  part  of  the  vessel  to  the  palm  of  the  hand. 

Plan  of  Relations  of  the  Ulnar  Artery  in  the  Forearm. 

In  front. 
Superficial  flexor  muscles.       |  ^         ^^^^^ 
Median  nerve.  )      ^^ 

Superficial  and  deep  fasciiE.        Lower  half. 

Inner  sid.  /  \  Outer  .tide. 

Flexor  Carpi  Ulnaris.  /       Ulnar       \         Flexor  Sublimis  Digitorum 

Ulnar  nerve  (lower  two-thirds). 


Behind. 
Brachialis  Anticus. 
Flexor  Profundus  Digitorum. 

At  the  wrist  (Fig.  286),  the  ulnar  artery  is  covered  by  the  integument  and 
fascia,  and  lies  upon  the  anterior  annular  ligament.  On  its  inner  side  is  the 
pisiform  bone.  The  ulnar  nerve  lies  at  the  inner  side,  and  somewhat  behind 
the  artery. 

In  the  palm  of  the  hand,  the  continuation  of  the  ulnar  artery  is  called  the 
superficial  palmar  arch  ;  it  passes  obliquely  outwards  to  the  interspace  between 
the  ball  of  the  thumb  and  the  index  finger,  where  it  occasionally  anastomoses 
with  the  superficialis  volaa,  and  a  branch  from  the  radialis  indicis,  thus  completing 
the  arch.  The  convexity  of  this  arch  is  directed  towards  the  fingers,  its  con- 
cavity towards  the  muscles  of  the  thumb.  If  the  thumb  be  put  at  right  angles 
to  the  hand,  the  position  of  the  superficial  palmar  arch  will  be  roughly  indi- 
cated by  a  line  drawn  along  the  lower  margin  of  the  thumb  across  the  palm  of 
the  hand ;  the  deep  palmar  arch  is  situated  about  a  finger's  breadth  nearer  to 
the  carpus. 

The  superficial  palmar  arch  is  covered  by  the  Palmaris  Brevis,  the  palmar 
fascia,  and  integument ;  and  lies  upon  the  annular  ligament,  the  muscles  of  the 
little  finger,  the  tendons  of  the  superficial  flexor,  and  the  divisions  of  the 
median  and  ulnar  nerves,  the  latter  accompanying  the  artery  a  short  part  of  its 
course. 

Relations  of  the  Superficial  Palmar. Arch. 

In  front.  f  \  j^^;^-^^ 

Integument.  ^uinar^  Annular  ligament. 

Pa  mans  Brevis,  \       Hand.       /  origin  of  muscles  of  little  finger. 

Palmar  fascia.  \  /  Superficial  flexor  tendons. 

— -^  Divisions  of  median  and  ulnar  nerves. 

Peculiarities.  The  ulnar  artery  has  been  found  to  vary  in  its  origin  nearly  in  the  proportion 
of  one  in  thirteen  cases,  in  one  case  arising  lower  than  usual,  about  two  or  three  incnes  beh)W 


492  ARTERIES. 

the  elbow,  and  in  all  the  other  cases  much  higher,  the  brachial  being  a  more  frequent  source  of 
origin  than  the  axillary.  .        .  . 

Variations  in  the  position  of  this  vessel  are  more  frequent  than  in  the  radial.  When  its  origm 
is  normal,  the  course  of  the  vessel  is  rarely  changed.  When  it  arises  high  up,  it  is  almost  in- 
variably superficial  to  the  flexor  muscles  in  the  forearm,  lying  commonly  beneath  the  fascia,  more 
rarely  between  the  fascia  and  integument.  In  a  few  cases,  its  position  was  subcutaneous  in  the 
upper  part  of  the  forearm,  subaponeurotic  in  the  lower  part. 

Surgical  Anatomu.  The  application  of  a  ligature  to  this  vessel  is  required  in  cases  of  wound 
of  the  artery,  or  of  "its  branches,  or  in  consequence  of  aneurism.  In  the  upper  half  of  the  fore- 
arm, the  artery  is  deeply  seated  beneath  the  superficial  flexor  muscles,  and  their  division  would 
be  requisite  in  a  case  of  recent  wound  of  the  artery  in  this  situation,  in  order  to  secure  it,  but 
under  no  other  circumstances.  In  the  middle  and  lower  third  of  the  forearm,  this  vessel  may  lie 
easily  secured  by  making  an  incision  on  the  radial  side  of  the  tendon  of  the  Flexor  Carpi  Ulna- 
ris ;  the  deep  fascia  being  divided,  and  the  Flexor  Carpi  Ulnaris  and  its  companion  muscle,  the 
Flexor  Sublimis.  being  separated  from  each  other,  the  vessel  will  be  exposed,  accompanied  by  its 
ven£B  comites,  the  ulnar  nerve  lying  on  its  inner  side.  The  veins  being  separated  from  the  artery, 
the  ligature  should  be  passed  from  the  ulnar  to  the  radial  side,  taking  care  to  avoid  the  ulnar  nerve. 

The  branches  of  the  ulnar  artery  may  be  arranged  into-the  following  groups : — 

'  Anterior  ulnar  recurrent. 
Posterior  ulnar  recurrent. 
Forearm.  {  j  .  j  Anterior  interosseous, 

interosseous.  |  pogtenor  interosseous. 

[_  Muscular. 
TTT  •  /    j  Anterior  carpal. 
*  I  Posterior  carpal. 
TT     -J    \  Deep  or  communicating  branch. 
nana.   I  j)ig^tal. 

The  anterior  ulnar  recurrent  (Fig,  287)  arises  immediately  below  the  elbow- 
joint,  passes  upwards  and  inwards  between  the  Brachialis  Anticusand  Pronator 
Eadii  Teres,  supplies  those  muscles,  and,  in  front  of  the  inner  condyle,  anasto- 
moses with  the  anastomotica  magna  and  inferior  profunda. 

The  posterior  ulnar  recurrent  is  much  larger,  and  arises  somewhat  lower  than 
the  preceding.  It  passes  backwards  and  inwards,  beneath  the  Flexor  Sublimis, 
and  ascends  behind  the  inner  condyle  of  the  humerus.  In  the  interval  between 
this  process  and  the  olecranon,  it  lies  beneath  the  Flexor  Carpi  Ulnaris,  ascend- 
ing between  the  heads  of  that  muscle,  beneath  the  ulnar  nerve ;  it  supplies  the 
neighboring  muscles  and  joint,  and  anastomoses  with  the  inferior  profunda, 
anastomotica  magna,  and  interosseous  recurrent  arteries  (Fig.  288). 

The  interosseous  artery  (Fig.  287)  is  a  short  trunk,  about  an  inch  in  length,  and 
of  considerable  size,  which  arises  immediately  below  the  tuberosity  of  the 
radius,  and,  passing  backwards  to  the  upper  border  of  the  interosseous  mem- 
brane, divides  into  two  branches,  the  anterior  and  posterior  interosseous. 

The  anterior  interosseous  passes  down  the  forearm  on  the  anterior  surface  of 
the  interosseous  membrane,  to  which  it  is  connected  by  a  thin  aponeurotic  arch. 
It  is  accompanied  by  the  interosseous  branch  of  the  median  nerve,  and  over- 
lapped by  the  contiguous  margins  of  the  Flexor  Profundus  Digitorum  and 
Flexor  Longus  Pollicis  muscles,  giving  off  in  this  situation  muscular  branches, 
and  the  nutrient  arteries  of  the  radius  and  ulna.  At  the  upper  border  of  the 
Pronator  Quadratus,  a  branch  descends  in  front  of  that  muscle,  to  anastomose 
in  front  of  the  carpus 'with  branches  from  the  anterior  carpal  and  deep  palmar 
arch.  The  continuation  of  the  artery  passes  behind  the  Pronator  Quadratus 
(Fig.  288),  and,  piercing  the  interosseous  membrane,  descends  to  the  back  of  the 
wrist,  wlierc  it  anastomoses  with  the  posterior  interosseous  and  the  posterior 
carpal  branches  of  the  radial  and  ulnar  arteries.  The  anterior  interosseous 
gives  off  a  long,  slender  branch,  which  accompanies  the  median  nerve,  and 
gives  offsets  to  its  substance.  This,  the  median  artery^  is  sometimes  much  en- 
larged. 

The  posterior  interosseous  artery  passes  backwards  through  the  interval  between 
the  oblique  ligament  and  the  upper  border  of  the  interosseous  membrane,  and 


SUPERFICIAL    PALMAR    ARCH. 


493 


runs  down  the  back  part  of  the  forearm  between  the  superficial  and  deep  layer 
of  muscles,  to  both  of  which  it  distributes  branches.  Descending  to  the  back 
of    the   wrist,   it   anastomoses 


288. — Arteries  of  the  Back  of  the  Forearm  and  Hand, 

/ VtreeTidinff  Bvnnch  froait 

Swjj  e  rio  r  Profu  n  da 


Anrtsln  nioflftt 
Mogna 


teriar  JiiferoMteout 


with  the  termination  of  the 
anterior  interosseous,  and  with 
the  posterior  carpal  branches 
of  the  radial  and  ulnar  arteries. 
This  artery  gives  off,  near  its 
origin,  the  interosseous  recurreyit 
branch,  a  large  vessel,  which 
ascends  to  the  interval  between 
the  external  condyle  and  ole- 
cranon, beneath  the  Anconeus 
and  Supinator  Brevis,  anasto- 
mosing with  a  branch  from  the 
superior  profunda,  and  with  the 
posterior  ulnar  recurrent,  and 
anastomotica  magna. 

The  muscular  branches  are 
distributed  to  the  muscles  along 
the  ulnar  side  of  the  forearm. 

The  carpal  branches  are  in- 
tended for  the  supply  of  the 
wrist-joint. 

The  anterior  carpal  is  a  small 
vessel  which  crosses  the  front 
of  the  carpus  beneath  the  ten- 
dons of  the  Flexor  Profundus, 
and  inosculates  with  a  corres- 
ponding branch  of  the  radial 
artery. 

The  posterior  carpal  arises 
immediately  above  the  pisiform 
bone,  winding  backwards  be- 
neath the  tendon  of  the  Flexor 
Carpi  Ulnaris ;  it  gives  off  a 
branch  which  passes  across  the 
dorsal  surface  of  the  carpus  be- 
neath the  extensor  tendons,  an- 
astomosing with  a  correspond- 
ing branch  of  the  radial  artery, 
and  forming  the  posterior  car- 
pal arch  ;  it  is  then  continued 
along  the  metacarpal  bone  of 
the  little  finger,  forming  its 
dorsal  branch. 

The  deep  or  communicating 
branch  (Fig.  287),  arises  at  the 
commencement  of  the  palmar 
arch,  and  passes  deeply  inwards 
between  the  Abductor  Minimi 

Digiti  and  Flexor  Brevis  Minimi  Digiti,  near  their  origins;  it  anastomoses  with 
the  termination  of  the  radial  artery,  completing  the  deep  palmar  arch. 

The  digital  branches  (Fig.  286),  four  in  number,  are  given  off  from  the  con- 
vexity of  the  superficial  palmar  arch.  They  supply  the  ulnar  side  of  the  little 
finger,  and  the  adjoining  sides  of  the  little,  ring,  middle,  and  index-fingers  ;  the 
radial  side  of  the  index-finger  and  thumb  being  supplied  from  the  radial  artery. 


IT§gtfrei}r  Carpal 
(  Ulnar) 


^erntinntlon     •/* 

\A  II  teriorlnUrotseoi 


Tosferior  Cai-pal 
(Radial ) 


DcmaUx  PolUn 
Dorsalit  Jitdiela 


494  ARTERIES. 

The  digital  arteries  at  first  lie  superficial  to  the  flexor  tendons,  but  as  thej  pass 
forwards  with  the  digital  nerves  to  the  clefts  between  the  fingers,  thej  lie  be- 
tween them,  and  are  there  joined  by  the  interosseous  branches  from  the  deep 
palmar  arch.  The  digital  arteries  on  the  sides  of  the  fingers  lie  beneath  the 
digital  nerves ;  and,  aljout  the  middle  of  the  last  phalanx,  the  two  branches  for 
each  finger  form  an  arch,  from  the  convexity  of  which  branches  pass  to  supply 
the  matrix  of  the  nail. 

The  Descending  Aorta. 

The  Descending  Aorta  is  divided  into  two  portions,  the  Thoracic,  and  Abdomi- 
nal, in  correspondence  with  the  two  great  cavities  of  the  trunk  in  which  it  is 
situated. 

The  Thoracic  Aorta  commences  at  the  lower  border  of  the  fourth  dorsal  ver- 
tebra, on  the  left  side,  and  terminates  at  the  aortic  opening  in  the  Diaphragm, 
in  front  of  the  last  dorsal  vertebra.  At  its  commencement,  it  is  situated  on  the 
left  side  of  the  spine ;  it  approaches  the  median  line  as  it  descends ;  and,  at  its 
termination,  lies  directly  in  front  of  the  column.  The  direction  of  this  vessel 
being  influenced  by  the  spine,  upon  which  it  rests,  it  describes  a  curve  which 
is  concave  forwards  in  the  dorsal  region.  As  the  branches  given  off  from  it 
are  small,  the  diminution  in  the  size  of  the  vessel  is  inconsiderable.  It  is  con- 
tained in  the  back  part  of  the  posterior  mediastinum,  being  in  relation,  in  fronts 
from  above  downwards,  with  the  left  pulmonary  artery,  the  left  bronchus,  the 
pericardium,  and  the  oesophagus;  behindj  with  the  vertebral  column,  and  the 
vena  azygos  minor ;  on  the  right  side,  with  the  vena  azygos  major,  and  thoracic 
duct;  on  the  left  side,  with  the  left  pleura  and  lung.  The  oesophagus,  with  its 
accompanying  nerves,  lies  on  the  right  side  of  the  aorta  above:  in  front  of  the 
artery,  in  the  middle  of  its  course ;  whilst,  at  its  lower  part,  it  is  on  the  left  si4e, 
on  a  plane  anterior  to  it. 

Plan  of  the  Relations  of  the  Thoracic  Aorta. 

In  front. 
Left  Pulmonary  artery. 
Left  Bronchus. 
Pericardium. 
CEsophagus. 

Riglxt  side.  /  \  Left  side. 

CEsophagus  (above).  /     Timracic     \  Pleura. 

Vena  azygos  major.  1       Aorta.        )  Left  lung. 

Thoracic  duct.  V  /  CEsophagus  (below). 

Behind. 
Vertebral  column. 
Vena  azygos  minor. 

Surgical  Anatomy.  The  student  should  now  consider  the  effects  likely  to  be  produced  by 
aneurMm  of  the  thoracic  aorta,  a  disease  of  common  occurrence.  When  we  consider  the  great 
depth  of  the  vessel  from  the  surface,  and  the  number  of  important  structures  which  surround  it 
on  every  side,  it  may  be  easily  conceived  what  a  variety  of  obscure  symptoms  may  arise  from 
disease  of  this  part  of  the  arterial  system,  and  how  they  may  l)e  liable  to  be  mistaken  for  those 
of  other  affections.  Aneurism  of  the  thoracic  aorta  most  usually  extends  backwards,  along  the 
left  side  of  the  spine,  producing  absorption  of  the  bodies  of  the  vertebraj,  with  curvature  of  the 
spine;  whilst  the  irritation  or  prossure  on  the  cord  will  give  rise  to  pain,  either  in  the  chest, 
back,  or  loins,  with  radiatinc:  pnin  in  the  left  upper  intercostal  spaces,  from  pressure  on  the 
intercostal  nerves;  at  the  same  time,  the  tumor  may  project  backwards  on  each  side  of  the  spine, 
beneath  the  integument,  as  a  pulsating  swelling,  simulating  abscess  connected  with  diseased  bone; 
or  it  may  displace  the  oesophagus,  and  compress  the  lung  on  one  or  the  other  side.  If  the  tumor 
extend  forward,  it  may  press  upon  and  displace  the  heart,  giving  rise  to  palpitation  and  other 
symptoms  of  di.sease  of  that  organ  ;  or  it  may  displace,  or  even  compress,  the  oesophagus,  caus- 
ing pain  and  difficulty  of  swallowing,  as  in  stricture  of  that  tube,  and  ultimately  even  open  into 
it  by  ulceration,  producing  fatal  hemorrhage.     If  the  disease  make  way  to  either  side,  it  may 


I 


H 


BRANCHES    OF    THE    THORACIC    AORTA.  495 

press  upon  the  thoracic  duct;  or  it  may  burst  into  the  pleural  cavity,  or  into  the  trachea  or 
lung ;  and  lastly,  it  may  open  into  the  posterior  mediastinum. 

The  aorta  is,  comparatively  often,  found  to  be  obliterated  at  a  particular  spot,  viz.,  at  the 
lunctiou  of  the  arch  with  the  thoracic  aorta,  just  below  the  ductus  arteriosus.  Whether  this  is 
the  result  of  disease,  or  of  congenital  malformation,  is  immaterial  to  our  present  purpose  ;  it 
affords  an  interesting  opportunity  of  observing  the  resources  of  the  collateral  circulation.  The 
course  of  the  anastomosing  vessels,  by  which  ihe  blood  is  brought  from  the  upper  to  the  lower 
part  of  the  artery,  will  be  found  well  described  in  an  account  of  two  cases  in  the  Pathological 
Transactions,  vols.  viii.  and  x.  In  the  former  (p.  162),  Mr.  Sydney  Jones  thus  sums  up  the 
detailed  description  of  the  anastomosing  vessels.  "The  principal  communications  by  which  the 
circulation  was  carried  on,  were — Firstly,  the  internal  mammary,  anastomosing  with  the  inter- 
costal arteries,  with  the  phrenic  of  the  abdominal  aorta  by  means  of  the  musculo-phrenic  and 
comes  nervi  phrenici.  and  largely  with  the  deep  epigastric.  Secondly,  the  superior  intercostal, 
anastomosing  anteriorly  by  means  of  a  large  branch  with  the  first  aortic  intercostal,  and  poste- 
riorly, with  the  posterior  branch  of  the  same  artery.  Thirdly,  the  inferior  thyroid,  by  means  of 
a  branch  about  the  size  of  an  ordinary  radial,  formed  a  communication  with  the  first  aortic  inter- 
costal. Fourthly,  the  transversalis  colli,  by  means  of  very  large  communications  with  the  poste- 
rior branches  of  the  intercostals.  Fifthly,  the  branches  (of  the  subclavian  and  axillary)  going  to 
the  side  of  the  chest  were  large,  and  anastomosed  freely  with  the  lateral  branches  of  the  inter- 
costals." In  the  eecond  case  also  (vol.  x.  p.  97),  Mr.  Wood  describes  the  anastomoses  in  a 
somewhat  similar  manner,  adding  the  remark,  that  "the  blood  which  was  brought  into  the  aorta 
through  the  anastomoses  of  the  intercostal  arteries,  appeared  to  be  expended  principally  in 
supplying  the  abdomen  and  pelvis ;  while  the  supply  to  the  lower  extremities  had  passed  through 
the  internal  mammary  and  epigastrics." 

Branches  of  the  Thoracic  Aorta. 

Pericardiac.  (Esopbageal. 

Bronchial.  Posterior  mediastinal. 

Intercostal. 

The  pericardiac  are  a  few  small  vessels,  irregular  in  their  origin,  distributed 
to  the  pericardium. 

The  bronchial  arteries  are  the  nutrient  vessels  of  the  lungs,  and  vary  in  num- 
ber, size,  and  origin.  That  of  the  right  side  arises  from  the  first  aortic  inter- 
costal, or  by  a  common  trunk  with  the  left  bronchial,  from  the  front  of  the 
thoracic  aorta.  Those  of  the  left  side,  usually  two  in  number,  arise  from  the 
thoracic  aorta,  one  a  little  lower  than  the  other.  Each  vessel  is  directed  to  the 
back  part  of  the  corresponding  bronchus,  along  which  they  run,  dividing  and 
subdividing,  upon  the  bronchial  tubes,  supplying  them,  the  cellular  tissue  of 
the  lungs,  the  bronchial  glands,  and  the  oesophagus. 

The  oesophageal  arteries,  usually  four  or  five  in  number,  arise  from  the  front  of 
the  aorta,  and  pass  obliquely  downwards  to  the  oesophagus,  forming  a  chain  of 
anastomoses  along  that  tube,  anastomosing  with  the  oesophageal  branches  of  the 
inferior  thyroid  arteries  above,  and  with  ascending  branches  from  the  phrenic 
and  gastric  arteries  below. 

The  posterior  mediastinal  arteries  are  numerous  small  vessels  which  supply  the 
glands  and  loose  areolar  tissue  in  the  mediastinum. 

The  intercostal  arteries  arise  from  the  back  part  of  the  aorta.  They  are  usually 
ten  in  number  on  each  side,  the  superior  intercostal  space  (and  occasionally  the 
second  one)  being  supplied  by  the  superior  intercostal,  a  branch  of  the  subcla- 
vian. The  right  intercostals  are  longer  than  the  left,  on  account  of  the  position 
of  the  aorta  to  the  left  side  of  the  spine ;  they  pass  outwards,  across  the  bodies 
of  the  vertebrae,  to  the  intercostal  spaces,  being  covered  by  the  pleura,  tlie 
oesophagus,  thoracic  duct,  sympathetic  nerve,  and  the  vena  azygos  major ;  the 
left  passing  beneath  the  superior  intercostal  vein,  the  vena  azygos  minor,  and 
sympathetic.  In  the  intercostal  spaces,  each  artery  divides  into  two  branches, 
an  anterior,  or  proper  intercostal  branch  ;  and  a  posterior,  or  dorsal  branch. 

The  anterior  branch  passes  outwards,  at  first  lying  upon  the  External  Inter- 
costal muscle,  covered  in  front  by  the  pleura,  and  a  thin  fascia.  It  then  passes 
between  the  two  layers  of  Intercostal  muscles,  and,  having  ascended  obliquely 
to  the  lower  border  of  the  rib  above,  divides,  near  the  angle  of  that  bone,  into 


496 


ARTERIES. 


two  branches ;  of  these,  the  larger  runs  in  the  groove,  on  the  lower  border  of 
the  rib  above ;  the  smaller  branch  along  the  upper  border  of  the  rib  below ; 
passing  forward,  they  supply  the  Intercostal  muscles,  and  anastomose  with  the 
anterior  intercostal  branches  of  the  internal  mammary,  and  with  the  thoracic 
branches  of  the  axillary  artery.  The  first  aortic  intercostal  anastomoses  with 
the  superior  intercostal,  and  the  last  three  pass  between  the  abdominal  muscles, 
inosculating  with  the  epigastric  in  front,  and  with  the  phrenic,  and  lumbar  arte- 
ries. Each  intercostal  artery  is  accompanied  by  a  vein  and  nerve,  the  former 
being  above,  and  the  latter  below,  except  in  the  upper  intercostal  spaces,  where 
the  nerve  is  at  first  above  the  artery.  The  arteries  are  protected  from  pressure 
during  the  action  of  the  Intercostal  muscles,  by  fibrous  arches  thrown  across, 
and  attached  by  each  extremity  to  the  bone. 

289. — The  Abdominal  Aorta  and  its  Branches. 


T\\G  posterior^  or  rhrsal  hrnnch,  of  each  intercostal  artery,  passes  backwards  to 
the  inner  side  of  the  anterior  costo-transverse  ligament,  and  divides  into  a  spinal 


I 


ABDOMINAL    AORTA.  497 

branch,  which  supplies  the  vertebrae,  the  spinal  cord  and  its  membranes,  and  a 
muscular  branch,  which  is  distributed  to  the  muscles  and  integument  of  the  back. 

The  Abdominal  Aoeta.    (Fig.  289.) 

The  Abdominal  Aorta  commences  at  the  aortic  opening  of  the  Diaphragm,  in 
front  of  the  body  of  the  last  dorsal  vertebra,  and,  descending  a  little  to  the  left 
side  of  the  vertebral  column,  terminates  on  the  left  side  of  the  body  of  the 
fourth  lumbar  vertebra,  where  it  divides  into  the  two  common  iliac  arteries.  It 
diminishes  rapidly  in  siiie,  in  consequence  of  the  many  large  branches  which  it 
gives  off.  As  it  lies  upon  the  bodies  of  the  vertebrae,  the  curve  which  it  de- 
scribes is  convex  forwards,  the  greatest  convexity  corresponding  to  the  third 
lumbar  vertebra,  which  is  a  little  above  and  to  the  left  side  of  the  umbilicus. 

Belatiotis.  It  is  covered,  infront^  by  the  lesser  omentum  and  stomach,  behind 
which  are  the  branches  of  the  coeliac  axis,  and  the  solar  plexus;  below  these,  by 
the  splenic  vein,  the  pancreas,  the  left  renal  vein,  the  transverse  portion  of  the 
duodenum,  the  mesentery,  and  aortic  plexus.  Behind,  it  is  separated  from  the 
lumbar  vertebrae  by  the  left  lumbar  veins,  the  receptaculum  chyli,  and  thoracic 
duct.  On  the  right  side,  it  is  in  relation  with  the  inferior  vena  cava  (the  right 
crus  of  the  Diaphragm  being  interposed  above),  the  vena  azygos,  thoracic  duct, 
and  right  semilunar  ganglion  ;  on  the  left  side,  with  the  sympathetic  nerve,  and 
left  semilunar  ganglion. 

Plan  of  the  Eelations  of  the  Abdominal  Aorta. 

In  front. 
Lesser  omentum  and  stomach. 
Branches  of  coeliac  axis  and  solar  plexus. 
Splenic  vein. 
Pancreas. 
Left  renal  vein. 
Transverse  duodenum. 
Mesentery. 
Aortic  plexus. 

Right  side.  ^       "\  Ii^ft  side. 

Eij?ht  crus  of  Diaphragm.  /  \  Sympathetic  nerve. 

Inferior  vena  cava.  /   Abdominal    \  Left  semilunar  ganglion. 

Yena  azygos. 
Thoracic  duct. 
Right  semilunar  ganglion. 

Behind. 
Left  lumbar  veins. 
Receptaculum  chyli. 
Thoracic  duct. 
Vertebral  column. 

Surgical  Anatomy.  Aneurisms  of  the  abdominal  aorta  near  the  coeliac  axis  communicate  in 
nearly  equal  proportion  with  the  anterior  and  posterior  parts  of  the  artery. 

When  an  aneurismal  sac  is  connected  with  the  back  part  of  the  abdominal  aorta,  it  usually 
produces  absorption  of  the  bodies  of  the  vertebrae,  and  forms  a  pulsating  tumor,  that  presents 
itself  in  the  left  hypochondriac  or  epigastric  regions,  accompanied  by  symptoms  of  disturbance 
of  the  alimentary  canal.  Pain  is  invariably  present,  and  is  usually  of  two  kinds,  a  fixed  and 
constant  pain  in  the  back,  caused  by  the  tumor  ])ressing  on  or  displacing  the  branches  of  the 
solar  plexus  and  splanchnic  nerves,  and  a  sharp  lancinating  pain,  radiating  along  those  branches 
of  the  lumbar  nerves  which  are  pressed  on  by  the  tumor;  hence  the  pain  in  the  loins,  the  testes, 
the  hypogastrium,  and  in  the  lower  limb  (usually  of  the  left  side).  This  form  of  aneurism  usually 
bursts  into  the  peritoneal  cavity,  or  behind  the  peritoneum,  in  the  left  hypochondriac  region ;  or 
it  may  form  a  large  aneurismal  sac,  extending  down  as  low  as  Poupart's  ligament;  hemorrhage 
in  these  cases  being  generally  very  extensive,  but  slowly  produced,  and  not  rapidly  fatal. 

When  an  aneurismal  sac  is  connected  with  the  front  of  the  aorta  near  the  coeliac  axis,  it  forms 
a  pulsating  tumor  in  the  left  hypochondriac  or  epigastric  regions,  usually  attended  with  symp- 
toms of  disturbance  of  the  alimentary  canal,  as  sickness,  dyspepsia,  or  constipation,  and  accom- 
panied by  pain,  which  is  constant,  but  nearly  always  fixed  in  the  loins,  epigastrium,  or  some 
part  of  the  abdomen  ;  the  radiating  pain  being  rare,  as  the  lumbar  nerves  are  seldom  implicated, 

(52 


498 


ARTERIES. 


This  form  of  aneurism  may  burst  into  the  peritoneal  cavity,  or  behind  the  peritoneum,  between 
the  layers  of  the  mesentery,  or,  more  rarely,  into  the  duodenum;  it  rarely  extends  backwards  so 
as  to  affect  the  spine. 

The  abdominal  aorta  has  been  tied  several  times,  aud  although  none  of  the  patients  perma- 
nently recovered,  still,  as  one  of  them  lived  as  long  as  ten  days,  the  possibility  of  the  re-estab- 
lishment of  the  circulation  may  be  considered  to  be  proved.  In  the  lower  animals  this  artery  is 
often  successfully  tied.     The  vessel  may  be  reached  in  several  ways.     In  the  original  operation, 

f)erformed  by  Sir  A.  Cooper,  an  incision  was  made  in  the  linea  alba,  the  peritoneum  opened  in 
ront,  the  finger  carried  down  amongst  the  intestines  towards  the  spine,  the  peritoneum  again 
opened  behind,  by  scratching  through  the  mesentery,  and  the  vessel  thus  reached.  Or  either 
of  the  operations,  described  below,  for  securing  the  common  iliac  artery,  may,  by  extending  the 
dissection  a  suflBcient  distance  upwards,  be  made  use  of  to  expose  the  aorta.  The  chief  difficulty 
in  the  dead  subject  consists  in  isolating  the  artery,  in  consequence  of  its  great  depth ;  but  in  the 
living  subject,  the  embarrassment  resulting  from  the  proximity  of  the  aneurismal  tumor,  and  the 
great  probability  of  disease  in  the  vessel  itself,  add  to  the  dangers  and  difficulties  of  this  formida- 
ble operation  so  greatly,  that  it  is  very  doubtful  whether  it  ought  ever  to  be  performed. 

The  collateral  circulation  would  be  carried  on  by  the  anastomosis  between  the  internal  mam- 
mary and  the  epigastric ;  by  the  free  communication  between  the  superior  and  inferior  mesen- 
teries, if  the  ligature  were  placed  above  the  latter  vessel ;  or  by  the  anastomosis  between  the 
inferior  mesenteric  and  the  internal  pudic,  when  (as  is  more  common)  the  point  of  ligature  is 
below  the  origin  of  the  inferior  mesenteric  ;  and  possibly  by  the  anastomoses  of  the  lumbar  arte- 
ries with  the  branches  of  the  internal  iliac. 

The  circulation  through  the  abdominal  aorta  may  be  commanded,  in  thin  persons,  by  firm  pres- 
sure with  the  fingers.  Mr.  Lister  has  invented  a  tourniquet  for  this  purpose,  which  is  of  the 
greatest  use  in  amputation  at  the  hip  joint,  and  some  other  operations. 

Branches  of  the  Abdominal  Aorta. 

Phrenic. 

{Gastric.  Renal. 

Hepatic.  Spermatic. 

Splenic.  Inferior  mesenteric. 

Superior  mesenteric.  Lumbar. 

Suprarenal.  Sacra  media. 

The  branches  may  be  divided  into  sets :  1.  Those  supplying  the  viscera.     2. 
Those  distributed  to  the  walls  of  the  abdomen. 


Parietal  Branchts. 
Phrenic. 
Lumbar. 
Sacra  media. 


Visceral  Branches. 

{Gastric. 
Hepatic. 
Splenic. 
Superior  mesenteric. 
Inferior  mesenteric.    • 
Suprarenal.     Renal.     Spermatic. 

Cceliac  Axis.    (Fig.  290.) 

To  expose  this  artery,  raise  the  liver,  draw  down  the  stomach,  and  then  tear  through  the  laj 
of  the  lesser  omentum. 

The  Coeliac  Axis  is  a  short  thick  trunk,  about  half  an  inch  in  lengtli,  whiuh 
arises  from  the  aorta,  opposite  the  margin  of  the  Diaphragm,  and  passing  nearly  ^ 
horizontally  forwards  (in  the  erect  posture),  divides  into  three  large  branches,! 
the  gastric,  hepatic,  and  splenic,  occasionally  giving  off  one  of  the   phrenioj 
arteries. 

Relations.  It  is  covered  by  the  lesser  omentum.  On  the  right  side,  it  is  ii 
relation  with  the  right  semilunar  ganglion,  and  the  lobus  Spigelii :  on  the  hj 
side,  with  the  left  semilunar  ganglion  and  cardiac  end  of  the  stomach.  Below^ 
it  rests  upon  the  upper  border  of  the  pancreas. 

The  Gastric  Artery  {doronaria  Ventriculi),  the  smallest  of  the  three  branchea 
of  the  coeliac  axis,  passes  upwards  and  to  the  left  side,  to  the  cardiac  orifice  of 
the  .stomach,  distributing  brunches  to  the  oesophagus,  which  anastomose  with 
the  aortic  oe.sophageal  arteries;  others  supply  the  cardiac  end  of  the  stomach, 
inosculating  with  branches  of  the  splenic  artery:  it  then  passes  from  left  to 


CCELIAC    AXIS. 


499 


right,  along  the  lesser  curvature  of  the  stomach  to  the  pylorus,  lying  in  its 
course  between  the  layers  of  the  lesser  omentum,  and  giving  branches  to  both 
surfaces  of  the  organ ;  at  its  termination  it  anastomoses  with  the  pyloric  branch 
of  the  hepatic. 

The  Hepatic  Artery  in  the  adult  is  intermediate  in  size  between  the  gastric 
and  splenic ;  in  the  foetus,  it  is  the  largest  of  the  three  branches  of  the  coeliac 

Fig.  290. — The  Cceliac  Axis  and  its  Branches,  the  Liver  having  been  raised,  and  the  Lesser 

Omentum  removed. 


axis.  It  passes  upwards  to  the  right  side,  between  the  layers  of  ihe  lesser 
omentum,  and  in  front  of  the  foramen  of  Winslovv,  to  the  transverse  fissure 
of  the  liver,  where  it  divides  into  two  branches,  right  and  left,  which  supply 
the  corresponding  lobes  of  that  organ,  accompanying  the  ramifications  of  the 
vena  portse  and  hepatic  duct.  The  hepatic  artery,  in  its  course  along  the  right 
border  of  the  lesser  omentum,  is  in  relation  with  the  ductus  communis  chole- 
dochus  and  portal  vein,  the  duct  lying  to  the  right  of  the  artery,  and  the  vena 
portse  behind. 

Its  branches  are  the 


Gastro-epiploica  dextra. 
Pancreatico-duodenalis. 


Pyloric. 
Gastro-duodenalis 

Cystic. 

The  pyloric  branch  arises  from  the  hepatic,  above  the  pylorus,  descends  to  the 
pyloric  end  of  the  stomach,  and  passes  from  right  to  left  along  its  lesser  curva- 
ture, supplying  it  with  branches,  and  inosculating  with  the  gastric  artery. 


500 


ARTERIES. 


The  gastro-duodenaUs  (Fig.  291)  is  a  short  but  large  branch,  which  descends 
behind  the  duodenum,  near  the  pylorus,  and  divides  at  the  lower  border  of  the 
stomach  into  two  branches,  the  gastro-epiploica  dextra  and  the  pancreatico- 
duodenalis.  Previous  to  its  division,  it  gives  off  two  or  three  small  infierior 
pyloric  branches  to  the  pyloric  end  of  the  stomach  and  pancreas. 

Fig.  291. — The  Ccelic  Axis  and  its  Branches,  the  Stomach  having  been  raised,  and  the  Transverse 

Meso-Colon  removed. 


The  gnsiro-epiploica  dextra  runs  from  right  to  left  along  the  greater  curvature 
of  the  stomach,  between  the  layers  of  the  great  omentum,  anastomosing  about 
the  middle  of  the  lower  border  of  the  stomach  with  the  gastro-epiploica  sinistra 
from  the  splenic  artery.  This  vessel  gives  off  numerous  branches,  some  of 
which  ascend  to  supply  both  surfaces  of  the  stomach,  whilst  others  descend  to 
supply  the  great  omentum. 

The  pancreatico-duodenalis  descends  along  the  contiguous  margins  of  the  duo- 
denum and  pancreas.  It  supplies  both  these  organs,  and  anastomoses  with  the 
inferior  pancreatico-duodenal  branch  of  the  superior  mesenteric  artery. 

In  ulceration  of  the  duodenum,  which  frequently  occurs  in  connection  with 
severe  burns,  this  artery  may  be  involved,  and  death  may  occur  from  hemor- 
rhage into  the  intestinal  canal. 

The  ajatic  artery  (Fig.  290),  usually  a  branch  of  the  right  hepatic,  passes  up- 
wards and  forwards  along  the  neck  of  the  gall  bladder,  and  divides  into  two 
branches,  one  of  which  ramifies  on  its  free  surface,  the  other,  between  it  and 
the  substance  of  the  liver. 

The  Splenic  Artery,  in  the  adult,  is  the  largest  of  the  three  branches  of  the 


SUPERIOR    MESENTERIC.  601 

coeliac  axis,  and  is  remarkable  for  the  extreme  tortuosity  of  its  course.  It 
passes  horizontally  to  the  left  side  behind  the  upper  border  of  the  pancreas, 
accompanied  by  the  splenic  vein,  which  lies  below  it;  and  on  arriving  near  the 
spleen,  divides  into  branches,  some  of  which  enter  the  hilum  of  that  organ  to 
be  distributed  to  its  structure,  whilst  others  are  distributed  to  the  great  end  of 
the  stomach. 

The  branches  of  this  vessel  are 

Pancreaticae  parvae.  Gastric  (vasa  brevia). 

Pancreatica  magna.  Gastro-epiploica  sinistra. 

The  pancreatic  are  numerous  small  branches  derived  from  the  splenic  as  it 
runs  behind  the  upper  border  of  the  pancreas,  supplying  its  middle  and  left 
parts.  One  of  these,  larger  than  the  rest,  is  given  off  from  the  splenic  near 
the  left  extremity  of  the  pancreas;  it  runs  from  left  to  right  near  the  posterior 
surface  of  the  gland,  following  the  course  of  the  pancreatic  duct,  and  is  called 
i\\Q  pancreatica  magna.  These  vessels  anastomose  with  the  pancreatic  branches 
of  the  pancreatico-duodenal  arteries. 

The  gastric  [vasa  brevia)  consist  of  from  five  to  seven  small  branches,  which 
arise  either  from  the  termination  of  the  splenic  artery,  or  from  its  terminal 
branches;  and  passing  from  left  to  right,  between  the  layers  of  the  gastro- 
splenic  omentum,  are  distributed  to  the  great  curvature  of  the  stomach;  anas- 
tomosing with  branches  of  the  gastric  and  gastro-epiploica  sinistra  arteries. 

The  gastro-epiploica  sinistra,  the  largest  branch  of  the  splenic,  runs  from  left 
to  right  along  the  great  curvature  of  the  stomach,  between  the  layers  of  the 
great  omentum;  and  anastomoses  with  the  gastro-epiploica  dextra.  In  its  course 
it  distributes  several  branches  to  the  stomach,  which  ascend  upon  both  surfaces: 
others  descend  to  supply  the  omentum. 

Superior  Mesenteric  Artery.    (Fig.  292.) 

In  order  to  expose  this  vessel,  raise  the  great  omentum  and  transverse  colon,  draw  down  the 
small  intestines,  and  cut  through  the  peritoneum,  where  the  transverse  mesocolon  and  mesen- 
tery join ;  the  artery  will  then  be  exposed,  just  as  it  issues  from  beneath  the  lower  border  of  the 
pancreas. 

The  Superior  Mesenteric  Artery  supplies  the  whole  length  of  the  small 
intestine,  except  the  first  part  of  the  duodenum ;  it  also  supplies  the  ctecum, 
ascending  and  transverse  colon ;  it  is  a  vessel  of  large  size,  arising  from  the 
fore  part  of  the  aorta,  about  a  quarter  of  an  inch  below  the  coeliac  axis;  being 
covered,  at  its  origin,  by  the  splenic  vein  and  pancreas.  It  passes  forwards, 
between  the  pancreas  and  transverse  portion  of  the  duodenum,  crosses  in  front 
of  this  portion  of  the  intestine,  and  descends  between  the  layers  of  the  mesen- 
tery to  the  right  iliac  fossa,  where  it  terminates,  considerably  diminished  in 
size.  In  its  course  it  forms  an  arch,  the  convexity  of  which  is  directed  for 
wards  and  downwards  to  the  left  side,  the  concavity  backwards  and  upwards  to 
the  right.  It  is  accompanied  by  the  superior  mesenteric  vein,  and  is  surrounded 
by  the  superior  mesenteric  plexus  of  nerves.     Its  branches  are  the 

Inferior  pancreatico-duodenal.  Ileo-colic. 

Vasa  intestini  tenuis.  Colica  dextra. 

Colica  media. 

The  inferior  pancreatico-duodenal  is  giyen  off  from  the  superior  mesenteric 
behind  the  pancreas,  and  is  distributed  to  the  head  of  the  pancreas,  and  the 
transverse  and  descending  portions  of  the  duodenum ;  anastomosing  with  the 
pancreatico-duodenal  artery. 

The  vasa  intestini  tenuis  arise  from  the  convex  side  of  the  superior  mesenteric 
artery.  They  are  usually  from  twelve  to  fifteen  in  number,  and  are  distributed 
to  the  jejunum  and  ileum.  They  run  parallel  with  one  another  between  the 
layers  of  the  mesentery ;  each  vessel  dividing  into  two  branches,  which  unite 


502 


ARTERIES. 


with  a  similar  branch  on  each  side,  forming  a  series  of  arches,  the  convexities 
of  which  are  directed  towards  the  intestine.  From  this  first  set  of  arches 
branches  arise,  which  again  unite  with  similar  branches  from  either  side,  and 
thus  a  second  series  of  arches  is  formed ;  and  from  these  latter,  a  third,  and  a 


Fig.  292. — The  Superior  Mesenteric  Artery  and  Branchea. 


fourth,  or  even  fifth  series  of  arches  are  constituted,  diminishing  in  size  the 
nearer  they  approach  the  intestine.  From  the  terminal  arches  numerous  small 
straight  vessels  arise,  which  encircle  the  intestine,  upon  which  they  are  dis- 
tributed,  ramifying  thickly  between  its  coats.  ■I 

The  ileo-colic  artery  is  the  lowest  branch  given  off  from  the  concavity  of  the 
superior  mesenteric  artery.  It  descends  between  the  layers  of  the  mesentery 
to  the  right  iliac  fossa,  where  it  divides  into  two  branches.  Of  these,  the  in- 
ferior one  inosculates  with  the  lowest  branches  of  the  vasa  intestini  tenuis, 
from  the  convexity  of  which  branches  proceed  to  supply  the  termination  of 
the  ileum,  the  ccecum  and  appendix  cocci,  and  the  ileo-ccecal  valve.  The 
superior  division  inosculates  with  the  colica  dextra,  and  supplies  the  commence- 
ment of  the  colon.  * 

The  colica  dextra  arises  from  about  the  middle  of  the  concavity  of  the  supe- 
rior mesenteric  artery,  and  passing  beneath  the  peritoneum  to  the  middle  of 
the  ascending  colon,  divides  into  two  branches;  a  descending  branch,  which 
inosculates  with  the  ileo-colic;  and  an  ascending  branch,  which  anastomoses 
witli  the  colica  media.     These  branches  form  arches,  from  the  convexity  of 


INFERIOR    MESENTERIC. 


503 


wliicli  vessels  are  distributed  to  the  ascending  colon.     The  branches  of  this 
vessel  are  covered  with  peritoneum  only  on  their  anterior  aspect. 

The  colica  media  arises  from  the  upper  part  of  the  concavity  of  the  superior 
mesenteric,  and,  passing  forwards  between  the  layers  of  the  transverse  meso- 
colon, divides  into  two  branches;  the  one  on  the  right  side  inosculating  with 
the  colica  dextra;  that  on  the  left  side,  with  the  colica  sinistra,  a  branch  of  the 
inferior  mesenteric.  From  the  arches  formed  by  their  inosculation,  branches 
are  distributed  to  the  transverse  colon.  The  branches  of  this  vessel  lie  between 
two  layers  of  peritoneum. 

Inferior  Mesenteric  Artery.     (Fig.  293.) 

In  order  to  expose  this  vessel,  draw  the  small  intestines  and  mesentery  over  to  the  right  side 
of  the  abdomen,  raise  the  transverse  colon  towards  the  thorax,  and  divide  the  peritoneum  cover- 
ing the  left  side  of  the  aorta. 

The  Inferior  Mesenteric  Artery  supplies  the  descending  and  sigmoid  flexure 
of  the  colon,  and  the  greater  part  of  the  rectum.     It  is  smaller  than  the  supe- 


Fig.  293. — The  Inferior  Mesenteric  Artery  and  its  Branches. 


Infenor  Utrmorrhoulul 


rior  mesenteric ;  and  arises  from  the  left  side  of  the  aorta,  between  one  and  two 
inches  above  its  division  into  the  common  iliacs.  It  passes  downwards  to  the 
left  iliac  fossa,  and  then  descends,  between  the  layers  of  the  meso-rectum,  into 
the  pelvis,  under  the  name  of  the  superior  hemorrhoidal  artery.     It  lies  at  first 


504  ARTERIES. 

in  close  relation  witli  the  left  side  of  the  aorta,  and  then  passes  in  front  of  the 
left  common  iliac  artery.     Its  branches  are  the 

Colica  sinistra.  Sigmoid.  Superior  haemorrhoidal. 

The  colica  sinistra  passes  behind  the  peritoneum,  in  front  of  the  left  kidnev, 
to  reach  the  descending  colon,  and  divides  into  two  branches ;  an  ascending 
branch,  which  inosculates  with  the  colica  media ;  and  a  descending  branch, 
which  anastomoses  with  the  sigmoid  artery.  From  the  arches  formed  by  these 
inosculations,  branches  are  distributed  to  the  descending  colon. 

The  sigmoid  artery  runs  obliquely  downwards  across  the  Psoas  muscle  to.  the 
sigmoid  flexure  of  the  colon,  and  divides  into  branches,  which  supply  that  part 
of  the  intestine;  anastomosing  above,  with  the  colica  sinistra;  and  below,  with 
the  superior  haemorrhoidal  artery.  This  vessel  is  sometimes  replaced  by  three 
or  four  small  branches. 

The  superior  haemorrhoidal  artery^  the  continuation  of  the  inferior  mesenteric, 
descends  into  the  pelvis  between  the  layers  of  the  meso-rectum,  crossing,  in  its 
course,  the  ureter,  and  left  common  iliac  vessels.  Opposite  the  middle  of  the 
sacrum  it  divides  into  two  branches,  which  descend,  one  on  each  side  of  the 
rectum,  where  they  divide  into  several  small  branches,  which  are  distributed 
between  the  mucous  and  muscular  coats  of  that  tube,  nearly  as  far  as  its  lower 
end;  anastomosing  with  each  other,  with  the  middle  haemorrhoidal  arteries, 
branches  of  the  internal  iliac,  and  with  the  inferior  haemorrhoidal,  branches  of 
the  internal  pudic. 

The  student  should  especially  remark,  that  the  trunk  of  the  vessel  descends 
along  the  back  part  of  the  rectum  as  far  as  the  middle  of  the  sacrum  before  it 
divides ;  this  is  about  a  finger's  length,  or  four  inches  from  the  anus.  In  dis- 
ease of  this  tube,  the  rectum  should  never  be  divided  beyond  this  point  in  that 
direction,  for  fear  of  involving  this  artery. 

Suprarenal  Arteries. 

The  Suprarenal  Arteries  (Fig.  289)  are  two  small  vessels  which  arise,  one 
on  each  side  of  the  aorta,  opposite  the  superior  mesenteric  artery.  They  pass 
obliquely  upwards  and  outwards,  to  the  under  surface  of  the  suprarenal  cap- 
sules, to  which  they  are  distributed,  anastomosing  with  capsular  branches  from 
the  phrenic  and  renal  arteries.  In  the  adult  these  arteries  are  of  small  size ; 
in  the  foetus  they  are  as  large  as  the  renal  arteries. 

Eenal  Arteries. 

The  Renal  Arteries  are  two  large  trunks,  which  arise  from  the  sides  of  the 
aorta,  immediately  below  the  superior  mesenteric  artery.  Each  is  directed 
outwards,  so  as  to  form 'nearly  a  right  angle  with  the  aorta.  The  right  is  longer 
than  the  left,  on  account  of  the  position  of  the  aorta;  it  passes  behind  the  in- 
ferior vena  cava.  The  left  is  somewhat  higher  than  the  right.  Previously  to 
entering  the  kidney,  each  artery  divides  into  four  or  live  branches,  which  are 
distributed  to  its  substance.  At  the  hilum,  these  branches  lie  between  the 
renal  vein  and  ureter,  the  vein  being  usually  in  front,  the  ureter  behind.  Each 
vessel  gives  off  some  small  branches  to  the  suprarenal  capsules,  the  ureter,  and 
the  surrounding  cellular  membrane  and  muscles. 

Spermatic  Arteries. 

The  Spermatic  Arteries  are  distributed  to  the  testes  in  the  male,  and  to  the 
ovaria  in  the  female.  They  are  two  slender  vessels,  of  considerable  length, 
which  arise  from  the  front  of  the  aorta,  a  little  below  the  renal  arteries.  Eacb 
artery  passes  obliquely  outwards  and  downwards,  behind  the  peritoneum, 
crossing  the  ureter,  and  resting  on  the  Psoas  muscle,  the  right  spermatic  lying 
in  front  of  the  inferior  vena  cava,  the  left  behind  the  sigmoid  flexure  of  the 


PHRENIC— LUMBAR.  505 

colon.  On  reaching  the  margin  of  the  pelvis,  each  vessel  passes  in  front  of  the 
corresponding  external  iliac  artery,  and  takes  a  different  course  in  the  two  sexes. 

In  the  male,  it  is  directed  outwards,  to  the  internal  abdominal  ring,  and 
accompanies  the  other  constituents  of  the  spermatic  cord  along  the  spermatic 
canal  to  the  testis,  where  it  becomes  tortuous,  and  divides  into  several  branches, 
two  or  three  of  which  accompany  the  vas  deferens,  and  supply  the  epididymis, 
anastomosing  with  the  artery  of  the  vas  deferens ;  others  pierce  the  back  part 
of  the  tunica  albuginea,  and  supply  the  substance  of  the  testis. 

In  the  female,  the  spermatic  arteries  (ovarian)  are  shorter  than  in  the  male, 
and  do  not  pass  out  of  the  abdominal  cavity.  On  arriving  at  the  margins  of 
the  pelvis,  each  artery  passes  inwards,  between  the  two  laminae  of  the  broad 
ligament  of  the  uterus,  to  be  distributed  to  the  ovary.  One  or  two  small 
branches  supply  the  Fallopian  tube ;  another  passes  on  to  the  side  of  the  uterus, 
and  anastomoses  with  the  uterine  arteries.  Other  offsets  are  continued  along 
the  round  ligament,  through  the  inguinal  canal,  to  the  integument  of  the  labium 
and  groin. 

At  an  early  period  of  foetal  life,  when  the  testes  lie  by  the  side  of  the  spine, 
below  the  kidneys,  the  spermatic  arteries  are  short ;  but  as  these  organs  descend 
from  the  abdomen  into  the  scrotum,  the  arteries  become  gradually  lengthened. 

Pheenic  Arteries. 

The  Phrenic  Arteries  are  two  small  vessels,  which  present  much  variety  in 
their  origin.  They  may  arise  separately  from  the  front  of  the  aorta,  immediately 
below  the  coeliac  axis,  or  by  a  common  trunk,  which  may  spring  either  from 
the  aorta,  or  from  the  coeliac  axis.  Sometimes  one  is  derived  from  the  aorta, 
and  the  other  from  one  of  the  renal  arteries.  In  only  one  out  of  thirty-six 
cases  examined,  did  these  arteries  arise  as  two  separate  vessels  from  the  aorta. 
They  diverge  from  one  another  across  the  crura  of  the  Diaphragm,  and  then 
pass  obliquely  upwards  and  outwards  upon  its  under  surface.  The  left  phrenic 
passes  behind  the  oesophagus,  and  runs  forwards  on  the  left  side  of  the  oeso- 
phageal opening.  The  right  phrenic  passes  behind  the  liver  and  inferior  vena 
cava,  and  ascends  along  the  right  side  of  the  aperture  for  transmitting  that 
vein.  Near  the  back  part  of  the  central  tendon,  each  vessel  divides  into  two 
branches.  The  internal  branch  runs  forwards  to  the  front  of  the  thorax,  sup- 
plying the  Diaphragm,  and  anastomosing  with  its  fellow  of  the  opposite  side, 
and  with  the  musculo-phrenic,  a  branch  of  the  internal  mammary.  The  exter- 
nal branch  passes  towards  the  side  of  the  thorax,  and  inosculates  with  the  in- 
tercostal arteries.  The  internal  branch  of  the  right  phrenic  gives  off"  a  few 
vessels  to  the  inferior  vena  cava;  and  the  left  one  some  branches  to  the  oeso- 
phagus. Bach  vessel  also  sends  capsular  branches  to  the  suprarenal  capsule 
of  its  own  side.  The  spleen  on  the  left  side,  and  the  liver  on  the  right,  also 
receives  a  few  branches  from  these  vessels. 

Lumbar  Arteries. 

The  Lumbar  Arteries  are  analogous  to  the  intercostal.  They  are  usually 
four  in  number  on  each  side,  and  arise  from  the  back  part  of  the  aorta,  nearly 
at  right  angles  with  that  vessel.  They  pass  outwards  and  backwards,  around 
the  sides  of  the  body  of  the  corresponding  lumbar  vertebra,  behind  the  sympa- 
thetic nerve  and  the  Psoas  muscle  ;  those  on  the  right  side  being  covered  by 
the  inferior  vena  cava,  and  the  two  upper  ones  on  each  side  by  the  crura  of  the 
Diaphragm.  In  the  interval  between  the  transverse  processes  of  the  vertebrae 
each  artery  divides  into  a  dorsal  and  an  abdominal  branch. 

The  dorsal  branch  gives  off,  immediately  after  its  origin,  a  spinal  branch,  which 
enters  the  spinal  canal;  it  then  continues  its  course  backwards,  between  the 
transverse  processes,  and  is  distributed  to  the  muscles  and  integument  of  the 
back,  anastomosing  with  each  other,  and  with  the  posterior  branches  of  the 
intercostal  arteries. 


606  ARTERIES. 

The  spinal  tranche  besides  supplying  offsets  whicli  run  along  the  nerves  to 
the  dura  mater  and  cauda  equina,  anastomosing  with  the  other  spinal  arteries, 
divides  into  two  branches,  one  of  which  ascends  on  the  posterior  surface  of  the 
body  of  the  vertebra  above,  and  the  other  descends  on  the  posterior  surface  of 
the  body  of  the  vertebra  below,  both  vessels  anastomosing  with  similar  branches 
from  neighboring  spinal  arteries.  The  inosculations  of  these  vessels  on  each 
side,  throughout  the  whole  length  of  the  spine,  form  a  series  of  arterial  arches 
behind  the  bodies  of  the  vertebrae,  which  are  connected  with  each  other,  and 
with  a  median  longitudinal  vessel,  extending  along  the  middle  of  the  posterior 
surface  of  the  bodies  of  the  vertebrae,  by  transverse  branches.  From  these 
vessels  offsets  are  distributed  to  the  periosteum  and  bones. 

The  abdominal  branches  pass  outwards,  behind  the  Quadratus  Lumborum,  the 
lowest  branch  occasionally  in  front  of  that  muscle,  and,  being  continued  between 
the  abdominal  muscles,  anastomose  with  branches  of  the  epigastric  and  in- 
ternal mammary  in  front^  the  intercostals  above,  and  those  of  the  ilio-lumbar 
and  circumflex  iliac  behw. 

Middle  Sacral  Arteries. 

The  Middle  Sacral  Artery  is  a  small  vessel,  about  the  size  of  a  crow-quill, 
which  arises  from  the  back  part  of  the  aorta,  just  at  its  bifurcation.  It  descends 
upon  the  last  lumbar  vertebra,  and  along  the  middle  line  of  the  front  of  the 
sacrum,  to  the  upper  part  of  the  coccyx,  where  it  anastomoses  with  the  lateral 
sacral  arteries,  and  terminates'  in  a  minute  branch,  which  runs  down  to  the 
situation  of  the  body  presently  to  be  described  as  "Luschka's  gland."  From 
it,  branches  arise  which  run  through  the  meso-rectum,  to  supply  the  posterior 
surface  of  the  rectum.  Other  branches  are  given  off  on  each  side,  which 
anastomose  with  the  lateral  sacral  arteries,  and  send  off  small  offsets  which 
enter  the  anterior  sacral  foramina. 


SI 


Coccygeal  Gland,  or  Luschka's  Gland. — Lying  near  the  tip  of  the  coccyx,  inn 
a  small  tendinous  interval  formed  by  the  union  of  the  Levator  Ani  muscles  of 
either  side,  and  just  above  the  coccygeal  attachment  of  the  Sphincter  Ani,  is  a 
oHiall  conglobate  body,  about  as  large  as  a  lentil  or  a  pea,  first  described  by 
Luschka,'  and  named  by  him  the  coccygeal  gland,  but  the  real  nature  and  uses  of 
which  are  doubtful,  nor  does  it  seem  at  present  certain  that  it  always  existsJI 
Its  most  obvious  connections  are  with  the  arteries  of  the  part.  It  receives 
comparatively  large  branches  from  the  middle  and  lateral  sacral  arteries,  and 
its  structure,  according  to  Julius  Arnold,^  consists  in  great  measure  of  dilated 
arterial  vessels.  On  this  account  Arnold  proposes  to  call  it  not  a  gland,  but 
"  glomerulus  arterio-coccygeus."  It  is  sometimes  single,  sometimes  formed  of 
several  lobes,  surrounded  by  a  very  definite  capsule,  into  which  the  sympathetic 
filaments  from  the  ganglion  impar  are  to  be  traced,  and  in  which  they  are  said 
by  some  observers  to  terminate.  The  structure  of  the  body  is  composed  of  a 
number  of  cavities,  which  Luschka  believes  to  be  glandular  follicles,  but  which 
are  regarded  by  Arnold  as  fusiform  dilatations  of  the  terminal  branches  from 
the  middle  sacral  arteries.  Nerves  pass  into  this  little  body  both  from  the 
sympathetic  and  from  the  fifth  sacral,  and  in  the  interstices  of  the  lobules  nerve 
cells  are  described. 

This  body  has  been  variously  regarded  as  an  appendage  to  the  nervous  or  U 
the  arterial  system.     The  former  seems  to  be  Luschka's  view,  the  latter  is 
Arnold's.     Arnold's  view  is  supported  by  the  observation  of  Dr.  Macalister,' 


I 


'  Der  Himanhang  tend  die  Steissdrilse  des  Menschen,  Berlin,  1860  :  Anatomie  des  Menschen, 
Tubinp^en,  1864.  vol.  ii.  pt.  2,  p.  187. 

«  Virchow,  Arch.,  1864,  5,  6  ;  see  also  Krause  and  Meyer  in  Henle  and  Pfeiffer's  Zeitach.  f. 
rat.  Mcdiztn. 

*  British  MedicalJournal,  Jan.  11,  1868. 


11 


I 


COMMON    ILIAC. 


507 


that  he  has  found  in  several  birds  the  middle  sacral  arteries  terminating  in  a 
bunch  of  inteulaciug  and  anastomosing  capillaries,  but  without  any  capsule,  and 
it  is  rendered  in  the  highest  degree  probable,  if  Arnold's  observation  be  correct, 
that  several  small  saccular  bodies,  of  a  somewhat  similar  kind,  may  be  found 
connected  with  the  middle  sacral  artery. 

For  a  more  detailed  description  of  this  body,  we  would  refer  to  the  elaborate 
account  in  "  Luschka's  Anatomic,"  and  to  the  authorities  quoted  in  Dr.  Macal- 
ister's  paper,  as  well  as  to  a  monograph  by  Dr.  W.  Mitchell  Banks,  reprinted 
in  1867  from  the  "  Glasgow  Medical  Journal." 

Common  Iliac  Aeteries. 

The  abdominal  aorta  divides  into  the  two  Common  Iliac  Arteries.  The  bifur- 
cation usually  takes  place  on  the  left  side  of  the  body  of  the  fourth  lumbar 
vertebra.  This  point  corresponds  to  the  left  side  of  the  umbilicus,  and  is  on  a 
level  with  a  line  drawn  from  the  highest  point  of  one  iliac  crest  to  the  other. 
The  common  iliac  arteries  are  about  two  inches  in  length ;  diverging  from  the 
termination  of  the  aorta,  they  pass  downwards  and  outwards  to  the  margin  of 
the  pelvis,  and  divide  opposite  the  intervertebral  substance,  between  the  last 
lumbar  vertebra  and  the  sacrum,  into  two  branches,  the  external  and  internal 
iliac  arteries ;  the  former  supplying  the  lower  extremity  ;  the  latter,  the  viscera, 
and  parietes  of  the  pelvis. 

The  right  common  iliac  is  somewhat  larger  than  the  left,  and  passes  more 
obliquely  across  the  body  of  the  last  lumbar  vertebra.  In  front  of  it  are  the 
peritoneum,  the  ileum,  branches  of  the  sympathetic  nerve,  and,  at  its  point 
of  division,  the  ureter.  Behind,  it  is  separated  from  the  last  lumbar  vertebra 
by  the  two  common  iliac  veins.  On  its  outer  side,  it  is  in  relation  with  the  in- 
ferior vena  cava,  and  right  common  iliac  vein,  above;  and  the  Psoas  Magnus 
muscle  below. 

The  left  common  iliac  is  in  relation,  in  front,  with  the  peritoneum,  branches 
of  the  sympathetic  nerve,  the  rectum  and  superior  haemorrhoidal  artery;  and  is 
crossed,  at  its  point  of  bifurcation,  by  the  ureter.  The  left  common  iliac  vein 
lies  partly  on  the  inner  side,  and  part  beneath  the  artery ;  on  its  outer  side,  the 
artery  is  in  relation  with  the  Psoas  Magnus. 

Branches.  The  common  iliac  arteries  give  off  small  branches  to  the  perito- 
neum, Psoas  muscles,  ureters,  and  the  surrounding  cellular  membrane,  and 
occasionally  give  origin  to  the  ilio-lurabar,  or  renal  arteries. 

Plan  of  the  Eelations  ofthe  Common  Iliac  Arteries. 


In  front. 
Peritoneum. 
.Small  intestines. 
Sympathetic  nerves. 
Ureter. 


Outer  side. 
Vena  cava. 
Kig-ht  common 

iliac  vein. 
Psoas  muscle. 


Inner  side. 

Left  common 

iliac  vein. 


In  front. 
Peritoneum. 
Sympathetic  nerves. 
Rectum. 

Superior  haemorrhoidal  artery. 
Ureter. 


Outer  side. 
Psoas  muscle. 


Behind. 
Eight  and  Left  common 
iliac  veins. 


Behind. 
Left  common 
iliac  vein. 


Peculiarities.  The  point  of  origin  varies  according'  to  the  bifurcation  of  the  aorta.  In  three- 
fourths  of  a  large  number  of  cases,  the  aorta  bifurcated  either  upon  the  fourth  lumbar  vertebra, 
or  upon  the  intervertebral  disk  between  it  and  the  fifth  ;  the  bifurcation  being,  in  one  case  out 
of  nine  below,  and  in  one  out  of  eleven  above  this  point.  In  ten  out  of  every  thirteen  cases, 
the  vessel  bifurcated  within  half  an  inch  above  or  below  the  level  of  the  crest  of  the  ilium  ; 
more  fretjuently  below  than  above. 


50S 


ARTERIES. 


'I'he  ■point  of  division  is  subject  to  great  variety.  In  two-thirds  of  a  large  number  of  cases, 
it  was  between  the  last  lumbar  vertebra  and  the  upper  border  of  the  sacrum  ;  being  above  that 
point  in  one  case  out  of  eight,  and  below  it  in  one  case  out  of  six.  The  left  common  iliac 
artery  divides  lower  down  more  frequently  than  the  right. 

The  relative  length,  also,  of  the  two  common  iliac  arteries  varies.  The  right  common  iliac 
was  longest  in  sixty-three  cases  ;  the  left,  in  fifty-two ;  whilst  they  were  both  equal  in  fifty-three. 
The  length  of  the  arteries  varied  in  five-sevenths  of  the  cases  examined,  from  an  inch  and  a 
half  to  three  inches  ;  in  about  half  of  the  remaining  cases,  they  artery  was  longer  ;  and  in  the 
other  half,  shorter ;  the  minimum  length  being  less  than  half  an  inch,  the  maximum  four  and  a 
half  inches.  In  one  instance,  the  right  common  iliac  was  found  wanting,  the  external  and  in- 
ternal iliacs  arising  directly  from  the  aorta. 

Surgical  Anatomi/.  The  application  of  a  ligature  to  the  common  iliac  artery  may  be  required 
on  account  of  aneurism  or  hemorrhage,  implicating  the  external  or  internal  iliacs,  or  on  account 
of  secondary  hemorrhage  after  amputation  of  the  thigh  high  up.  It  has  been  seen  that  the 
origin  of  this  vessel  corresponds  to  the  left  side  of  the  umbilicus  on  a  level  with  a  line  drawn 
from  the  highest  point  of  one  iliac  crest  to  the  opposite  one,  and  its  course  to  a  line  extending 
from  the  left  side  of  the  umliilicus  downwards  towards  the  middle  of  Poupart's  ligament.  The 
line  of  incision  required  in  the  first  steps  of  an  operation  for  securing  this  vessel,  would  ma- 
terially depend  upon  the  nature  of  the  disease.  If  the  surgeon  select  the  iliac  region,  a  curved 
incision,  about  five  inches  in  length,  may  be  made,  commencing  on  the  left  side  of  the  umbilicus, 
carried  outwards  towards  the  anterior  superior  iliac  spine,  and  then  along  the  upper  border  of 
Poupart's  ligament,  as  far  as  its  middle.     But  if  the  aneurismal  tumor  should  extend  high  up 

Fig.  294. — Arteries  of  the  Pelvis. 


In  the  abdomen,  along  the  external  iliac,  it  is  better  to  select  the  side  of  the  abdomen,  approach- 
ing the  artery  from  above,  by  making  an  incision  from  four  to  five  inches  in  length,  from  about 
two  inches  above  and  to  the  left  of  the  umbilicus,  carried  outwards  in  a  curved  direction  towards 


<l 


INTERNAL    ILIAC.  509 

the  lumbar  refrion,  and  terminatitiij:  a  little  below  the  anterior  superior  iliac  spine.  The  abdominal 
muscles  (in  either  case)  havini;  bien  cautiously'  divided  in  succession,  the  transversalis  fascia 
must  be  carefully  cut  through  ami  ihe  peritoneum,  together  with  the  ureter,  separated  from  the 
artery,  and  pushed  aside  ;  the  sacroiliac  articulation  must  then  be  felt  for,  and  upon  it  the  vessel 
■will  be  felt  pulsating,  and  may  be  fully  exposed  in  close  connection  with  its  accompanying 
vein.  On  the  right  side,  both  common  iliac  veins,  as  well  as  the  interior  vena  cava,  are  in  close 
connection  with  the  artery,  and  must  be  carefully  avoided.  On  the  left  side,  the  vein  usually 
lies  on  the  inner  side,  and  behind  the  artery;  but  it  occasionally  happens  that  the  two  conimnu 
iliac  veins  are  joined  on  the  left  instead  of  the  right  side,  which  would  add  much  to  the  diffi- 
culty of  an  operation  in  such  a  case.  The  common  iliac  artery  may  be  so  short  that  danger  may 
be  apprehended  from  secondary  hemorrhage  if  a  ligature  is  applied  to  it.  It  would  be  prefer- 
able, in  such  a  case,  to  tie  both  the  external  and  internal  iliacs  near  their  origin. 

Collateral  Circulation.  The  principal  agents  in  carrying  on  the  collateral  circulation  after 
the  application  of  a  ligature  to  the  common  iliac,  are,  the  anastomoses  of  the  ha;morrhoidal 
branches  of  the  internal  iliac,  with  the  superior  hajmorrhoidal  from  the  inferior  mesenteric ;  the 
anastomoses  of  the  uterine  and  ovarian  arteries,  and  of  the  vesical  arteries  of  opposite  sides  ;  of 
the  lateral  sacral,  with  the  middle  sacral  artery;  of  the  epigastric,  with  the  internal  mammary, 
inferior  intercostal,  and  lumbar  arteries  ;  of  the  ilio-lumbar,  with  the  last  lumbar  artery  ;  of  the 
obturator  artery,  by  means  of  its  pubic  branch,  with  the  vessel  of  the  opposite  side,  and  with 
the  internal  epigastric;  and  of  the  gluteal,  with  the  posterior  branches  of  the  sacral  arteries. 

Internal  Iliac  Artery.    (Fig.  294.) 

The  Internal  Iliac  Artery  supplies  the  walls  and  viscera  of  the  pelvis,  the 
generative  organs,  and  inner  side  of  the  thigh.  It  is  a  short,  thick  vessel, 
smaller  than  the  external  iliac,  and  about  an  inch  and  a  half  in  length,  which 
arises  at  the  point  of  bifurcation  of  the  common  iliac  ;  and,  passing  downwards 
to  the  upper  margin  of  the  great  sacro-sciatic  foramen,  divides  into  two  large 
trunks,  an  anterior  and  posterior ;  a  partially  obliterated  cord,  the  hypogastric 
artery,  extending  from  the  extremity  of  the  vessel  forwards  to  the  bladder. 

Relations.  In  front.,  with  the  ureter,  which  separates  it  from  the  peritoneum. 
Behind,  with  the  internal  iliac  vein,  the  lumbo-sacral  nerve,  and  Pyriformis 
muscle.     By  its  outer  side,  near  its  origin  with  the  Psoas  muscle. 

Plan  of  the  Eelations  of  the  Internal  Iliac  Artery. 

In  frovf. 
Peritoneum. 
Ureter. 

Outer  side. 
Psoas  Magnus, 


Behind. 

Internal  iliac  vein. 
LTim bo-sacral  nerve. 
Pyriformis  muscle. 

/n  the  foetus,  the  internal  iliac  artery  (hypogastric)  is  twice  as  large  as  the 
external  iliac,  and  appears  to  be  the  continuation  of  the  common  iliac.  Passing 
forwards  to  the  bladder,  it  ascends  along  the  side  of  that  viscus  to  its  summit, 
to  which  it  gives  branches ;  it  then  passes  upwards  along  the  back  part  of  the 
anterior  wall  of  the  abdomen  to  the  umbilicus,  converging  towards  its  fellow  of 
the  opposite  side.  Having  passed  through  the  umbilical  opening,  the  two  ar- 
teries  twine  round  the  umbilical  vein,  forming  with  it  the  umbilical  cord ;  and, 
ultimately,  ramify  in  the  placenta.  The  portion  of  the  vessel  within  the  ab- 
domen is  called  the  hypogastric  artery ;  and  that  external  to  that  cavity,  the 
umbilical  artery. 

At  birth,  when  the  placental  circulation  ceases,  that  portion  of  the  hypogastric 
artery  which  extends  from  the  umbilicus  to  the  summit  of  the  bladder,  con- 
tracts, and  ultimately  dwindles  to  a  solid  fibrous  cord;  the  portion  of  the  same 


510  ARTERIES. 

vessel  extending  from  the  summit  of  the  bladder  to  within  an  inch  and  a  half 
of  its  origin  is  not  totally  impervious,  though  it  becomes  considerably  reduced 
in  size ;  and  serves  to  convey  blood  to  the  bladder,  under  the  name  of  the 
superior  vesical  artery. 

Pendtarities,  as  regards  length.  In  two-thirds  of  a  large  number  of  cases,  the  length  of  the 
internal  iliac  varied  between  an  inch  and  a  half;  in  the  remaining  third,  it  was  more  frequently 
longer  than  shorter,  the  maximum  length  being  three  inches,  the  minimum  half  an  inch. 

The  lengths  of  the  common  and  internal  iliac  arteries  bear  an  inverse  proportion  to  each  other, 
the  internal  iliac  artery  being  long  when  the  common  iliac  is  short,  and  vice  versa. 

As  regards  its  place  of  division.  The  place  of  division  of  the  internal  iliac  varies  between 
the  upper  margin  of  the  sacrum,  and  the  upper  border  of  the  sacro-sciatic  foramen. 

The  arteries  of  the  two  sides  in  a  series  of  cases  often  differed  in  length,  but  neither  seemed 
constantly  to  exceed  the  other. 

Surgical  Anatomy.  The  application  of  a  ligature  to  the  internal  iliac  artery,  may  be  required 
in  cases  of  aneurism  or  hemorrhage  affecting  one  of  its  branches.  The  vessel  may  be  secured 
by  making  an  incis-ion  through  the  abdominal  parietes  in  the  iliac  region,  in  a  direction  and  to 
an  extent  similar  to  that  for  securing  the  common  iliac  ;  the  transversalis  fascia  having  been 
cautiously  divided,  and  the  peritoneum  pushed  inwards  from  the  iliac  fossa  towards  the  pelvis, 
the  finger  may  feel  the  pulsation  of  the  external  iliac  at  the  bottom  of  the  wound  ;  and,  by  tracing 
this  vessel  upwards,  the  internal  iliac  is  arrived  at,  opposite  the  sacro-iliac  articulation.  It  should 
be  remembered  that  the  vein  lies  behind,  and  on  the  right  side,  a  little  external  to  the  artery,  and 
in  close  contact  with  it ;  the  ureter  and  peritoneum,  which  lie  in  front,  must  also  be  avoided. 
The  degree  of  facility  in  applying  a  ligature  to  this  vessel  will  mainly  depend  upon  its  length. 
It  has  been  seen  that,  in  the  great  majority  of  the  cases  examined,  the  artery  was  short,  vary- 
insr  from  an  inch  to  an  inch  and  a  half;  in  these  cases,  the  artery  is  deeply  seated  in  the  pelvis ; 
when,  on  the  contrary,  the  vessel  is  longer,  it  is  found  partly  above  that  cavity.  If  the  artery  is 
very  short,  as  occasionally  happens,  it  would  be  preferable  to  apply  a  ligature  to  the  common 
iliac,  or  upon  the  external  and  internal  iliacs  at  their  origin. 

Collateral  Circulation.  In  Mr.  Owen's  dissection  of  a  case  in  which  the  internal  iliac  artery 
had  been  tied  by  Stevens  ten  years  before  death,  for  aneurism  of  the  sciatic  artery,  the  internal 
iliac  was  found  impervious  for  about  an  inch  above  the  point  where  the  ligature  had  been  applied ; 
but  the  obliteration  did  not  extend  to  the  origin  of  the  external  iliac,  as  the  ilio-lumbar  artery 
arose  just  above  this  point.  Below  the  point  of  obliteration,  the  artery  resumed  its  natuml 
diameter,  and  continued  so  for  half  an  inch ;  the  obturator,  lateral  sacral,  and  gluteal,  arising  in 
succession  from  the  latter  portion.  The  obturator  artery  was  entirely  obliterated.  The  lateral 
sacral  artery  was  as  large  as  a  crow's  quill,  and  had  a  very  free  anastomosis  with  the  artery  of  the 
opposite  side,  and  with  the  middle  sacral  artery.  The  sciatic  artery  was  entirely  obliterated  as  far 
as  its  point  of  connection  with  the  aneurismal  tumor;  but,  on  the  distal  side  of  the  sac,  it  was  con- 
tinued down  along  the  back  of  the  thigh  nearly  a«  large  in  size  as  the  femoral,  being  pervious 
about  an  inch  below  the  sac  by  receiving  an  anastomosing  vessel  from  the  profunda.'  In  ad- 
dition to  the  above,  the  circulation  in  the  parts  supplied  by  the  internal  iliac  would  be  carried  on 
by  the  anastomoses  of  the  uterine  and  ovarian  arteries ;  of  the  opposite  vesical  arteries  ;  of  the 
hsEmorrhoidal  branches  of  the  internal  iliac,  with  those  from  the  inferior  mesenteric  ;  of  the  ob- 
turator artery,  by  means  of  its  pubic  branch,  with  the  vessel  of  the  opposite  side,  and  with  the 
epigastric  and  internal  circumflex  ;  by  the  anastomoses  of  the  circumflex  and  perforating  branches 
of  the  femoral,  with  the  sciatic;  of  the  gluteal,  with  the  posterior  branches  of  the  sacral  arteries; 
of  the  ilio-lumbar,  with  the  last  lumbar;  of  the  lateral  sacral,  with  the  middle  sacral;  and  by  the 
anastomoses  of  the  circumflex  iliac,  with  the  ilio-lumbar  and  gluteal. 

Branches  of  the  Intern.vl  Iliac. 

From  the  Anterior  Trunk.  From  the  Posterior  Trunk. 

Superior  vesical.  Gluteal. 

Middle  vesical.  Iliolumbar. 

Inferior  vesical.  Lateral  sacral. 

Middle  hasmorrhoidal. 
Obturator. 
Internal  pudic. 
Sciatic. 


7-    /.       7    (  Uterine. 
In  female.  <  tt     •     i 
•^  {  Vagmal. 


The  superior  vesical  is  that  part  of  the  foetal  hypogastric  artery  which  remains 
pervious  after  birth.  It  extends  to  the  side  of  the  bladder,  distributing 
numerous  branches  to  the  body  and  fundus  of  the  organ.     From  one  of  these 

'  Medico-Chirurgical  Trans.,  vol.  xvi. 


k 


OBTURATOR.  511 

a  slender  vessel  is  derived,  wtich  accompanies  the  vas  deferens  in  its  course  to 
the  testis,  where  it  anastomoses  with  the  spermatic  artery.  This  is  the  artery 
of  the  vas  deferens.     Other  branches  supply  the  ureter. 

The  middle  vesicle,  usually  a  branch  of  the  superior,  is  distributed  to  the  base 
of  the  bladder,  and  under  surface  of  the  vesiculse  seminales. 

The  inferior  vesicle  arises  from  the  anterior  division  of  the  internal  iliac,  in 
common  with  the  middle  hasmorrhoidal,  and  is  distributed  to  the  base  of  the 
bladder,  the  prostate  gland,  and  vesiculae  seminales.  The  branches  distributed 
to  the  prostate  communicate  with  the  corresponding  vessel  of  the  opposite  side. 

The  middle  hemorrhoidal  artery  usually  arises  together  with  the  preceding 
vessel.  It  supplies  the  rectum,  anastomosing  with  the  other  hgemorrhoidal 
arteries. 

The  uterine  artery  passes  downwards  from  the  anterior  trunk  of  the  internal 
iliac  to  the  neck  of  the  uterus.  Ascending,  in  a  tortuous  course,  on  the  side  of 
this  viscus,  between  the  layers  of  the  broad  ligament,  it  distributes  branches  to 
its  substance,  anastomosing,  near  its  termination,  with  a  branch  from  the  ova- 
rian artery.  Branches  from  this  vessel  are  also  distributed  to  the  bladder  and 
ureter. 

The  vaginal  artery  is  analogous  to  the  inferior  vesical  in  the  male  ;  it  descends 
upon  the  vagina,  supplying  its  mucous  membrane,  and  sending  branches  to  the 
neck  of  the  bladder  and  contiguous  part  of  the  rectum. 

The  obturator  artery  usually  arises  from  the  anterior  trunk  of  the  internal  iliac, 
frequently  from  the  posterior.  It  passes  forwards  below  the  brim  of  the  pelvis, 
to  the  canal  in  the  upper  border  of  the  obturator  foramen,  and  escaping  from 
the  pelvic  cavity  through  this  aperture,  divides  into  an  internal  and  an  external 
branch.  In  the  pelvic  cavity  this  vessel  lies  upon  the  pelvic  fascia,  beneath  the 
peritoneum,  and  a  little  below  the  obturator  nerve  ;  and,  whilst  passing  through 
the  obturator  foramen,  is  contained  in  an  oblique  canal,  formed  by  the  horizon- 
tal branch  of  the  pubes,  above ;  and  the  arched  border  of  the  obturator  mem- 
brane, below. 

Branches.  Within  the  pelvis,  the  obturator  artery  gives  off  an  iliac  branch  to 
the  iliac  fossa,  which  supplies  the  bone  and  the  Iliacus  muscle,  and  anastomoses 
with  the  ilio-lumbar  artery  ;  a  vesical  branch,  which  runs  backwards  to  supply 
the  bladder;  and  a  pubic  branch,  which  is  given  off  from  the  vessel  just  before 
it  leaves  the  pelvic  cavity.  This  branch  ascends  upon  the  back  of  the  pubes, 
communicating  with  offsets  from  the  epigastric  artery,  and  with  the  correspond- 
ing vessel  of  the  opposite  side.  This  branch  is  placed  on  the  inner  side  of  the 
femoral  ring.  External  to  the  pelvis,  the  obturator  arter}''  divides  into  an  external 
and  an  internal  branch,  which  are  deeply  situated  beneath  the  Obturator  Exter- 
nus  muscle ;  skirting  the  circumference  of  the  obturator  foramen,  they  anasto- 
mose at  the  lower  part  of  this  aperture  with  each  other,  and  with  branches  of 
the  internal  circumflex  artery. 

The  internal  branch  curves  inwards  along  the  inner  margin  of  the  obturator 
foramen,  distributing  branches  to  the  Obturator  muscles,  Pectineus,  Adductors, 
and  Gracilis,  and  anastomoses  with  the  external  branch,  and  with  the  internal 
circumflex  artery. 

The  external  branch  curves  round  the  outer  margin  of  the  foramen,  to  the 
space  between  the  Gemellus  Inferior  and  Quadratus  Femoris,  where  it  anasto- 
moses with  the  sciatic  artery.  It  supplies  the  Obturator  muscles,  anastomoses, 
as  it  passes  backwards,  with  the  internal  circumflex,  and  sends  a  branch  to  the 
hip-joint  through  the  cotyloid  notch,which  ramifies  on  the  round  ligament  as 
far  as  the  head  of  the  femur. 

Peculiarilies.  In  two  out  of  every  three  cases  the  obturator  arises  from  the  internal  iliac ; 
in  one  case  in  3^  from  the  epigastric  ;  and  in  about  one  in  seventy-two  cases  by  two  roots  from 
both  vessels.  It  arises  in  about  the  same  proportion  from  the  external  iliac  artery.  The  origin 
of  the  obturator  from  the  epigastric  is  not  commonly  found  on  both  sides  of  the  same  body. 

When  the  obturator  artery  arises  at  the  front  of  the  pelvis  from  the  epigastric,  it  descends 
almost  vertically  to  the  upper  part  of  the  obturator  foramen.     The  artery  in  this  course  usually 


512 


ARTERIES. 


lies  ia  contact  with  the  external  iliac  vein,  and  on  the  outer  side  of  the  femoral  ring  (Fig.  295, 
1);  ill  such  cases  it  would  not  be  endangered  iu  the  operation  for  femoral  hernia.  Occasionally, 
however,  it  curves  inwards  along  the  free  margin  of  Girabernat's  ligament  (Fig.  295,  2).  and 
under  such  circumstances  would  almost  completely  encircle  the  neck  of  a  hernial  sac  (supposing 
a  hernia  to  exist  in  such  a  case),  and  would  be  in  great  danger  of  being  wounded  if  an  operation 
was  performed. 

Fig.  295,— Variations  in  Origin  and  Course  of  Obturator  Artery. 

,1 


The  Internal  Pudic  is  tlie  smaller  of  the  two  terminal  branches  of  the  ante- 
rior trunk  of  the  internal  iliac,  and  supplies  the  external  organs  of  generation. 
It  passes  downwards  and  outwards  to  tlie  lower  border  of  the  great  sacro-sciatic 
foramen,  and  emerges  from  the  pelvis  between  the  Pyriformis  and  Coccygeus 
muscles;  it  then  crosses  the  spine  of  the  ischium,  and  re-enters  the  pelvis 
through  the  lesser  sacro-sciatic  foramen.     The  artery  now  crosses-  the  Obtu- 

Mg.  296. — The  Internil  Pudic  Artery  and  its  Branches. 


rator  Tnternus  muscle,  to  the  ramus  of  the  ischium,  being  covered  by  the  obtu- 
rator fascia,  and  situated  about  au  inch  and  a  half  from  the  margin  of  the  tube- 


I 


INTERNAL    PUDIC.  513 

rosity ;  it  then  ascends  forwards  and  upwards  along  tlie  ramus  of  the  ischium, 
pierces  the  posterior  layer  of  the  deep  perineal  fascia,  and  runs  forwards  along 
the  inner  margin  of  the  ramus  of  the  pubes ;  finally,  it  perforates  the  a.nterior 
layer  of  the  deep  perineal  fascia,  and  divides  into  its  two  terminal  branches, 
the  dorsal  artery  of  the  penis,  and  the  artery  of  the  corpus  cavernosum. 

Belalions.  In  the  first  part  of  its  course,  within  the  pelvis,  it  lies  in  front  of 
the  Pyriformis  muscle  and  sacral  plexus  of  nerves,  and  on  the  outer  side  of  the 
rectum  (on  the  left  side).  As  it  crosses  the  spine  of  the  ischium,  it  is  covered 
by  the  Gluteus  Maximus,  and  great  sacro-sciatic  ligament.  In  the  pelvis,  it  lies 
on  the  outer  side  of  the  ischio-rectal  fossa,  upon  the  surface  of  the  Obturator 
Internus  muscle,  contained  in  a  fibrous  canal  formed  by  the  obturator  fascia 
and  the  falciform  process  of  the  great  sacro-sciatic  ligament.  It  is  accompanied 
by  the  pudio  veins,  and  the  internal  pudic  nerve. 

Peculiarities.  The  internal  pudic  is  sometimes  smaller  than  usual,  or  fails  to  give  off  one  or 
two  of  its  usual  branches;  in  such  cases,  the  deficiency  is  supplied  by  branches  derived  from  au 
additional  vessel,  the  accessory  pudic,  which  generally  arises  from  the  pudic  artery  before  its 
exit  from  the  great  sacro-sciatic  foramen,  and  passes  forwards  near  the  base  of  the  bladder,  on 
the  upper  part  of  the  prostate  gland,  to  the  perineum,  where  it  gives  off  the  branches,  usually 
derived  from  the  pudic  artery.  The  deficiency  most  frequently  met  with,  is  that  in  which  the 
internal  pudic  ends  as  the  artery  of  the  bulb ;  the  artery  of  the  corpus  cavernosum  and  arteria 
dorsalis  penis  being  derived  from  the  accessory  pudic.  Or  the  pudic  may  terminate  as  the 
superficial  perineal,  the  artery  of  the  bulb  being  derived,  with  the  other  two  branches,  from  the 
accessory  vessel. 

The  relation  of  the  accessory  pudic  to  the  prostate  gland  and  urethra  is  of  the  greatest 
interest  in  a  surgical  point  of  view,  as  this  vessel  is  in  danger  of  being  wounded  in  the  lateral 
operation  of  lithotomy. 

Branches.  Within  the  pelvis^  the  internal  pudic  gives  off  several  small  branches, 
which  supply  the  muscles,  sacral  nerves,  and  pelvic  viscera.  In  the  perineum 
the  following  branches  are  given  off: — 

Inferior  or  external  haemorrhoidal.        Artery  of  the  bulb. 

Superficial  perineal.  Artery  of  the  corpus  cavernosum. 

Transverse  perineal.  Dorsal  artery  of  the  penis. 

The  external  hemorrhoidal  are  two  or  three  small  arteries,  which  arise  from 
the  internal  pudic  as  it  passes  above  the  tuberosity  of  the  ischium.  Crossing 
the  ischio-rectal  fossa,  they  are  distributed  to  the  muscles  and  integument  of 
the  anal  region. 

The  superficial  perineal  artery  supplies  the  scrotum,  and  muscles  and  integu- 
ment of  the  perineum.  It  arises  from  the  internal  pudic,  in  front  of  the  pre- 
ceding branches,  and  piercing  the  lower  border  of  the  deep  perineal  fascia,  runs 
across  the  Transversus  Perinasi,  and  through  the  triangular  space  between  the 
Accelerator  Urinae  and  Erector  Penis,  both  of  which  it  supplies,  and  is  finally 
distributed  to  the  skin  of  the  scrotum  and  dartos.  In  its  passage  through  the 
perineum  it  lies  beneath  the  superficial  perineal  fascia. 

The  transverse  perineal  is  a  small  branch  which  arises  either  from  the  inter- 
nal pudic,  or  from  the  superficial  perineal  artery  as  it  crosses  the  Transversus 
Perinasi  muscle.  Piercing  the  lower  border  of  the  deep  perineal  fascia,  it  runs 
transversely  inwards  along  the  cutaneous  surface  of  the  Transversus  Perinsei 
muscle,  which  it  supplies,  as  well  as  the  structures  between  the  anus  and  bulb 
of  the  urethra. 

The  artery  of  the  bulb  is  a  large  but  very  short  vessel,  which  arises  from  the 
internal  pudic  between  the  two  layers  of  the  deep  perineal  fascia,  and  passing 
nearly  transversely  inwards,  pierces  the  bulb  of  the  urethra,  in  which  it  rami- 
fies. It  gives  off"  a  small  branch,  which  descends  to  supply  Cowper's  gland. 
This  artery  is  of  considerable  importance  in  a  surgical  point  of  view,  as  it  is 
in  danger  of  being  wounded  in  the  lateral  operation  of  lithotomy,  an  accident 
usually  attended  in  the  adult  with  alarming  hemorrhage.  The  vessel  is  some- 
times very  small,  occasionally  wanting,  or  even  double.  It  sometimes  arises 
from  the  internal  pudic  earlier  than  usual,  and  crosses  the  perineum  to  reach 
33 


bU 


ARTERIES. 


the  back  part  of  the  bulb.     In  such  a  case  the  vessel  coultl  hardly  fail  to  be 
wounded  in  the  performance  of  the  lateral  operation  for  lithotomy.     If,  on  the 

contrary,  it  should  arise  from 


Fig.  297.— The  Arteries  of  the  Gluteal  and  Posterior  Fe- 
moral Kegions. 


an  accessory  pudic,  it  lies 
more  forward  than  usual,  and 
is  out  of  danger  in  the  ope» 
ration. 

The  artery  of  the  corpus  ca- 
vernosum,  one  of  the  terminal 
branches  of  the  internal  pudic, 
arises  from  that  vessel  while 
it  is  situated  between  the  crus 
penis  and  the  ramus  of  the 
pubes;  piercing  the  crus  penis 
obliquely,  it  runs  forwards  in 
the  corpus  cavernosum  by  the 
side  of  the  septum  pectini- 
forme,  to  which  its  branches 
are  distributed. 

The  dorsal  artery  of  the  penis 
ascends  between  the  crus  and 
pubic  symphysis,  and  piercing 
the  suspensory  ligament,  runs 
forward  on  the  dorsum  of  the 
penis  to  the  glans,  where  it 
divides  into  two  branches, 
which  supply  the  glans  and 
prepuce.  On  the  dorsum  of 
the  penis,  it  lies  immediately  |l 
beneath  the  integument,  pa-  ' 
rallel  with  the  dorsal  vein, 
and  the  corresponding  ar- 
tery of  the  opposite  side.  It 
supplies  the  integument  and 
fibrous  sheath  of  the  corpus 
cavernosum. 

The  internal  pudic  artery  in 
the  female  is  smaller  than  in  the 
male.  Its  origin  and  course 
are  similar,  and  there  is  con- 
siderable analogy  in  the  dis- 
tribution of  its  branches.  The 
superficial  artery  supplies  the 
labia  pudenda ;  the  artery  of 
the  bulb  supplies  the  erectile 
tissue  of  the  bulb  of  the  va- 
gina, whilst  the  two  terminal 
branches  supply  the  clitoris; 
the  artery  of  the  corpus  cavernosum,  the  cavernous  body  of  the  clitoris ;  and 
the  arteria  dorsalis  clitoridis,  the  dorsum  of  that  organ. 

The  Sciatic  Artery  (Fig.  297),  the  larger  of  the  two  terminal  branches  of  the 
anterior  trunk  of  the  internal  iliac,  is  distributed  to  the  muscles  on  the  back 
of  the  pelvis.  It  passes  down  to  the  lower  part  of  the  great  sacro-sciatic  fora- 
men, behind  the  internal  pudic,  resting  on  the  sacral  plexus  of  nerves  and 
Pyriformis  muscle,  and  escapes  from  the  pelvis  between  the  Pyriformis  and 
Coccygeus.  It  then  descends  in  the  interval  between  the  trochanter  major  and 
tuberosity  of  the  ischium,  accompanied  by  the  eciatio  nerves,  and  covered  by 


^f^^hacmaiJMnJ. 


Ii^rrhr  tZuMtulr^ 


SCIATIC.  515 

the  Gluteus  Maxiraus,  and  divides  into  branches,  which  supply  the  deep  mus- 
cles at  the  back  of  the  hip. 

W^ithin  the  pelvis  it  distributes  branches  to  the  Pyriforrnis,  Coccygeus,  and 
Levator  Ani  muscles ;  some  haemorrhoidal  branches,  which  supply  the  rectum, 
and  occasionally  take  the  place  of  the  middle  hajmorrhoidal  artery;  and  vesical 
branches  to  the  base  and  neck  of  the  bladder,  vesiculse  seminales,  and  prostate 
gland.  External  to  the  pelvis,  it  gives  off  the  coccygeal,  inferior  gluteal,  comes 
nervi  ischiadic!,  muscular,  and  articular  branches. 

The  coccygeal  branch  runs  inwards,  pierces  the  great  sacro-sciatic  ligament, 
and  supplies  the  Gluteus  Maximus,  the  integument,  and  other  structures  on  the 
back  of  the  coccyx. 

The  inferior  gluteal  branches^  three  or  four  in  number,  supply  the  Gluteus 
Maximus  muscle. 

The  comes  nervi  ischiadici  is  a  long  slender  vessel,  which  accompanies  the 
great  sciatic  nerve  for  a  short  distance;  it  then  penetrates  it,  and  runs  in  its 
substance  to  the  lower  part  of  the  thigh. 

The  muscular  branches  supply  the  muscles  on  the  back  part  of  the  hip,  anas- 
tomosing with  the  gluteal,  internal  and  external  circumflex,  and  superior  per- 
forating arteries. 

Some  articular  branches  are  distributed  to  the  capsule  of  the  hip-joint. 

The  Gluteal  Artery  is  the  largest  branch  of  the  internal  iliac,  and  appears  to 
be  the  continuation  of  the  posterior  division  of  that  vessel.  It  is  a  short, 
thick  trunk,  which  passes  out  of  the  pelvis  above  the  upper  border  of  the 
Pyriformis  muscle,  and  immediately  divides  into  a  superficial  and  deep  branch. 
Within  the  pelvis,  it  gives  off  a  few  muscular  branches  to  the  Iliacus,  Pyri- 
formis, and  Obturator  Intern  us,  and  just  previous  to  quitting  that  cavity  a  nu- 
trient artery,  which  enters  the  ilium. 

The  superficial  branch  passes  beneath  the  Gluteus  Maximus,  and  divides  into 
numerous  branches,  some  of  which  supply  that  muscle,  whilst  others  perforate 
its  tendinous  origin,  and  supply  the  integument  covering  the  posterior  surface 
of  the  sacrum,  anastomosing  with  the  posterior  branches  of  the  sacral  arteries. 

The  deep  branch  runs  between  the  Gluteus  Medius  and  Gluteus  Minimus,  and 
subdivides  into  two.  Of  these,  the  superior  division,  continuing  the  original 
course  of  the  vessel,  passes  along  the  upper  border  of  the  Gluteus  Minimus  to 
the  anterior  superior-spine  of  the  ilium,  anastomosing  with  the  circumflex  iliac 
and  ascending  branches  of  the  external  circumflex  artery.  The  inferior  division 
crosses  the  Gluteus  Minimus  obliquely  to  the  trochanter  major,  distributing 
branches  to  the  Glutei  muscles,  and  inosculates  with  the  external  circumflex 
artery.     Some  branches  pierce  the  Gluteus  Minimus  to  supply  the  hip-joint. 

The  llio-lumbar  Artery  ascends  beneath  the  Psoas  muscle  and  external  iliac 
vessels,  to  the  upper  part  of  the  iliac  fossa,  where  it  divides  into  a  lumbar  and 
an  iliac  branch. 

The  lumhar  branch  supplies  the  Psoas  and  Quadratus  Lumborum  muscles, 
anastomosing  with  the  last  lumbar  artery,  and  sends  a  small  spinal  branch 
through  the  intervertebral  foramen,  between  the  last  lumbar  vertebra  and  the 
sacrum,  into  the  spinal  canal,  to  supply  the  spinal  cord  and  its  membranes. 

The  iliac  branch  descends  to  supply  the  Iliacus  Internus,  some  offsets  running 
between  the  muscle  and  the  bone,  one  of  which  enters  an  oblique  canal  to 
supply  the  diploe,  whilst  others  run  along  the  crest  of  the  ilium,  distributing 
branches  to  the  Gluteal  and  abdominal  muscles,  and  anastom.osing  in  their 
course  with  the  gluteal,  circumflex  iliac,  external  circumflex,  and  epigastric 
arteries. 

The  Lateral  Sacral  Arteries  (Fig.  294)  are  usually  two  in  number  on  each 
side,  superior  and  inferior. 

The  superior,  which  is  of  large  size,  passes  inwards,  and,  after  anastomosing 
with  branches  from  the  middle  sacral,  enters  the  first  or  second  sacral  foramen, 
is  distributed  to  the  contents  of  the  sacral  canal,  and  escaping  by  the  corres- 


f,16  ARTERIES. 

ponding  posterior  sacral  foramen,  supplies  the  skin  and  muscles  on  the  dorsum 
of  the  sacrum. 

The  inferior  branch  passes  obliquely  across  the  front  of  the  Pyriformis  muscle 
and  sacral  nerves  to  the  inner  side  of  the  anterior  sacral  foramina,  descends  on 
the  front  of  the  sacrum,  and  anastomoses  over  the  coccyx  with  the  sacra  media 
and  opposite  lateral  sacral  arteries.  In  its  course,  it  gives  off"  branches,  which 
enter  the  anterior  sacral  foramina :  these,  after  supplying  the  bones  and  mem- 
branes of  the  interior  of  the  spinal  canal,  escape  by  the  posterior  sacral  fora- 
mina, and  are  distributed  to  the  muscles  and  skin  on  the  dorsal  surface  of  the 
sacrum. 

External  Iliac  Artery.    (Fig.  294.) 

The  External  Iliac  Artery  is  the  chief  vessel  which  supplies  the  lower  limb. 
It  is  larger  in  the  adult  than  the  internal  iliac,  and  passes  obliquely  downwards 
and  outwards  along  the  inner  border  of  the  Psoas  muscle,  from  the  bifurcation 
of  the  common  iliac  to  the  femoral  arch,  where  it  enters  the  thigh,  and  becomes 
the  femoral  artery.  The  course  of  this  vessel  would  be  indicated  by  a  line 
drawn  from  the  left  side  of  the  umbilicus  to  a  point  midway  between  the  ante- 
rior superior  spinous  process  of  the  ilium  and  the  symphysis  pubis. 

Relations.  In  front,  with  the  peritoneum,  subperitoneal  areolar  tissue,  the 
intestines,  and  a  thin  layer  of  fascia,  derived  from  the  iliac  fascia,  which  sur- 
rounds the  artery  and  vein.  At  its  origin  it  is  occasionally  crossed  by  the 
ureter.  The  spermatic  vessels  descend  for  some  distance  upon  it  near  its 
termination,  and  it  is  crossed  in  this  situation  by  a  branch  of  the  genito-crural 
nerve  and  the  circumflex  iliac  vein ;  the  vas  deferens  curves  down  along  its 
inner  side.  Behind,  it  is  in  relation  with  the  external  iliac  vein,  which,  at  the 
femoral  arch,  lies  at  its  inner  side ;  on  the  left  side  the  vein  is  altogether  inter- 
nal to  the  artery.  Externally,  it  rests  against  the  Psoas  muscle,  from  which  it 
is  separated  by  the  iliac  fascia.  The  artery  rests  upon  this  muscle  near  Pou- 
part's  ligament.  Numerous  lymphatic  vessels  and  glands  are  found  lying  on 
the  front  and  inner  side  of  the  vessel. 

Plan  of  the  Relations  of  the  External  Iliac  Artery. 

In  front. 
PeritoneHm,  intestines,  and  iliac  fascia. 
Near       f  Spermatic  vessels. 

T»-.„^„.,+'o     (ienito-c rural  nerve, 
x^oupart  s  ■{  (X-  ^      a      -i- 
Ligament   I  ^"'<^"™"^x  "'*c  vein. 
°  '  [  Lymphatic  vessels  and  glands. 


Oviier  aide.  f  \  Inner  side. 

Psoas  Magnus.  ^nfa"*'  External  iliac  vein  and  vas  deferent 

Iliac  fascia.  V  /  at  femoral  arch. 


Behi7id. 
External  iliac  vein. 
Psoas  Magnus. 

Suvfiical  Anatomy.  The  application  of  a  ligature  to  the  external  iliac  may  be  requireflTT 
cases  of  aneurism  of  the  fomorul  artery,  or  in  cases  of  secondary  hemorrhage,  after  the  latter 
vessel  has  beeu  tied  for  popliteal  aneurism.  This  vessel  may  be  secured  in  any  part  of  its 
course,  exfepting  near  its  upper  end,  which  is  to  bo  avoided  on  account  of  the  proximity  of  the 
great  stream  »»f  blood  in  the  internal  iliac,  and  near  its  lower  end,  which  should  also  be  avoided, 
on  account  of  the  proximity  of  the  epiuftistric  and  circumflex  iliac  vessels.  One  of  the  chief 
points  in  the  performance  of  the  operation  is  to  secure  the  ves.sel  without  injury  to  the  perito- 
neum. The  patient  having  l)een  placed  in  the  recumbent  position,  an  incision  should  be  made, 
commencing  below  at  a  point  about  three-quarters  of  an  inch  above  Poupart's  ligament,  and  a 
little  external  to  its  centre,  and  running  upwards  and  outwards,  parallel  to  Poupart's  ligament, 
to  a  point  above  the  anterior  superior  spine  of  the  ilium.     When  the  artery  is  deeply  seated, 


EXTERNAL    ILIAC.  517 

more  room  will  be  required,  and  may  be  obtained  by  curving  the  incision  from  the  point  last 
named  inwards  towards  the  umbilicus  for  a  short  distance ;  or,  if  the  lower  part  of  the  artery  is 
to  be  reached,  the  surgeon  may  commence  the  incision  nearer  the  inner  end  of  Poupart's  liga- 
ment, taking  care  to  avoid  the  epigastric  artery.  Abernethy,  who  first  tied  this  artery,  made 
his  incision  in  the  course  of  the  vessel.  The  precise  line  of  incision  selected  is  of  less  moment, 
provided  an  easy  access  to  the  deeper  parts  is  secured.  The  abdominal  muscles  and  transver- 
salis  fascia  having  been  cautiously  divided,  the  peritoneum  should  be  separated  from  the  iliac 
fossa  and  pushed  towards  the  pelvis  ;  and  on  introducing  the  finger  to  the  bottom  of  the  wound 
the  artery  may  be  felt  pulsating  along  the  inner  border  of  the  Psoas  muscle.  The  e.xternal  iliac 
vein  is  generally  found  on  the  inner  side  of  the  artery,  and  must  be  cautiously  separated  from  it 
by  the  finger-nail,  or  handle  of  the  knife,  and  the  aneurism  needle  should  be  introduced  on  the 
inner  side,  between  the  artery  and  vein. 

Collateral  Circulation.  'J'he  principal  anastomoses  in  carrying  on  the  collateral  circulation, 
after  the  application  of  a  ligature  to  the  external  iliac,  are — the  ilio-lumbar  with  the  circumflex 
iliac;  the  gluteal  with  the  external  circumflex  ;  the  obturator  with  the  internal  circumflex  ;  the 
sciatic  with  the  superior  perforating  and  circumflex  branches  of  the  profunda  artery;  the  interna] 
pudic  with  the  external  pudic,  and  with  the  internal  circumflex.  When  the  obturator  arises 
from  the  epigastric,  it  is  supplied  with  blood  by  branches,  either  from  the  internal  iliac,  the 
lateral  sacral,  or  the  internal  pudic.  The  epigastric  receives  its  supply  from  the  internal  mam- 
mary and  inferior  intercostal  arteries,  and  from  the  internal  iliac,  by  the  anastomoses  of  its 
branches  with  the  obturator. 

In  the  dissection  of  a  limb,  eighteen  years  after  the  successful  ligature  of  the  external  iliac 
artery,  by  Sir  A.  Cooper,  which  is  to  be  found  in  Guy's  Hospital  Reports,  vol.  1.  page  50,  the 
anastomosing  branches  are  described  in  three  sets.  An  anterior  set.  1.  A  very  large  branch 
from  the  ilio-lumbar  artery  to  the  circumflex  iliac;  2.  Another  branch  from  the  ilio-lumbar, 
joined  by  one  from  the  obturator,  and  breaking  up  into  numerous  tortuous  branches  to  anasto- 
mose with  the  external  circumflex ;  3.  Two  other  branches  from  the  obturator,  which  passed 
over  the  brim  of  the  pelvis,  communicated  with  the  epigastric,  and  then  broke  up  into  a  plexus 
to  anastomose  with  the  internal  circumflex.  An  internal  set.  Branches  given  off  from  the 
obturator,  after  quitting  the  pelvis,  which  ramified  among  the  adductor  muscles  on  the  inner  side 
of  the  hip-joint,  and  joined  most  freely  with  branches  of  the  internal  circumflex,  A  posterior  set. 
1.  Three  large  branches  from  the  gluteal  to  the  external  circumflex ;  2.  Several  branches  from 
the  sciatic  around  the  great  sciatic  notch  to  the  internal  and  external  circumflex,  and  the  per- 
forating branches  of  the  profunda. 

Branches.  Besides  several  small  branches  to  the  Psoas  muscles  and  the 
neighboring  lymphatic  glands,  the  external  iliac  gives  off  two  branches  of  con- 
siderable size,  the 

Epigastric.  Circumflex  iliac. 

The  epigastric  artery  arises  from  the  external  iliac,  a  few  lines  above  Pou- 
part's ligament.  It  at  first  descends  to  reach  this  ligament,  and  then  ascends 
obliquely  inwards  between  the  peritoneum  and  transversal  is  fascia,  to  the  mar- 
gin of  the  sheath  of  the  Rectus  muscle.  Having  perforated  the  sheath  near  its 
lower  third,  it  runs  vertically  upwards  behind  the  Rectus,  to  which  it  is  dis- 
tributed, dividing  into  numerous  branches,  which  anastomose  above  the  umbili- 
cus with  the  terminal  branches  of  the  internal  mammary  and  inferior  intercostal 
arteries.  It  is  accompanied  by  two  veins,  which  usually  unite  into  a  single 
trunk  before  their  termination  in  the  external  iliac  vein.  As  this  artery 
ascends  from  Poupart's  ligament  to  the  Rectus,  it  lies  behind  the  inguinal 
canal,  to  the  inner  side  of  the  internal  abdommal  ring,  and  immediately  above 
the  femoral  ring.  The  vas  deferens  in  the  male,  and  the  round  ligament  in  the 
female,  cross  behind  the  artery  in  descending  into  the  pelvis. 

Branches.  The  branches  of  this  vessel  are  the  following;  the  cremasteric^ 
which  accompanies  the  spermatic  cord,  and  supplies  the  Cremaster  muscle, 
anastomosing  with  the  spermatic  artery ;  a  puhic  hranch^  which  runs  across 
Poupart's  ligament,  and  then  descends  behind  the  pubes  to  the  inner  side  of  the 
femoral  ring,  and  anastomoses  with  offsets  from  the  obturator  artery ;  imiscular 
branches^  some  of  which  are  distributed  to  the  abdominal  muscles  and  peritoneum, 
anastomosing  with  the  lumbar  and  circumflex  iliac  arteries;  others  perforate 
the  tendon  of  the  External  Oblique  and  supply  the  integument,  anastomosing 
with,  branches  of  the  external  epigastric. 

Peculiarities.  The  origin  of  the  epigastric  may  take  place  from  any  part  of  the  external  iliac 
between  Poupart's  ligament  and  two  inches  and  a  half  above  it;  or  it  may  arise  below  this  liga- 
ment, from  the  femoral,  or  from  the  deep  femoral. 


518  ARTERIES. 

Union  with  Branches.  It  frequently  arises  from  the  external  iliac,  by  a  common  trunk  with 
the  obturator.  Sometimes  the  epigastric  arises  from  the  obturator,  the  latter  vessel  being  fur- 
nished by  the  internal  iliac,  or  the  epigastric  may  be  formed  of  two  branches,  one  derived  from 
the  external  iliac,  the  others  from  the  internal  iliac. 

The  circumflex  iliac  artery  arises  from  the  o'uter  side  of  the  external  iliac, 
nearly  opposite  the  epigastric  artery.  It  ascends  obliquely  outwards  behind 
Poupart's  ligament,  and  runs  along  the  inner  surface  of  the  crest  of  the  ilium 
to  about  its  middle,  where  it  pierces  the  Transversalis,  and  runs  backwards 
between  that  muscle  and  the  Internal  Oblique,  to  anastomose  with  the  ilio- 
lumbar and  gluteal  arteries.  Opposite  the  anterior  superior  spine  of  the  ilium, 
it  gives  off  a  large  branch,  which  ascends  between  the  Internal  Oblique  and 
Transversalis  muscles,  supplying  them  and  anastomosing  with  the  lumbar  and 
epigastric  arteries.  The  circumflex  iliac  artery  is  accompanied  by  two  veins. 
These  unite  into  a  single  trunk  which  crosses  the  external  iliac  artery  just  above 
Poupart's  ligament,  and  enters  the  external  iliac  vein. 

Femoral  Artery.    (Fig.  298.) 

The  Femoral  Artery  is  the  continuation  of  the  external  iliac.  It  commences 
immediately  beneath  Poupart's  ligament,  midway  between  the  anterior  superior 
spine  of  the  ilium  and  the  symphysis  pubis,  and  passing  down  the  forepart  and 
inner  side  of  the  thigh,  terminates  at  the  opening  in  the  Adductor  Magnus,  at 
the  junction  of  the  middle  with  the  lower  third  of  the  thigh,  where  it  becomes 
the  popliteal  artery.  A  line  drawn  from  a  point  midway  between  the  anterior 
superior  spine  of  the  ilium  and  the  symphysis  pubis  to  the  inner  side  of  the 
inner  condyle  of  the  femur,  will  be  nearly  parallel  with  the  course  of  the  artery. 
This  vessel,  at  the  upper  part  of  the  thigh,  lies  a  little  internal  to  the  head  of 
the  femur ;  in  the  lower  part  of  its  course,  on  the  inner  side  of  the  shaft  of  the 
bone,  and  between  these  two  parts,  the  vessel  is  separated  from  the  bone  by  a 
considerable  interval. 

In  the  upper  third  of  the  thigh  the  femoral  artery  is  very  superficial,  being 
covered  by  the  integument,  inguinal  glands,  and  the  superficial  and  deep  fasciae, 
and  is  contained  in  a  triangular  space,  called  "  Scarpa's  triangle." 

Scarpa's  Triangle.  Scarpa's  triangle  corresponds  to  the  depression  seen  imme- 
diately below  the  fold  of  the  groin.  It  is  a  triangular  space,  the  apex  of  which 
is  directed  downwards,  and  the  sides  of  which  are  formed  externally  by  the 
Sartorius,  internally  by  the  Adductor  Longus,  and  above  by  Poupart's  ligament. 
The  floor  of  this  space  is  formed  from  without  inwards  by  the  Iliacus,  Psoas,  • 
Pectineus,  Adductor  Longus,  and  a  small  part  of  the  Adductor  Brevis  muscles; 
and  it  is  divided  into  two  nearly  equal  parts  by  the  femoral  vessels,  which 
extend  from  the  middle  of  its  base  to  its  apex;  the  artery  giving  off  in  this 
situation  its  cutaneous  and  profunda  branches,  the  vein  receiving  the  deep 
femoral  and  internal  saphenous  veins.  In  this  space  the  femoral  artery  rests  on  jjM 
the  inner  margin  of  the  Psoas  muscle,  which  separates  it  from  the  capsular  ■' 
ligament  of  the  hip-joint.  The  artery  in  this  situation  has  in  front  of  it  fila- 
ments from  tlie  crural  branch  of  the  genito-crural  nerve,  and  branches  from  the 
anterior  crural,  one  of  which  is  usually  of  considerable  size;  behind  the  artery 
is  the  bratich  to  the  Pectineus  from  the  anterior  crural.  The  femoral  vein  lies 
at  its  inner  side,  between  the  margins  of  the  Pectineus  and  Psoas  muscles.  The 
anterior  crural  nerve  lies  about  half  an  inch  to  the  outer  side  of  the  femoral 
artery,  deeply  imbedded  between  the  Iliacus  and  Psoas  muscles.  The  feteoral 
artery  and  vein  are  inclosed  in  a  strong  fibrous  sheath,  formed  by  fibrous  and 
cellular  tissue,  and  by  a  process  of  fascia  sent  inwards,  from  the  fascia  lata ;  the  MM 
vessels  are  separated,  however,  from  one  another  by  thin  fibrous  partitions.         n 

f7i  the  middle  third  of  the  thigh,  the  femoral  artery  is  more  deeply  seated,  being 
covered  by  the  integument,  the  superficial  and  deep  fascia,  and  the  Sartorius, 
and  is  contained  in  an  aponeurotic  canal,  formed  by  a  dense  fibrous  band,  which 


II 


FEMORAL. 


619 


extends  transversely  from  the  Vastus  Internus  to  the  tendons  of  the  Adductor 
Longus  and  Adductor  Magnus  muscles.     In  this  part  of  its  course  it  lies  in  a 
depression,    bounded    exter- 
nally by  the  Vastus  Internus,         Fig.  298.— Surgical  Anatomy  of  the  Femoral  Artery, 
internally  by   the   Adductor 
Longus  and  Adductor  Mag- 
nus.    The  femoral  vein  lies 
on  the  outer  side  of  the  arte- 
ry, in  close  apposition  with 
it,  and,  still  more  externally, 
is  the  internal  (long)  saphe- 
nous nerve. 

Relations.  From  above  down- 
wards, the  femoral  artery 
rests  upon  the  Psoas  muscle, 
which  separates  it  from  the 
margin  of  the  pelvis  and  cap- 
sular ligament  of  the  hip ;  it 
is  next  separated  from  the 
Pectineus  by  the  profunda 
vessels  and  femoral  vein ;  it 
then  lies  upon  the  Adductor 
Longus ;  and  lastly,  upon  the 
tendon  of  the  Adductor  Mag- 
nus, the  femoral  being  inter- 
posed. To  its  inner  side,  it  is 
in  relation  above,  with  the  fe- 
moral vein,  and,  lower  down, 
with  the  Adductor  Longus, 
and  Sartorius.  To  its  outer 
side,  the  Vastus  Internus  sepa- 
rates it  from  the  femur,  in 
the  lower  part  of  its  course. 

The  femoral  vein,  at  Pou- 
part's  ligament,  lies  close  to 
tlft  inner  side  of  the  artery, 
separated  from  it  by  a  thin 
fibrous  partition,  but,  as  it 
descends,  gets  behind  it,  and 
then  to  its  outer  side. 

The  internal  sapheno^is  nerve 
is  situated  on  the  outer  side 
of  the  artery,  in  the  middle 
third  of  the  thigh,  beneath 
the  aponeurotic  covering,  but 
not  usually  within  the  sheath 
of  the  vessels.  Small  cuta- 
neous nerves  cross  the  front 
of  the  sheath. 


JSlasaa 


Super.  ExtrmiS 


UMAUU.^A/I 


Antex.  Ti,\nx 


520 


ARTERIES. 


Plan  of  the  Relations  of  the  Femoral  Arteky. 

In  front. 
Fascia  lata. 

Branch  of  anterior  crural  nerve. 
Sartorius. 

Long  saphenous  nerve. 
Aponeurotic  covering  of  Hunter's  canal. 


Inner  side. 
Femoral  vein  (at  upper  part) 
Abductor  Longus. 
Sartorius. 


Outer  side. 
Vastus  Internus. 
Femoral  vein  (at  lower  part). 


Behind. 
Psoas  muscle. 
Profunda  vein. 
Pectincus  muscle. 
Adductor  Longus. 
Femoral  vein. 
Adductor  Magnus. 

Peculiarities.  Double  femoral  re-unitcd.  Four  cases  are  at  present  recorded,  in  which  the 
femoral  artery  divided  into  two  trunks  below  the  origin  of  the  profunda,  and  became  re-united 
near  the  opening  in  the  Adductor  Magnus,  so  as  to  form  a  single  popliteal  artery.  One  of  them 
occurred  in  a  patient  operated  upon  for  popliteal  aneurism. 

Change  of  Position.  A  similar  number  of  cases  have  been  recorded,  in  which  the  femoral 
artery  was  situated  at  the  back  of  the  thigh,  the  vessel  being  continuous  above  with  the  internal 
iliac,  escaping  from  the  pelvis  through  the  great  sacro-sciatic  foramen,  and  accompanying  the 
great  sciatic  nerve  to  the  popliteal  space,  where  its  division  occurred  in  the  usual  manner. 

Position  of  the  Vein.  The  femoral  vein  is  occasionally  placed  along  the  inner  side  of  the 
artery,  throughout  the  entire  extent  of  Scarpa's  triangle ;  or  it  may  be  slit,  so  that  a  large  vein 
is  placed  on  each  side  of  the  artery  for  a  greater  or  less  extent. 

Origin  of  the  Profunda.  This  vessel  occasionally  arises  from  the  inner  side,  and  more  rarely, 
from  the  back  of  the  common  trunk ;  but  the  more  important  peculiarity,  in  a  surgical  point  of 
view,  is  that  which  relates  to  the  height  at  which  the  vessel  arises  from  the  femoral.  In  three- 
fourths  of  a  large  number  of  cases,  it  arose  between  one  or  two  inches  below  Poupart's  liga- 
ment ;  in  a  few  cases,  the  distance  was  less  than  an  inch ;  more  rarely,  opposite  the  ligament ; 
and  in  one  case,  above  Poupart's  ligament,  from  the  external  iliac.  Occasionally,  the  distance 
between  the  origin  of  the  vessel  and  Poupart's  ligament  exceeds  two  inches,  and  in  one  case  it 
was  found  to  be  as  much  as  four  inches. 

Surgical  Anatomi/.     Compression  of  the  femoral  artery,  which  is  constantly  requisite  in  am- 

?atations  and  other  operations  on  the  lower  limb,  is  most  effectually  made  immediately  below 
'oupart's  ligament.  In  this  situation  the  artery  is  very  superficial,  and  is  merely  separated 
from  the  margin  of  the  acetabulum  and  front  of  the  head  of  the  femur,  by  the  Psoas  muscle; 
so  that  the  surgeon,  by  means  of  his  thumb,  or  a  compressor,  may  eflTectually  control  the  circu- 
lation through  it.  This  vessel  may  also  be  compressed  in  the  middle  third  of  the  thigh,  by 
placing  a  compress  over  the  artery,  beneath  the  tourniquet,  and  directing  the  pressure  from 
within  outwards,  so  as  to  compress  the  vessel  on  the  inner  side  of  the  shaft  of  the  femur. 

The  application  of  a  ligature  to  the  femoral  artery  may  be  required  in  cases  of  wound  or 
aneurism  of  the  arteries  of  the  leg,  of  the  popliteal  or  femoral;  and  the  vessel  may  be  exposed 
and  tied  in  any  part  of  its  course.  The  great  depth  of  this  vessel  at  its  lower  part,  its  close 
connection  with  important  structures,  and  the  density  of  its  sheath,  render  the  operation  in  this 
situation  one  of  much  greater  difficulty  than  the  application  of  a  ligature  at  its  upper  part, 
where  it  is  more  superficial. 

Ligature  of  the  femoral  artery,  within  two  inches  of  its  origin,  is  usually  considered  unsafe, 
on  account  of  the  connection  of  large  branches  with  it,  the  epigastric  and  circumflex  iliac  aris- 
ing just  above  its  origin;  the  profunda,  from  one  to  two  inches  below,  occasionally,  also,  one  of 
the  circumflex  arteries  arises  from  the  vessel  in  the  interspace  between  these.  The  profund* 
sometimes  arises  higher  than  the  point  above  mentioned,  and  rarely  between  two  or  three  inches 
(in  one  case  four),  below  Poupart's  ligament.  It  would  appear,  then,  that  the  most  favorable 
situation  fi>r  the  application  of  a  ligature  to  the  femoral,  is  between  four  and  five  inches  from  its 
point  of  origin  In  order  to  expuse  the  artery  in  this  situation,  an  incision,  l)etween  two  and 
three  inches  long,  should  be  made  in  the  course  of  the  vessel,  the  patient  lying  in  the  recumbent 
position,  with  tlie  limb  slightly  flexed  and  abducted.  A  large  vein  is  frequently  met  with,  pass- 
ing in  the  course  of  the  artery  to  join  tlie  saphena ;  this  must  be  avoided,  and  the  fascia  lata 
having  been  cautiously  divided,  and  the  Sartorius  exposed,  that  muscle  must  be  drawn  outwards. 
\n  order  to  fully  expose  the  sheath  of  the  vessels  'I'he  finger  being  introduced  into  the  wound, 
and  the  pulsation  of  the  artery  felt,  the  sheath  should  be  divided  over  the  artery  to  a  sufficient 
extent  to  allow  of  the  introduction  of  the  ligature,  but  no  further;  otherwise  the  nutrition  of 


FEMORAL.  621 

the  coats  of  the  vessel  may  be  interfered  with,  or  muscular  branches  which  arise  from  the  ves- 
sel at  irregular  intervals  may  be  divided.  In  this  part  of  the  operation,  a  small  nerve  which 
crosses  the  sheath  should  be  avoided.  The  anuerism  needle  must  be  carefully  introduced,  and 
kept  close  to  the  artery,  to  avoid  the  femoral  vein,  which  lies  behind  the  vessel  in  this  part  of 
its  course. 

To  expose  the  artery  in  the  middle  of  the  thigh,  an  incision  should  be  made  through  the  in- 
tegument, between  three  and  four  inches  in  length,  over  the  inner  margin  of  the  Sartorius, 
taking  care  to  avoid  the  internal  saphenous  vein,  the  situation  of  wliich  may  be  previously 
known  by  compressing  it  higher  up  in  the  thigh.  The  fascia  lata  having  been  divided,  and  the 
Sartorius  muscle  exposed,  it  should  be  drawn  outwards,  when  the  strong  fascia,  which  is 
stretched  across  from  the  Adductors  to  the  Vastus  Internus,  will  be  exposed,  and  must  be  freely 
divided ;  the  sheath  of  the  vessels  is  now  seen,  and  must  be  opened,  and  the  artery  secured  by 
passing  the  aneurism  needle  between  the  vein  and  artery,  in  the  direction  from  within  outwards. 
The  femoral  vein  in  this  situation  lies  on  the  outer  side  of  the  artery,  the  long  saphenous  nerve 
on  its  anterior  and  outer  side. 

It  has  been  seen  that  the  femoral  artery  occasionally  divides  into  two  trunks,  below  the  origin 
of  the  profunda.  If,  in  the  operation  for  tying  the  femoral,  two  vessels  are  met  with,  the  sur- 
geon should  alternately  compress  each,  in  order  to  ascertain  which  vessel  is  connected  with  the 
aneurismal  tumor,  or  with  the  bleeding  from  the  wound,  and  that  one  only  should  be  tied  which 
controls  the  pulsation  or  hemorrhage.  If,  however,  it  is  necessary  to  compress  both  vessels 
before  the  circulation  in  the  tumor  is  controlled,  both  should  be  tied,  as  it  would  be  probable 
that  they  became  reunited,  as  in  the  four  instances  referred  to  above. 

Collateral  Circulation.  When  the  common  femoral  is  tied,  the  main  channels  for  carrying 
on  the  circulation  are  the  anastomoses  of  the  gluteal  and  circumflex  iliac  arteries  above  with 
the  external  circumflex  below;  of  the  obturator  and  sciatic  above  with  the  internal  circumflex 
below;  of  the  ilio-lumbar  with  the  external  circumflex,  and  of  the  comes  nervi  ischiadici  with 
the  arteries  in  the  ham. 

The  principal  agents  in  carrying  on  the  collateral  circulation  after  ligature  of  the  superficial 
femoral  artery  are,  according  to  Sir  A.  Cooper,  as  follows : — ' 

"The  arteria  profunda  formed  the  new  channel  for  the  blood."  "  The  first  artery  sent  off 
passed  down  close  to  the  back  of  the  thigh-bone,  and  entered  the  two  superior  articular  branches 
of  the  popliteal  artery." 

"  The  second  new  large  vessel  arising  from  the  profunda  at  the  same  part  with  the  former, 
passed  down  by  the  inner  side  of  the  Biceps  muscle,  to  an  artery  of  the  popliteal,  which  was 
distributed  to  the  Gastrocnemius  muscle ;  whilst  a  third  artery,  dividing  into  several  branches, 
passed  down  with  the  sciatic  nerve  behind  the  knee-joint,  and  some  of  its  branches  united  them- 
selves with  the  inferior  articular  arteries  of  the  popliteal,  with  some  recurrent  branches  of  those 
arteries,  with  arteries  passing  to  the  Gastrocnemii,  and,  lastly,  with  the  origin  of  the  anterior 
and  posterior  tibial  arteries." 

"It  appears,  then,  that  it  is  those  branches  of  the  profunda  which  accompany  the  sciatic 
nerve,  that  are  the  principal  supporters  of  the  new  circulation." 

In  Porta's  work^  (Tab.  xii.  xiii.)  is  a  good  representation  of  the  collateral  circulation  after  the 
ligature  of  the  femoral  artery.  The  patient  had  survived  the  operation  three  years.  The  lower 
part  of  the  artery  is,  at  least,  as  large  as  the  upper ;  about  two  inches  of  the  vessel  appear  to 
have  been  obliterated.  The  external  and  internal  circumflex  arteries  are  seen  anastomosing  by 
a  great  number  of  branches  with  the  lower  branches  of  the  femoral  (muscular  and  anastomotica 
magna),  and  with  the  articular  branches  of  the  popliteal.  The  branches  from  the  external  cir- 
cumflex are  extremely  large  and  numerous,  one  very  distinct  anastomosis  can  be  traced  between 
this  artery  on  the  outside,  and  the  anastomotica  magna  on  the  inside,  through  the  interventicn 
of  the  superior  external  articular  artery  with  which  they  both  anastomose,  and  blood  reaches  even 
the  anterior  tibial  recurrent  from  the  external  circumflex  by  means  of  an  anastomosis  with  the  sam :: 
external  articular  artery.  The  perforating  branches  of  the  profunda  are  also  seen  bringing  blood 
round  the  obliterated  portion  of  the  artery  into  long  branches  (muscular)  which  have  been  given 
off  just  below  that  portion.  The  termination  of  the  profunda  itself  anastomoses,  most  freely 
with  the  superior  external  articular.  A  long  branch  of  anastomosis  is  also  traced  down  from 
the  internal  iliac  by  means  of  the  comes  norvi  ischiadici  of  the  sciatic  which  anastomoses  on  the 
popliteal  nerves  with  branches  from  the  popliteal  and  posterior  tibial  arteries.  In  this  case  the 
anastomosis  had  been  too  free,  since  the  pulsation  and  growth  of  the  aneurism  recurred,  and  the 
patient  died  after  ligature  of  the  external  iliac. 

There  is  an  interesting  preparation  in  the  Museum  of  the  Eoyal  College  of  Surgeons,  of  a 
limb  on  which  John  Hunter  had  tied  the  femoral  artery  fifty  years  before  the  patient's  death. 
The  whole  of  the  superficial  femoral  and  popliteal  artery  seems  to  have  been  obliterated.  The 
anastomosis  by  means  of  the  comes  nervi  ischiadici,  which  is  shown  in  Porta's  plate,  is  distinctly 
seen  ;  the  external  circumflex,  and  the  termination  of  the  profunda  artery,  seem  to  have  been  the 
chief  channels  of  anastomosis;  but  the  injection  has  not  been  a  very  successful  one. 

Branches.     The  branches  of  the  femoral  artery  are  the 
Superficial  epigastric. 
Superficial  circumflex  iliac. 

'  Med.-Chir.  Trans.,  vol.  ii.  1811.  *  Alterazinni patologiche  delle  Arteriz. 


622  ARTERIES. 

Superficial  external  pudic. 
Deep  external  pudic. 

{External  circumflex. 
Internal  circumflex. 
Three  perforating. 
Muscular. 
Anastomotica  magna. 

The  superficial  epigastric  arises  from  the  femoral,  about  half  an  inch  below 
Poupart's  ligament,  and,  passing  through  the  saphenous  opening  in  the  fascia 
lata,  ascends  on  to  the  abdomen,  in  the  superficial  fascia  covering  the  external 
oblique  muscle,  nearly  as  high  as  the  umbilicus.  It  distributes  branches  to  the 
inguinal  glands,  the  superficial  fascia,  and  the  integument,  anastomosing  with 
branches  of  the  deep  epigastric  and  internal  mammary  arteries. 

The  superficial  circumflex  iliac,  the  smallest  of  the  cutaneous  branches,  arises 
close  to  the  preceding,  and,  piercing  the  fascia  lata,  runs  outwards,  parallel  with 
Poupart's  ligament,  as  far  as  the  crest  of  the  ilium,  dividing  into  branches  which 
supply  the  integument  of  the  groin,  the  superficial  fascia,  and  inguinal  glands, 
anastomosing  witb  the  circumflex  iliac,  and  with  the  gluteal  and  external  cir- 
cumflex arteries. 

The  superficial  external  pudic  (superior)  arises  from  the  inner  side  of  the 
femoral  artery,  close  to  the  preceding  vessels,  and,  after  piercing  the  fascia  lat;\ 
at  the  saphenous  opening,  passes  inwards,  across  the  spermatic  cord,  to  be  dis- 
tributed to  the  integument  on  the  lower  part  of  the  abdomen,  and  of  the  penis 
and  scrotum  in  the  male,  and  to  the  labia  in  the  female,  anastomosing  with 
branches  of  the  internal  pudic. 

The  deep  external  pudic  (inferior),  more  deeply  seated  than  the  preceding, 
passes  inwards  on  the  Pectineus  muscle,  covered  by  the  fascia  lata,  which  it 
pierces  opposite  the  ramus  of  the  pubes,  its  branches  being  distributed,  in  the 
male,  to  the  integument  of  the  scrotum  and  perineum,  and  in  the  female,  to  the 
labium,  anastomosing  with  branches  of  the  superficial  perineal  artery. 

The  Profunda  Femoris  (deep  femoral  artery)  nearly  equals  the  size  of  the 
superficial  femoral.  It  arises  from  the  outer  and  back  part  of  the  femoral 
artery,  from  one  to  two  inches  below  Poupart's  ligament.  It  at  first  lies  on  the 
outer  side  of  the  superficial  femoral,  and  then  passes  beneath  it  and  the  femoral 
vein  to  the  inner  side  of  the  femur,  and  terminates  at  the  lower  third  of  the 
thigh  in  a  small  branch,  which  pierces  the  Adductor  Magnus,  to  be  distributed 
to  the  flexor  muscles  on  the  back  of  the  thigh,  anastomosing  with  branches  of 
the  popliteal  and  inferior  perforating  arteries. 

Relations.  Behind,  it  lies  first  upon  the  Iliacus,  and  then  on  the  Adductor 
Brevis  and  Adductor  Magnus  muscles.  In  front,  it  is  separated  from  the  femoral 
artery,  above  by  the  femoral  and  profunda  veins,  and  below  by  the  Adductor 
Longus.  On  its  outer  side,  the  origin  of  the  Vastus  Internus  separates  it  from 
the  femur. 

Plan  of  the  Relations  of  the  Profunda  Artery. 

In  front. 
Femoral  and  profunda  veius. 
Adductor  Lonirus. 


Outer  fiide. 
Vastus  Intcmus. 


II 


Behind. 
Iliacus. 

Adductor  Brevis. 
Adductor  Mngans. 


PROFUNDA.  528 

The  External  Circumflex  Artery  supplies  the  muscles  on  the  front  of  the 
thigh.  It  arises  from  the  outer  side  of  the  profunda,  passes  horizontally  out- 
wards, between  the  divisions  of  the  anterior  crural  nerve,  and  beneath  the  Sar- 
torius  and  Eectus  muscles,  and  divides  into  three  sets  of  branches,  ascending, 
transverse,  and  descending. 

The  ascending  branches  pass  upwards,  beneath  the  Tensor  Vaginae  Femoris 
muscle,  to  the  outer  side  of  the  hip,  anastomosing  with  the  terminal  branches 
of  the  gluteal  and  circumflex  iliac  arteries. 

The  descending  branches^  three  or  four  in  number,  pass  downwards,  beneath 
the  Rectus,  upon  the  Vasti  muscles,  to  which  they  are  distributed,  one  or  two 
passing  beneath  the  Vastus  Externus  as  far  as  the  knee,  anastomosing  with  the 
superior  articular  branches  of  the  popliteal  artery. 

The  transverse  branches^  the  smallest  and  least  numerous,  pass  outwards  over 
the  Cruraeus,  pierce  the  Vastus  Externus,  and  wind  round  the  femur  to  its  back 
part,  just  below  the  great  trochanter,  anastomosing  at  the  back  of  the  thigh  with 
the  internal  circumflex,  sciatic,  and  superior  perforating  arteries. 

The  Internal  Circumflex  Artery,  smaller  than  the  external,  arises  from  the 
inner  and  back  part  of  the  profunda,  and  winds  round  the  inner  side  of  the 
femur,  between  the  Pectineus  and  Psoas  muscles.  On  reaching  the  tendon  of 
the  Obturator  Externus,  it  gives  off  two  branches,  one  of  which  ascends  to  be 
distributed  to  the  Adductor  muscles,  the  Gracilis,  and  Obturator  Externus, 
anastomosing  with  the  obturator  artery;  the  other  descends,  and  passes  beneath 
the  Adductor  Brevis,  to  supply  it  and  the  great  Adductor;  while  the  continua- 
tion of  the  vessel  passes  backwards,  between  the  Quadratus  Femoris  and  upper 
border  of  the  Adductor  Magnus,  anastomosing  with  the  sciatic,  external  circum- 
flex, and  superior  perforating  arteries.  Opposite  the  hip-joint,  this  branch  gives 
off  an  articular  vessel,  which  enters  the  joint  beneath  the  transverse  ligament; 
and,  after  supplying  the  adipose  tissue,  passes  along  'the  round  ligament  to  the 
head  of  the  bone. 

The  Perforating  Arteries  (Fig.  297),  usually  three  in  number,  are  so  called 
from  their  perforating  the  tendons  of  the  Adductor  Brevis  and  Adductor 
Magnus  muscles  to  reach  the  back  of  the  thigh.  The  first  is  given  off  above 
the  Adductor  Brevis,  the  second  in  front  of  that  muscle,  and  the  third  imme- 
diately below  it. 

1l!\\q  flrst  or  superior  perforating  artery  passes  backwards  between  the  Pectineus 
and  Abductor  Brevis  (sometimes  perforates  the  latter);  it  then  pierces  the  Ad- 
ductor Magnus  close  to  the  linea  aspera,  and  divides  into  branches  which  supply 
both  Adductors,  the  Biceps,  and  Gluteus  Maximus  muscle ;  anastomosing  with 
the  sciatic,  internal  circumflex,  and  middle  perforating  arteries. 

The  second  or  middle  perforating  artery,  larger  than  the  first,  pierces  the  ten- 
dons of  the  Adductor  Brevis  and  Adductor  Magnus  muscles,  and  divides  into 
ascending  and  descending  branches,  which  supply  the  flexor  muscles  of  the 
thigh,  anastomosing  with  the  superior  and  inferior  perforating.  The  nutrient 
artery  of  the  femur  is  usually  given  off  from  this  branch. 

The  third  or  inferior  perforating  artery  is  given  off  below  the  Adductor  Brevis; 
it  pierces  the  Adductor  Magnus,  and  divides  into  branches  which  supply  the 
flexor  muscles  of  the  thigh ;  anastomosing  with  the  perforating  arteries  above, 
and  with  the  terminal  branches  of  the  profunda  below. 

Muscular  branches  are  given  off  from  the  superficial  femoral  throughout  its 
entire  course.  They  vary  from  two  to  seven  in  number,  and  supply  chiefly  the 
Sartorius  and  Vastus  Internus. 

The  Anastomotica  Magna  arises  from  the  femoral  artery  just  before  it  passes 
through  the  tendinous  opening  in  the  Adductor  Magnus  muscle,  and  divides 
into  a  superficial  and  deep  branch. 

The  superficial  branch  accompanies  the  long  saphenous  nerve,  beneath  the 
Sartorius,  and,  piercing  the  fascia  lata,  is  distributed  to  the  integument. 

The  deep  branch  descends  in  the  substance  of  the  Vastus  Internus,  lying  in 


524  ARTERIES. 

front  of  the  tendon  of  the  Adductor  Magnus,  to  the  inner  side  of  the  knee, 
where  it  anastomoses  with  the  superior  internal  articular  artery  and  recurrent 
branch  of  the  anterior  tibial.  A  branch  from  this  vessel  crosses  outwards 
above  the  articular  surface  of  the  femur,  forming  an  anastomotic  arch  with  the 
superior  external  articular  artery,  and  supplies  branches  to  the  knee-joint. 

Popliteal  Artery. 

The  Popliteal  Artery  commences  at  the  termination  of  the  femoral,  at  the 
opening  in  the  Adductor  Magnus,  and,  passing  obliquely  downwards  and  out- 
wards behind  the  knee-joint  to  the  lower  border  of  the  Popliteus  muscle,  divides 
into  the  anterior  and  posterior  tibial  arteries.  Through  the  whole  of  this  extent 
the  artery  lies  in  the  popliteal  space. 

The  Popliteal  Space.    (Fig.  299.) 

Dissection.  A  vertical  incision  about  eight  inches  in  length  should  be  made  along  the  back 
part  of  the  knee-joint,  connected  above  and  below  by  a  transverse  incision  from  the  inner  to  the 
outer  side  of  the  limb.  The  flaps  of  integument  included  between  these  incisions  should  be  re- 
flected in  the  direction  shown  in  Fig.  256,  p.  412. 

On  removing  the  integument,  the  superficial  fascia  is  exposed,  and  ramifying 
in  it  along  the  middle  line  are  found  some  filaments  of  the  small  sciatic  nerve, 
and  towards  the  inner  part  some  offsets  from  the  internal  cutaneous  nerve. 

The  superficial  fascia  having  been  removed,  the  fascia  lata  is  brought  into 
view.  In  this  region  it  is  strong  and  dense,  being  strengthened  by  transverse 
fibres,  and  firmly  attached  to  the  tendons  on  the  inner  and  outer  sides  of  the 
space.  It  is  perforated  below  by  the  external  saphenous  vein.  This  fascia 
having  been  reflected  back  in  the  same  direction  as  the  integument,  the  small 
sciatic  nerve  and  external  saphenous  vein  are  seen  immediately  beneath  it,  in 
the  middle  line.  If  the  loose  adipose  tissue  is  now  removed,  the  boundaries  and 
contents  of  the  space  may  be  examined. 

Boundaries.  The  popliteal  space,  or  the  ham,  occupies  the  lower  third  of  the 
thigh  and  the  upper  fifth  of  the  leg ;  extending  from  the  aperture  in  the  Ad- 11 
ductor  Magnus,  to  the  lower  border  of  the  Popliteus  muscle.  It  is  a  lozenge- II 
shaped  space,  being  widest  at  the  back  part  of  the  knee-joint,  and  deepest  above 
the  articular  end  of  the  femur.  It  is  bounded,  externally,  above  the  joint,  ^7 ^m 
the  Biceps,  and  below  the  joint  by  the  Plantaris  and  external  head  of  the  Gas-^| 
trocnemius.  Internally,  above  the  joint,  by  the  Semimembranosus,  Semiten- 
dinosus.  Gracilis,  and  Sartorius ;  below  the  joint,  by  the  inner  head  of  the 
Gastrocnemius. 

Above,  it  is  limited  by  the  apposition  of  the  inner  and  outer  hamstring  mus- 
cles ;  below  by  the  junction  of  the  two  heads  of  the  Gastrocnemius.  The  floor 
is  formed  by  the  lower  part  of  the  posterior  surface  of  the  shaft  of  the  femur, 
the  posterior  ligament  of  the  knee-joint,  the  upper  end  of  the  tibia,  and  the 
fascia  covering  the  Popliteus  muscle,  and  the  space  is  covered  in  by  the  fascia 
lata. 

Contents.     It  contains  the  popliteal  vessels  and  their  branches,  together  with 
the  termination  of  the  external  saphenous  vein,  the  internal  and  external  pop- 
liteal nerves  and  their  branches,  the  small  sciatic  nerve,  the  articular  branch 
from  the  obturator  nerve,  a  few  small   lymphatic  glands,  and  a  considerableJI 
quantity  of  loose  adipose  tissue.  *l 

Position  of  contained  jmrts.  The  internal  popliteal  nerve  descends  in  the 
middle  line  of  the  space,  lying  superficial  and  a  little  external  to  the  vein  and 
artery.  The  external  popliteal  nerve  descends  on  the  outer  side  of  the  space, 
lying  close  to  the  tendon  of  the  Biceps  muscle.  More  deeply  at  the  bottom  of 
the  space  are  the  popliteal  vessels,  the  vein  lying  superficial  and  a  little  ex- 
ternal to  the  artery,  to  which  it  is  closely  united  by  dense  areolar  tissue ;  some- 
times the  vein  is  placed  on  the  inner  instead  of  the  outer  side  of  the  artery; 


11 


I 


POPLITEAL.  625 

or  the  vein  may  be  double,  the  artery  lying  between  the  two  venae  comites, 
which  are  usually  connected  by  short  transver.>^e  branches.  More  deeply,  and 
close  to  the  surface  of  the  bone,  is  the  popliteal  artery,  and  passing  off"  from 
it  at  right  angles  are  its  articular  branches.  The  articular  branch  from  the 
obturator  nerve  descends  upon  the  popliteal  artery  to  supply  the  knee ;  and 
occasionally  there  is  found  deep  in  the  space  an  articular  filament  from  the 
great  sciatic  nerve.  The  popliteal  lymphatic  glands,  four  or  five  in  number, 
are  found  surrounding  the  artery ;  one  usually  lies  superficial  to  the  vessel, 
another  is  situated  between  it  and  the  bone,  and  the  rest  are  placed  on  either 
side  of  it.  The  bursas  usually  found  in  this  space  are  :  1.  On  the  outer  side, 
one  beneath  the  outer  head  of  the  Gastrocnemius  (which  sometimes  communi- 
cates with  the  joint)  and  one  beneath  the  tendon  of  the  Popliteus,  which  is 
almost  always  an  extension  of  the  synovial  membrane.  Sometimes  also  there 
is  a  bursa  above  the  tendon  of  the  Popliteus,  between  it  and  the  external  lateral 
ligament.  2.  On  the  inner  side  of  the  joint  there  is  a  large  bursa  between  the 
inner  head  of  the  Gastrocnemius  and  the  femur,  which  sends  a  prolongation 
between  the  tendons  of  the  Gastrocnemius  and  Semimembranosus,  and  lies  in 
contact  with  the  ligament  of  Winslow.  This  bursa  often  communicates  with 
the  joint.  There  is  a  second  bursa  between  the  tendon  of  the  Semimembra- 
nosus and  the  head  of  the  tibia  ;  and  sometimes  a  bursa  between  the  tendons 
of  the  Semitendinosus  and  Semimembranosus. 

The  Popliteal  Artery,  in  its  course  downwards  from  the  aperture  in  the  Ad- 
ductor Magnus  to  the  lower  border  of  the  Popliteus  muscle,  rests  first  on  the 
inner,  and  then  on  the  posterior  surface  of  the  femur ;  in  the  middle  of  its 
course,  on  the  posterior  ligament  of  the  knee-joint ;  and  below,  on  the  fascia 
covering  the  Popliteus  muscles.  /Swper/icia%,  it  is  covered,  above,  by  the 
Semimembranosus;  in  the  middle  of  its  course,  by  a  quantity  of  fat,  which 
separates  it  from  the  deep  fascia  and  integument ;  and  below,  it  is  overlapped 
by  the  Gastrocnemius,  Plantaris,  and  Soleus  muscles,  the  popliteal  vein,  and  the 
internal  popliteal  nerve.  The  popliteal  vein,  which  is  intimately  attached  to 
the  artery,  lies  superficial  and  external  to  it,  until  near  its  termination,  when  it 
crosses  it  and  lies  to  its  inner  side.  The  popliteal  nerve  is  still  more  superficial 
and  external,  crossing,  however,  the  artery  below  the  joint,  and  lying  on  its 
inner  side.  Laterally^  the  artery  is  bounded  by  the  muscles  which  form  the 
boundaries  of  the  popliteal  space. 

Plan  of  Eelations  of  Popliteal  Artery. 

In  front. 
Femur. 

Ligamentum  posticum. 
Popliteus. 


Inner  aide.  I    popiueal     \  Outer  side. 

Semimembranosus.  I      Artery,      j  Biceps. 


Behind. 
Popliteal  vein. 
Internal  popliteal  nerve. 
Fascia. 

Peculiarities  in  point  of  division.  Occasionally  the  popliteal  artery  divides  prematurely  into 
its  terminal  branches ;  this  division  occurs  most  frequently  opposite  the  knee-joint. 

Unusual  branches.  The  artery  sometimes  divides  into  the  anterior  tibial  and  peroneal,  the 
posterior  tibial  being  wanting,  or  very  small.  In  a  single  case,  the  popliteal  was  found  to  divide 
into  three  branches,  the  anterior  and  posterior  tibial,  and  peroneal. 

Surgical  Anatomy.  Ligature  of  the  popliteal  artery  is  required  in  cases  of  wound  of  that 
vessel,  but  for  aneurism  of  the  posterior  tibial  it  is  preferable  to  tie  the  superficial  femoral.  The 
popliteal  may  be  tied  in  the  upper  or  lower  part  of  its  course  ;  but  in  the  middle  of  the  ham  the 


526  ARTERIES. 

operation  is  attended  with  considerable  difficulty,  from  the  great  depth  of  the  artery,  and  from 
the  extreme  degree  of  tension  of  the  lateral  boundaries  of  the  space. 

In  order  to  expose  the  vessel  in  the  upper  part  of  its  course,  the  patient  should  be  placed  in 
the  pronu  position,  with  the  limb  extended.  An  incision  about  three  inches  in  length  should 
then  be  made  through  the  integument,  along  the  posterior  margin  of  the  .Semimembranosus, 
and  the  fascia  lata  having  been  divided,  this  muscle  must  be  drawn  inwards,  when  the  pulsation 
of  the  vessel  will  be  detected  with  the  finger ;  the  nerve  lies  on  the  outer  or  fibular  side  of  the 
artery,  the  vein,  superficial,  and  also  to  its  outer  side  ;  the  vein  having  been  cautiously  separated 
from  the  artery,  the  aneurism  needle  should  be  passed  around  the  latter  vessel  from  without 
inwards. 

To  expose  the  vessel  in  the  lower  part  of  its  course,  where  the  artery  lies  between  the  two 
heads  of  the  Gastrocnemius,  the  patient  should  be  placed  in  the  same  position  as  in  the  preced- 
ing operation.  An  incision  should  then  be  made  through  the  integument  in  the  middle  line, 
commencing  opposite  the  bend  of  the  knee-joint,  care  being  taken  to  avoid  the  external  saphe- 
nous vein  and  nerve.  After  dividing  the  deep  fascia,  and  separating  some  dense  cellular  mem- 
brane,  the  artery,  vein,  and  nerve  will  be  exposed,  descending  between  the  two  heads  of  the 
Gastrocnemius.  Some  muscular  branches  of  the  popliteal  should  be  avoided  if  possible,  or  if 
divided,  tied  immediately.  The  leg  being  now  flexed,  in  order  the  more  effectually  to  separate 
the  two  heads  of  the  Gastrocnemius,  the  nerve  should  be  drawn  inwards  and  the  vein  outwards, 
and  the  aneurism  needle  passed  between  the  artery  and  vein  from  without  inwards. 

The  branches  of  the  popliteal  artery  are,  the 

Muscular      |  ^Xrior'or  Sural. 

Cutaneous. 

Superior  external  articular. 

Superior  internal  articular. 

Azygos  articular. 

Inferior  external  articular. 

Inferior  internal  articular. 

The  superior  muscular  branches^  two  or  three  in  number,  arise  from  the  upper 
part  of  the  popliteal  artery,  and  are  distributed  to  the  Vastus  Externus  and 
flexor  muscles  of  the  thigh ;  anastomosing  with  the  inferior  perforating,  and 
terminal  branches  of  the  profunda. 

The  inferior  muscular  (sural)  are  two  large  branches,  which  are  distributed 
to  the  two  heads  of  the  Gastrocnemius  and  to  the  Plantaris  muscle.  They  ariso^ 
from  the  popliteal  artery  opposite  the  knee-joint. 

Cutaneous  branches  descend  on  each  side  and  in  the  middle  of  the  limby 
between  the  Gastrocnemius  and  integument ;  they  arise  separately  from  the 
popliteal  artery,  or  from  some  of  its  branches,  and  supply  the  integument  of 
the  calf. 

The  superior  articular  arteries,  two  in  number,  arise  one  on  either  side  of  the 
popliteal,  and  wind  round  the  femur  immediately  above  its  condyles  to  the 
front  of  the  knee-joint.  The  internal  branch  passes  beneath  the  tendon  of  the 
Adductor  Magnus,  and  divides  into  two,  one  of  which  supplies  the  Vastus 
Internus,  inosculating  with  the  anastomotica  magna  and  inferior  internal  arti- 
cular; the  other  ramifies  close  to  the  surface  of  the  femur,  supplying  it  and  the 
knee-joint,  and  anastomosing  with  the  superior  external  articular  artery.  The 
external  branch  passes  above  the  outer  condyle,  beneath  the  tendon  of  the  Biceps, 
and  divides  into  a  superficial  and  deep  branch :  the  superficial  branch  supplies 
the  Vastus  Externus,  and  anastomoses  with  the  descending  branch  of  the  exter- 
nal circumflex  artery ;  the  deep  branch  supplies  the  lower  part  of  the  femur 
and  knee-joint,  and  forms  an  anastomotic  arch  across  the  bone  with  the  anas- 
tomotica magna  artery. 

The  azygos  articular  is  a  small  branch,  arising  from  the  popliteal  artery  oppo- 
site the  bend  of  the  knee-joint.     It  pierces  the  posterior  ligament,  and  supplies  ,— 
the  ligaments  and  synovial  membrane  in  the  interior  of  the  articulation.  II 

The  inferior  articular  arteries,  two  in  number,  ari.se  from  the  popliteal,  be- 
neath the  Gastrocnemius,  and  wind  round  the  head  of  the  tibia,  below  the 
joint.  The  internal  one  pas.'^cs  below  the  inner  tuberosity,  beneath  the  internal 
lateral  ligament,  at  the  anterior  border  of  which  it  ascends  to  the  front  and 


M 


I 


I 


ANTERIOR    TIBIAL.  52t 

inner  side  of  the  joint,  to  supply  the  bead  of  the  tibia  and  the  articulation  of 
the  knee.  The  external  one  passes  outwards  above  the  head  of  the  fibula,  to 
the  front  of  the  knee-joint,  lying  in  its  course  beneath  the  outer  head  of  the 
Gastrocnemius,  the  external  lateral  ligament,  and  the  tendon  of  the  Biceps 
muscle,  and  divides  into  branches,  which  anastomose  with  the  inferior  internal 
articular  artery,  the  superior  articular  arteries,  and  the  recurrent  branch  of  the 
anterior  tibial. 

Anterior  Tibial  Artery.    (Fig.  300.) 

The  Anterior  Tibial  Artery  commences  at  the  bifurcation  of  the  popliteal, 
at  the  lower  border  of  the  Popliteus  muscle,  passes  forwards  between  the  two 
heads  of  the  Tibialis  Posticus,  and  through  the  aperture  left  between  the  bones 
at  the  upper  part  of  the  interosseous  membrane,  to  the  deep  part  of  the  front 
of  the  leg ;  it  then  descends  on  the  anterior  surface  of  the  interosseous  liga- 
ment, and  of  the  tibia,  to  the  front  of  the  ankle-joint,  where  it  lies  more  super- 
ficially, and  becomes  the  dorsalis  pedis,  A  line  drawn  from  the  inner  side  of 
the  head  of  the  fibula  to  midway  between  the  two  malleoli  will  mark  the  course 
of  the  artery. 

Relations.  In  the  upper  two-thirds  of  its  extent,  it  rests  upon  the  interosseous 
ligament,  to  which  it  is  connected  by  delicate  fibrous  arches  thrown  across  it. 
In  the  lower  third,  upon  the  front  of  the  tibia,  and  the  anterior  ligament  of  the 
ankle-joint.  In  the  upper  third  of  its  course,  it  lies  between  the  Tibialis  Anti- 
cus  and  Extensor  Longus  Digitorum;  in  the  middle  third,  between  the  Tibialis 
Anticus  and  Extensor  Proprius  Pollicis.  In  the  lower  third  it  is  crossed  by  the 
tendon  of  the  Extensor  Proprius  Pollicis,  and  lies  between  it  and  the  innermost 
tendon  of  the  Extensor  Longus  Digitorum.  It  is  covered,  in  the  upper  two- 
thirds  of  its  course,  by  the  muscles  which  lie  on  either  side  of  it,  and  by  the 
deep  fascia;  in  the  lower  third,  by  the  integument,  annular  ligament,  and  fascia. 

The  anterior  tibial  artery  is  accompanied  by  two  veins  (venae  comites),  which 
lie  one  on  either  side  of  the  artery;  the  anterior  tibial  nerve  lies  at  first  to  its 
outer  side,  and  about  the  middle  of  the  leg  is  placed  superficial  to  it ;  at  the 
lower  part  of  the  artery  the  nerve  is  generally  again  on  the  outer  side. 

Plan  op  the  Relations  of  the  Anterior  Tibial  Artery. 

In  front. 
Integument,  superficial  and  deep  fasciae. 
Tibialis  Anticus  (overlaps  it  in  upper  part  of  leg). 
Extensor  Longus  Digitorum  )  ,        i       -x    r  uti  \ 
Extensor  Proprius  Pollicis    |  (^^^-^^^P  '^  ^^'^^^^^)- 
Anterior  tibial  nerve. 

Infier  side.  /^        ^\  Outer  side. 

Tibialis  Anticus  /  \  Anterior  tibial  nerve. 

Extensor  Proprius  Pollicis  [     ■^r^l*''?''      j  Extensor  Longus  Digitorum. 

(crosses  it  at   its  lower  \        ^  '^ '      I  Extensor  Proprius  Pollicis. 

part).  \  y 

Behind. 
Interosseous  membrane. 
Tibia. 
Anterior  ligament  of  ankle-joint. 

Peculiarities  in  Size.  This  vessel  may  be  diminished  in  size,  may  be  deficient  to  a  greater  or 
less  extent,  or  may  be  entirely  wanting,  its  place  being  supplied  by  perforating  branches  from 
the  posterior  tibial,  or  by  the  anterior  division  of  the  peroneal  artery. 

Course.  The  artery  occasionally  deviates  in  its  course  towards  the  fibular  side  of  the  leg, 
regaining  its  usual  position  beneath  the  annular  ligament  at  the  front  of  the  ankle.  In  two 
instances,  the  vessel  has  been  found  to  approach  the  surface  in  the  middle  of  the  leg,  being 
covered  merely  by  the  integument  and  fascia  below  that  point. 

Surgical  Anatomy .  'I"he  anterior  tibial  artery  may  be  tied  in  the  upper  or  lower  part  of  the 
leg.     In  the  upper  part,  the  operation  is  attended  with  great  difficulty,  on  account  of  the  depth 


528 


ARTERIES. 


of  the  vessel  from  the  surface.  An  incision,  about  four  inches  in  length,  should  be  made  through 
the  integument,  midway  between  the  spine  and  the  tibia  and  the  outer  margin  of  the  fibula,  the 
fascia  and  intermuscular  septum  between  the  Tibialis  Anticus  and  Hxtensor  Longus  Digitorum 
being  divided  to  the  same  extent.    The  foot  must  be  flexed  to  relax  these  muscles,  and  they  must 


Fig.  299.— The  Popliteal,  Posterior  Tibial, 
and  Peroneal  Arteries. 


^Anttrior  Peroneal 


Fig.  300.— Surgical  Anatomy  of  the  Anterior 
Tibial  and  Dorsalis  Pedis  Arteries. 


DORSALIS    PEDIS.  529 

be  separated  from  each  other  by  the  finger.  The  artery  is  then  exposed,  deeply  seated,  lying 
upon  the  interosseous  membrane,  the  nerve  lying  externally,  and  one  of  the  venae  comites  on 
either  side ;  these  must  be  separated  from  the  artery  before  the  aneurism  needle  is  passed  round  it. 

To  tie  the  vessel  in  the  lower  third  of  the  leg  above  the  ankle-joint,  an  incision  about  three 
inches  in  length  should  be  made  through  the  integument  between  the  tendons  of  the  Tibialis 
Anticus  and  Extensor  Proprius  Pollicis  muscles,  the  deep  fascia  being  divided  to  the  same 
extent ;  the  tendon  on  either  side  should  be  held  aside,  when  the  vessel  will  be  seen  lying  upon 
the  tibia,  with  the  nerve  superficial  to  it,  and  one  of  the  venaj  comites  on  either  side. 

In  order  to  secure  the  artery  over  the  instep,  an  incision  should  be  made  on  the  fibular  side  of 
the  ten<?on  of  the  Extensor  Proprius  Pollicis,  between  it  and  the  innermost  tendon  of  the  long 
Extensor ;  the  deep  fascia  having  been  divided,  the  artery  will  be  exposed,  the  nerve  lying  either 
superficial  to  it,  or  to  its  outer  side. 

The  branches  of  the  anterior  tibial  artery  are,  the 

Eecurrent  tibial.  Internal  malleolar. 

Muscular.  External  malleolar. 

The  recurrent  branch  arises  from  the  anterior  tibial,  as  soon  as  that  vessel  has 
passed  through  the  interosseous  space ;  it  ascends  in  the  Tibialis  Anticus  muscle, 
and  ramifies  on  the  front  and  sides  of  the  knee-joint,  anastomosing  with  the 
articular  branches  of  the  popliteal. 

The  muscular  branches  are  numerous ;  they  are  distributed  to  the  muscles 
which  lie  on  either  side  of  the  vessel,  some  piercing  the  deep  fascia  to  supply 
the  integument,  others  passing  through  the  interosseous  membrane,  and  anas- 
tomosing with  branches  of  the  posterior  tibial  and  peroneal  arteries. 

The  malleolar  arteries  supply  the  ankle-joint.  The  internal  arises  about  two 
inches  above  the  articulation,  and  passes  beneath  the  tendon  of  the  Tibialis 
Anticus  to  the  inner  ankle,  upon  which  it  ramifies,  anastomosing  with  branches 
of  the  posterior  tibial  and  internal  plantar  arteries.  The  external  passes  beneath 
the  tendons  of  the  Extensor  Longus  Digitorum  and  Extensor  Proprius  Pollicis, 
and  supplies  the  outer  ankle,  anastomosing  with  the  anterior  peroneal  artery, 
and  with  ascending  branches  from  the  tarsal  branch  of  the  dorsalis  pedis. 

DoRSALis  Pedis  Artery.    (Fig.  300.) 

The  Dorsalis  Pedis,  the  continuation  of  the  anterior  tibial,  passes  forwards 
from  the  bend  of  the  ankle  along  the  tibial  side  of  the  foot  to  the  back  part  of 
the  first  interosseous  space,  where  it  divides  into  two  branches,  the  dorsalis 
hallucis  and  communicating. 

Relations.  This  vessel,  in  its  course  forwards,  rests  upon  the  astragalus,  sca- 
phoid, and  internal  cuneiform  bones  and  the  ligaments  connecting  them,  being 
covered  by  the  integument  and  fascia,  and  crossed  near  its  termination  by  the 
innermost  tendon  of  the  Extensor  Brevis  Digitorum.  On  its  tibial  side  is  the 
tendon  of  the  Extensor  Proprius  Pollicis;  on  its  fibular  side,  the  innermost 
tendon  of  the  Extensor  Longus  Digitorum,  and  the  termination  of  the  anterior 
tibial  nerve.     It  is  accompanied  by  two  veins. 

Plan  of  the  Eelations  of  the  Dorsalis  Pedis  Artery. 

In  front. 
Integument  and  fascia. 
Innermost  tendon  of  Extensor  Brevis  Digitorum. 


Ttbial  side.  /  \  Fibular  side. 

Extensor  Proprius  Pollicis.  [      ^pJdti'^      1  Extensor  Longus  Digitorum. 

Anterior  tibial  nerve. 


Behind. 

Astragulus, 

Scaphoid, 
^  Internal  cuneiform, 

"^  and  their  ligaments. 


530  ^  ARTERIES. 

Peculiarities  in  Size.    The  dorsal  artery  of  the  foot  may  be  larger  than  usaal,  to  compensate  ' 
for  a  deficient  plantar  artery ;  or  it  may  be  deficient  in  its  terminal  branches  to  the  toes,  which 
are  then  derived  from  the  internal  plantar ;  or  its  place  may  be  supphed  altogether  by  a  large 
anterior  peroneal  artery. 

Position.  This  artery  frequently  curves  outwards,  lying  external  to  the  line  between  the 
middle  of  the  ankle  and  the  back  part  of  the  first  interosseous  space. 

Surgical  Anatomy.  This  artery  may  be  tied,  by  making  an  incision  through  the  integument, 
between  two  and  three  inches  in  length,  on  the  fibular  side  of  the  tendon  of  the  Extensor  Pro- 
prius  Pollicis,  in  the  interval  between  it  and  the  inner  border  of  the  short  Extensor  muscle. 
The  incision  should  not  extend  further  forwards  than  the  back  part  of  the  first  interosseous 
space,  as  the  artery  divides  in  that  situation.  The  deep  fascia  being  divided  to  the  same  extent, 
the  artery  will  be  exposed,  the  nerve  lying  upon  its  outer  side. 

Branches.     The  branches  of  the  dorsalis  pedis  are,  the 

Tarsal.  Dorsalis  hallucis  (dorsalis  pollicis). 

Metatarsal.  Communicating. 

Interosseous. 

The  tarsal  artery  arises  from  the  dorsalis  pedis,  as  that  vessel  crosses  the 
scaphoid  bone ;  it  passes  in  an  arched  direction  outwards,  lying  upon  the  tarsal 
bones,  and  covered  bj  the  Extensor  Brevis  Digitorum ;  it  supplies  that  muscle 
and  the  articulations  of  the  tarsus,  and  anastomoses  with  branches  from  the 
metatarsal,  external  malleolar,  peroneal,  and  external  plantar  arteries. 

The  metatarsal  arises  a  little  anterior  to  the  preceding  ;  it  passes  outwards  to 
the  outer  part  of  the  foot,  over  the  bases  of  the  metatarsal  bones,  beneath  the 
tendons  of  the  short  Extensor,  its  direction  being  influenced  by  its  point  of 
origin;  and  it  anastomoses  with  the  tarsal  and  external  plantar  arteries.  This 
vessel  gives  off  three  branches,  the  interosseous,  which  pass  forwards  upon  the 
three  outer  Dorsal  Interossei  muscles,  and,  in  the  clefts  between  the  toes,  divide 
into  two  dorsal  collateral  branches  for  the  adjoining  toes.  At  the  back  part  of 
each  interosseous  space  these  vessels  receive  the  posterior  perforating  branches 
from  the  plantar  arch ;  and  at  the  fore  part  of  each  interosseous  space,  they  are 
joined  by  the  anterior  perforating  branches,  from  the  digital  arteries.  The 
outermost  interosseous  artery  gives  off  a  branch  which  supplies  the  outer  side 
of  the  little  toe. 

The  dorsalis  hallucis  runs  forwards  along  the  outer  border  of  the  first  raeta» 
tarsal  bone,  and,  at  the  cleft  between  the  first  and  second  toes,  divides  into 
two  branches,  one  of  which  passes  inwards,  beneath  the  tendon  of  the  Ex- 
tensor Proprius  Pollicis,  and  is  distributed  to  the  inner  border  of  the  great  toe; 
the  other  branch  bifurcating  to  supply  the  adjoining  sides  of  the  great  ^ii<^| 
second  toes.  vl 

The  commxinicating  artery  dips  down  into  the  sole  of  the  foot,  between  the 
two  heads  of  the  first  Dorsal  Interosseous  muscle,  and  inosculates  with  the 
termination  of  the  external  plantar  artery,  to  complete  the  plantar  arch.  It 
here  gives  off  two  digital  branches;  one  runs  along  the  inner  side  of  the  great 
toe,  on  its  plantar  surface;  the  other  passes  forwards  along  the  first  metatarsal 
space,  and  bifurcates  for  the  supply  of  the  adjacent  sides  of  the  great  an' 
second  toes. 


Posterior  Tibial  Artery.    (Fig.  299.) 

The  Posterior  Tibial  is  an  artery  of  large  size,  which  extends  obliquely  down- 
wards from  the  lower  border  of  the  Popliteus  muscle,  along  the  tibial  side  of 
the  leg,  to  the  fossa  between  the  inner  ankle  and  the  heel,  where  it  divides 
beneath  the  origin  of  the  Abductor  Pollicis,  into  the  internal  and  external 
plantar  arteries.  At  its  origin  it  lies  opposite  the  interval  between  the  tibia 
and  fibula  ;  as  it  descends,  it  approaches  the  inner  side  of  the  leg,  lying  behind 
the  tibia,  and,  in  the  lower  part  of  its  course,  is  situated  midway  between  the 
inner  malleolus  and  the  tuberosity  of  the  os  calcis. 

Relations.  It  lies  successively  upon  the  Tibialis  Posticus,  the  Flexor  Longus 
Digitorum,  the  tibia  and  the  back  part  of  the  ankle-joint.     It  is  covered  by  the 


I 


POSTERIOR    TIBIAL.  531 

intermuscular  fascia,  wiiich  separates  it  above  from  the  Gastrocnemius  and 
Soleus  muscles.  In  the  lower  third,  where  it  is  more  superficial,  it  is  covered 
only  bv  the  integument  and  fascia,  and  runs  parallel  with  the  inner  border  of 
the  tendo  Achillis.  It  is  accompanied  by  two  veins,  and  by  the  posterior  tibial 
nerve,  which  lies  at  first  to  the  inner  side  of  the  artery,  but  soon  crosses  it,  and 
is,  in  the  greater  part  of  its  course,  on  its  outer  side. 

Plan  of  the  Relations  of  the  Posterior  Tibial  .Artery. 

In  front. 
Tibialis  Posticus. 
Flexor  Lon<rus  Digitornm. 
Tibia. 
Ankle-joint. 


Inner  side.  (     posterior     |  Outer  side. 

Posterior  tibial  nerve,  \       Tibial.       )  Posterior  tibial  nerve, 

upper  third.  \  /  lower  two-thirds. 

Behind. 
Gastrocnemius. 
Soleus. 
Deep  fascia  and  integument. 

Behind  the  Inner  Ankle^  the  tendons  and  bloodvessels  are  arranged  in  the  fol- 
lowing order,  from  within  outwards :  First,  the  tendons  of  the  Tibialis  Posticus 
and  Flexor  Longus  Digitorum,  lying  in  the  same  groove,  behind  the  inner 
malleolus,  the  former  being  the  most  internal.  External  to  these  is  the  poste- 
rior tibial  artery,  having  a  vein  on  either  side ;  and,  still  more  externally,  the 
posterior  tibial  nerve.  About  half  an  inch  nearer  the  heel  is  the  tendon  of  the 
Flexor  Longus  Pollicis. 

Peculiarities  in  Size.  The  posterior  tibial  is  not  unfrequenfly  smaller  than  usual,  or  absent, 
its  place  being  supplied  by  a  large  peroneal  artery,  which  passes  inwards  at  the  lower  end  of  the 
tibia,  and  either  joins  the  small  tibial  artery,  or  continues  alone  to  the  sole  of  the  foot. 

Surgical  Anatomy.  The  application  of  a  ligature  to  the  posterior  tibial  may  be  required  in 
cases  of  wound  of  the  sole  of  the  foot,  attended  with  great  hemorrhage,  when  the  vessel  should 
be  tied  at  the  inner  ankle.  In  cases  of  wound  of  the  posterior  tibial,  it  will  be  necessary  to 
enlarge  the  wound  so  as  to  expose  the  vessel  at  the  wounded  point,  excepting  where  the  vessel 
is  injured  by  a  punctured  wound  from  the  front  of  the  leg.  In  cases  of  aneurism  from  wound  of 
the  artery  low  down,  the  vessel  should  be  tied  in  the  middle  of  the  leg.  But  in  aneurism  of  the 
posterior  tibial  high  up,  it  would  be  better  to  tie  the  femoral  artery. 

To  tie  the  posterior  tibial  artery  at  the  ankle,  a  semilunar  incision  should  be  made  through 
the  integument,  about  two  inches  and  a  half  in  length,  midwny  between  the  heel  and  inner  ankle, 
or  a  little  nearer  the  latter.  The  subcutaneous  cellular  membrane  having  been  divided,  a  strong 
and  dense  fascia,  the  internal  annular  ligament,  is  exposed.  'I'his  ligament  is  continuous  above 
with  the  deep  fascia  of  the  leg,  covers  the  vessels  and  nerves,  and  is  intimately  adherent  to  the 
sheaths  of  the  tendons.  This  having  been  cautiously  divided  upon  a  director,  the  sheath  of  the 
vessels  is  exposed,  and  being  opened,  the  artery  is  seen  with  one  of  the  vente  comites  on  each 
side.  The  aneurism  needle  should  be  passed  round  tlie  vessel  from  the  heel  towards  the  ankle, 
in  order  to  avoid  the  posterior  tibial  nerve,  care  being  at  the  same  time  taken  not  to  include  the 
vense  comites. 

The  vessel  may  also  be  tied  in  the  lower  third  of  the  leg  by  making  an  incision  about  three 
inches  in  length,  parallel  with  the  inner  margin  of  the  lendo  Achillis.  The  internal  saphenous 
vein  being  carefully  avoided,  the  two  layers  of  fascia  must  be  divided  upon  a  director,  when  the 
artery  is  exposed  along  the  outer  margin  of  the  Flexor  Longus  Digitorum,  with  one  of  its  vense 
comites  on  either  side,  and  the  nerve  lying  external  to  it. 

To  tie  the  posterior  tibial  in  the  middle  of  the  leg  is  a  very  difficult  operation,  on  account  of 
the  great  depth  of  the  vessel  from  the  surface,  and  its  being  covered  by  the  Gastrocnemius  and 
Soleus  muscles.  The  patient  being  placed  in  the  recumbent  position,  the  injured  limb  should 
rest  on  its  outer  side,  the  knee  being  partially  bent,  and  the  foot  extended,  so  as  to  relax  the 
muscles  of  the  calf.  An  incision  about  four  inches  in  length  should  then  be  made  through  the 
integument,  along  the  inner  margin-  of  the  tibia,  taking  care  to  avoid  the  internal  saphenous 
vein.  'I'he  deep  fascia  having  heen  divided,  the  margin  of  the  (Gastrocnemius  is  exposed,  and 
must  be  drawn  aside,  and  the  tibial  attachment  of  the  Soleus  divided,  a  director  b«ing  previously 


532  ARTERIES. 

passed  beneath  it.  The  artery  may  now  be  felt  pulsating  beneath  the  deep  fascia,  about  an  inch 
from  the  margin  of  the  tibia.  The  fascia  having  been  divided,  and  the  limb  placed  in  such  a 
position  as  to  relax  the  muscles  of  the  calf  as  much  as  possible,  the  veins  should  be  separated 
from  the  artery,  and  the  aneurism  needle  passed  round  the  vessel  from  without  inwards,  so  as  to 
avoid  wounding  the  posterior  tibial  nerve. 

The  branches  of  the  posterior  tibial  artery  are,  the 

Peroneal.  Nutrient. 

Anterior  peroneal.  Communicating, 

Muscular.  Internal  calcanean. 

The  Peroneal  Artery  lies,  deeply  seated,  along  the  back  part  of  the  fibular 
side  of  the  leg.  It  arises  from  the  posterior  tibial,  about  an  inch  below  the 
lower  border  of  the  Popliteus  muscle,  passes  obliquely  outwards  to  the  fibula, 
and  then  descends  along  the  inner  border  of  that  bone  to  the  loAyer  third  of  the 
leg,  where  it  gives  off  the  anterior  peroneal.  It  then  passes  across  the  articula- 
tion between  the  tibia  and  fibula,  to  the  outer  side  of  the  os  calcis,  supplying 
the  neighboring  muscles  and  back  of  the  ankle,  and  anastomosing  with  the 
external  malleolar,  tarsal,  and  external  plantar  arteries. 

Relations.  This  vessel  rests  at  first  upon  the  Tibialis  Posticus,  and,  in  the 
greater  part  of  its  course,  in  the  fibres  of  the  Flexor  Longus  Pollicis,  in  a  groove 
between  the  interosseous  ligament  and  the  bone.  It  is.  covered  in  the  upper  part 
of  its  course  by  the  Soleus  and  deep  fascia;  helow^  by  the  Flexor  Longus  Pollicis. 

Plan  of  the  Relations  of  the  Peroneal  Artery. 

Tnfrovt. 
Tibialis  Posticus. 
Flexor  Longus  Pollicis. 

Outer  side.  I      Peroneal      \ 

Fibula.  I        Ariery.        I 

Behind. 
Soleus. 
Deep  fascia. 
Flexor  Longus  Pollicis. 

Peculiarities  in  Orifjin.  The  peroneal  artery  may  arise  three  inches  below  the  Popliteus,  oi 
from  the  posterior  tibial  high  up,  or  even  from  the  popliteal. 

Itx  Size  *is  more  frequeutly  increased  than  diminished ;  and  then  it  either  reinforces  the  poste 
rior  tibial  by  its  junction  with  it.  or  altogether  takes  the  place  of  the  posterior  tibial  in  the  lower^ 
part  of  the  leg  and  foot,  the  latter  vessel  only  existing  as  a  short  muscular  branch.     In  those 
rare  cases  where  the  peroneal  artery  is  smaller  than  usual,  a  branch  from  the  posterior  tibial 
supplies  its  place,  and  a  branch  from  the  anterior  tibial  compensates  for  the  diminished  anterioi 
peroneal  artery.     In  one  case,  the  peroneal  artery  has  been  found  entirely  wanting. 

The  anterior  peroneal  is  sometimes  enlarged,  and  takes  the  place  of  the  dorsal  artery  of  the 
foot. 

The  peroneal  artery,  in  its  course,  gives  off  branches  to  the  Soleus,  Tibial i 
Posticus,  Flexor  Longus  Pollicis,  and  Peronei  muscles,  and  a  nutrient  branchl 
to  the  fibula. 

The  Anterior  Peroneal^  the  only  named  branch  of  the  peroneal  artery,  pierces 
the  interosseous  membrane,  about  two  inches  above  the  outer  malleolus,  to 
reach  the  fore  part  of  the  leg,  and,  passing  down  beneath  the  Peroneus  Tertiu 
to  the  outer  ankle,  ramifies  on  the  front  and  outer  side  of  the  tarsus,  anastomos 
ing  with  the  external  malleolar  and  tarsal  arteries. 

The  nutrient  artery  of  the  tibia  ari.ses  from  the  posterior  tibial  near  its  origin, 
and  after  supplying  a  few  muscular  branches,  enters  the  nutrient  canal  of  tliat 
bone,  which  it  traverses  obliquely  from  above  downwards.  This  is  the  largest 
nutrient  artery  of  bone  in  the  body. 


1 


PERONEAL 


533 


The  muscular  branches  of  the  posterior  tibial  are  distributed  to  the  Soleus  and 
^eep  muscles  along  the  back  of  the  leg. 

The  communicating  branch  to  the  peroneal  runs  transversely  across  the  back 
of  the  tibia,  about  two  inches  above  its  lower  end,  passing  beneath  the  Flexor 
Longus  Pollicis. 

The  internal  calcanean  consist  of  several  large  branches,  which  arise  from  the 
posterior  tibial  just  before  its  division;  they  are  distributed  to  the  fat  and 
integument  behind  the  tendo  Achillis  and  about  the  heel,  and  to  the  muscles 
on  the  inner  side  of  the  sole,  anastomosing  with  the  peroneal  and  internal 
malleolar  arteries. 

The  Internal  Plantar  Artery  (Figs.  301,  802),  much  smaller  than  the  external, 
passes  forwards  along  the  inner  side  of  the  foot.  It  is  at  first  situated  above 
the  Abductor  Pollicis,  and  then  between  it  and  the  Flexor  Brevis  Digitorum, 
both  of  which  it  supplies.  At  the  base  of  the  first  metatarsal  bone,  where  it 
has  become  much  diminished  in  size,  it  passes  along  the  inner  border  of  the 
great  toe,  inosculating  with  its  digital  branches. 


Fig.  301.— The  Plantar  Arteries. 
Superficial  View. 


Fig.  302.— The  Plantar  Arteries, 
Deep  View. 


The  External  Plantar  Artery,  much  larger  than  the  internal,  passes  obliquely 
outwards  and  forwards  to  the  base  of  the  fifth  metatarsal  bone.  It  then  turns 
obliquely  inwards  to  the  interval  between  the  bases  of  the  first  and  second 
metatarsal  bones,  where  it  anastomoses  with  the  communicating  branch  from 
the  dorsalis  pedis  artery,  thus  completing  the  plantar  arch.  As  this  artery 
passes  outwards,  it  is  at  first  placed  between  the  os  calcis  and  Abductor  Pollicis, 
and  then  between  the  Flexor  Brevis  Digitorum  and  Flexor  Accessorius;  and 
as  it  passes  forwards  to  the  base  of  the  little  toe,  it  lies  more  superficially 
between  the  Flexor  Brevis  Digitorum  and  Abductor  Minimi  Digiti,  covered  by 
the  deep  fascia  and  integument.  The  remaining  portion  of  the  vessel  is  deeply 
situated  :  it  extends  from  the  base  of  the  metatarsal  bone  of  the  little  toe  to  the 
back  part  of  the  first  interosseous  space,  and  forms  the  plantar  arch ;  it  is  con- 
vex forwards,  lies  upon  the  Interossei  muscles,  opposite  the  tarsal  ends  of  the 


534  ARTERIES. 

metatarsal  bones,  and  is  covered  by  the  Adductor  Pollicis,  the  flexor  tendons 
of  the  toes,  and  the  Lumbricales. 

Branches.  The  phintar  arch,  besides  distributing  numerous  branches  to  the 
muscles,  integument,  and  fascias  in  the  sole,  gives  off  the  following  branches: — 

Posterior  perforating.  Digital — Anterior  perforating. 

The  posterior  perforating  are  three  small  branches,  which  ascend  through  the 
back  part  of  the  three  outer  interosseous  spaces,  between  the  heads  of  trie 
Dorsal  Interossei  muscles,  and  anastomose  with  the  interosseous  branches  from 
the  metatarsal  artery. 

The  digital  branches  are  four  in  number,  and  supply  the  three  outer  toes  and 
half  the  second  toe.  l^he  first  passes  outwards  from  the  outer  side  of  the  plantar 
arch,  and  is  distributed  to  the  outer  side  of  the  little  toe,  passing  in  its  course 
beneath  the  Abductor  and  short  Flexor  muscles.  The  second,  third,  aud  fourth 
run  forwards  along  the  metatarsal  spaces,  and  on  arriving  at  the  clefts  between 
the  toes,  divide  into  collateral  branches,  which  supply  the  adjacent  sides  of  the 
three  outer  toes  and  the  outer  side  of  the  second.  At  the  bifurcation  of  the 
toes,  each  digital  artery  sends  upwards,  through  the  fore  part  of  the  correspond- 
ing metatarsal  space,  a  small  branch,  which  inosculates  with  the  interosseous 
branches  of  the  metatarsal  artery.     These  are  the  anterior  perforating  branches. 

From  the  arrangement  already  described  of  the  distribution  of  the  vessels  to 
the  toes,  it  will  be  seen  that  both  sides  of  the  three  outer  toes,  and  the  outer  side 
of  the  second  toe,  are  supplied  by  branches  from  the  plantar  arch  ;  both  sides 
of  the  great  toe,  and  the  inner  side  of  the  second,  being  supplied  by  the  dorsal 
artery  of  the  foot. 

Pulmonary  Artery. 

The  Pulmonary  Artery  conveys  the  venous  blood  from  the  right  side  of  the 
heart  to  the  lungs.  It  is  a  short  wide  vessel,  about  two  inches  in  length,  arising 
from  the  left  side  of  the  base  of  the  right  ventricle,  in  front  of  the  aorta.  It 
ascends  obliquely  upwards,  backwards,  and  to  the  left  side,  as  far  as  the  under 
surface  of  the  arch  of  the  aorta,  where  it  divides  into  two  branches  of  nearly 
equal  size,  the  right  and  left  pulmonary  arteries. 

Relations.  The  greater  part  of  this  vessel  is  contained,  together  with  the 
ascending  part  of  the  arch  of  the  aorta,  in  the  pericardium,  being  inclosed  Avith  _ 
it  in  a  tube  of  serous  membrane,  continued  upwards  from  the  base  of  the  heart,  ■■ 
and  has  attached  to  it,  above,  the  fibrous  layer  of  the  membrane.  Behind,  it 
rests  at  first  upon  the  ascending  aorta,  and  higher  up  lies  in  front  of  the  left 
auricle.  On  either  side  of  its  origin  is  the  appendix  of  the  corresponding 
auricle,  and  a  coronary  artery  ;  and  higher  up  it  passes  to  the  left  side  of  the 
ascending  aorta.  A  little  to  the  left  of  its  point  of  bifurcation,  it  is  connected 
to  the  under  surface  of  the  arch  of  the  aorta  by  a  short  fibrous  cord,  the  remains 
of  a  vessel  peculiar  to  fcetal  life,  the  ductus  arteriosus. 

The  right  ptdmonary  artery,  longer  and  larger  than  the  left,  runs  horizontally 
outwards,  behind  the  ascending  aorta  and  superior  vena  cava,  to  the  root  of  the 
right  lung,  where  it  divides  into  two  branches,  of  which  the  lower,  which  is 
the  larger,  supplies  the  lower  lobe ;  the  upper  giving  a  branch  to  the  middle 
lobe. 

The  left  pulmonary  artery,  shorter  but  somewhat  smaller  than  the  right,  passes 
horizontally  in  front  of  the  descending  aorta  and  left  bronchus  to  the  root  of 
the  left  lung,  where  it  divides  into  two  branches  for  the  two  lobes. 

The  terminal  branches  of  the  pulmonary  artery  will  be  described  with  the 
anatomy  of  the  lung.  Jl 

The  author  has  to  acknowledpe  valualile  aid  derived  from  the  followinor  works  :  Harrison's 
"8iir>ricul  Anatomy  of  the  Arteries  of  the  Human  Body."  Dublin,  1824.  Richard  Quain's 
"  Anatomy  of  the  Arteries  of  the  Human  Body."  London.  1844.  Sih.'jon's  "Medical  Anatomy," 
and  the  other  works  on  General  and  Microscopic  Anatomy  before  referred  to. 


■I 


i 
I 


I 


Of  the  Veins. 

The  Veins  are  the  vessels  which  serve  to  return  the  blood  from  the  capilla- 
ries of  the  different  parts  of  the  body  to  the  heart.  They  consist  of  two  distinct 
sets  of  vessels,  the  pulmonary  and  systemic. 

The  Pulmonary  Veins^  unlike  other  vessels  of  this  kind,  contain  arterial 
blood,  which  they  return  from  the  lungs  to  the  left  auricle  of  the  heart. 

The  Systemic  Veins  return  the  venous  blood  from  the  body  generally  to  the 
right  auricle  of  the  heart. 

The  Portal  Vein,  an  appendage  to  the  systemic  venous  system,  is  confined  to 
the  abdominal  cavity,  returning  the  venous  blood  from  the  viscera  of  digestion, 
and  carrying  it  to  the  liver  by  a  single  trunk  of  large  size,  the  vena  portae. 
From  this  organ,  the  same  blood  is  conveyed  to  the  inferior  vena  cava  by 
means  of  the  hepatic  veins. 

The  veins,  like  the  arteries,  are  found  in  nearly  every  tissue  of  the  body. 
They  commence  by  minute  plexuses,  which  communicate  with  the  capillaries. 
The  branches  which  have  their  commencement  in  these  plexuses  unite  together 
into  trunks,  and  these,  in  their  passage  towards  the  heart,  constantly  increase 
in  size  as  they  receive  branches,  and  join  other  veins  similar  in  size  to  them- 
selves. The  veins  are  larger  and  altogether  more  numerous  than  the  arteries ; 
hence,  the  entire  capacity  of  the  venous  system  is  much  greater  than  that  of 
the  arterial ;  the  pulmonary  veins  excepted,  which  do  not  exceed  in  capacity 
the  pulmonary  arteries.  From  the  combined  area  of  the  smaller  venous 
branches  being  greater  than  the  main  trunks,  it  results,  that  the  venous  system 
represents  a  cone,  the  summit  of  which  corresponds  to  the  heart;  its  base  to  the 
circumference  of  the  body.  In  form,  the  veins  are  not  perfectly  cylindrical 
like  the  arteries,  their  walls  being  collapsed  when  empty,  and  the  uniformity 
of  their  surface  being  interrupted  at  intervals  by  slight  contractions,  which 
indicate  the  existence  of  valves  in  their  interior.  They  usually  retain,  however, 
the  same  calibre  as  long  as  they  receive  no  branches. 

The  veins  communicate  very  freely  with  one  another,  especially  in  certain 
regions  of  the  body;  and  this  communication  exists  between  the  larger  trunks 
as  well  as  between  the  smaller  branches.  Thus,  in  the  cavity  of  the  cranium, 
and  between  the  veins  of  the  nQck,  where  obstruction  would  be  attended  with 
imminent  danger  to  the  cerebral  venous  system,  we  find  that  the  sinuses  and 
larger  veins  have  large  and  very  frequent  anastomoses.  The  same  free  com- 
munication exists  between  the  veins  throughout  the  whole  extent  of  the  spinal 
canal,  and  between  the  veins  composing  the  various  venous  plexuses  in  the 
abdomen  and  pelvis,  as  the  spermatic,  uterine,  vesical,  prostatic,  etc. 

The  veins  are  subdivided  into  three  sets:  superficial,  deep,  and  sinuses. 

The  Superficial  or  Cutaneous  Veins  are  found  between  the  layers  of  superfi- 
cial fascia,  immediately  beneath  the  integument;  they  return  the  blood  from 
these  structures,  and  communicate  with  the  deep  veins  by  perforating  the  deep 
fascia. 

The  Deep  Veins  accompany  the  arteries,  and  are  usually  inclosed  in  the  same 
sheath  with  those  vessels.  In  the  smaller  arteries,  as  the  radial,  ulnar,  brachial, 
tibial,  peroneal,  they  exist  generally  in  pairs,  one  lying  on  each  side  of  the 
vessel,  and  are  called  vense  comites.  The  larger  arteries,  as  the  axillary,  sub- 
clavian, popliteal,  and  femoral,  and  have  usually  only  one  accompanying  vein. 
In  certain  organs  of  the  body,  however,  the  deep  veins  do  not  accompany  the 
arteries  ;  for  instance,  the  veins  in  the  skull  and  spinal  canal,  the  hepatic  veins 
in  the  liver,  and  the  larger  veins  returning  blood  from  the  osseous  tissue. 

535 


636  VEINS. 

Sinuses  are  venous  channels,  which,  ir^  their  structure  and  mode  of  distribu- 
tion, differ  altogether  from  the  veins.  They  are  found  only  in  the  interior  of 
the  skull,  and  are  formed  by  a  separation  of  the  layers  of  the  dura  mater ;  their 
outer  coat  consisting  of  fibrous  tissue,  their  inner  of  a  serous  membrane  con- 
tinuous with  the  serous  membrane  of  the  veins. 

Veins  have  thinner  walls  than  arteries,  the  difference  in  thickness  being  due 
to  the  small  amount  of  elastic  and  muscular  tissues  which  the  veins  contain. 
The  superficial  veins  usually  have  thicker  coats  than  the  deep  veins,  and  the 
veins  of  the  lower  limb  are  thicker  than  those  of  the  upper. 

The  minute  structure  of  these  vessels  is  described  in  the  Introduction. 

The  veins  may  be  arranged  into  three  groups :  1.  Those  of  the  head  and 
neck,  upper  extremity,  and  thorax,  which  terminate  in  the  superior  vena  cava. 
3.  Those  of  the  lower  limb,  pelvis,  and  abdomen,  which  terminate  in  the  infe- 
rior vena  cava.  3.  The  cardiac  veins,  which  open  directly  into  the  right  auricle 
of  the  heart. 

Veins  of  the  Head  and  Neck. 

The  Veins  of  the  Head  and  Neck  may  be  subdivided  into  three  groups  :  1. 
The  veins  of  the  exterior  of  the  head.  2.  The  veins  of  the  neck.  3.  The  veins 
of  the  diploe  and  interior  of  the  cranium. 

The  Veins  of  the  Exterior  of  the  Head  are,  the 

Facial.  Temporo-maxillary. 

Temporal.  Posterior  auricular. 

Internal  maxillary.  Occipital. 

The  Facial  Vein  passes  obliquely  across  the  side  of  the  face,  extending  from 
the  inner  angle  of  the  orbit,  downwards  and  outwards,  to  the  anterior  margin 
of  the  Masseter  muscle.  It  lies  to  the  outer  side  of  the  fascial  artery,  and  is 
not  so  tortuous  as  that  vessel.  It  commences  in  the  frontal  region,  where  it  is 
called  the  frontal  vein ;  at  the  inner  angle  of  the  eye  it  has  received  the  name 
of  the  angular  vein;  and  from  this  point  to  its  termination  is  called  the  facial 
vein. 

The/row^aZmw  commences  on  the  anterior  part  of  the  skull,  by  a  venous 
plexus,  which  communicates  with  the  anterior  branches  of  the  temporal  vein ; 
the  veins  converge  to  form  a  single  trunk,  which  runs  downwards  near  the 
middle  line  of  the  forehead  parallel  with  the  vein  of  the  opposite  side,  and 
unites  with  it  at  the  root  of  the  nose,  by  a  transverse  trunk,  called  the  na^al 
arch.  Occasionally  the  frontal  veins  join  to  form  a  single  trunk,  which  bifur- 
cates at  the  root  of  the  nose  into  the  two  angular  veins.  At  the  nasal  arch  the 
branches  diverge,  and  run  along  the  side  of  the  root  of  the  nose.  The  frontal 
vein  as  it  descends  upon  the  forehead  receives  the  supraorbital  vein ;  the  dorsal  11 
veins  of  the  nose  terminate  in  the  nasal  arch ;  and  the  angular  vein  receives  '■ 
the  veins  of  the  ala  nasi  on  its  inner  side,  and  the  superior  palpebral  veins  on 
its  outer  side ;  it  moreover  communicates  with  the  ophthalmic  vein,  which 
establishes  an  important  anastomosis  between  this  vessel  and  the  cavernous 
sinus. 

The  facial  vein  commences  at  the  inner  angle  of  the  orbit,  being  a  continua- 
tion of  the  angular  vein.  It  passes  obliquely  downwards  and  outwards,  be- 
neath the  great  zygomatic  muscle,  descends  along  the  anterior  border  of  the 
Masseter,  crosses  over  the  body  of  the  lower  jaw,  with  the  facial  artery,  and, 
passing  obliquely  outwards  and  backwards,  beneath  the  Platysma  and  cervical 
fascia,  unites  with  a  branch  of  communication  from  the  temporo-maxillary  vein, 
to  form  a  trunk  of  large  size  which  enters  the  internal  jugular. 

Branches.  The  facial  vein  receives,  near  the  angle  of  the  mouth,  communi- 
cating branches  from  the  pterygoid  plexus.  It  is  also  joined  by  the  inferior 
palpebral,  the  superior  and  inferior  labial  veins,  the  buccal  veins  from  the 
cheek,  and  the  masseteric  veins.     Below  the  jaw,  it  receives  the  submental,  the 


OF    THE    HEAD    AND    NECK. 


68T 


inferior  palatine,  which  returns  the  blood  from  the  plexus  around  the  tonsil  and 
soft  palate;  the  submaxillary  vein,  which  commences  in  the  submaxillary  gland; 
and  lastly,  the  ranine  vein. 

Fig.  303. — Veins  of  the  Head  and  Neck. 


al 
Luryvgeai 


The  Temporal  Vein  commences  by  a  minute  plexus  on  the  side  and  vertex  of 
the  skull,  which  communicates  with  the  frontal  vein  in  front,  the  corresponding 
vein  of  the  Opposite  side,  and  the  posterior  auricular  and  occipital  veins  behind. 
From  this  network,  anterior  and  posterior  branches  are  formed  which  unite 
above  the  zygoma,  forming  the  trunk  of  the  vein.  This  trunk  is  joined  in  this 
situation  by  a  large  vein,  the  middle  temporal,  which  receives  the  blood  from 
the  substance  of  the  Temporal  muscle  and  pierces  the  fascia  at  the  upper  border 
of  the  zygoma.  The  temporal  vein  then  descends  between  the  external  auditory 
meatus  and  the  condyle  of  the  jaw,  enters  the  substance  of  the  parotid  gland, 
and  unites  with  the  internal  maxillary  vein,  to  form  the  temporo-maxillary. 

Branches.  The  temporal  vein  receives  in  its  course  some  parotid  veins,  an 
articular  branch  from  the  articulation  of  the  jaw,  anterior  auricular  veins  from 
the  external  ear,  and  a  vein  of  large  size,  the  transverse  facial,  from  the  side  of 
the  face. 


688  VEINS. 

The  Internal  Maxillary  Vein  is  a  vessel  of  considerable  size,  receiving  branches 
which  correspond  with  those  of  the  internal  maxillary  artery.  Thus  it  receives 
the  middle  meningeal  veins,  the  deep  temporal,  the  pterygoid,  masseteric,  and 
buccal,  some  palatine  veins,  and  the  inferior  dental.  These  branches  form  a 
large  plexus,  the  pterygoid,  which  is  placed  between  the  Temporal  and  External 
Pterygoid,  and  partly  between  the  Pterygoid  muscles.  This  plexus  communi- 
cates very  freely  with  the  facial  vein,  and  with  the  cavernous  sinus,  by  branches 
through  the  base  of  the  skull.  The  trunk  of  the  vein  then  passes  backwards, 
behind  the  neck  of  the  lower  jaw,  and  unites  with  the  temporal  vein,  forming 
the  temporo-maxillary. 

The  Temporo-maxillary  Vein,  formed  by  the  union  of  the  temporal  and  inter- 
nal maxillary  vein,  descends  in  the  substance  of  the  parotid  gland,  between  the 
ramus  of  the  jaw  and  the  Sterno-mastoid  muscle,  and  divides  into  two  branches, 
one  of  which  passes  inwards  to  join  the  facial  vein,  the  other  is  continuous  with 
the  external  jugular.  It  receives  near  its  termination  the  posterior  auricular 
vein. 

The  Posterior  Auricular  Vein  commences  upon  the  side  of  the  head,  by  a 
plexus  which  communicates  with  the  branches  of  the  temporal  and  occipital 
veins.  The  vein  descends  behind  the  external  ear  and  joins  the  temporo-maxil- 
lary, just  before  that  vessel  terminates  in  the  external  jugular.  This  vessel 
receives  the  stylo-mastoid  vein,  and  some  branches  from  the  back  part  of  the 
external  ear. 

The  Occipital  Vein  commences  at  the  back  part  of  the  vertex  of  the  skull,  by 
a  plexus  in  a  similar  manner  with  the  other  veins.  It  follows  the  course  of  the 
occipital  artery,  passing  deeply  beneath  the  muscles  of  the  back  part  of  the 
neck,  and  terminates  in  the  internal  jugular,  occasionally  in  the  external  jugular. 
As  this  vein  passes  opposite  the  mastoid  process,  it  receives  the  mastoid  veinj 
which  establishes  a  communication  with  the  lateral  sinus. 

The  Veins  of  the  Neck,  which  return  the  blood  from  the  head  and  face,  are 
the 

External  jugular.  Anterior  jugular. 

Posterior  external  jugular.  Internal  jugular. 

Vertebral. 

The  External  Jugular  Vein  receives  the  greater  part  of  the  blood  from  the 
exterior  of  the  cranium  and  deep  parts  of  the  face,  being  a  continuation  of  the_g 
temporo-maxillary  and  posterior  auricular  veins.    It  commences  in  the  substanc^l 
of  the  parotid  gland,  on  a  level  with  the  angle  of  the  lower  jaw,  and  runs  per-"" 
pendicularly  down  the  neck,  in  the  direction  of  a  line  drawn  from  the  angle  of 
the  jaw  to  the  middle  of  the  clavicle.     In  its  course  it  crosses  the  Sterno- 
mastoid  muscle,  and  runs  parallel  with  its  posterior  border  as  far  as  its  attach- 
ment to  the  clavicle,  where  it  perforates  the  deep  fascia,  and  terminates  in  thMl 
subclavian  vein,  on  the  outer  side  of  the  internal  jugular.     In  the  neck,  it  is"' 
separated  from  the  Sterno-mastoid  by  the  anterior  layer  of  the  deep  cervical 
fascia,  and  is  covered  by  the  Platysma,  the  superficial  fascia,  and  the  integument. 
This  vein  is  crossed  about  its  centre  by  the  superficial  cervical  nerve,  and  its 
upper  half  is  accompanied  by  the  auricularis  magnus  nerve.     The  external 
jugular  vein  varies  in  size,  bearing  an  inverse  proportion  to  that  of  the  other 
veins  of  the  neck ;  it  is  occasionally  double.     It  is  provided  with  two  pairs  ofsl 
valves,  the  lower  pair  being  placed  at  its  entrance  into  the  subclavian  vein,  the" 
upper  pair  in  most  cases  about  an  inch  and  a  half  above  the  clavicle.     These 
valves  do  not  prevent  the  regurgitation  of  the  blood,  or  the  passage  of  injection 
from  below  upwards.* 

'  The  student  may  refer  to  an  interesting  paper  liy  Dr.  Struthers.  "  On  Jujriilar  Venesection 
in  Asphyxia,  Anatomically  and  Experimentally  Considered,  including  the  Demonstration  of 
Valves  in  the  Veins  of  the  Neck,"  in  the  Edinburgh  Medical  Journal,  for  November,  1856. 


OF    THE    NECK.  539 

Branches.  This  vein  receives  the  occipital  occasionally,  the  posterior  exter- 
nal jugular,  and,  near  its  termination,  the  suprascapular  and  transverse  cervical 
veins.  It  communicates  with  the  anterior  jugular,  and,  in  the  substance  of  the 
parotid,  receives  a  large  branch  of  communication  from  the  internal  jugular. 

The  Posterior  External  Jugular  Vein  returns  the  blood  from  the  integument 
and  superficial  muscles  in  the  upper  and  back  part  of  the  neck,  lying  between 
the  Splenius  and  Trapezius  muscles.  It  runs  down  the  back  part  of  the  neck, 
and  opens  into  the  external  jugular  just  below  the  middle  of  its  course. 

The  Anterior  Jugular  Vein  collects  the  blood  from  the  integument  and  mus- 
cles in  the  middle  of  the  anterior  region  of  the  neck.  It  passes  down  between 
the  median  line  and  the  anterior  border  of  the  Sterno-mastoid,  and,  at  the  lower 
part  of  the  neck,  passes  beneath  that  muscle  to  open  into  the  subclavian  vein, 
near  the  termination  of  the  external  jugular.  This  vein  varies  considerably  in 
size,  bearing  almost  always  an  inverse  proportion  to  the  external  jugular.  Most 
frequently  there  are  two  anterior  jugulars,  a  right  and  left;  but  occasionally 
only  one.  This  vein  receives  some  laryngeal  branches,  and  occasionally  an 
inferior  thyroid  vein.  Just  above  the  sternum,  the  two  anterior  jugular  veins 
communicate  by  a  transverse  trunk,  which  receives  branches  from  the  inferior 
thyroid  veins.  It  also  communicates  with  the  external  and  with  the  internal 
jugular.     There  are  no  valves  in  this  vein. 

The  Internal  Jugular  Vein  collects  the  blood  from  the  interior  of  the  cranium, 
from  the  superficial  parts  of  the  face,  and  from  the  neck.  It  commences  at  the 
jugular  foramen,  in  the  base  of  the  skull,  being  formed  by  the  coalescence  of 
the  lateral  and  inferior  petrosal  sinuses.  At  its  origin  it  is  somewhat  dilated, 
and  this  dilatation  is  called  the  sinus,  or  gulf  of  the  internal  jugular  vein.  It 
runs  down  the  side  of  the  neck  in  a  vertical  direction,  lying  at  first  on  the 
outer  side  of  the  internal  carotid,  and  then  on  the  outer  side  of  the  common 
carotid,  and  at  the  root  of  the  neck  unites  with  the  subclavian  vein,  to  form 
the  vena  innominata.  The  internal  jugular  vein,  at  its  commencement,  lies 
upon  the  Rectus  Lateralis,  behind,  and  at  the  outer  side  of  the  internal  carotid, 
and  the  eighth  and  ninth  pairs  of  nerves;  lower  down,  the  vein  and  artery  lie 
upon  the  same  plane,  the  glosso-pharyngeal  and  hypoglossal  nerves  passing 
forwards  between  them  ;  the  pneumogastric  descends  between  and  behind  them, 
in  the  same  sheath  ;  and  the  spinal  accessory  passes  obliquely  outwards,  behind 
the  vein.  At  the  root  of  the  neck  the  vein  of  the  right  side  is  placed  at  a 
little  distance  from  the  artery  ;  on  the  left  side,  it  usually  crosses  it  at  its  lower 
part.  The  right  internal  jugular  vein  crosses  the  first  part  of  the  subclavian 
artery.  This  vein  is  of  considerable  size,  but  varies  in  dififerent  individuals, 
the  left  one  being  usually  the  smaller.  It  is  provided  with  a  pair  of  valves, 
which  are  placed  at  its  point  of  termination,  or  from  half  to  three-quarters  of 
an  inch  above  it. 

Branches.  This  vein  receives  in  its  course  the  facial,  lingual,  pharyngeal, 
superior  and  middle  thyroid  veins,  and  sometimes  the  occipital.  At  its  point 
of  junction  with  the  branch  common  to  the  temporal  and  facial  veins  it  becomes 
greatly  increased  in  size. 

The  lingual  veins  commence  on  the  dorsum,  sides,  and  under  surface  of  the 
tongue,  and  passing  backwards,  following  the  course  of  the  lingual  artery  and 
its  branches,  terminate  in  the  internal  jugular. 

^\\Q  pharyngeal  vein  commences  in  a  minute  plexus,  the  pharyngeal,  at  the 
back  part  and  sides  of  the  pharynx,  and  after  receiving  meningeal  branches, 
and  the  Vidian  and  spheno-palatine  veins,  terminates  in  the  internal  jugular. 
It  occasionally  opens  into  the  facial,  lingual,  or  superior  thyroid  vein. 

The  superior  thyroid  vein  commences  in  the  substance  and  on  the  surface  of 
the  thyroid  gland,  by  branches  corresponding  with  those  of  the  superior  thyroid 
artery,  and  terminates  in  the  upper  part  of  the  internal  jugular  vein. 

The  middle  thyroid  vein  collects  the  blood  from  the  lower  part  of  the  lateral 


540 


VEINS. 


lobe  of  the  thyroid  gland,  and,  being  joined  by  some  branches  from  the  larynx 
and  trachea,  terminates  in  the  lower  part  of  the  internal  jugular  vein. 

The  occipital  vein  has  been  described  above. 

The  Vertebral  Vein  commences  in  the  occipital  region,  by  numerous  small 
branches,  from  the  deep  muscles  at  the  upper  and  back  part  of  the  neck,  passes 
outwards,  and  enters  the  foramen  in  the  transverse  process  of  the  atlas,  and 
descends  by  the  side  of  the  vertebral  artery,  in  the  canal  formed  by  the  trans- 
verse processes  of  the  cervical  vertebrae.  Emerging  from  the  foramen  in  the 
transverse  process  of  the  sixth  cervical,  it  terminates  at  the  root  of  the  neck  in 
the  back  part  of  the  innominate  vein  near  its  origin,  its  mouth  being  guarded 
by  a  pair  of  valves.  On  the  right  side,  it  crosses  the  first  part  of  the  subcla- 
vian artery.  This  vein,  in  the  lower  part  of  its  course,  occasionally  divides 
into  two  branches,  one  of  which  emerges  with  the  artery  at  the  sixth  cervical 
vertebra;  the  other  escapes  through  the  foramen  in  the  seventh  cervical. 

Branches.  The  vertebral  vein  receives  in  its  course  the  posterior  condyloid 
vein,  muscular  branches  from  the  muscles  in  the  prevertebral  region ;  dorsi- 
spinal  veins,  from  the  back  part  of  the  cervical  portion  of  the  spine;  meningo- 
rachidian  veins,  from  the  interior  of  the  spinal  canal ;  and  lastly,  the  ascending 
and  deep  cervical  veins. 

Veins  of  the  Diploe. 

The  diploe  of  the  cranial  bones  is  channelled,  in  the  adult,  by  a  number  of 
tortuous  canals,  which  are  lined  by  a  more  or  less  complete  layer  of  compact 

Fig.  304. — Veins  of  the  Diploe,  as  displayed  by  the  Removal  of  the  Outer  Table  of  the  Skull. 


ti.ssue.  The  veins  they  contain  are  large  and  capacious,  their  walls  being  thin, 
and  formed  only  of  epithelium,  resting  upon  a  layer  of  elastic  tissue,  and  they 
present,  at  irregular  intervals,  pouch-like  dilatations,  or  culs-de-sac,  which  serve 
as  reservoirs  for  the  blood.  These  are  the  veins  of  the  diploe:  they  can  only 
be  displayed  by  removing  the  outer  table  of  the  skull. 

In  adult  life,  as  long  as  the  cranial  bones  are  distinct  and  separable,  these 
veins  are  confined  to  the  particular  bones;  but  in  old  age,  when  the  sutures  are 
united,  they  communicate  with  each  other,  and  increase  in  size.  These  vessels 
communicate,  in  the  interior  of  the  cranium,  with  the  meningeal  veins,  and 
with  the  sinuses  of  the  dura  mater ;  and  on  the  .exterior  of  the  skull,  with  the 


CEREBRAL.  541 

veins  of  the  pericranium.  They  are  divided  into  the  frontal,  which  opens  into 
the  supraorbital  vein,  by  an  aperture  at  the  supraorbital  notch ;  the  anterior 
temporal,  which  is  confined  chiefly  to  the  frontal  bone,  and  opens  into  one  of 
the  deep  temporal  veins,  after  escaping  by  an  aperture  in  the  great  wing  of  the 
sphenoid ;  the  posterior  temporal,  which  is  confined  to  the  parietal  bone,  and 
terminates  in  the  lateral  sinus  by  an  aperture  .at  the  posterior  inferior  angle  of 
the  parietal  bone ;  and  the  occipital,  which  is  confined  to  the  occipital  bone  and 
opens  either  into  the  occipital  vein,  or  the  occipital  sinus. 

Cerebral  Yeins. 

The  Cerebral  Yeins  are  remarkable  for  the  extreme  thinness  of  their  coats, 
in  consequence  of  the  muscular  tissue  in  them  being  wanting,  and  for  the 
absence  of  valves.  They  may  be  divided  into  two  sets,  the  superficial,  which 
are  placed  on  the  surface,  and  the  deep  veins,  which  occupy  the  interior  of  the 
organ. 

The  Superficial  Cerebral  Yeins  ramify  upon  the  surface  of  the  brain,  being 
lodged  in  the  sulci,  between  the  convolutions,  a  few  running  across  the  convo- 
lutions. They  receive  branches  from  the  substance  of  the  brain,  and  terminate 
in  the  sinuses.  They  are  named,  from  the  position  they  occupy,  superior,  in- 
ferior, internal,  and  external. 

The  Superior  Cerebral  Veins,  seven  or  eight  in  number  on  each  side,  pass 
forwards  and  inwards  towards  the  great  longitudinal  fissure,  where  they  receive 
the  internal  cerebral  veins,  which  return  the  blood  from  the  convolutions  of 
the  flat  surface  of  the  corresponding  hemisphere;  near  their  termination,  they 
become  invested  with  a  tubular  sheath  of  the  arachnoid  membrane,  and  open 
into  the  superior  longitudinal  sinus,  in  the  opposite  direction  to  the  course  of 
the  blood. 

The  Inferior  Anterior  Cerebral  Yeins  commence  on  the  under  surface  of  the 
anterior  lobes  of  the  brain,  and  terminate  in  the  cavernous  sinuses. 

The  Inferior  Lateral  Cerebral  Yeins  commence  on  the  lateral  parts  of  the 
hemispheres,  and  at  the  base  of  the  brain ;  they  unite  to  form  from  three  to 
five  veins,  which  open  into  the  lateral  sinus  from  before  backwards. 

The  fnferior  Median  Cerebral  Yeins,  which  are  very  large,  commence  at  the 
fore  part  of  the  under  surface  of  the  cerebrum,  and  from  the  convolutions  of 
the  posterior  lobe,  and  terminate  in  the  straight  sinus  behind  the  vense  Galeni. 

The  Deep  Cerebral,  or  Yentricular  Yeijis  (venae  Galeni),  are  two  in  number, 
one  from  the  right,  the  other  from  the  left,  ventricle.  They  are  each  formed 
by  two  veins,  the  vena  corporis  striati,  and  the  choroid  vein.  They  run  back- 
wards, parallel  with  one  another,  inclosed  within  the  velum  interpositum,  and 
pass  out  of  the  brain  at  the  great  transverse  fissure,  between  the  under  surface  of 
the  corpus  callosum  and  the  tubercula  quadrigemina,  to  enter  the  straight  sinus. 

The  vena  corporis  striati  commences  in  the  groove  between  the  corpus  striatum 
and  thalamus  opticus,  receives  numerous  veins  from  both  of  these  parts,  and 
unites  behind  the  anterior  pillar  of  the  fornix  with  the  choroid  vein,  to  form 
one  of  the  vense  Galeni. 

The  choroid  vein  runs  along  the  whole  length  of  the  outer  border  of  the^ 
choroid  plexus,  receiving  veins  from  the  hippocampus  major,  the  fornix  and 
corpus  callosum,  and  unites  at  the  anterior  extremity  of  the  choroid  plexus, 
with  the  vein  of  the  corpus  striatum. 

The  Cerebellar  Yeins  occupy  the  surface  of  the  cerebellum,  and  are  disposed 
in  three  sets,  superior,  inferior,  and  lateral.  The  superior  pass  forwards  and 
inwards,  across  the  superior  vermiform  process,  and  terminate  in  the  straight 
sinus ;  some  open  into  the  vense  Galeni.  The  inferior  cerebellar  veins,  of  large 
size,  run  transversely  outwards,  and  terminate  by  two  or  three  trunks  in  the 
lateral  sinuses.  The  lateral  anterior  cerebellar  veins  terminate  in  the  superior 
petrosal  sinuses. 


542 


VEINS. 


Sinuses  of  the  Dura  Mater. 

The  Sinuses  of  tlie  Dura  Mater  are  venous  channels,  analogous  to  the  veins, 
their  outer  coat  being  formed  by  the  dura  mater;  their  inner,  by  a  continuation 
of  the  serous  membrane  of  the  veins.  They  are  fifteen  in  number,  and  are 
divided  into  two  sets.  1.  Those  situated  at  the  upper  and  back  part  of  the  skull. 
2.  Those  at  the  base  of  the  skull.     The  former  are  the 


Superior  longitudinal. 
Inferior  longitudinal. 


Straight  sinus. 
Lateral  sinuses. 


Occipital  sinuses. 

The  Superior  LonrjUudinnl  Sinus  occupies  the  attached  margin  of  the  falx 
cerebri.     Commencing  at  the  crista   Galli,  it  runs   from   before   backwards, 

Fig.  305. — Vertical  Section  of  the  Skull,  showing  the  Sinuses  of  the  Dura  Mater. 


Cacmr 


grooving  the  inner  surface  of  the  frontal,  the  adjacent  margins  of  the  two 
parietal,  and  the  superior  division  of  the  crucial  ridge  of  the  occipital  bone, 
and  terminates  by  dividing  into  the  two  lateral  sinuses.  This  sinus  is  triangular 
in  form,  narrow  in  front,  and  gradually  increasing  in  size  as  it  passes  back- 
wards. On  examining  its  inner  surface,  it  presents  the  internal  openings  of  the 
cerebral  veins,  which  run,  for  the  most  part,  from  behind  forwards,  and  open 
chiefly  at  the  back  part  of  the  sinus,  their  orifices  being  concealed  by  fibrous 
areola) ;  numerous  fibrous  bands  {chorche  Willisii)  are  also  seen,  which  extend 
transversely  across  the  inferior  angle  of  the  sinus ;  and  lastly,  some  small,  white, 
projecting  bodies,  the  glandulte  Pacchioni.  This  sinus  receives  the  superior 
cerebral  veins,  numerous  veins  from  the  diploc  and  dura  mater,  and,  at  tlie 
posterior  extremity  of  the  sagittal  suture,  the  parietal  veins  from  the  peri- 


II 


cranium. 

The  point  where  the  superior  longitudinal  and  lateral  sinuses  are  continuous 
is  called  the  conjlnence  of  the  sinuses,  or  the  tnrcular  Ilerophili.  It  presents  a 
considerable  dilatation,  of  very  irregular  form,  and  is  the  point  of  meeting  of 
six  sinuses,  the  superior  longitudinal,  the  two  lateral,  the  two  occipital,  and  the 
straight.  •« 

The  Inferior  Longitudinal  Sinus,  more  correctly  described  astheni/enor  longi'^ 
indinal  vein,  is  contained  in  the  posterior  part  of  the  free  margin  of  the  falx 
cerebri.     It  is  of  a  circular  form,  increases  in  size  as  it  passes  backwards,  and 


SINUSES    OF    THE    DURA    MATER.  543 

terminates  in  the  straight  sinus.  It  receives  several  veins  from  the  falx  cerebri, 
and  occasionally  a  few  from  the  flat  surface  of  the  hemispheres. 

The  Straight  Sinus  is  situated  at  the  line  of  junction  of  the  falx  cerebri  with 
the  tentorium.  It  is  triangular  in  form,  increases  in  size  as  it  proceeds  back- 
wards, and  runs  obliquely  downwards  and  backwards  from  the  termination  of 
the  inferior  longitudinal  sinus  to  the  torcular  Herophili.  Besides  the  inferior 
longitudinal  sinus,  it  receives  the  vena3  Galeni,  the  inferior  median  cerebral 
veins,  and  the  superior  cerebellar.     A  few  transverse  bands  cross  its  interior. 

The  Lateral  Sinuses  are  of  large  size,  and  are  situated  in  the  attached  margin 
of  the  tentorium  cerebelli.  They  commence  at  the  torcular  Herophili,  and 
passing  horizontally  outwards  to  the  base  of  the  petrous  portion  of  the  temporal 
bone,  curve  downwards  and  inwards  on  each  side  to  reach  the  jugular  foramen, 
where  they  terminate  in  the  internal  jugular  vein.  Each  sinus  rests,  in  its 
course,  upon  the  inner  surface  of  the  occipital,  the  posterior  inferior  angle  of 
the  parietal,  the  mastoid  portion  of  the  temporal,  and  on  the  occipital  again 
just  before  its  termination.  These  sinuses  are  frequently  of  unequal  size,  and 
they  increase  in  size  as  they  proceed  from  behind  forwards.  The  horizontal 
portion  is  of  a  triangular  form,  the  curved  portion  semi-cylindrical ;  their  inner 
surface  is  smooth,  and  not  crossed  by  the  fibrous  bands  found  in  the  inner 
sinuses.  These  sinuses  receive  blood  from  the  superior  longitudinal,  the 
straight,  and  the  occipital  sinuses;  and  in  front  they  communicate  with  the 
superior  and  inferior  petrosal.  They  communicate  with  the  veins  of  the  peri- 
cranium by  means  of  the  mastoid  and  posterior  condyloid  veins,  and  they  re- 
ceive the  inferior  cerebral  and  inferior  cerebellar  veins,  and  some  veins  from 
the  diploe. 

The  Occipital  are  the  smallest  of  the  cranial  sinuses.  They  are  usually  two 
in  number,  and  situated  in  the  attached  margin  of  the  falx  cerebelli.  They 
commence  by  several  small  veins  around  the  posterior  margin  of  the  foramen 
magnum,  which  communicate  with  the  posterior  spinal  veins,  and  terminate  by 
separate  openings  (sometimes  by  a  single  aperture)  in  the  torcular  Herophili. 

The  sinuses  at  the  base  of  the  skull  are : — 

Cavernous.  Inferior  petrosal. 

Circular.  Superior  petrosal. 

Transverse. 

The  Cavernous  Sinuses  are  named  from  their  presenting  a  reticulated  structure. 
They  are  two  in  number,  of  large  size,  and  placed  one  on  each  side  of  the  sella 
Turcica,  extending  from  the  sphenoidal  fissure  to  the  apex  of  the  petrous  por- 
tion of  the  temporal  bone ;  they  receive  anteriorly  the  ophthalmic  vein  through 
the  sphenoidal  fissure,  and  communicate  behind  with  the  petrosal  sinuses,  and 
with  each  other  by  the  circular  and  transverse  sinuses.  On  the  inner  wall  of 
each  sinus  is  found  the  internal  carotid  artery,  accompanied  by  filaments  of  the 
carotid  plexus  and  by  the  sixth  nerve ;  and  on  its  outer  wall,  the  third,  fourth, 
and  ophthalmic  nerves.  These  parts  are  separated  from  the  blood  flowing  along 
the  sinus  by  the  lining  membrane,  which  is  continuous  with  the  inner  coat  of 
the  veins.  The  cavity  of  the  sinus,  which  is  larger  behind  than  in  front,  is 
intersected  by  filaments  of  fibrous  tissue  and  small  vessels.  The  cavernous 
sinuses  receive  the  inferior  anterior  cerebral  veins;  they  communicate  with  the 
lateral  sinuses  by  means  of  the  superior  and  inferior  petrosal,  and  with  the 
facial  vein  through  the  ophthalmic. 

The  ophthalmic  is  a  large  vein,  which  connects  the  frontal  vein  at  the  inner 
angle  of  the  orbit  with  the  cavernous  sinus ;  it  pursues  the  same  course  as  the 
ophthalmic  artery,  and  receives  branches  corresponding  to  those  derived  from 
that  vessel.  Forming  a  short  single  trunk,  it  passes  through  the  inner  ex- 
tremity of  the  sphenoidal  fissure,  and  terminates  in  the  cavernous  sinus. 

The  Circular  Sinus  completely  surrounds  the  pituitary  body,  and  commu- 
nicates on  each  side  with  the  cavernous  sinuses.     Its  posterior  half  is  larger 


544 


VEINS. 


than  the  anterior ;  and  in  old  age  it  is  more  capacious  than  at  an  early  period 
of  life.  It  receives  veins  from  the  pituitary  body,  and  from  the  adjacent  bone 
and  dura  mater. 

The  Inferior  Petrosal  Sinus  is  situated  in  the  groove  formed  by  the  junction 
of  the  inferior  border  of  the  petrous  portion  of  the  temporal  with  the  basilar 
process  of  the  occipital.  It  commences  in  front  at  the  termination  of  the 
cavernous  sinus,  and  opens  behind,  into  the  jugular  foramen,  forming  with  the 
lateral  sinus  the  commencement  of  the  internal  jugular  vein.  These  sinuses  are 
semi-cylindrical  in  form. 

Fig.  306.— The  Sinuses  at  the  Base  of  the  Skull. 


i 


The  Transverse  Sinus  is  placed  transversely  across  the  fore  part  of  the  basilar 
process  of  the  occipital  bone  serving  to  connect  the  two  inferior  petrosal  and 
cavernous  sinuses.  A  second  is  occasionally  found  opposite  the  foramen  magnum. 

The  Superior  Petrosal  Sinus  is  situated  along  the  upper  border  of  the  petrous  Jl 
portion  of  the  temporal  bone,  in  the  front  part  of  the  attached  margin  of  the™ 
tentorium.     It  is  small  and  narrow,  and  connects  together  the  cavernous  and 
lateral  sinuses  at  each  side.     It  receives  a  cerebral  vein  (inferior  lateral  cerebral) 
from  the  under  part  of  the  middle  lobe,  and  a  cerebellar  vein  (anterior  lateral 
cerebellar)  from  the  anterior  border  of  the  cerebellum. 


VEINS  OF  THE  UPPER  EXTREMITY. 

The  Veins  of  the  Upper  Extremity  are  divided  into  two  sets,  superficial  andj 
deep.  I 

The  Superficial  Veins  are  placed  immediately  beneath  the  integument  be- 
tween the  two  layer.s  of  superficial  fascia;  they  commence  in  the  hand  chiefly 
on  its  dorsal  aspect,  where  they  form  a  more  or  less  complete  arch.  MM 

The  Deep  Veins  accompany  the  arteries,  and  constitute  the  vense  comites  of  Mm 
those  vessels. 

Both  sets  of  vessels  arc  provided  with  valves,  which  are  more  numerous  in 
the  deep  than  in  the  superficial. 


OF    THE    UPPER    EXTREMITY 


545 


The  Superficial  Veins  of  the  Upper  Ex- 
tremity are  the 


Fig.  307.— The  Superficial  Veins  of  the 
Upper  Extremity. 


Anterior  ulnar. 
Posterior  ulnar. 
Basilic. 
Radial. 


Cephalic. 
Median. 
Median  basilic. 
Median  cephalic. 

The  Anterior  Ulnar  Vein  commences  on 
the  anterior  surface  of  the  wrist  and  ulnar 
side  of  the  hand,  and  ascends  along  the 
inner  side  of  the  forearm  to  the  bend  of  the 
elbow,  where  it  joins  with  the  posterior 
ulnar  vein  to  form  the  basilic.  It  com- 
municates with  branches  of  the  median 
vein  in  front,  and  with  the  posterior  ulnar 
behind. 

The  Posterior  Ulnar  Vein  commences  on 
the  posterior  surface  of  the  ulnar  side  of 
the  hand,  and  from  the  vein  of  the  little 
finger  (vena  salvatella),  situated  over  the 
fourth  metacarpal  space.  It  ascends  on 
the  posterior  surface  of  the  ulnar  side  of 
the  forearm,  and  just  below  the  elbow 
unites  with  the  anterior  ulnar  vein  to  form 
the  basilic. 

The  Basilic  is  a  vein  of  considerable 
size,  formed  by  the  coalescence  of  the 
anterior  and  posterior  ulnar  veins;  ascend- 
ing along  the  inner  side  of  the  elbow,  it 
receives  the  median  basilic  vein,  and  pass- 
ing upwards  along  the  inner  side  of  the 
arm,  pierces  the  deep  fascia,  and  ascends 
in  the  course  of  the  brachial  artery,  termi- 
nating either  in  one  of  the  venae  comites 
of  that  vessel,  or  in  the  axillary  vein. 

The  Radial  Vein  commences  from  the 
dorsal  surface  of  the  thumb,  index  finger, 
and  radial  side  of  the  hand,  by  branches 
communicating  with  the  vena  salvatella, 
and  forming  by  their  union  a  large  vessel, 
which  ascends  along  the  radial  side  of  the 
forearm,  and  receives  numerous  branches 
from  both  its  surfaces.  At  the  bend  of  the 
elbow  it  receives  the  median  cephalic, 
when  it  becomes  the  cephalic  vein. 

The  Cephalic  Vein  ascends  along  the 
outer  border  of  the  Biceps  muscle,  to  tlie 
upper  third  of  the  arm;  it  then  passes  in 
the  interval  between  the  Pectoralis  Major 
and  Deltoid  muscles,  accompanied  by  the 
descending  branch  of  the  thoracica  acro- 
mialis  artery,  and  terminates  in  the  axil- 
lary vein  just  below  the  clavicle.  This 
vein  is  occasionally  connected  with  the 

external  jugular  or  subclavian,  by  a  branch  which  passes  from  it  upwards  in 
front  of  the  clavicle. 

The  Median  Vein  collects  the  blood  from  the  superficial  structures  on  the 
35 


646  VEINS. 

palmar  surface  of  the  hand  and  middle  line  of  the  forearm,  communicating  with 
the  anterior  ulnar  and  radial  veins.  At  the  bend  of  the  elbow,  it  receives  a 
branch  of  communication  from  the  deep  veins,  accompanying  the  brachial 
artery,  and  divides  into  two  branches,  the  median  cephalic  and  median  basilic, 
which  diverge  from  each  other  as  they  ascend. 

The  Median  Cephalic,  usually  the  smaller  of  the  two,  passes  outwards  in  the 
groove  between  the  Supinator  Longus  and  Biceps  muscles,  and  joins  with  the 
cephalic  vein.  The  branches  of  the  external  cutaneous  nerve  pass  behind  this 
vessel. 

The  Median  Basilic  vein  passes  obliquely  inwards,  in  the  groove  between  the 
Biceps  and  Pronator  Radii  Teres,  and  joins  with  the  basilic.  This  vein  passes 
in  front  of  the  brachial  artery,  from  which  it  is  separated  by  a  fiVjrous  expan- 
sion, given  off'  from  the  tendon  of  the  Biceps  to  the  fascia  covering  the  flexor 
muscles  of  the  forearm.  Filaments  of  the  internal  cutaneous  nerve  pass  in  front 
as  well  as  behind  this  vessel.' 

The  Deep  Veins  of  the  Upper  Extremity  follow  the  course  of  the  arteries, 
forming  their  venae  comites.  They  are  generally  two  in  number,  one  lying  on 
each  side  of  the  corresponding  artery,  and  they  are  connected  at  intervals  by 
short  transverse  branches. 

There  are  two  digital  veins,  accompanying  each  artery  along  the  sines  of  the 
fingers;  these,  uniting  at  their  base,  pass  along  the  interosseous  spaces  in  the 
palm,  and  terminate  in  the  two  superficial  palmar  veins.  Branches  fromi  these 
vessels  on  the  radial  side  of  the  hand  accompany  the  superficialis  volae,  and  on 
the  ulnar  side  terminate  in  the  deep  ulnar  veins.  The  deep  ulnar  veins,  as  they, 
pass  in  front  of  the  wrist,  communicate  with  the  interosseous  and  superficial 
veins,  and  unite,  at  the  elbow,  with  the  deep  radial  veins,  to  form  the  ven» 
comites  of  the  brachial  artery. 

The  Interosseous  Veins  accompany  the  anterior  and  posterior  interosseous 
arteries.  The  anterior  interosseous  veins  commence  in  front  of  the  wrist, 
where  they  communicate  with  the  deep  radial  and  ulnar  veins;  at  the  upper 
part  of  the  forearm'they  receive  the  posterior  interosseous  veins,  and  terminate 
in  the  venae  comines  of  the  ulnar  artery. 

The  Deeii  Palmar  Veins  accompany  the  deep  palmar  arch,  being  formed  b 
branches  which  accompany  the  ramifications  of  that  vessel.     They  communi- 
cate with  the  superficial  palmar  veins  at  the  inner  side  of  the  hand;  and  on  th^^ 
outer  side  terminate  in  the  venae  comites  of  the  radial  artery.     At  the  wristJB 
they  receive  a  dorsal  and  a  palmar  branch  from  the  thumb,  and  unite  with  the 
deep  radial  veins.     Accompanying  the  radial  artery,  these  vessels  terminate  in 
the  venae  comites  of  the  brachial  artery. 

The  Brachial  Veins  are  placed  one  on  each  side  of  the  brachial  artery,  receiv- 
ing branches  corresponding  with  those  given  off  from  that  vessel ;  at  the  lowe; 
margin  of  the  axilla  they  unite  with  the  basilic  to  form  the  axillary  vein. 

The  deep  veins  have  numerous  anastomoses,  not  only  with  each  other,  but 
also  with  the  superficial  veins. 

The  Axillary  Vein  is  of  large  size  and  formed  by  the  continuation  upwardi 
of  the  basilic  vein.  It  commences  at  the  lower  part  of  the  axillary  space,  in 
creases  in  size  as  it  ascends,  by  receiving  branches  corresponding  with  those  o: 
the  axillary  artery,  and  terminates  immediately  beneath  the  clavicle  at  the  oute: 
margin  of  the  first  rib,  where  it  becomes  the  subclavian  vein.  This  vessel  is' 
covered  in  front  by  the  Pectoral  muscles  and  costo-coracoid  membrane,  and  lies 
on  the  thoracic  side  of  the  axillary  artery.  Opposite  the  Subscaj^ularis,  it  is 
joined  by  a  large  vein,  formed  by  tha  junction  of  the  venae  comites  of  the  bra 


I 


)^l 


in 

Lit 


'  Crnveilhier  says :  "  Numerous  varieties  are  observed  in  the  disposition  of  the  veins  of  the 
elbow;  sometimes  the  common  median  vein  is  wanting;  but  in  those  cases,  its  two  branches  of 
bifurcation  are  furnished  by  the  radial  vein,  and  ihe  cephalic  is  almost  always  in  a  rudimentary 
condition.  In  other  cases,  only  two  veins  are  found  at  the  bend  of  the  elbow,  the  radial  and 
ulnar,  which  are  continuous,  without  any  demarcation,  with  the  cephalic  and  basilic." 


<i 


SUBCLAVIAN  — INNOMINATE.  547 

chial;  and  near  its  termination  it  receives  tbe  ceplialic  vein.  This  vein  is  pro- 
vided with  a  pair  of  valves,  opposite  tbe  lower  border  of  the  Subscapularis 
muscle;  valves  are  also  found  at  the  termination  of  the  cephalic  and  sub- 
scapular veins. 

The  Subclavian  Vein,  the  continuation  of  the  axillary,  extends  from  the  outer 
margin  of  the  first  rib  to  the  inner  end  of  the  sterno-clavicular  articulation, 
where  it  unites  with  the  internal  jugular,  to  form  the  vena  innominata.  It  is 
in  relation,  in  front,  with  the  clavicle  and  Subclavius  muscle;  behind,  with  the 
subclavian  artery,  from  which  it  is  separated  internally  by  the  Scalenus  Anticus 
and  phrenic  nerve.  Below,  it  rests  in  a  depression  on  the  first  rib  and  upon 
the  pleura.     Above,  it  is  covered  by  the  cervical  fascia  and  integument. 

The  subclavian  vein  occasionally  rises  in  the  neck  to  a  level  with  the  third 
part  of  the  subclavian  artery,  and  in  two  instances  has  been  seen  passing  with 
this  vessel  behind  the  Scalenus  Anticus.  This  vessel  is  provided  with  valves 
about  an  inch  from  its  termination  in  the  innominate,  just  external  to  the 
entrance  of  the  external  jugular  vein. 

Branches.  It  receives  the  external  and  anterior  jugular  veins  and  a  small 
branch  from  the  cephalic,  outside  the  Scalenus ;  and  on  the  inner  side  of  that 
muscle,  the  internal  jugular  vein. 

The  Venx  Innominatse  (Fig.  308)  are  two  large  trunks,  placed  one  on  each 
side  of  the  root  of  the  neck,  and  formed  by  the  union  of  the-  internal  jugular 
and  subclavian  veins  of  the  corresponding  side. 

The  right  vena  innominata.  is  a  short  vessel,  about  an  inch  and  a  half  in  length, 
which  commences  at  the  inner  end  of  the  clavicle,  and,  passing  almost  vertically 
downwards,  joins  with  the  left  vena  innominata  just  below  the  cartilage  of  the 
first  rib,  to  form  the  superior  vena  cava.  It  lies  superficial  and  external  to  the 
arteria  innominata;  on  its  right  side  the  pleura  is  interposed  between  it  and  the 
apex  of  the  lung.  This  vein,  at  its  angle  of  junction  with  the  subclavian, 
receives  the  right  vertebral  vein,  and  right  lymphatic  duct;  and,  lower  down, 
the  right  internal  mammary,  right  inferior  thyroid,  and  right  superior  inter- 
costal veins. 

The  left  vena  innominata,  about  three  inches  in  length,  and  larger  than  the 
right,  passes  obliquely  from  left  to  right  across  the  upper  and  fore  part  of  the 
chest,  to  unite  with  its  fellow  of  the  opposite  side,  forming  the  superior  vena 
cava.  It  is  in  relation,  in  front,  with  the  sternal  end  of  the  clavicle,  the  sterno- 
clavicular articulation,  and  the  first  piece  of  the  sternum,  from  which  it  is  sepa- 
rated by  the  Sterno-hyoid  and  Sterno-thyroid  muscles,  the  thymus  gland  or  its 
remains,  and  some  loose  areolar  tissue.  Behind,  it  lies  across  the  roots  of  the 
three  large  arteries  arising  from  the  arch  of  the  aorta.  This  vessel  is  joined 
by  the  left  vertebral,  left  inferior  thyroid,  left  internal  mammary,  and  the  left 
superior  intercostal  veins,  and  occasionally  some  thymic  and  pericardiac  veins. 
There  are  no  valves  in  the  venae  innominatae. 

Peculiarities.  Sometimes  the  innominate  veins  open  separately  into  the  right  auricle ;  in 
such  cases  the  right  vein  takes  the  ordinary  course  of  the  superior  vena  cava,  but  the  left  vein,  after 
communicating  by  a  small  branch  with  the  right  one,  passes  in  front  of  the  root  of  the  left  lung, 
and  turning  to  the  back  of  the  heart,  receives  the  cardiac  veins,  and  terminates  in  the  back  of 
the  right  auricle.  This  occasional  condition  of  the  veins  in  the  adult,  is  a  regular  one  in  the 
foetus  at  an  early  period,  and  the  two  vessels  are  persistent  in  birds  and  some  mammalia.  'J'he 
subsequent  changes  which  take  place  in  these  vessels  are  the  following  :  'The  communicating 
branch  between  the  two  trunks  enlarges  and  forms  the  future  left  innominate  vein;  the  remain- 
ing part  of  the  left  trunk  is  obliterated  as  far  as  the  heart,  where  it  remains  pervious,  and  forms 
the  coronary  sinus ;  a  remnant  of  the  obliterated  vessel  is  seen  in  adult  life  as  a  fibrous  band 
passing  along  the  back  of  the  left  auricle  and  in  front  of  the  root  of  the  left  lung,  called  by  Mr. 
Marshall  the  vestigial  fold  of  the  pericardium. 

The  internal  mammary  veins,  two  in  number  to  each  artery,  follow  the  course 
of  that  vessel,  and  receive  branches  corresponding  with  those  derived  from 
it.  The  two  veins  unite  into  a  single  trunk,  which  terminates  in  the  innomi- 
nate vein. 


548 


VEINS. 


The  inferior  thyroid  veins,  two,  frequent!}'-  three  or  four  in  number,  arise 
in  the  venous  plexus,  on  the  thyroid  body,  communicating  with  the  mid- 
dle   and     superior     thyroid 
Fig.  308. — The  Venae  Cavae  and  Azygos  Veins, 
with  their  Formative  Branches. 


Anterior  Juguleil^ 


uptfiar  Tkyroii 


TdidJU  Tkwr»i<f- 


nl  Juoular 


Veins.  The  left  one  descends 
in  front  of  the  trachea,  be- 
hind the  Sterno-thyroid  mus- 
cles, communicating  with  its 
fellow  by  transverse  branches, 
and  terminates  in  the  left 
vena  innominata.  The  right 
one,  which  is  placed  a  little 
to  the  right  of  the  median 
line,  opens  into  the  right 
vena  innominata,  just  at  its 
junction  with  the  superior 
cava.  These  veins  receive 
tracheal  and  inferior  laryn- 
geal branches,  and  are  pro- 
vided with  valves  at  their 
termination  in  the  innominate 
veins. 

The    Superior    Intercostal 
Veins  return  the  blood  from  ^ 
the  upper  intercostal  spaces.  '■■ 

The  right  superior  inter- 
costal, much  smaller  than  the 
left,  closely  corresponds  with 
the  superior  intercostal  ar- 
tery, receiving  the  blood  from 
the  first,  or  first  and  second 
intercostal  spaces,  and  termi- 
nates in  the  right  vena  in- 
nominata. Sometimes  it 
passes  down,  and  opens  into 
the  vena  azygos  major. 

The  left  superior  intercostal 
is  always  larger  than  the 
right,  but  varies  in  size  in 
different  subjects,  being  small 
when  the  left  upper  azygos 
vein  is  large,  and  vice  versd. 
It  is  usually  formed  byj 
branches  from  the  two  oi 
three  upper  intercostal  spaces^ 
and,  passing  across  the  arcl 
of  the  aorta,  terminates  ii 
the  left  vena  innominata.' 
The  left  bronchial  vein  opens 
into  it. 

The  Superior  Vena  Cava 
receives  the  blood  which  is 
conveyed  to  the  heart  from 
the  whole  of  the  upper  half 
of  the  body.  It  is  a  short 
trunk,  varying  from  two 
inches  and   a    half  to  three 


d. 

1 


SPINAL.  549 

inches  in  length,  formed  by  the  junction  of  the  two  venae  innominatre.  It  com- 
mences immediately  below  the  cartilage  of  the  first  rib  on  the  right  side,  and, 
descending  vertically,  enters  the  pericardium  about  an  inch  and  a  half  above 
the  heart,  and  terminates  in  the  upper  part  of  the  right  auricle.  In  its  course, 
it  describes  a  slight  curve,  the  convexity  of  which  is  turned  to  the  right  side. 

Relations.  Infront^  with  the  thoracic  fascia,  which  separates  it  from  the  thy- 
mus gland,  and  from  the  sternum ;  behind^  with  the  root  of  the  right  lung.  On 
its  right  side,  with  the  phrenic  nerve  and  right  pleura ;  on  its  left  side,  with  the 
ascending  part  of  the  aorta.  The  portion  contained  within  the  pericardium  is 
covered  bythe  serous  layer  of  that  membrane,  in  its  anterior  three- fourths.  It 
receives  the  vena  azygos  major,  just  before  it  enters  the  pericardium,  and  seve- 
ral small  veins  from  the  pericardium  and  parts  in  the  mediastinum.  The  supe- 
rior vena  cava  has  no  valves. 

The  Azygos  Veins  connect  together  the  superior  and  inferior  venae  cavae,  sup- 
plying the  place  of  those  vessels  :in  the  part  of  the  chest  which  is  occupied  by 
the  heart. 

The  larger,  or  right  azygos  vein,  commences  opposite  the  first  or  second  lumbar 
vertebra,  by  a  branch  from  the  right  lumbar  veins;  sometimes  by  a  branch  from 
the  renal  vein,  or  from  the  inferior  vena  cava.  It  enters  the  thorax  through 
the  aortic  opening  in  the  Diaphragm,  and  passes  along  the  right  side  of  the  ver- 
tebral column  to  the  third  dorsal  vertebra,  where  it  arches  forward,  over  the 
root  of  the  right  lung,  and  terminates  in  the  superior  vena  cava,  just  before  that 
vessel  enters  the  pericardium.  Whilst  passing  through  the  aortic  opening  of 
the  Diaphragm,  it  lies  with  the  thoracic  duct  on  the  right  side  of  the  aorta;  and 
in  the  thorax,  it  lies  upon  the  intercostal  arteries,  on  the  right  side  of  the  aorta 
and  thoracic  duct,  covered  by  the  pleura. 

Branches.  It  receives  nine  or  ten  lower  intercostal  veins  of  the  right  side, 
the  vena  azygos  minor,  several  oesophageal,  mediastinal,  and  vertebral  veins ; 
near  its  termination,  the  right  bronchial  vein ;  and  is  occasionally  connected 
with  the  right  superior  intercostal  vein.  A  few  imperfect  valves  are  found  in 
this  vein  ;  but  its  branches  are  provided  with  complete  valves. 

The  intercostal  veins  on  the  left  side,  below  the  two  or  three  upper  intercos- 
tal spaces,  usually  form  two  trunks,  named  the  left  lower,  and  the  left  upper, 
azygos  veins. 

The  left  lower,  or  smaller  azygos  vein,  commences  in  the  lumbar  region,  by  a 
branch  from  one  of  the  lumbar  veins,  or  from  the  left  renal.  It  passes  into  the 
thorax,  through  the  left  crus  of  the  Diaphragm,  and  ascending  on  the  left  side 
of  the  spine,  as  high  as  the  sixth  or  seventh  dorsal  vertebra,  passes  across  the 
column,  behind  the  aorta  and  thoracic  duct,  to  terminate  in  the  right  azygos 
vein.  It  receives  the  four  or  five  lower  intercostal  veins  of  the  left  side,  and 
some  oesophageal  and  mediastinal  veins. 

The  left  upper  azygos  vein  varies  according  to  the  size  of  the  left  superior  in- 
tercostal. It  receives  veins  from  the  intercostal  spaces  between  the  left  superior 
intercostal  vein,  and  highest  branch  of  the  left  lower  azygos.  They  are  usually 
two  or  three  in  number,  and  join  to  form  a  trunk  which  ends  in  the  right  azy- 
gos vein,  or  in  the  left  lower  azygos.  When  this  vein  is  small,  or  altogether 
wanting,  the  left  superior  intercostal  vein  will  extend  as  low  as  the  fifth  or  sixth 
intercostal  space. 

The  bronchial  veins  return  the  blood  from  the  substance  of  the  lungs ;  that  of 
the  right  side  opens  into  the  vena  azygos  major,  near  its  termination ;  that  of 
the  left  side,  into  the  left  superior  intercostal  vein. 

The  Spinal  Veins. 

The  numerous  venous  plexuses  placed  upon  and  within  the  spine  may  be 
arranged  into  four  sets. 


550 


VEINS. 


1.  Those  placed  on  the  exterior  of  the  spinal  column  (the  dorsi-spinal  veins). 

2.  Those  situated  in  the  interior  of  the  spinal  canal,  between  the  vertebree 
and  the  theca  vertebralis  (meningo-rachidian  veins). 

3.  The  veins  of  the  bodies  of  the  vertebrse. 

4.  The  veins  of  the  spinal  cord  (medulli-spinal). 

1.  The  Dorsi-spinal  Veins  commence  by  small  branches,  which  receive  their' 
blood  from  the  integument  of  the  back  of  the  spine,  and  from  the  muscles  in 
the  vertebral  grooves.  They  form  a  complicated  network,  which  surrounds 
the  spinous  processes,  the  laminae,  and  the  transverse  and  articular  processes 
of  all  the  vertebrae.  At  the  bases  of  the  transverse  processes,  they  communi- 
cate, by  means  of  ascending  and  descending  branches,  with  the  veins  surround- 
ing the  contiguous  vertebrae,  and  they  join  with  the  veins  in  the  spinal  canal 
by  branches  which  perforate  the  ligamenta  subflava;  they  terminate  in  the 
intervals  between  the  arches  of  the  vertebrae,  by  joining  the  vertebral  veins  in 
the  neck,  the  intercostal  veins  in  the  thorax,  and  the  lumbar  and  sacral  veins 
in  the  loins  and  pelvis. 

2.  The  principal  veins  contained  in  the  spinal  canal  are  situated  between  the 
theca  vertebralis  and  the  vertebrae.  They  consist  of  two  longitudinal  plexuses, 
one  of  which  runs  along  the  posterior  surface  of  the  bodies  of  the  vertebras 
throughout  the  entire  length  of  the  spinal  canal  (anterior  longitudinal  spinal 
veins),  receiving  the  veins  belonging  to  the  bodies  of  the  vertebrae  (venas  basis 
vertebrarum).  The  other  plexus  (posterior  longitudinal  spinal  veins)  is  placed 
on  the  inner,  or  anterior  surface  of  the  laminae  of  the  vertebrae,  and  extends  also 
along  the  entire  length  of  the  spinal  canal. 

The  Anterior  Longitudinal  Spinal  Veins  consist  of  two  large,  tortuous,  venous 
canals,  which  extend  along  the  whole  length  of  the  vertebral  column,  from  the 
foramen  magnum  to  the  base  of  the  coccyx,  being  placed  one  on  each  side  of 
the  posterior  surface  of  the  bodies  of  the  vertebrae,  external  to  the  posterior 
common  ligament.  These  veins  communicate  together  opposite  each  vertebra, 
by  transverse  trunks,  which  pass  beneath  the  ligament,  and  receive  the  large 
venae  basis  vertebrarum,  from  the  interior  of  the  body  of  each  vertebra.     The 

Fig.  309. — Transverse  Section  of  a  Dorsal  Vertebra,  showing  the  Spinal  Veins. 


if' 


anterior  longitudinal  spinal  veins  are  least  developed  in  the  cervical  and  sacral 
regions.  They  are  not  of  uniform  size  throughout,  being  alternately  enlarged 
and  constricted.  At  the  intervertebral  foramina,  they  communicate  with  the 
dorsi-spinal  veins,  and  with  the  vertebral  veins  in  the  neck,  with  the  intercostal 


OF    THE    LOWER    EXTREMITY.  551 

veins  in  the  dorsal  region,  and  with  the  lumbar  and  sacral  veins  in  the  corres- 
ponding regions. 

The  Posterior  Longitudinal  Spinal  Veins,  smaller  than  the  anterior,  are  situ- 
ated one  on  either  side,  between  the  inner  surface  of  the  laminye  and  the  theca 
vertebralis.  They  communicate  (lil^e  the  anterior),  opposite  each  vertebra,  by 
transverse  trunks;  and  with  the  anterior  longitudinal  veins,  by  lateral  trans- 
verse brandies,  which  pass  from  behind  forwards.  These  veins,  at  the  inter- 
vertebral foramina,  join  with  the  dorsi-spinal  veins. 

3.  The  Veins  of  the  Bodies  of  the  Vertehrse  (venae  basis  vertebrarum)  emerge 
from  the  foramina  on  their  posterior  surface,  and  join  the  transverse  trunk 
connecting  the  anterior  longitudinal  spinal  veins.  They  are  contained  in  large 
tortuous  channels,  in  the  substance  of  the  bones,  similar  in  every  respect  to 
those  found  in  the  diploe  of  the  cranial  bones.  These  canals  lie  parallel  to  the 
upper  and  lower  surface  of  the  bones,  arise  from  the  entire  circumference  of  the 
vertebra,  communicate  with  veins  which  enter  through  the  foramina,  on  the 
anterior  surface  of  the  bodies,  and  converge  to  the  principal  canal,  which  is 
sometimes  double  towards  its  posterior  part.  They  become  greatly  developed 
in  advanced  age. 

4.  The  Veins  of  the  Spinal  Corr^  (medulli-spinal)  consist  of  a  minute  tortuous 
venous  plexus,  which  covers  the  entire  surface  of  the  cord,  being  situated 
between  the  pia  mater  and  arachnoid.  These  vessels  emerge  chiefly  from  tbe 
posterior  median  furrow,  and  are  largest  in  the  lumbar  region.  Near  the  base 
of  the  skull  they  unite,  and  form  two  or  three  small  trunks,  which  communi- 

Fig.  310. — Vertical  Section  of  two  Dorsal  Yertebrse,  showing  the  Spinal  Veins. 


cate  with  the  vertebral  veins,  and  then  terminate  in  the  inferior  cerebellar  veins, 
or  in  the  petrosal  sinuses.  Each  of  the  spinal  nerves  is  accompanied  by  a 
branch  as  far  as  the  intervertebral  foramina,  where  they  join  the  other  veins 
from  the  spinal  canal. 

There  are  no  valves  in  the  spinal  veins. 

VEINS  OF  THE  LOWER  EXTREMITY. 

The  Veins  of  the  Lower  Extremity  are  subdivided,  like  those  of  the  upper, 
into  two  sets,  superficial  and  deep;  the  superficial  veins  being  placed  beneath 
the  integument,  between  the  two  layers  of  superficial  fascia ;  the  deep  veins 
accompanying  the  arteries,  and  forming  the  vena^  comites  of  those  vessels. 
Both  sets  of  veins  are  provided  with  valves,  which  are  more  numerous  in  the 
deep  than  in  the  superficial  set.  These  valves  are  also  more  numerous  in  the 
lower  than  in  the  upper  limb. 

The  Superficial  Veins  of  the  lower  extremity  are  the  internal  or  long  saphenous, 
and  the  external  or  short  saphenous. 


552 


VEINS. 


Fig.  311.— The  Internal  or 
Long  Saphenous  Vein  and  its 
Branches. 


\ 


N: 


^i 


The  internal  saphenotis  vein  (Fig,  311)  commences 
from  a  minute  plexus,  which  covers  the  dorsum  and 
inner  side  of  the  foot ;  it  ascends  in  front  of  the  inner 
ankle,  and  along  the  inner  side  of  the  leg,  behind 
the  inner  margin  of  the  tibia,  accompanied  by  the 
internal  saphenous  nerve.  At  the  knee,  it  passes 
backwards  behind  the  inner  condyle  of  the  femur, 
~\4^5  J  ascends  along  the  inside  of  the  thigh,  and,  passing 

through  the  saphenous  opening  in  the  fascia  lata, 
tl\  terminates  in  the  femoral  vein  about  an  inch  and  a 

half  below  Poupart's  ligament.  This  vein  receives 
in  its  course  cutaneous  branches  from  the  leg  and 
thigh,  and  at  the  saphenous  opening,  the  superficial 
epigastric,  superficial  circumflex  iliac,  and  external 
pudic  veins.  The  veins  from  the  inner  and  back 
part  of  the  thigh  frequently  unite  to  form  a  large 
vessel,  which  enters  the  main  trunk  near  the  saphe- 
nous opening;  and  sometimes  those  on  the  outer 
side  of  the  thigh  join  to  form  a  large  branch ;  so  that 
occasionally  three  large  veins  are  seen  converging 
from  different  parts  of  the  thigh  towards  the  saphe- 
nous opening.  The  internal  saphenous  vein  com- 
municates in  the  foot  with  the  internal  plantar  vein; 
in  the  leg,  with  the  posterior  tibial  veins,  by  branches 
which  perforate  the  tibial  origin  of  the  Soleus  mus- 
cle, and  also  with  the  anterior  tibial  veins ;  at  the 
knee,  with  the  articular  veins;  in  the  thigh,  with 
the  femoral  vein  by  one  or  more  branches.  The 
valves  in  this  vein  vary  from  two  to  six  in  number; 
they  are  more  numerous  in  the  thigh  than  in  the  leg. 
The  external  or  short  saphenous  vein  (Fig.  812)  is 
formed  by  branches  which  collect  the  blood  from 
the  dorsum  and  outer  side  of  the  foot ;  it  ascends 
behind  the  outer  ankle,  and  along  the  outer  border 
of  the  tendo  Achillis,  across  which  it  passes  at  an 
acute  angle  to  reach  the  middle  line  of  the  posterior 
aspect  of  the  leg.  Passing  directly  upwards,  it  per 
forates  the  deep  fascia  in  the  lower  part  of  the  pop- 
liteal space,  and  terminates  in  the  popliteal  vein, 
between  the  heads  of  the  Gastrocnemius  muscle.  !&«■ 
is  accompanied  by  the  external  saphenous  nerve.  Iwl 
receives  numerous  large  branches  from  the  back  part 
of  the  leg,  and  communicates  with  the  deep  veins  on 
the  dorsum  of  the  foot,  and  behind  the  outer  malleo- 
lus. This  vein  has  only  two  valves,  one  of  which  ia 
al  ways  found  near  its  termination  in  the  popliteal  vein^w 

The  Deep  Veins   of  the  lower  extremity  accom- 
pany the  arteries  and  their  branches,  and  are  called 
^*tl  the  vence  comites  of  those  vessels. 

The  external  and  internal  plantar  veins  unite  t( 
form  the  posterior  tibial.     They  accompany  the  pos-^ 
terior  tibial  artery,  and  are  joined  by  the  peroneal 
veins. 
The  anterior  tibial  veins  are  formed  by  a  continuation  upwards  of  the  venaa' 
comites  of  the  dorsalis  pedis  artery.    They  perforate  the  interosseous  membrane 
at  the  upper  part  of  the  leg,  and  form,  by  their  junction  with  the  posterior 
tibial,  the  popliteal  vein. 


5d 


POPLITEAL— FEMORAL  — ILIAC. 


558 


Fig.  312.— External  or 
Short  Saphenous  Vein. 


CV^: 


I 


m 


The  valves  in  the  deep  veins  are  very  numerous. 

The  Popliteal  Vein  is  formed  by  the  junction  of  the  venae  comites  of  the  ante- 
rior and  posterior  tibial  vessels ;  it  ascends  through  the  popliteal  space  to  the 
tendinous  aperture  in  the  Adductor  Magnus,  where  it 
becomes  the  femoral  vein.  In  the  lower  part  of  its 
course,  it  is  placed  internal  to  the  artery ;  between  the 
heads  of  the  Gastrocnemius,  it  is  superficial  to  that 
vessel ;  but  above  the  knee-joint,  it  is  close  to  its  outer 
side.  It  receives  the  sural  veins  from  the  Gastroc- 
nemius muscle,  the  articular  veins,  and  the  external 
saphenous.  The  valves  in  this  vein  are  usually  four 
in  number. 

The  Femoral  Vein  accompanies  the  femoral  artery 
through  the  upper  two-thirds  of  the  thigh.  In  the 
lower  part  of  its  course,  it  lies  external  to  the  artery ; 
higher  up,  it  is  behind  it ;  and  beneath  Poupart's  liga- 
ment, it  lies  to  its  inner  side,  and  on  the  same  plane. 
It  receives  numerous  muscular  branches ;  the  pro- 
funda femoris  joins  it  about  an  inch  and  a  half  below 
Poupart's  ligament,  and  near  its  termination  the  in- 
ternal saphenous  vein.  The  valves  in  this  vein  are 
four  or  five  in  number. 

The  External  Iliac  Vein  commences  at  the  termi- 
nation of  the  femoral,  beneath  the  crural  arch,  and 
passing  upwards  along  the  brim  of  the  pelvis,  termi- 
nates opposite  the  sacro-iliac  symphysis,  by  uniting 
with  the  internal  iliac  to  form  the  common  iliac  vein. 
On  the  right  side,  it  lies  at  first  along  the  inner  side 
of  the  external  iliac  artery;  but  as  it  passes  upwards, 
gradually  inclines  behind  it.  On  the  left  side,  it  lies 
altogether  on  the  inner  side  of  the  artery.  It  receives, 
immediately  above  Poupart's  ligament,  the  epigastric 
and  circumflex  iliac  veins.     It  has  no  valves. 

The  Internal  Iliac  Vein  is  formed  by  the  venae  comites 
of  the  branches  of  the  internal  iliac  artery,  the  umbili- 
cal arteries  excepted.  It  receives  the  blood  from  the 
exterior  of  the  pelvis  by  the  gluteal,  sciatic,  internal 
pudic,  and  obturator  veins  ;  and  from  the  organs  in 
the  cavity  of  the  pelvis  by  the  hsemorrhoidal  and 
vesico-prostatic  plexuses  in  the  male,  and  the  uterine 
and  vaginal  plexuses  in  the  female.  The  vessels  forming  these  plexuses  are 
remarkable  for  their  large  size,  their  frequent  anastomoses,  and  the  number  of 
valves  which  they  contain.  The  internal  iliac  vein  lies  at  first  on  the  inner 
side  and  then  behind  the  internal  iliac  artery,  and  terminates  opposite  the  sacro- 
iliac articulation,  by  uniting  with  the  external  iliac,  to  form  the  common  iliac 
vein.     This  vessel  has  no  valves. 

The  hsemorrhoidal  plexus  surrounds  the  lower  end  of  the  rectum,  being  formed 
by  the  superior  haemorrhoidal  veins  (branches  of  the  inferior  mesenteric), and 
the  middle  and  inferior  hasmorrhoidal,  which  terminate  .in  the  internal  iliac. 
The  portal  and  general  venous  systems  have  a  free  communication  by  means  of 
the  branches  composing  this  plexus. 

The  vesico-prostatic  plexus  surrounds  the  neck  and  base  of  the  bladder  and 
prostate  gland.  It  communicates  with  the  ha3morrhoidal  plexus  behind,  and 
receives  the  dorsal  vein  of  the  penis,  which  enters  the  pelvis  beneath  the  sub- 
pubic ligament.  This  plexus  is  supported  upon  the  sides  of  the  bladder  by  a 
reflection  of  the  pelvic  fascia.  The  veins  composing  it  are  very  liable  to  be- 
come varico.se,  and  often  contain  hard  earthy  concretions,  called  phlebolithes. 


554  VEINS. 

The  dorsal  vein  of  the  penis  is  a  vessel  of  large  size,  which  returns  the  blood 
from  the  body  of  that  organ.  At  first  it  consists  of  tAvo  branches,  which  are 
contained  in  the  groove  on  the  dorsum  of  the  penis,  and  it  receives  veins  from 
the  glans,  the  corpus  spongiosum,  and  numerous  superficial  veins  ;  these  unite 
near  the  root  of  the  penis  into  a  single  trunk,  which  pierces  the  triangular 
ligament  beneath  the  pubic  arch,  and  divides  into  two  branches,  which  enter 
Ihe  ])rostatic  plexus. 

The  vaginal  plexus  surrounds  the  mucous  membrane,  being  especially  de- 
veloped at  the  orifice  of  the  vagina ;  it  communicates  with  the  vesical  plexus 
in  front,  and  with  the  haemorrhoidal  plexus  behind. 

The  uterine  plexus  is  situated  along  the  sides  and  superior  angles  of  the  uterus, 
receiving  large  venous  canals  (the  uterine  sinuses)  from  its  substance.  The 
veins  composing  this  plexus  anastomose  frequently  with  each  other  and  with 
the  ovarian  veins.     They  are  not  tortuous  like  the  arteries. 

The  Common  Iliac  Veins  are  formed  by  the  union  of  the  external  and  internal 
iliac  veins  in  front  of  the  sacro- vertebral  articulation;  passing  obliquely  up- 
wards towards  the  right  side,  they  terminate  upon  the  intervertebral  substance 
between  the  fourth  and  fifth  lumbar  vertebrae,  where  the  veins  of  the  two  sides 
unite  at  an  acute  angle  to  form  the  inferior  vena  cava.  The  right  common  iliac 
is  shorter  than  the  left,  nearly  vertical  in  its  direction,  and  ascends  behind  and 
then  to  the  outer  side  of  its  corresponding  artery.  The  left  common  iliac,  longer 
and  more  oblique  in  its  course,  is  at  first  situated  on  the  inner  side  of  the  cor- 
responding artery,  and  then  behind  the  right  common  iliac.  Each  common  iliac 
receives  the  ilio-lumbar,  and  sometimes  the  lateral  sacral  veins.  The  left  re- 
ceives, in  addition,  the  middle  sacral  vein.     No  valves  are  found  in  these  veins. 

The  middle  sacral  vein  accompanies  its  corresponding  artery  along  the  front 
of  the  sacrum,  and  terminates  in  the  left  common  iliac  vein  ;  occasionally  in 
the  commencement  of  the  inferior  vena  cava. 

Peculiarttte.t.  The  left  common  iliac  vein,  instead  of  joining  with  the  right  in  its  usual  posi- 
tion, occasionally  ascends  on  the  left  side  of  the  aorta  as  high  as  the  kidney,  where,  after  receiving 
the  left  renal  vein, it  crosses  over  the  aorta,  and  then  joins  with  the  right  vein  to  form  the  vena 
cava.  Jn  these  cases,  the  two  common  iliacs  are  connected  by  a  small  communicating  branch 
at  the  spot  where  they  are  usually  united. 

The  Inferior  Vena  Cava  returns  to  the  heart  the  blood  from  all  the  parts  below 
the  Diaphragm.  It  is  formed  by  the  junction  of  the  two  common  iliac  veins  on 
the  right  side  of  the  intervertebral  substance  between  the  fourth  and  fifth  lumbar 
vertebrae.  It  passes  upwards  along  the  front  of  the  spine,  on  the  right  side  of 
the  aorta,  and  having  reached  the  under  surface  of  the  liver,  is  contained  in  a 
groove  in  its  posterior  border.  It  then  perforates  the  tendinous  centre  of  the 
Diaphragm,  enters  the  pericardium,  where  it  is  covered  by  its  serous  layer,  and 
terminates  in  the  lower  and  back  part  of  the  right  auricle.  At  its  termination 
in  the  auricle,  it  is  provided  with  a  valve,  the  Eustachian,  which  is  of  large  size 
during  foetal  life. 

Relations.  In  front,  from  below  upwards,  with  the  mesentery,  transverse 
portion  of  the  duodenum,  the  pancreas,  portal  vein,  and  the  posterior  border  of 
the  liver,  which  partly  and  occasionally  completely  surrounds  it ;  behind,  with 
the  vertebral  column,  the  right  cms  of  the  Diaphragm,  the  right  renal  and 
lumbar  arteries;  on  the  left  side^  with  the  aorta.  It  receives  in  its  course  the 
following  branches: — 

Lumbar.  Suprarenal. 

Right  spermatic.  Phrenic. 

Renal.  Hepatic. 

Pecnliarflies.  Jn  Pnsitiny).  This  vessel  i->  sometimes  placed  on  the  left  side  of  the  aorta,  as 
high  as  the  left  renal  vein,  after  receiving  wliich.  it  crosses  over  to  its  usual  position  on  the 
right  side;  or  it  may  be  placed  altogether  on  the  left  side  of  the  aorta,  as  far  upwards  ns  is 
termination  in  the  heart :  in  such  cases,  the  abdominal  and  thoracic  viscera,  together  with  the 
great  vessels,  are  all  t  ransposed. 


INFERIOR    YEXA    CAVA.  •     555 

Point  of  Termination.  Occasionally  the  inferior  vena  cava  joins  the  right  azygos  vein,  which 
is  then  of  large  size.  In  such  cases,  the  superior  cava  receives  the  whole  of  the  blood  from  the 
body  before  transmitting  it  to  the  right  auricle,  except  the  blood  from  the  hepatic  veins,  which 
terminate  directly  in  the  right  auricle. 

The  lumbar  veins,  three  or  four  in  number  on  each  side,  collect  the  blood  by 
dorsal  branches  from  the  muscles  and  integument  of  the  loins,  and  by  abdomi- 
nal branches  from  the  walls  of  the  abdomen,  where  they  communicate  with  the 
epigastric  veins.  At  the  spine,  they  receive  branches  from  the  spinal  plexuses, 
and  then  pass  forwards  round  the  sides  of  the  bodies  of  the  vertebras  beneath 
the  Psoas  Magnus,  and  terminate  at  the  back  part  of  the  inferior  cava.  The 
left  lumbar  veins  are  longer  than  the  right,  and  pass  behind  the  aorta.  The 
lumbar  veins  communicate  with  each  other  by  branches  which  pass  in  front 
of  the  transverse  processes.  Occasionally  two  or  more  of  these  veins  unite  to 
form  a  single  trunk,  the  ascending  lumbar,  which  serves  to  connect  the  com- 
mon iliac,  ilio-lumbar,  lumbar,  and  azygos  veins  of  the  corresponding  side 
of  the  body. 

The  spermatic  veins  emerge  from  the  back  of  the  testis,  and  receive  branches 
from  the  epididymis;  they  form  a  branched  and  convoluted  plexus,  called  the 
spermatic  plexus  (plexus  pampiniformis),  below  the  abdominal  ring:  the  vessels 
composing  this  plexus  are  very  numerous,  and  ascend  along  the  cord  in  front 
of  the  vas  deferens;  having  entered  the  abdomen,  they  coalesce  to  form  two 
branches,  which  ascend  on  the  Psoas  muscle,  behind  the  peritoneum,  lying  one 
on  each  side  of  the  spermatic  artery,  and  unite  to  form  a  single  vessel,  which 
opens  on  the  right  side  in  the  inferior  vena  cava,  at  an  acute  angle,  on  the  left 
side  in  the  left  renal  vein,  at  a  right  angle.  The  spermatic  veins  are  provided 
with  valves.  The  left  spermatic  vein  passes  behind  the  sigmoid  flexure  of  the 
colon,  a  part  of  the  intestine  in  which  fecal  accumulation  is  common;  this  cir- 
cumstance, as  well  as  the  indirect  communication  of  the  vessel  with  the  inferior 
vena  cava,  may  serve  to  explain  the  more  frequent  occurrence  of  varicocele  on 
the  left  side. 

The  ovarian  veins  are  analogous  to  the  spermatic  in  the  male;  they  form  a 
plexus  near  the  ovary,  and  in  the  broad  ligament  and  Fallopian  tube,  commu- 
nicating with  the  uterine  plexus.  They  terminate  as  in  the  male.  Valves  are 
occasionally  found  in  these  veins.  These  vessels,  like  the  uterine  veins,  become 
much  enlarged  during  pregnancy. 

The  renal  veins  are  of  large  size,  and  placed  in  front  of  the  renal  arteries.* 
The  left  is  longer  than  the  right,  and  passes  in  front  of  the  aorta,  just  below 
the  origin  of  the  superior  mesenteric  artery.  It  receives  the  left  spermatic  and 
left  inferior  phrenic  veins.  It  usually  opens  into  the  vena  cava,  a  little  higher 
than  the  right. 

The  suprarenal  vein  terminates,  on  the  right  side,  in  the  vena  cava;  on  the 
left  side,  in  the  left  renal  or  phrenic  vein. 

The  phrenic  veins  follow  the  course  of  the  phrenic  arteries.  The  two  superior, 
of  small  size,  accompany  the  phrenic  nerve  and  comes  nervi  phrenici  artery; 
the  right  terminating  opposite  the  junction  of  the  two  venae  innominate,  the 
left  in  the  left  superior  intercostal  or  left  internal  mammary.  The  two  inferior 
phrenic  veins  follow  the  course  of  the  phrenic  arteries,  and  terminate,  the  right 
in  the  inferior  vena  cava,  the  left  in  the  left  renal  vein. 

The  hepatic  veins  commence  in  the  substance  of  the  liver,  in  the  capillary 
terminations  of  the  vena  portaa:  these  branches,  gradually  uniting,  form  three 
large  veins,  which  converge  towards  the  posterior  border  of  the  liver,  and  open 
into  the  inferior  vena  cava,  whilst  that  vessel  is  situated  in  the  groove  at  the 
back  part  of  this  organ.     Of  these  three  veins,  one  from  the  right,  and  another 

'  The  student  may  observe  that  all  veins  above  the  Diaphragm,  which  do  not  lie  on  the  same 
plane  as  the  arteries  which  they  accompany,  lie  in  front  of  them;  and  that  all  veins  below  ihe 
biaphragm,  which  do  not  lie  on  the  same  phine  as  the  arteries  which  they  accompany,  lie  behind 
them,  except  the  renal  and  profunda  femoris  vein. 


656  VEINS. 

from  the  left  lobe,  open  obliquely  into  the  vena  cava;  that  from  the  middle 
of  the  organ  and  lobulus  Spigelii  having  a  straight  course.  The  hepatic  veins 
run  singly,  and  are  in  direct  contact  with  the  hepatic  tissue.  They  are  destitute 
of  valves. 

Portal  System  of  Veins. 

The  Portal  Venous  System  is  composed  of  four  large  veins,  which  collect  the 
venous  blood  from  the  viscera  of  digestion.  The  trunk  formed  by  their  union 
(vena  portae)  enters  the  liver  and  ramifies  throughout  its  substance;  and  its 
branches  again  emerging  from  that  organ  as  the  hepatic  veins,  terminate  in  the 
inferior  vena  cava.  The  branches  of  this  vein  are  in  all  cases  single,  and 
destitute  of  valves. 

The  veins  forming  the  portal  system  are,  the 

Inferior  mesenteric.  Splenic. 

Superior  mesenteric.  Gastric. 

The  inferior  mesenteric  vein  returns  the  blood  from  the  rectum,  sigmoid 
flexure,  and  descending  colon,  corresponding  with  the  ramifications  of  the 
branches  of  the  inferior  mesenteric  artery.  Ascending  beneath  the  peritoneum 
in  the  lumbar  region,  it  passes  behind  the  transverse  portion  of  the  duodenum 
and  pancreas,  and  terminates  in  the  splenic  vein.  Its  hsemorrhoidal  branches 
inosculate  with  those  of  the  internal  iliac,  and  thus  establish  a  communication 
between  the  portal  and  the  general  venous  system.^ 

The  superior  mesenteric  vein  returns  the  blood  from  the  small  intestines,  and 
from  the  caecum  and  ascending  and  transverse  portions  of  the  colon,  correspond- 
ing with  the  distribution  of  the  branches  of  the  superior  mesenteric  artery. 
The  large  trunk  formed  by  the  union  of  these  branches  ascends  along  the  right 
side  and  in  front  of  the  corresponding  artery,  passes  in  front  of  the  transverse 
portion  of  the  duodenum,  and  unites  behind  the  upper  border  of  the  pancreas 
with  the  splenic  vein,  to  form  the  vena  portae. 

The  splenic  vein  commences  by  five  or  six  large  branches,  which  return  the 
blood  from  the  substance  of  the  spleen.  These  uniting  form  a  single  vessel, 
which  passes  from  left  to  right  behind  the  upper  border  of  the  pancreas,  and 
terminates  at  its  greater  end  by  uniting  at  a  right  angle  with  the  superior 
mesenteric  to  form  the  vena  portae.  The  splenic  vein  is  of  large  size,  and  not 
tortuous  like  the  artery.  It  receives  the  vasa  brevia  from  the  left  extremity 
of  the  stomach,  the  left  gastro-epiploic  vein,  pancreatic  branches  from  the  pan- 
creas, the  pancreatico-duodenal  vein,  and  the  inferior  mesenteric  vein. 

The  gastric  is  a  vein  of  small  size,  which  accompanies  the  gastric  artery  from 
left  to  right  along  the  lesser  curvature  of  the  stomach,  and  terminates  in  the 
vena  portae. 

The  Portal  Vein  is  formed  by  the  junction  of  the  superior  mesenteric  and 
splenic  veins,  their  union  taking  place  in  front  of  the  vena  cava,  and  behind 
the  upper  border  of  the  great  end  of  the  pancreas.  Passing  upwards  through 
the  right  border  of  the  lesser  omentum  to  the  under  surface  of  the  liver,  it 
enters  the  transverse  fissure,  where  it  is  somewhat  enlarged,  forming  the  sinus 
of  the  portal  vein,  and  divides  into  two  branches,  which  accompany  the  rami- 
fications of  the  hepatic  artery  and  hepatic  duct  throughout  the  substance  of  the 
liver.  Of  these  two  branches  the  right  is  the  larger  but  the  shorter  of  the  two. 
The  portal  vein  is  about  four  inches  in  length,  and,  whilst  contained  in  the 
lesser  omentum,  lies  behind  and  between  the  hepatic  duct  and  artery,  the  former 
being  to  the  right,  the  latter  to  the  left.     These  structures  are  accompanied  by 

'  Besides  this  anastomosis  between  the  portal  vein  and  the  branches  of  the  vena  cava,  other 
anastomoses  between  the  portal  and  systemic  veins  are  formed  bv  the  oommnnication  between 
the  left  renal  vein  and  the  veins  of  tlie  intestines,  especially  of  tlie  colon  and  duodenum,  and 
between  superficial  branches  of  the  portal  veins  of  the  liver  and  the  phrenic  veins,  as  pointed 
out  by  Mr.  Kiernan  (Todd  and  Bowman). 


CARDIAC. 


557 


filaments  of  the  hepatic  plexus  of  nerves,  and  numerous  lymphatics,  surrounded 
by  a  quantity  of  loose  areolar  tissue  (capsule  of  Glisson),  and  placed  between 

Fig.  313. — Portal  Vein  and  its  Branches. 


the  layers  of  the  lesser  omentum.  The  vena  portoe  receives  the  gastric  and 
cystic  veins;  the  latter  vein  sometimes  terminates  in  the  right  branch  of  the 
vena  portae.  Within  the  liver  the  portal  vein  receives  the  blood  from  the 
branches  of  the  hepatic  artery. 

Cardiac  Yeins. 
The  veins  which  return  the  blood  from  the  substance  of  the  heart  are,  the 


Great  cardiac  vein. 
Posterior  cardiac  vein. 


Anterior  cardiac  veins. 
Yense  Thebesii. 


The  great  cardiac  vein  is  a  vessel  of  considerable  size,  which  commences  at 
the  apex  of  the  heart,  and  ascends  along  the  anterior  interventricular  groove  to 
the  base  of  the  ventricles.  It  then  curves  to  the  left  side,  around  the  auriculo- 
ventricular  groove,  between  the  left  auricle  and  ventricle,  to  the  back  part  of 


558  VEINS. 

the  heart,  and  opens  into  the  coronary  sinus,  its  aperture  being  guarded  hy  two 
valves.  It  receives  the  posterior  cardiac  vein,  and  the  left  cardiac  veins  from 
the  left  auricle  and  ventricle,  one  of  which,  ascending  along  the  left  margin  of 
the  ventricle,  is  of  large  size.  The  branches  joining  it  are  provided  with 
valves. 

The  2>osterior  cardiac  vein  commences,  by  small  branches,  at  the  apex  of  the 
heart,  communicating  with  those  of  the  preceding.  It  ascends  along  the  pos- 
terior interventricular  groove  to  the  base  of  the  heart,  and  terminates  in  the 
coronary  sinus,  its  orifice  being  guarded  by  a  valve.  It  receives  the  veins 
from  the  posterior  surface  of  both  ventricles. 

The  anterior  cardiac  veins  are  three  or  four  small  branches,  which  collect  the 
blood  from  the  anterior  surface  of  the  right  ventricle.  One  of  these  (the  vein 
of  Galen),  larger  than  the  rest,  runs  along  the  right  border  of  the  heart.  They 
open  separately  into  the  lower  part  of  the  right  auricle. 

The  venoe  Thehesii  are  numerous  minute  veins,  which  return  the  blood 
directly  from  the  muscular  substance,  without  entering  the  venous  current. 
They  open,  by  minute  orifices  {foramina  Thehesii),  on  the  inner  surface  of  the 
right  auricle. 

The  Coronary  Sinus  is  that  portion  of  the  great  cardiac  vein  which  is 
situated  in  the  posterior  part  of  the  left  auriculo-ventricular  groove.  It  is 
about  an  inch  in  length,  presents  a  considerable  dilatation,  and  is  covered  by 
the  muscular. fibres  of  the  left  auricle.  It  receives  the  great  cardiac  vein,  the 
posterior  cardiac  vein,  and  an  oblique  vein  from  the  back  part  of  the  left 
auricle,  the  remnant  of  the  obliterated  left  innominate  trunk  of  the  foetus, 
described  by  Mr.  Marshall.  The  coronary  sinus  terminates  in  the  right  auricle, 
between  the  inferior  vena  cava  and  the  auriculo-ventricular  aperture,  its  orifice 
being  guarded  by  a  semilunar  fold  of  the  lining  membrane  of  the  heart,  the 
coronary  valve.  All  the  branches  joining  this  vessel,  excepting  the  oblique 
vein  above  mentioned,  are  provided  with  valves. 

The  Pulmonaky  Veins. 

The  Pulmonary  Veins  return  the  arterial  blood  from  the  lungs  to  the  left 
auricle  of  the  heart.  They  are  four  in  number,  two  for  each  lung.  The 
pulmonary  differ  from  other  veins  in  several  respects.  1.  They  carry  arterial,  __ 
instead  of  venous  blood.  2.  They  are  destitute  of  valves.  3.  They  are  only  H 
slightly  larger  than  the  arteries  they  accompany.  4.  They  accompany  those 
vessels  singly.  They  commence  in  a  capillary  network,  upon  the  parietes  of 
the  bronchial  cells,  where  they  are  continuous  with  the  ramifications  of  the 
pulmonary  artery,  and,  uniting  together,  form  a  single  trunk  for  each  lobule. 
These  branches,  uniting  successively,  form  a  single  trunk  for  each  lobe,  three 
for  the  right,  and  two  for  the  left  lung.  The  vein  from  the  middle  lobe  of  the 
right  lung  unites  with  that  from  the  upper  lobe,  in  most  cases,  forming  two 
trunks  on  each  side,  which  open  separately  into  the  left  auricle.  Occasionally 
they  remain  separate;  there  are  then  three  veins  on  the  right  side.  Not 
unfrequently,  the  two  left  pulmonary  veins  terminate  by  a  common  opening. 

Within  the  lun;/,  the  branches  of  the  pulmonary  artery  are  in  front,  the  veins 
behind,  and  the  bronchi  between  the  two. 

At  the  root  of  the  lunrj,  the  veins  are  in  front,  the  artery  in  the  middle,  and  the 
bronchus  behind. 

Within  the  pericardium,  their  anterior  surface  is  invested  by  the  serous  layer 
of  this  membrane.  The  right  pulmonary  veins  pass  beliind  the  right  auricle 
and  ascending  aorta;  the  left  pass  in  front  of  the  thoracic  aorta,  with  the  left 
pulmonary  artery. 


Of  the  Lymphatics. 


The  Lymphatics  have  derived  their  name  from  the  appearance  of  the  fluid 
contained  in  their  interior  {lympha^  water).  They  are  also  called  absorbents, 
from  the  property  they  possess  of  absorbing  certain  materials  from  the  tissues, 
and  conveying  it  into  the  circulation. 

The  lymphatic  system  includes  not  only  the  lymphatic  vessels  and  the  glands 
through  which  they  pass,  but  also  the  lacteal,  or  chyliferous  vessels.  The  lacteals 
are  the  lymphatic  vessels  of  the  small  intestine,  and  differ  in  no  respect  from 
the  lymphatics  generally,  excepting  that  they  contain  a  milk-white  fluid,  the 
chyle,  during  the  process  of  digestion,  and  convey  it  into  the  blood  through 
the  thoracic  duct. 

The  lymphatics  are  exceedingly  delicate  vessels,  the  coats  of  which  are  so 
transparent,  that  the  fluid  they  contain  is  readily  seen  through  them.  They 
retain  a  nearly  uniform  size,  being  interrupted  at  intervals  by  constrictions, 
which  give  them  a  knotted  or  beaded  appearance.  These  constrictions  are  due 
to  the  presence  of  valves  in  their  interior.  Lymphatics  have  been  found  in 
nearly  every  texture  and  organ  of  the  body,  with  the  exception  of  the  sub- 
stance  of  the  brain  and  spinal  cord,  the  eyeball,  cartilage,  tendon,  the  mem- 
branes of  the  ovum,  the  placenta,  and  umbilical  cord,  the  nails,  cuticle,  and 
hair.     Their  existence  in  the  substance  of  bone  is  doubtful. 

The  lymphatics  are  arranged  into  a  superficial  and  deep  set.  The  superficial 
lymphatics,  on  the  surface  of  the  body,  are  placed  immediately  beneath  the  in- 
tegument, accompanying  the  superficial  veins  ;  they  join  the  deep  lymphatics 
in  certain  situations  by  perforating  the  deep  fascia.  In  the  interior  of  the  body, 
they  lie  in  the  submucous  areolar  tissue,  throughout  the  whole  length  of  the 
gastro-pulmonary  and  genito- urinary  tracts;  and  in  the  subserous  areolar  tissue 
in  the  cranial,  thoracic,  and  abdominal  cavities.  These  vessels  probably  arise 
in  the  form  of  a  dense  plexiform  network  interspersed  among  the  proper  elements 
and  bloodvessels  of  the  several  tissues ;  the  vessels  composing  which,  as  well 
as  the  meshes  between  them,  are  much  larger  than  those  of  the  capillary  plexus. 
From  these  networks  small  vessels  emerge,  which  pass,  either  to  a  neighboring 
gland,  or  to  join  some  larger  lymphatic  trunk.  The  deep  lymphatics,  fewer  in 
number,  and  larger  than  the  superficial,  accompany  the  deep  bloodvessels. 
Their  mode  of  origin  is  not  known ;  it  is,  however,  probably,  similar  to  that 
of  the  superficial  vessels.  The  lymphatics  of  any  part  or  organ  exceed,  in 
number,  the  veins ;  but  in  size  they  are  much  smaller.  Their  anastomoses 
also,  especially  those  of  the  large  trunks,  are  more  frequent,  and  are  effected 
by  vessels  equal  in  diameter  to  those  which  they  connect,  the  continuous  trunks 
retaining  the  same  diameter. 

The  lymphatic  or  absorbent  glands,  named  also  conglobate  glands,  are  small 
solid  glandular  bodies,  situated  in  the  course  of  the  lymphatic  and  lacteal  ves- 
sels. They  are  found  in  the  neck  and  on  the  external  parts  of  the  head  ;  in  the 
upper  extremity,  in  the  axilla  and  front  of  the  elbow ;  in  the  lower  extremity, 
in  the  groin  and  popliteal  space.  In  the  abdomen,  they  are  found  in  large 
numbers  in  the  mesentery,  and  along  the  side  of  the  aorta,  vena  cava,  and  iliac 
vessels  ;  and  in  the  thorax,  in  the  anterior  and  posterior  mediastina.  They  are 
somewhat  flattened,  and  of  a  round  or  oval  form.  In  size,  they  vary  from  a 
hemp-seed  to  an  almond,  and  their  color,  on  section,  is  of  a  pinkish-gray  tint, 
excepting  the  bronchial  glands,  which  in  the  adult  are  mottled  with  black. 
Each  gland  has  a  layer,  or  capsule,  of  cellular  tissue  investing  it,  from  which 

55tJ 


5G0 


LYMPHATICS. 


prolongations  dip  into  its  substance  forming  partitions.  The  lymphatic  and 
lacteal  vessels  pass  through  these  bodies  in  their  passage  to  the  thoracic  and 
lymphatic  ducts.  A  lymphatic  or  lacteal  vessel,  previous  to  entering  a  gland 
divides  into  several  small  branches,  which  are  named  afferent  vessels.  As  they 
enter,  their  external  coat  becomes  continuous  with  the  capsule  of  the  gland, 
and  the  vessels,  much  thinned,  and  consisting  only  of  their  internal  coat  and 
epithelium,  pass  into  the  gland,  where  they  subdivide  and  pursue  a  tortuous 

course ;   and  they  finally  anasto- 
Fig.  314.— The  Thoracic  and  Right  Lymphatic  Duct,     rnose,  so  as  to  form  a  plexus.    The 

vessels  composing  this  plexus 
unite  to  form  two  or  more  efferent 
vessels,  which,  on  emerging  from 
the  gland,  are  again  invested  with 
their  external  coat.  Further  de- 
tails on  the  minute  anatomy  of 
the  lymphatic  vessels  and  glands 
will  be  found  in  the  Introduction. 


Thoracic  Duct. 

The  Thoracic  Duct  (Fig.  314) 
conveys  the  great  mass  of  the 
lymph  and  chyle  into  the  blood. 
It  is  the  common  trunk  of  all  the 
lymphatic  vessels  of  the  body, 
excepting  those  of  the  right  side 
of  the  head,  neck,  and  thorax,  and 
right  upper  extremity,  the  right 
lung,  right  side  of  the  heart,  and 
the  convex  surface  of  the  liver. 
It  varies  from  eighteen  to  twenty 
inches  in  length  in  the  adult,  and 
extends  from  the  second  lumbar 
vertebra  to  the  root  of  the  neck. 
It  commences  in  the  abdomen  by 
a  triangular  dilatation,  the  recep- 
taculum  chyli  (reservoir  or  cistern 
of  Pecquet),  which  is  situated  up- 
on the  front  of  the  body  of  the 
second  lumbar  vertebra,  to  the 
right  side  and  behind  the  aorta, 
by  the  side  of  the  right  crus  of 
the  Diaphragm.  It  ascends  into 
the  thorax  through  the  aortic 
opening  in  the  Diaphragm,  and 
is  placed  in  the  posterior  medias- 
tinum in  front  of  the  vertebral 
column  lying  between  the  aorta 
and  vena  azygos.  Opposite  the 
fourth  dorsal  vertebra,  it  inclines 
towards  the  left  side  and  ascends 
behind  the  arch  of  the  aorta,  on 
tlie  left  side  of  the  oesophagus, 
and  behind  the  first  portion  of  the 
left  subclavian  artery,  to  the 
upper  orifice  of  the  thorax.  Op- 
posite the  upper   border  of  the 


I 


OF  THE  HEAD,  FACE,  AND  NECK.         661 

seventh  cervical  vertebra,  it  curves  downwards  above  the  subclavian  artery, 
and  in  front  of  the  Scalenus  muscle,  so  as  to  form  an  arch ;  and  terminates  near 
the  angle  of  junction  of  the  left  internal  jugular  and  subclavian  veins.  Tlie 
thoracic  duct,  at  its  commencement,  is  about  equal  in  size  to  the  diameter  of  a 
goose-quill,  diminishes  considerably  in  its  calibre  in  the  middle  of  the  thorax, 
and  is  again  dilated  just  before  its  termination.  It  is  generally  flexuous  in  its 
course,  and  constricted  at  intervals  so  as  to  present  a  varicose  appearance.  The 
thoracic  duct  not  unfrequently  divides  in  the  middle  of  its  course  into  two 
Ibranches  of  unequal  size,  which  soon  reunite,  or  into  several  branches  which 
form  a  plexiforra  interlacement.  It  occasionally  bifurcates,  at  its  upper  part, 
into  two  branches,  of  which  the  one  on  the  left  side  terminates  in  the  usual 
manner,  while  that  on  the  right  opens  into  the  right  subclavian  vein,  in  con- 
nection with  the  right  lymphatic  duct.  The  thoracic  duct  has  numerous  valves 
throughout  its  whole  course,  but  they  are  more  numerous  in  the  upper  than  in 
the  lower  part;  at  its  termination  it  is  provided  with  a  pair  of  valves,  the  free 
borders  of  which  are  turned  towards  the  vein,  so  as  to  prevent  the  regurgita- 
tion of  venous  blood  into  the  duct. 

Branches.  The  thoracic  duct,  at  its  commencement,  receives  four  or  five  large 
trunks  from  the  abdominal  lymphatic  glands,  and  also  the  trunk  of  the  lacteal 
vessels.  Within  the  thorax,  it  is  joined  by  the  lymphatic  vessels  from  the  left 
half  of  the  wall  of  the  thoracic  cavity,  the  lymphatics  from  the  sternal  and 
intercostal  glands,  those  of  the  left  lung,  left  side  of  the  heart,  trachea,  and 
oesophagus;  and  just  before  its  termination,  receives  the  lymphatics  of  the  left 
side  of  the  head  and  neck,  and  left  upper  extremity. 

Structure.  The  thoracic  duct  is  composed  of  three  coats,  which  differ  in  some 
respects  from  those  of  the  lymphatic  vessels.  The  internal  coat  consists  of  a 
layer  of  epithelium,  resting  upon  some  striped  lamellae,  and  an  elastic  fibrous 
coat,  the  fibres  of  which  run  in  a  longitudinal  direction.  The  middle  coat  con- 
sists of  a  laj'-er  of  connective  tissue,  beneath  which  are  several  laminas  of  mus- 
cular tissue,  the  fibres  of  which  are  disposed  transversely,  and  intermixed  with 
the  elastic  fibres.  The  external  coat  is  composed  of  areolar  tissue,  with  elastic 
fibres  and  isolated  fasciculi  of  muscular  fibres. 

The  Right  Lymithatic  Duct  is  a  short  trunk,  about  an  inch  in  length,  and  a 
line  or  a  line  and  a  half  in  diameter,  which  receives  the  lymph  from  the  right 
side  of  the  head  and  neck,  the  right  upper  extremity,  the  right  side  of  the 
thorax,  the  right  lung  and  right  side  of  the  heart,  and  from  the  convex  surface 
of  the  liver,  and  terminates  at  the  angle  of  union  of  the  right  subclavian  and 
right  internal  jugular  veins.  Its  orifice  is  guarded  by  two  semilunar  valves, 
which  prevent  the  entrance  of  blood  from  the  veins. 

Lymphatics  of  the  Head,  Face,  and  Neck. 

The  superficial  lymphatic  glands  of  the  head  (Fig.  315)  are  of  small  size,  few 
in  number,  and  confined  to  its  posterior  region.  They  are  the  occipital,  placed 
at  the  back  of  the  head  along  the  attachment  of  the  Occipito-frontalis ;  and  the 
posterior  auricular,  near  the  upper  end  of  the  Sterno-mastoid.  These  glands  are 
affected  in  cutaneous  eruptions  and  other  diseases  of  the  scalp.  In  the  face,  the 
superficial  lymphatic  glands  are  more  numerous:  they  are  %\-iQ parotid,  some  of 
which  are  superficial  and  others  deeply  placed  in  the  substance  of  the  parotid 
gland ;  the  zygomatic,  situated  under  the  zygoma ;  the  buccal,  on  the  surface  of 
the  Buccinator  muscle;  and  the  suhmaxillary,  the  largest,  beneath  the  body  of 
the  lower  jaw. 

The  superftcicd  lymjohatics  of  the  head  are  divided  into  an  anterior  and  a  pos- 
terior set,  which  follow  the  course  of  the  temporal  and  occipital  vessels.  The 
temporal  set  accompany  the  temporal  artery  in  front  of  the  ear,  to  the  parotid 
lymphatic  glands,  from  which  they  proceed  to  the  lymphatic  glands  of  the  neck. 
The  occipital  set  follow  the  course  of  the  occipital  artery,  descend  to  the  occipital 
36 


502 


LYMPHATICS. 


and  posterior  auricular  lymphatic  glands,  and  from  thence  join  the  cervical 
glands. 

The  superficial  lymphatics  of  the  face  are  more  numerous  than  those  of  the 
head,  and  commence  over  its  entire  surface.  Those  from  the  frontal  region 
accompany  the  frontal  vessels ;  they  then  pass  obliquely  across  the  face,  run- 
ning with  the  facial  vein,  pass  through  the  buccal  glands  on  the  surface  of  the 
Buccinator  muscle,  and  join  the  submaxillary  lymphatic  glands.  The  latter 
receive  the  lymphatic  vessels  from  the  lips,  and  are  often  found  enlarged  in 
cases  of  malignant  disease  of  those  parts. 

Fig.  315. — The  Superficial  Lymphatics  and  Glands  of  the  Head,  Face,  and  Neck. 


The  deep  lymphatics  of  the  face  are  derived  from  the  pituitary  membrane  of 
the  nose,  the  mucous  membrane  of  the  mouth  and  pharynx,  and  the  contents 
of  the  temporal  and  orbital  fossae  ;  they  accompany  the  branches  of  the  internal 
maxillary  artery,  and  terminate  in  the  deep  parotid  and  cervical  lymphatic 
glands. 

The  deep  hjmphatics  of  the  cranium  consist  of  two  sets,  the  meningeal  and  cere- 
bral. The  meningeal  lymphatics  accompany  the  meningeal  vessels,  escape 
through  foramina  at  the  base  of  the  skull,  and  join  the  deep  cervical  lymphatic 
glands.  The  cerebral  lymphatics  are  described  by  Fohmann  as  being  situated 
between  the  arachnoid  and  pia  mater,  as  well  as  in  the  choroid  plexuses  of  the 
lateral  ventricles;  they  accompany  the  trunks  of  the  carotid  and  vertebral  arte- 
ries, and  probably  pass  through  foramina  at  the  base  of  the  skull,  to  terminate 


II 


OF  THE  HEAD,  FACE,  AND  NECK. 


663 


in  the  deep  cervical  glands.  They  have  not  at  present  been  demonstrated  in 
the  dura  mater,  or  in  the  substance  of  the  brain. 

The  Lymphatic  Glands  of  the  Neck  are  divided  into  two  sets,  superficial  and  deep. 

The  superficial  cervical  glands  are  placed  in  the  course  of  the  external  jugular 
vein,  between  the  Platysma  and  Sterno-mastoid.  They  are  most  numerous  at 
the  root  of  the  neck,  in  the  triangular  interval  between  the  clavicle,  the  Sterno- 
mastoid,  and  the  Trapezius,  where  they  are  continuous  with  the  axillary  glands. 
A  few  small  glands  are  also  found  on  the  front  and  sides  of  the  larynx. 

The  deep  cervical  glands  (Fig.  316)  are  numerous  and  of  large  size;  they  form 
an  uninterrupted  chain  along  the  sheath  of  the  carotid  artery  and  internal  jugu- 

Fig.  316. — The  Deep  Lymphatics  and  Glands  of  the  Neck  and  Thorax. 


lar  vein,  lying  by  the  side  of  the  pharynx,  oesophagus,  and  trachea,  and  extend- 
ing from  the  base  of  the  skull  to  the  tliorax,  where  they  communicate  with  the 
lymphatic  glands  in  that  cavity. 

The  superficial  and  deep  cervical  lymphatics  are  a  continuation  of  those  already 
described  on  the  cranium  and  face.  After  traversing  the  glands  in  those  regions, 
they  pass  through  the  chain  of  glands  which  lie  along  the  sheath  of  the  carotid 
vessels,  being  joined  by  the  lymphatics  from  the  pharynx,  oesophagus,  larynx, 
trachea,  and  thyroid  gland.  At  the  lower  part  of  the  neck,  after  receiving 
some  lymphatics  from  the  thorax,  they  unite  into  a  single  trunk,  which  termi- 
nates on  the  left  side,  in  the  thoracic  duct ;  on  the  right  side,  in  the  right  lym- 
phatic duct. 


564  LYMPHATICS 

Lymphatics  of  the  Upper  Extremity. 

The  Lymphatic  Glands  of  the  Upper  Extremity  (Fig.  317)  may  be  subdivided 
into  two  sets,  superficial  and  deep. 

The  superficial  lymphatic  glands  are  few,  and  of  small  size.  There  are  occa- 
sionally two  or  three  in  front  of  the  elbow,  and  one  or  two  above  the  internal 
condyle  of  the  humerus,  near  the  basilic  vein. 

Fig.  317. — The  Superficial  Lymphatics  and  Glands  of  the  Upper  Extremity. 


jLrtZTary  Qttndt^ 


The  deep  lymphatic  glands  are  also  few  in  number.  In  the  forearm  a  few 
small  ones  are  occasionally  found  in  the  course  of  the  radial  and  ulnar  vessels; 
and  in  the  arm,  there  is  a  chain  of  small  glands  along  the  inner  side  of  the 
brachial  artery. 

The  axillary  glayids  arc  of  large  size,  and  usually  ten  or  twelve  in  number. 
A  chain  of  these  glands  surrounds  the  axillary  vessels  imbedded  in  a  quantity 
of  loose  areolar  tissue ;  they  receive  the  lymphatic  vessels  from  the  arm ;  others 
are  dispersed  in  the  areolar  tissue  of  tlie  axilla;  the  remainder  are  arranged  in 
two  series,  a  small  chain  running  along  the  lower  border  of  the  Pectoralis 


OF    THE    LOWER    EXTREMITY.  565 

Major,  as  far  as  the  mammary  gland,  receiving  the  lymphatics  from  the  front 
of  the  chest  and  mamma  ;  and  others  are  placed  along  the  lower  margin  of  the 
posterior  wall  of  the  axilla,  which  receive  the  lymphatics  from  the  integument 
of  the  back.  Two  or  three  subclavian  lymphatic  glands  are  placed  imme- 
diately beneath  the  clavicle  ;  it  is  through  these  that  the  axillary  and  deep 
cervical  glands  communicate  with  each  other.  One  is  figured  by  Mascagni  near 
the  umbilicus.  In  malignant  diseases,  tumors,  or  other  affections  implicating 
the  upper  part  of  the  back  and  shoulder,  the  front  of  the  chest  and  mamma, 
the  upper  part  of  the  front  and  side  of  the  abdomen,  or  the  hand,  forearm,  and 
arm,  the  axillary  glands  are  liable  to  be  found  enlarged. 

The  superficial  lym'phatics  of  the  upper  extremity  arise  from  the  skin  of  the 
hand,  and  run  along  the  sides  of  the  fingers  chiefly  on  the  dorsal  surface  of 
the  hand ;  they  then  pass  up  the  forearm,  and  subdivide  into  two  sets,  which 
take  the  course  of  the  subcutaneous  veins.  Those  from  the  inner  border  of  the 
hand  accompany  the  ulnar  veins  along  the  inner  side  of  the  forearm  to  the 
bend  of  the  elbow,  where  they  join  with  some  lymphatics  from  the  outer  side 
of  the  forearm ;  they  then  follow  the  course  of  the  basilic  vein,  communicate 
with  the  glands  immediately  above  the  elbow,  and  terminate  in  the  axillary 
glands,  joining  with  the  deep  lymphatics.  The  superficial  lymphatics  from  the 
outer  and  back  part  of  the  hand  accompany  the  radial  veins  to  the  bend  of  the 
elbow.  They  are  less  numerous  than  the  preceding.  At  the  bend  of  the  elbow, 
the  greater  number  join  the  basilic  group ;  the  rest  ascend  with  the  cephalio 
vein  on  the  outer  side  of  the  arm,  some  crossing  the  upper  part  of  the  Biceps 
obliquely,  to  terminate  in  the  axillary  glands,  whilst  one  or  two  accompany  the 
cephalio  vein  in  the  cellular  interval  between  the  Pectoralis  Major  and  Deltoid, 
and  enter  the  subclavian  lymphatic  glands. 

The  deep  lymj)hatics  of  the  upper  extremity  accompany  the  deep  bloodvessels. 
In  the  forearm,  they  consist  of  three  sets,  corresponding  with  the  radial,  ulnar, 
and  interosseous  arteries ;  they  pass  through  the  glands  occasionally  found  in 
the  course  of  those  vessels,  and  communicate  at  intervals  with  the  superficial 
lymphatics.  In  their  course  upward,  some  of  them  pass  through  the  glands 
which  lie  upon  the  brachial  artery ;  they  then  enter  the  axillary  and  subclavian 
glands,  and  at  the  root  of  the  neck  terminate,  on  the  left  side,  in  the  thoracic 
duct,  and  on  the  right  side  in  the  right  lymphatic  duct. 

Lymphatics  of  the  Lower  Extremity. 

The  Lymphatic  Glands  of  the  Lower  Extremity  may  be  subdivided  into  two 
sets,  superficial  and  deep ;  the  former  are  confined  to  the  inguinal  region. 

The  superficial  inguinal  glands,  placed  immediately  beneath  the  integument, 
are  of  large  size,  and  vary  from  eight  to  ten  in  number.  They  are  divisible 
into  two  groups  ;  an  upper,  disposed  irregularly  along  Poupart's  ligament,  which 
receive  the  lymphatic  vessels  from  the  integument  of  the  scrotum,  penis, 
parietes  of  the  abdomen,  perineum,  and  gluteal  regions ;  and  an  inferior  group, 
which  surround  the  saphenous  opening  in  the  fascia  lata,  a  few  being  sometimes 
continued  along  the  saphenous  vein  to  a  variable  extent.  The  latter  receive 
the  superficial  lymphatic  vessels  from  the  lower  extremity.  These  glands 
frequently  become  enlarged  in  diseases  implicating  the  parts  from  which  their 
lymphatics  originate.  Thus,  in  malignant  or  syphilitic  affections  of  the  prepuce 
and  penis,  or  of  the  labia  majora  in  the  female,  in  cancer  scroti,  in  abscess  in 
the  perineum,  or  in  any  other  disease  affecting  the  integument  and  superficial 
structures  of  these  parts,  or  the  sub-umbilical  part  of  the  abdomen  or  gluteal 
region,  the  upper  chain  of  glands  is  almost  invariably  enlarged,  the  lower  chain 
being  implicated  in  diseases  affecting  the  lower  limb. 

The  deep  lymphatic  glands  are,  the  anterior  tibial,  popliteal,  deep  inguinal, 
gluteal,  and  ischiatic. 

The   anterior  tibial  gland  is  not  constant  in  its  existence.     It  is  generally 


50  G 


LYMPHATICS. 


Fig.  318. — The  Superficial  Lymphatics  und 
Glands  of  the  Lower  Extremity. 


S^= 


CupirfltiaT\  i 


7upf 


l\ 


iii  /\l 


iy'M 


found  by  the  side  of  the  anterior  tibial 
artery,  upon  the  interosseous  membrane 
at  the  upper  part  of  the  leg.  Occasion- 
ally two  glands  are  found  in  this  situa- 
tion. 

The  deep  popliteal  glancls,  four  or  five 
in  number,  are  of  small  size ;  they  sur- 
round the  popliteal  vessels,  imbedded  in 
the  cellular  tissue  and  fat  of  the  popliteal 
space. 

The  deep  inguinal  glands  are  placed 
beneath  the  deep  fascia  around  the  femo- 
ral artery  and  vein.  They  are  of  small 
size,  and  communicate  with  the  super- 
ficial inguinal  glands  through  the  saphe- 
nous openings. 

The  gluteal  and  ischiatic  glands  are 
placed,  the  former  above,  the  latter  below 
the  Pyriformis  muscle,  resting  on  their 
corresponding  vessels  as  they  pass 
through  the  great  sacro-sciatic  foramen. 

The  Lymphatics  of  the  lower  extre- 
mity, like  the  veins,  may  be  divided  into 
two  sets,  superficial  and  deep. 

The  superficial  lymphatics  are  placed 
between  the  integument  and  superficial 
fascia,  and  are  divisible  into  two  groups, 
an  internal  group,  which  follow  the 
course  of  the  internal  saphenous  vein ; 
and  an  external  group,  which  accom- 
pany the  external  saphenous.  The  in- 
ternal group,  the  larger,  commence  on 
the  inner  side  and  dorsum  of  the  foot ; 
they  pass,  some  in  front,  and  some  be- 
hind the  inner  ankle,  run  up  the  leg 
with  the  internal  saphenous  vein,  pass 
with  it  behind  the  inner  condyle  of  the 
femur,  and  accompany  it  to  the  groin, 
where  they  terminate  in  the  group  of  in- 
guinal glands  which  surround  the  saphe- 
nous opening.  Some  of  the  efferent 
vessels  from  these  glands  pierce  the  crib- 
riform fascia  and  sheath  of  the  femoral 
vessels,  and  terminate  in  a  lymphatic 
gland  contained  in  the  femoral  canal, 
thus  establishing  a  communication  be- 
tween the  lymphatics  of  the  lower  ex- 
tremity and  those  of  the  trunk ;  others 
))ierce  the  fascia  lata,  and  join  the  deep 
inguinal  glands.  The  external  group  arise 
from  the  outer  side  of  the  foot,  ascend 
in  front  of  the  leg,  and,  just  below  the 
knee,  cross  the  tibia  from  without  in- 
wards, to  join  the  lymphatics  on  the 
inner  side  of  the  thigh.  Others  com- 
mence on  the  outer  side  of  the  foot,  pass 
behind  the  outer  malleolus,  and  accom- 


OF    THE    PELVIS    AND    ABDOMEN.  567 

pany  the  external  saphenous  vein  along  the  back  of  the  leg,  where  they  enter 
the  popliteal  glands. 

The  deep  lymi^hatics  of  the  lower  extremity  are  few  in  number,  and  accompany 
the  deep  bloodvessels.  In  the  leg,  they  consist  of  three  sets,  the  anterior  tibial, 
peroneal,  and  posterior  tibial,  which  accompany  the  corresponding  bloodvessels, 
two  or  three  to  each  artery ;  they  ascend  with  the  bloodvessels,  and  enter  the 
lymphatic  glands  in  the  popliteal  space ;  the  efferent  vessels  from  these  glands 
accompany  the  femoral  vein,  and  join  the  deep  inguinal  glands;  from  these, 
the  vessels  pass  beneath  Poupart's  ligament,  and  communicate  with  the  chain 
of  glands  surrounding  the  external  iliac  vessels. 

The  deep  lymphatics  of  the  gluteal  and  ischiatic  regions  follow  the  course 
of  the  bloodvessels,  and  join  the  gluteal  and  ischiatic  glands  at  the  great 
sacro-sciatic  foramen. 

Lymphatics  of  the  Pelvis  and  Abdomen. 

The  Deep  L3''mphatiG  Glands  in  the  Pelvis  are,  the  external  iliac,  the  internal 
iliac,  and  the  sacral.     Those  of  the  abdomen  are  the  lumbar  glands. 

The  externaliliac  glands  form  an  uninterrupted  chain  round  the  external  iliac 
vessels,  three  being  placed  round  the  commencement  of  the  vessel  just  behind 
the  crural  arch.  They  communicate  below  with  the  femoral  lymphatics,  and 
above  with  the  lumbar  glands. 

The  internal  iliac  glands  surround  the  internal  iliac  vessels;  they  receive  the 
lymphatics  corresponding  to  the  branches  of  the  internal  iliac  artery,  and 
communicate  with  the  lumbar  glands. 

The  sacral  glands  occupy  the  sides  of  the  anterior  surface  of  the  sacrum, 
some  being  situated  in  the  meso-rectal  fold.  These  and  the  internal  iliac 
glands  are  affected  in  malignant  disease  of  the  bladder,  rectum,  or  uterus. 

The  lumbar  glands  are  very  numerous;  they  are  situated  on  the  front  of  the 
lumbar  vertebrae,  surrounding  the  common  iliac  vessels,  the  aorta,  and  vena 
cava;  they  receive  the  lymphatic  vessels  from  the  lower  extremities  and 
pelvis,  as  well  as  from  the  testes  and  some  of  the  abdominal  viscera;  the 
efferent  vessels  from  these  glands  unite  into  a  few  large  trunks,  which,  with 
the  lacteals,  form  the  commencement  of  the  thoracic  duct.  In  some  cases  of 
malignant  disease,  these  glands  become  enormously  enlarged,  completely 
surrounding  the  aorta  and  vena  cava,  and  occasionally  greatly  contracting  the 
calibre  of  those  vessels.  In  all  cases  of  malignant  disease  of  the  testis,  and  in 
malignant  disease  of  the  lower  limb,  before  any  operation  is  attempted,  careful 
examination  of  the  abdomen  should  be  made,  in  order  to  ascertain  if  any 
enlargement  exists;  and  if  any  should  be  detected,  all  operative  measures 
should  be  avoided  as  fruitless. 

The  Lymphatics  of  the  Pelvis  and  Abdomen  may  be  divided  into  two  sets, 
superficial  and  deep. 

The  superficial  lymphatics  of  the  walls  of  ihe  abdomen  and  pelvis  follow  the 
course  of  the  superficial  bloodvessels.  Those  derived  from  the  integument 
of  the  lower  part  of  the  abdomen  below  the  umbilicus,  follow  the  course  of  the 
superficial  epigastric  vessels,  and  converge  to  the  superior  group  of  the  super- 
ficial inguinal  glands;  the  deep  set  accompany  the  deep  epigastric  vessels,  and 
communicate  with  the  external  iliac  glands.  The  superficial  lymphatics  from 
the  sides  and  lumbar  part  of  the  abdominal  wall  wind  round  the  crest  of  the 
ilium,  accompanying  the  superficial  circumflex  iliac  vessels,  to  join  the 
superior  group  of  the  superficial  inguinal  glands;  the  greater  number,  how- 
ever, run  backwards  along  with  the  ilio-lumbar  and  lumbar  vessels,  to  join  the 
lumbar  glands. 

The  superficial  lymphatics  of  ihe  gluteal  region  turn  horizontally  round  the 
outer  side  of  the  nates,  and  join  the  superficial  ingunial  glands. 

The  superficial  lymphatics  of  the  scrotum  and  perineum  follow  the  course  of 
the  external  pudic  vessels,  and  terminate  in  the  superficial  inguinal  glands. 


568 


LYMPHATICS. 


The  svperficial  lymphaiics  of  the  penis  occupy  the  sides  and  dorsum  of  the 
organ,  the  latter  receiving  the  lymphatics  from  the  skin  covering  the  glans 
penis;  they  all  converge  to  the  upper  chain  of  the  superficial  inguinal  glands. 
The  deep  lymphatic  vessels  of  the  penis  follow  the  course  of  the  internal  pudic 
vessels,  and  join  the  internal  iliac  glands. 

Fig.  319. — The  Deep  Lymphatic  Vessels  and  Glands  of  the  Abdomen  and  Pelvis. 


UanJr 


Xxttmal 
tliae  Glauit 


Tnau$4itti 

GlamHt 


In  the  female,  the  lymphatic  vessels  of  the  mucous  membrane  of  tne  labia, 
nymphfB,  and  clitoris,  terminate  in  the  upper  chain  of  the  inguinal  glands. 

The  Deep  Lymphatics  of  the  Pelvis  and  Abdomen  take  the  course  of  the 
principal  bloodvessels.  Those  of  the  parietes  of  the  pelvis,  which  accompany 
the  gluteal,  ischiatic,  and  obturator  vessels,  follow  the  course  of  the  internal 
iliac  artery,  and  ultimately  join  the  lumbar  lymphatics. 

The  efforent  vessels  from  the  inguinal  glands  enter  the  pelvis  beneath  Pou- 
part's  ligament,  where  they  lie  in  close  relation  with  the   femoral  vein  ;  they 


OF    THE    PELVIS    AND    ABDOMEN.  569 

then  pass  through  the  chain  of  glands  surrounding  the  external  iliac  vessels, 
and  finally  terminate  in  the  lumbar  glands.  They  receive  the  deep  epigastric, 
circumflex  iliac,  and  ilio-lumbar  lymphatics. 

The  lymphatics  of  the  bladder  arise  from  the  entire  surface  of  the  organ  ;  the 
greater  number  run  beneath  the  peritoneum  on  its  posterior  surface,  and,  after 
passing  through  the  lymphatic  glands  in  that  situation,  join  with  the  lymphatics 
from  the  prostate  and  vesicula9  seminales,  and  enter  the  internal  iliac  glands. 

The  lymphatics  of  the  rectum  are  of  large  size ;  after  passing  through  some 
small  glands  that  He  upon  its  outer  wall  and  in  the  meso-rectum,  they  pass  to 
the  sacral  or  lumbar  glands. 

The  lymphatics  of  the  uterus  consist  of  two  sets,  superficial  and  deep ;  the 
former  being  placed  beneath  the  peritoneum,  the  latter  in  the  substance  of  the 
organ.  The  lymphatics  of  the  cervix  uteri,  together  with  those  from  the  vagina, 
enter  the  internal  iliac  and  sacral  glands  ;  those  from  the  body  and  fundus  of 
the  uterus  pass  outwards  in  the  broad  ligaments,  and,  being  joined  by  the 
lymphatics  from  the  ovaries,  broad  ligaments,  and  Fallopian  tubes,  ascend  with 
the  ovarian  vessels  to  open  into  the  lumbar  glands.  In  the  unimpregnated 
uterus,  they  are  small;  but  during  gestation,  the}'-  become  very  greatly  enlarged. 

The  lymphatics  of  the  testicle  consist  of  two  sets,  superficial  and  deep ;  the 
former  commence  on  the  surface  of  the  tunica  vaginalis,  the  latter  in  the  epi- 
didymis and  body  of  the  testis.  They  form  several  large  trunks,  which  ascend 
with  the  spermatic  cord,  and  accompanying  the  spermatic  vessels  into  the  abdo- 
men, open  into  the  lumbar  glands;  hence  the  enlargement  of  these  glands  in 
malignant  disease  of  the  testis. 

The  lymphatics  of  the  kidney  arise  on  the  surface,  and  also  in  the  interior  of 
the  organ;  they  join  at  the  hilum,  and,  after  receiving  the  lymphatic  vessels 
from  the  ureter  and  suprarenal  capsule,  open  into  the  lumbar  glands. 

The  lymphatics  of  the  liver  are  divisible  into  two  sets,  superficial  and  deep. 
The  former  arise  in  the  sub-peritoneal  areolar  tissue  over  the  entire  surface  of 
the  organ.     Those  on  the  convex  surface  may  be  divided  into  four  groups  ; 

1.  Those  which  pass  from  behind  forwards,  consisting  of  three  or  four  branches, 
which  ascend  in  the  longitudinal  ligament,  and  unite  to  form  a  single  trunk, 
which  passes  up  between  the  fibres  of  the  Diaphragm,  behind  the  ensiform 
cartilage,  to  enter  the  anterior  mediastinal  glands,  and  finally  ascends  to  the 
root  of  the  neck,  to  terminate  in  the  right  lymphatic  duct.  2.  Another  group, 
which  also  incline  from  behind  forwards,  are  reflected  over  the  anterior  margin 
of  the  liver  to  its  under  surface,  and  from  thence  pass  along  the  longitudinal 
fissure  to  the  glands  in  the  gastro-hepatic  omentum.  3.  A  third  group  incline 
outwards  to  the  right  lateral  ligament,  and  uniting  into  one  or  two  large  trunks, 
pierce  the  Diaphragm,  and  run  along  its  upper  surface  to  enter  the  anterior 
mediastinal  glands ;  or,  instead  of  entering  the  thorax,  turn  inwards  across  the 
crus  of  the  Diaphragm,  and  open  into  the  commencement  of  the  thoracic  duct. 
4.  The  fourth  group  incline  outwards  from  the  surface  of  the  left  lobe  of  the 
liver  to  the  left  lateral  ligament,  pierce  the  Diaphragm,  and  passing  forwards, 
terminate  in  the  glands  in  the  anterior  mediastinum. 

The  superficial  lymphatics  on  the  under  surface  of  the  liver  are  divided  into  three 
sets :  1.  Those  on  the  right  side  of  the  gall-bladder  enter  the  lumbar  glands. 

2.  Those  surrounding  the  gall-bladder  form  a  remarkable  plexus ;  they  accom- 
pany the  hepatic  vessels,  and  open  into  the  glands  in  the  gastro-hepatic  omen- 
tum. 3.  Those  on  the  left  of  the  gall-bladder  pass  to  the  oesophageal  glands, 
and  to  the  glands  which  are  situated  along  the  lesser  curvature  of  the  stomach. 

The  deep  lymphatics  accompany  the  branches  of  the  portal  vein  and  the  hepatic 
artery  and  duct  through  the  substance  of  the  liver ;  passing  out  at  the  transverse 
fissure,  they  enter  the  lymphatic  glands  along  the  lesser  curvature  of  the  stomach 
and  behind  the  pancreas,  or  join  with  one  of  the  lacteal  vessels  previous  to  its 
termination  in  the  thoracic  duct. 

The  lymphatic  glands  of  the  stomach  are  of  small  size  ;  they  are  placed  along 


570  LYMPHATICS. 

tbe  lesser  and  greater  curvatures,  some  within  the  gastro-splenic  omentum, 
whilst  others  surround  the  cardiac  and  pyloric  orifices. 

The  lymphatics  of  the  stomach  consist  of  two  sets,  superficial  and  deep ;  the 
former  originating  in  the  snbserous,  and  the  latter  in  the  submucous  coat.  They 
follow  the  course  of  the  bloodvessels,  and  may^  consequently,  be  arranged  into 
three  groups.  The^rs^  group  accompany  the  coronary  vessels  along  the  lesser 
curvature,  receiving  branches  from  both  surfaces  of  the  organ,  and  pass  to  the 
glands  around  the  pylorus.  The  second  group  pass  from  the  great  end  of  the 
stomach,  accompany  the  vasa  brevia,  and  enter  the  splenic  lymphatic  glands. 
The  third  grotip  run  along  the  greater  curvature  with  the  right  gastro-epiploic 
vessels,  and  terminate  at  the  root  of  the  mesentery  in  one  of  the  principal  lac- 
teal vessels. 

The  lymphatic  glands  of  the  spleen  occupy  the  hilum.  Its  lymphatic  vessels  con- 
sist of  two  sets,  superficial  and  deep;  the  former  are  placed  beneath  its  peritoneal 
covering,  the  latter  in  the  substance  of  the  organ ;  they  accompany  the  blood- 
vessels, passing  through  a  series  of  small  glands,  and  after  receiving  the  lym- 
phatics from  the  pancreas,  ultimately  pass  into  the  thoracic  duct. 

The  Lymphatic  System  of  the  Intestines. 

The  Lymphatic  Glands  of  the  Small  Intestine  are  placed  between  the  layers 
of  the  mesentery,  occupying  the  meshes  formed  by  the  superior  mesenteric 
vessels,  and  hence  called  mesenteric  glands.  They  vary  in  number  from  a  hun- 
dred to  a  hundred  and  fifty ;  and  in  size,  from  that  of  a  pea  to  that  of  a  small 
almond.  These  glands  are  most  numerous,  and  largest,  above  near  the  duode- 
num, and  below  opposite  the  termination  of  the  ileum  in  the  colon.  This  latter 
group  becomes  enlarged  and  infiltrated  with  deposit  in  cases  of  fever  accompa- 
nied with  ulceration  of  the  intestines. 

The  Lymphatic  Glands  of  the  Large  Intestine  are  much  less  numerous  than 
the  mesenteric  glands :  they  are  situated  along  the  vascular  arches  formed  by 
the  arteries  previous  to  their  distribution,  and  even  sometimes  upon  the  intes- 
tine itself.     They  are  fewest  in  number  along  the  transverse  colon,  where  they_ 
form  an  uninterrupted  chain  with  the  mesenteric  glands.  ■ 

The  Lymphatics  of  the  Small  Intestine  are  called  lacteals,  from  the  milk-white^ 
fluid  they  usually  contain ;  they  consist  of  two  sets,  superficial  and  deep ;  the 
former  lie  beneath  the  peritoneal  coat,  taking  a  longitudinal  course  along  the 
outer  side  of  the  intestine ;  the  latter  occupy  the  submucous  tissue,  and  course 
transversely  round  the  intestine,  accompanied  by  the  branches  of  the  mesenteric 
vessels:  they  pass  between  the  layers  of  the  mesentery,  enter  the  mesenterl 
glands,  and  finally  unite  to  form  two  or  three  large  trunks,  which  terminate  i 
the  thoracic  duct. 

The  Lymphatics  of  the  Large  Intestine  consist  of  two  sets:  those  of  th 
caecum,  ascending  and  transverse  colon,  which,  after  passing  through  their 
proper  glands,  enter  the  mesenteric  glands  ;  and  those  of  the  descending  colon 
and  rectum,  which  pass  to  the  lumbar  glands. 


1 


The  Lymphatics  of  the  Thorax. 

The  Deep  Lymphatic  Glands  of  the  Thorax  are  the  intercostal,  internal  mam<f 
mary,  anterior  mediastinal,  and  posterior  mediastinal. 

The  intercostal  glands  are  small,  irregular  in  number,  and  situated  on  eacl 
side  of  the  spine,  near  the  costo-vertebral  articulations,  some  being  placed  be 
tween  the  two  planes  of  intercostal  muscles. 

The  internal  m.ammary  glands  are  placed  at  the  anterior  extremity  of  each 
intercostal  space,  by  the  side  of  the  internal  mammary  vessels. 

The  anterior  mediastinal  glands  are  placed  in  the  loose  areolar  tissue  of  the 
anterior  mediastinum,  some  lying  upon  the  Diaphragm  in  front  of  the  pericar- 
dium, and  others  round  the  great  vessels  at  the  base  of  the  heart. 

The  posterior  mediastinal  glands  are  situated  in  the  areolar  tissue  in  the  pos- 


OF    THE    THORAX.  5tl 

terior  mediastinum,  forming  a  continuous  chain  by  the  side  of  the  aorta  and 
oesophagus  ;  they  communicate  on  each  side  with  the  intercostal,  below  with 
the  lumbar  glands,  and  above  with  the  deep  cervical. 

The  Superficial  Lymphatics  of  the  Front  of  the  Thorax  run  across  the  great 
Pectoral  muscle,  and  those  on  the  back  part  of  this  cavity  lie  upon  the  Trapezius 
and  Latissimus  Dorsi ;  they  all  converge  to  the  axillary  glands.  The  lymphatics 
from  the  mamma  run  along  the  lower  border  of  the  Pectoralis  Major,  through  a 
chain  of  small  lymphatic  glands,  and  communicate  with  the  axillary  glands. 

The  Deep  Lymphatics  of  the  Thorax  are  the  intercostal,  internal  mammary, 
and  diaphragmatic. 

The  inlncostal  lymphatics  follow  the  course  of  the  intercostal  vessels,  receiving 
lymphatics  from  the  intercostal  muscles  and  pleura;  they  pass  backwards  to 
the  spine,  and  unite  with  lymphatics  from  the  back  part  of  the  thorax  and 
spinal  canal.  After  traversing  the  intercostal  glands,  they  incline  down  the 
spine,  and  terminate  in  the  thoracic  duct. 

The  internal  mammary  lymphatics  follow  the  course  of  the  internal  mammary 
vessels;  they  commence  in  the  muscles  of  the  abdomen  above  the  umbilicus, 
communicating  with  the  epigastric  lymphatics,  ascend  between  the  fibres  of  the 
Diaphragm  at  its  attachment  to  the  ensiform  appendix,  and  in  their  course  behind 
the  costal  cartilages  are  joined  by  the  intercostal  lymphatics,  terminating  on 
the  right  side  in  the  right  lymphatic  duct,  on  the  left  side  in  the  thoracic  duct. 

The  lymphatics  of  the  Diaphragm  follow  the  course  of  their  corresponding 
vessels,  and  terminate,  some  in  front,  in  the  anterior  mediastinal  and  internal 
mammary  glands,  some  behind  in  the  intercostal  and  hepatic  lymphatics. 

The  bronchial  glands  are  situated  round  the  bifurcation  of  the  trachea  and 
roots  of  the  lungs.  They  are  ten  or  twelve  in  number,  the  largest  being  placed 
opposite  the  bifurcation  of  the  trachea,  the  smallest  round  the  bronchi  and  their 
primary  divisions  for  some  little  distance  within  the  substance  of  the  lungs. 
In  infancy,  they  present  the  same  appearance  as  lymphatic  glands  in  other  situa- 
tions, in  the  adult  they  assume  a  brownish  tinge,  and  in  old  age  a  deep  black 
color.  Occasionally  they  become  sufficiently  enlarged  to  compress  and  narrow 
the  canal  of  the  bronchi ;  and  they  are  often  the  seat  of  tubercle  or  deposits  of 
phosphate  of  lime. 

The  lymphatics  of  the  lung  consist  of  two  sets,  superficial 'and  deep:  the  former 
are  placed  beneath  the  pleura,  forming  a  minute  plexus,  which  covers  the  outer 
surface  of  the  lung;  the  latter  accompany  the  bloodvessels,  and  run  along  the 
bronchi :  they  both  terminate  at  the  root  of  the  lungs  in  the  bronchial  glands. 
The  efferent  vessels  from  these  glands,  two  or  three  in  number,  ascend  upon 
the  trachea  to  the  root  of  the  neck,  traverse  the  tracheal  and  oesophageal  glands, 
and  terminate  on  the  left  side  in  the  thoracic  duct,  and  on  the  right  side  in  the 
right  lymphatic  duct. 

The  cardiac  lymphatics  consist  of  two  sets,  superficial  and  deep;  the  former  arise 
in  the  subserous  areolar  tissue  of  the  surface,  and  the  latter  beneath  the  inter- 
nal lining  membrane  of  the  heart.  They  follow  the  course  of  the  coronary  ves- 
sels; those  of  the  right  side  unite  into  a  trunk  at  the  root  of  the  aorta,  which, 
ascending  across  the  arch  of  that  vessel,  passes  backwards  to  the  trachea,  upon 
which  it  ascends,  to  terminate  at  the  root  of  the  neck  in  the  right  lymphatic 
duct.  Those  of  the  left  side  unite  into  a  single  vessel  at  the  base  of  the  heart, 
which,  passing  along  the  pulmonary  artery,  and  traversing  some  glands  at  the 
root  of  the  aorta,  ascends  on  the  trachea  to  terminate  in  the  thoracic  duct. 

The  thymic  lym^yhadcs  arise  from  the  spinal  surface  of  the  thymus  gland,  and 
terminate  on  each  side  in  the  internal  jugular  veins. 

The  thyroid  lymphatics  arise  from  either  lateral  lobe  of  this  organ;  they  con- 
verge to  form  a  short  trunk,  which  terminates  on  the  right  side  in  the  right 
lymphatic  duct,  on  the  left  side  in  the  thoracic  duct. 

The  lymphatics  of  the  oesophagus  form  a  plexus  round  that  tube,  traverse  the 
glands  in  the  posterior  mediastinum,  and,  after  communicating  with  the  pulmo- 
nary lymphatic  vessels  near  the  roots  of  the  lungs,  terminate  in  the  thoracic  duct 


KervoTis  System. 


I 


The  Nervous  System  is  composed:  1,  of  a  series  of  connected  central 
organs,  called,  collectively,  the  cerebrospinal  centre^  or  axis;  2,  of  the  ganglia; 
and,  3,  of  the  nerves. 

The  Cerebro-spinal  Centre  consists  of  two  parts,  the  spinal  cord  and  the 
encephal-on:  the  latter  may  be  subdivided  into  the  cerebrum,  the  cerebellum, 
the  pons  Varolii,  and  the  medulla  oblongata. 

The  Spinal  Cord  and  its  Membranes. 

Dissection.  To  dissect  the  cord  and  its  membranes,  it  will  be  necessary  to  lay  open  the 
whole  length  of  the  spinal  canal.  For  this  purpose,  the  muscles  must  be  separated  from  the 
vertebral  grooves,  so  as  to  expose  the  spinous  processes  and  laminae  of  the  vertebrae ;  and  the 
latter  must  be  sawn  through  on  each  side,  close  to  the  roots  of  the  transverse  processes,  from 
the  third  or  fourth  cervical  vertebra,  above,  to  the  sacrum  below.  The  vertebral  arches  having 
been  displaced,  by  means  of  a  chisel,  and  the*  separate  fragments  removed,  the  dura  mater  will 
be  exposed,  covered  by  a  plexus  of  veins  and  a  quantity  of  loose  areolar  tissue,  often  infiltrated 
with  a  serous  fluid.  The  arches  of  the  upper  vertebra?  are  best  divided  by  means  of  a  strong 
pair  of  cutting  bone-forceps. 

Membranes  of  the  Cord. 

The  Membranes  which  envelop  the  spinal  cord  are  three  in  number.  The 
most  external  is  the  dura  mater,  a  strong  fibrous  membrane,  which  forms  a 
loose  sheath  around  the  cord.  The  most  internal  is  the  pia  mater,  a  cellulo 
vascular  membrane,  which  closely  invests  the  entire  surface  of  the  cord. 
Between  the  two  is  the  arachnoid  membrane,  an  intermediate  serous  sac,  which 
envelops  the  cord,  and  is  then  reflected  on  the  inner  surface  of  the  dura  mater 

The  Dura  Mater'o?  the  cord,  continuous  with  that  which  invests  the  brain, 
is  a  loose  sheath  which  surrounds  the  cord,  and  is  separated  from  the  bonv 
walls  of  the  spinal  canal  by  a  quantity  of  loose  areolar  adipose  tissue,  and  a 
plexus  of  veins.  It  is  attached  to  the  circumference  of  the  foramen  magnum, 
and  to  the  posterior  common  ligament,  throughout  the  whole  length  of  the 
spinal  canal,  by  fibrous  tissue,  and  extends,  below,  as  far  as  the  top  of  the 
sacrum;  but,  beyond  this  point,  it  is  impervious,  being  continued,  in  the  form 
of  a  slender  cord,  to  the  back  of  the  coccyx,  where  it  blends  with  the  perios- 
teum. This  sheath  is  much  larger  than  is  necessary  for  its  contents,  and  its 
size  is  greater  in  tlio  cervical  and  lumbar  regions  than  in  the  dorsal.  Its  inner 
surface  is  smooth,  covered  by  a  layer  of  polygonal  cells;  and  on  each  side  may 
be  seen  the  double  openings  which  transmit  the  two  roots  of  the  corresponding 
spinal  nerve,  the  fibrous  layer  of  the  dura  mater  being  continued  in  the  form 
of  a  tubular  prolongation  on  them  as  they  issue  from  these  apertures.  These 
])rolongations  of  the  dura  mater  are  short  in  the  upper  part  of  the  spine,  but 
become  gradually  longer  below,  forming  a  number  of  tubes  of  fibrous  mera-JI 
brane,  which  inclose  the  sacral  nerves,  and  are  contained  in  the  spinal  canal,    ^i 

The  chief  peculiarities  of  the  dura  mater  of  the  cord,  as  compared  with  that 
investing  the  brain,  are  the  following: — 

The  dura  mater  of  the  cord  is  not  adherent  to  the  bones  of  the  spinal  canal 
which  have  an  independent  periosteum. 

It  does  not  send  partitions  into  the  fissures  of  the  cord,  as  in  the  brain. 

Its  fibrous  lamina?  do  not  separate,  to  form  venous  sinuses,  as  in  the  brain. 

Structure.      The  dura  mater  consists  of  white  fibrous   tissue,  arranged  in 
572 


I 


I 


MEMBRANES    OF    THE    CORD. 


573 


Fig.  320.— The  Spinal  Cord 
and  its  Membranes. 


bands  wliicli  intersect  one  another.     It  is  sparingly  supplied  witli  vessels;  and 
no  nerves  have  as  yet  been  traced  to  it. 

The  Arachnoid  is  exposed  by  slitting  up  the  dura  mater,  and  reflecting  that 
membrane  to  either  side  (Fig.  320).  It  is  a  thin,  delicate,  serous  membrane, 
which  invests  the  outer  surface  of  the  cord,  and  is 
then  reflected  upon  the  inner  surface  of  the  dura 
mater,  to  which  it  is  intimately  adherent.  Above, 
it  is  continuous  with  the  cerebral  arachnoid;  below, 
it  is  reflected  on  the  various  nerves,  so  that  its  parie- 
tal and  visceral  layers  become  continuous  with  each 
other.  The  visceral  layer  is  the  portion  which  sur- 
rounds the  cord,  and  that  which  lines  the  inner  sur- 
face of  the  dura  mater  is  called  the  parietal  layer ;^ 
the  interval  between  the  two,  is  called  the  cavity  of 
the  arachnoid.  The  visceral  layer  forms  a  loose 
sheath  around  the  cord,  so  as  to  leave  a  considerable 
interval  between  the  two,  which  is  called  the  suh- 
arachnoidean  space.  This  space  is  largest  at  the  lower 
part  of  the  spinal  canal,  and  incloses  the  mass  of 
nerves  which  form  the  cauda  equina.  It  contains  an 
abundant  serous  secretion,  the  cerebro-spinal  fluid, 
and  usually  communicates  with  the  general  ventricu- 
lar cavity  of  the  brain,  by  means  of  an  opening  in 
the  fibrous  layer  of  the  inferior  boundary  of  the 
fourth  ventricle.  This  secretion  is  sufficient  in 
amount  to  expand  the  arachnoid  membrane,  so  as 
to  completely  fill  up  the  whole  of  the  space  included 
in  the  dura  mater.  The  sub-arachnoidean  space  is 
crossed,  at  the  back  part  of  the  cord,  by  numerous 

fibrous  bands,  which  stretch  from  the  arachnoid  to  the  pia  mater,  especially  in 
the  cervical  region,  and  is  partially  subdivided  by  a  longitudinal  membranous 
partition,  which  serves  to  connect  the 
arachnoid  with  the  pia  mater,  opposite  the 
posterior  median  fissure.  This  partition 
is  incomplete,  and  cribriform  in  structure, 
consisting  of  bundles  of  white  fibrous  tis- 
sue, interlacing  with  each  other.  The  vis- 
ceral layer  of  the  arachnoid  surrounds  the 
spinal  nerves  where  they  arise  from  the 
cord,  and  incloses  them  in  a  tubular  sheath 
as  far  as  their  point  of  exit  from  the  dura 
mater,  where  it  becomes  continuous  with 
the  parietal  layer. 

The  arachnoid  is  destitute  of  vessels.  No  nerves  have  as  yet  been  traced 
into  this  membrane. 

The  Pia  Mater  of  the  cord  is  exposed  on  the  removal  of  the  arachnoid 
(Fig.  320).  It  is  less  vascular  in  structure  than  the  pia  mater  of  the  brain,  with 
which  it  is  continuous,  being  thicker,  more  dense  in  structure,  and  composed 
of  fibrous  tissue,  arranged  in  longitudinal  bundles.  It  covers  the  entire  surface 
of  the  cord  to  which  it  is  very  intimately  adherent,  forming  its  neurilemma, 
and  sends  a  process  downwards  into  its  anterior  fissure,  and  another,  extremely 
delicate,  into  the  posterior  fissure.  It  also  forms  a  sheath  for  each  of  the  fila- 
ments of  the  spinal  nerves,  and  invests  the  nerves  themselves.     A  longitudinal 

'  Kijlliker  denies  that  the  inner  surface  of  the  dura  mater  is  covered  by  an  outer  layer  of  the 
arachnoid,  and  states  that  nothing  is  found  here  except  an  epithelial  layer,  no  trace  of  a  special 
membrane  existing. 


Fig.  321. — Transverse  Section  of  the 
Spinal  Cord  and  its  Membranes. 


5U  NERVOUS    SYSTEM. 

fibrous  band  extends  along  the  middle  line  on  its  anterior  surface,  called  by 
Haller  the  linea  splendens;  and  a  somewhat  similar  band,  the  ligamentum 
denticulatum,  is  situated  on  each  side.  At  the  point  where  the  cord  terminates, 
the  pia  mater  becomes  contracted,  and  is  continued  down  as  a  long,  slender 
filament  {filum  terminale),  which  descends  through  the  centre  of  the  mass  of 
nerves  forming  the  cauda  equina,  and  is  blended  with  the  impervious  sheath 
of  dura  mater,  on  a  level  with  the  top  of  the  sacral  canal.  It  assists  in  main- 
taining the  cord  in  its  position  during  the  movements  of  the  trunk,  and  is, 
from  this  circumstance,  called  the  central  ligament  of  the  spinal  cord.  It 
contains  a  little  nervous  substance,  which  may  be  traced  for  some  distance  into 
its  upper  part,  and  is  accompanied  by  a  small  artery  and  vein. 

Structvre.  The  pia  mater  of  the  cord,  though  less  vascular  than  that  which 
invests  the  brain,  contains  a  network  of  delicate  vessels  in  its  substance.  It  is 
also  supplied  with  nerves,  which  are  derived  from  the  sympathetic,  and  from 
the  posterior  roots  of  the  spinal  nerves.  At  the  upper  part  of  the  cord,  the  pia 
mater  presents  a  grayish,  mottled  tint,  which  is  owing  to  yellowish  or  brown 
pigment  cells  being  scattered  within  its  tissue. 

The  Ligamentum  Denticulaium  (Fig.  320)  is  a  narrow,  fibrous  band,  situated 
on  each  side  of  the  spinal  cord,  throughout  its  entire  length,  and  separating  the 
anterior  from  the  posterior  roots  of  the  spinal  nerves,  having  received  its  name 
from  the  serrated  appearance  which  it  presents.  Its  inner  border  is  continuous 
with  the  pia  mater,  at  the  side  of  the  cord.  Its  outer  border  presents  a  series 
of  triangular,  dentated  serrations,  the  points  of  which  are  fixed,  at  intervals,  to 
the  dura  mater,  serving  to  unite  together  the  two  layers  of  the  arachnoid  mem- 
brane. These  serrations  are  about  twenty  in  number,  on  each  side,  the  first 
being  attached  to  the  dura  mater,  opposite  the  margin  of  the  foramen  magnum, 
between  the  vertebral  artery  and  the  hypoglossal  nerve;  and  the  last  near  the 
lower  end  of  the  cord.  Its  use  is  to  support  the  cord  in  the  fluid  by  which  it 
is  surrounded. 

The  Spinal  Cord. 

The  Spinal  Cord  {medulla  Spinalis)  is  the  cylindrical  elongated  part  of  the 
cerebro-spinal  axis,  which  is  contained  in  the  spinal  canal.  Its  length  is 
usually  about  sixteen  or  seventeen  inches,  and  its  weight,  when  divested  of  its 
membranes  and  nerves,  about  one  ounce  and  a  half,  its  proportion  to  the  ence- 
phalon  being  about  one  to  thirty-three.  It  does  not  nearly  fill  the  canal  in 
which  it  is  contained,  its  investing  membranes  being  separated  from  the  sur- 
rounding walls  by  areolar  tissue  and  a  plexus  of  veins.  It  occupies,  in  the 
adult,  the  upper  two-thirds  of  the  spinal  canal,  extending  from  the  foramen 
magnum  to  the  lower  border  of  the  body  of  the  first  lumbar  vertebra,  where  it 
terminates  in  a  slender  filament  of  gray  substance,  which  is  continued  for  some 
distance  into  the  filnm  ierminale.  In  the  foetus,  before  the  third  month,  it 
extends  to  the  bottom  of  the  sacral  canal;  but,  after  this  period,  it  gradually 
recedes  from  below,  as  the  growth  of  the  bones  composing  the  canal  is  more 
rapid  in  proportion  than  that  of  the  cord;  so  that,  in  the  child  at  birth,  the 
cord  extends  as  far  as  the  third  lumbar  vertebra.  Its  position  varies  also 
according  to  the  degree  of  curvature  of  the  spinal  column,  being  raised  some-™ 
what  in  flexion  of  the  spine.  On  examining  its  surface,  it  presents  a  differenceij 
in  its  diameter  in  different  parts,  being  marked  by  two  enlargements,  an  upper 
or  cervical,  and  a  lower  or  lumbar.  The  cervical  enlargement,  which  is  the 
larger,  extends  from  the  third  cervical  to  the  first  dorsal  vertebra:  its  greatest 
diameter  is  in  the  transverse  direction,  and  it  corresponds  with  the  origin  of  the 
nerves  which  supply  the  upper  extremities.  The  lower,  or  lumbar  enlarge- 
ment, is  situated  opposite  the  last  dorsal  vertebra,  its  greatest  diameter  being 
from  before  backwards.  It  corresponds  with  the  origin  of  the  nerves  which 
supply  the  lower  extremities.  In  form,  the  spinal  cord  is  a  flattened  cylinder. 
It  presents,  on  its  anterior  surface,  along  the  middle  line,  a  longitudinal  fissure, 


SPINAL    CORD. 


575 


Fig.  322.  — Spinal  Cord. 
Side  View.  Plan  of  the  Fis- 
sures and  Columns. 


PMft-rntr 


tbe  anterior  median  fissure;  and,  on  its  posterior  surface,  another  fissure,  which 
also  extends  along  the  entire  length  of  the  cord,  the  posterior  median  fissure. 
These  fissures  serve  to  divide  the  cord  into  two  symmetrical  halves,  which  are 
united  in  the  middle  line,  throughout  their  entire  length,  by  a  transverse  band 
of  nervous  substance,  the  commissure. 

The  anterior  median  fissure  is  wider,  but  of  less  depth  than  the  posterior, 
extending  into  the  cord  for  about  one-third  of  its  thickness,  and  is  deepest  at 
the  lower  part  of  the  cord.  It  contains  a  prolongation  from  the  pia  mater;  and 
its  floor  is  formed  by  the  anterior  white  commissure,  which  is  perforated  by 
numerous  bloodvessels,  passing  to  the  centre  of  the  cord. 

The  2)osterior  Tuedian  fissure  is  much  more  delicate  than  the  anterior,  and  most 
distinct  at  the  upper  and  lower  parts  of  the  cord.  It  extends  into  the  cord  to 
about  one-half  of  its  depth.  It  contains  a  very  slen- 
der process  of  the  pia  mater,  and  numerous  blood- 
vessels, and  its  floor  is  formed  by  a  thin  layer  of 
white  substance,  the  posterior  white  commissure. 
Some  anatomists  state,  that  the  bottom  of  this  fissure 
corresponds  to  the  gray  matter,  except  in  the  cervical 
region,  and  at  a  point  corresponding  to  the  enlarge- 
ment in  the  lumbar  region. 

Lateral  Fissures.  On  either  side  of  the  anterior 
median  fissure,  a  linear  series  of  foramina  may  be 
observed,  indicating  the  points  where  the  anterior 
roots  of  the  spinal  nerves  emerge  from  the  cord. 
This  is  called,  by  some  anatomists,  the  anterior 
lateral  fissure  of  the  cord,  although  no  actual  fissure 
exists  in  this  situation.  And  on  either  side  of  the 
posterior  median  fissure,  along  the  line  of  attachment 

of  the  posterior  roots  of  the  nerves,  a  delicate  fissure  may  be  seen,  leading 
down  to  the  gray  matter  which  approaches  the  surface  in  this  situation:  this  is 
called  the  posterior  lateral  fissure  of  the  spinal  cord.  On  the  posterior  surface 
of  the  spinal  cord,  on  either  side  of  the  posterior  median  fissure,  is  a  slight 
longitudinal  furrow,  marking  off  two  slender  tracts,  the  posterior  median 
columns.  These  are  most  distinct  in  the  cervical  region,  but  are  stated  by 
Foville  to  exist  throughout  the  whole  length  of  the  cord. 

Columns  of  the  Cord.  The  fissures  divide  each  half  of  the  spinal  cord  into 
four  columns,  an  anterior  column,  a  lateral  column,  a  posterior  column,  and  a 
posterior  median  column. 

The  anterior  column  includes  all  the  portion  of  the  cord  between  the  anterior 
median  fissure  and  the  anterior  lateral  fissure,  from  which  the  anterior  roots 
of  the  nerves  arise.  It  is  continuous  with  the  anterior  pyramid  of  the  medulla 
oblongata. 

The  lateral  cohimn,  the  largest  segment  of  the  cord,  includes  all  the  portion 
between  the  anterior  and  posterior  lateral  fissures.  It  is  continuous  with  the 
lateral  column  of  the  medulla.  By  some  anatomists,  the  anterior  and  lateral 
columns  are  included  together,  under  the  name  of  the  antero- lateral  column, 
which  forms  rather  more  than  two-thirds  of  the  entire  circumference  of  the  cord. 

The  posterior  column  is  situated  between  the  posterior  median  and  posterior 
lateral  fissures.     It  is  continuous  with  the  restiform  body  of  the  medulla. 

The  posterior  median  column  is  that  narrow  segment  of  the  cord  which  is  seen 
on  each  side  of  the  posterior  median  fissure,  usually  included  with  the  pre- 
ceding, as  the  posterior  column. 

Structure  of  the  Cord.  If  a  transverse  section  of  the  spinal  cord  be  made,  it 
will  be  seen  to  consist  of  white  and  gray  nervous  substance.  The  white  matter 
is  situated  externally,  and  constitutes  the  greater  part.  The  gray  substance 
occupies  the  centre,  and  is  so  arranged  as  to  present  on  the  surface  of  the  sec- 
tion two  crescentic  masses  placed  one  in  each  lateral  half  of  the  cord,  united 


576  NERVOUS    SYSTEM. 

together  by  a  transverse  band  of  gray  matter,  the  gray  commissure.  Each 
crescentic  mass  has  an  anterior  and  posterior  horn.  The  posterior  horn  is  long 
and  narrow,  and  approaches  the  surface  of  the  posterior  lateral  fissure,  near 
which  it  presents  a  slight  enlargement.  The  anterior  horn  is  short  and  thick, 
and  does  not  quite  reach  the  surface,  but  extends  towards  the  point  of  attach- 
ment of  the  anterior  roots  of  the  nerves.  Its  margin  presents  a  dentate  or  stel- 
late appearance.  Owing  to  the  projections  towards  the  surface  of  the  anterior 
and  posterior  horns  of  the  gray  matter,  each  half  of  the  cord  is  divided,  more 
or  leas  completely,  into  three  columns,  anterior,  middle,  and  posterior;  the 
anterior  and  middle  being  joined  to  form  the  antero-lateral  column,  as  the 
anterior  horn  does  not  quite  reach  the  surface. 

The  gray  commissure,  which  connects  the  two  crescentic  masses  of  gray 
matter,  is  separated  from  the  bottom  of  the  anterior  median  fissure  by  the  ante- 
rior white  commissure ;  and  from  the  bottom  of  the  posterior  fissure  by  the 
posterior  white  commissure.     The  gray  commissure   consists  of  a  transverse 

band  of  gray  matter,  and  of  white  fibres,  derived 

Fig.  323.— Transverse  Sections     from  the  opposite  half  of  the  cord  and  the  posterior 

01  me  i^ora.  roots  of  the  nerves.     The  anterior  commissure  is 

formed  of  fibres,  partly  from  the  anterior  column, 

and  partly  from  the  fibrils  of  the  anterior  roots  of 

the  spinal  nerve,  which  decussate  as  they  pass  across 

OfpctiuMUdU  4!f  ctrvieal  re^s     f^o"^  One  to  the  Other  side. 

The  mode  of  arrangement  of  the  gray  matter,  and 
its  amount  in  proportion  to  the  white,  vary  in  dif- 
ferent parts  of  the  cord.  Thus,  the  posterior  horns 
are  long  and  narrow,  in  the  cervical  region ;  short 

and  narrower  in  the  dorsal ;  short,  but  wider,  in  the 

ojffontt Middii  op DoTiai  rej*        lumbar  legiou.    In  the  cervical  region,  the  crescentic 

portions  are  small,  the  white  matter  more  abundant 
than  in  any  other  region  of  the  cord.  In  the  dorsal 
region,  the  gray  matter  is  least  developed,  the  white 

matter  being  also  small  in  quantity.     In  the  lumbar 

o/fotiu  Lumiarrtgion.  Tcgiou,  the  gray  matter  is  more  abundant  than  in 

any  other  region  of  the  cord.  Towards  the  lower 
end  of  the  cord,  the  white  matter  gradually  ceases.  The  crescentic  portions  of 
the  gray  matter  soon  blend  into  a  single  mass,  which  forms  the  only  constituent 
of  the  extreme  point  of  the  cord.  The  minute  anatomy  of  the  cord  is  described 
in  the  Introduction. 


The  Brain  and  its  Membranes. 

Dissection.  To  examine  the  brain  with  its  membranes,  the  skullcap  must  bo  removed.  In 
order  to  effect  this,  saw  through  the  external  table,  the  section  commencing,  in  front,  about  an 
inch  above  the  margin  of  the  orbit,  and  extending,  behind,  to  a  level  with  the  occipital  protube- 
rance. Then  break  the  internal  table  witli  the  chisel  and  hummer,  to  avoid  injuring  the  investing 
membranes  or  brain  ;  loosen,  and  forcildy  detach  the  skull,  when  the  dura  mator  will  be  exposed. 
The  adhesion  between  the  bone  and  the  dura  mater  is  very  intimate,  and  much  more  so  in  the 
young  subject  than  in  the  adult. 

Tlic  Membranes  of  the  Brain  are,  the  dura  mater,  arachnoid  membrane,  and 
pia  mater. 

Dura  Mater. 

The  Dura  Mater  is  a  thick  and  dense  inelastic  fibrous  membrane,  which  lines! 
the  interior  of  the  skull.  Its  outer  surface  is  rough  and  fibrillated,  and  adheres 
closely  to  the  inner  surface  of  the  bones,  forming  their  internal  periosteum,  this 
adhesion  being  more  intimate  opposite  the  sutures  and  at  the  base  of  the  skull ; 
at  the  margin  of  the  foramen  magnum,  it  becomes  continuous  with  the  dura 
matoi    lining  the  spinal  canal.     Its  inner  surface  is  smooth  and  epitheliated, 


I 


DURA    MATER.  671 

being  lined  by  the  parietal  layer  of  the  arachnoid.  The  dura  mater  is,  there- 
fore, a  fibro-serous  membrane,  composed  of  an  external  fibrous  lamella,  and  an 
internal  serous  layer.  It  sends  numerous  processes  inwards,  into  the  cavity  of 
the  skull,  for  the  support  and  protection  of  the  dift'erent  parts  of  the  brain;  and 
is  prolonged  to  the  outer  surface  of  the  skull,  through  the  various  foramina 
which  exist  at  the  base,  and  thus  becomes  continuous  with  the  pericranium  ;  its 
fibrous  layer  forms  sheaths  for  the  nerves  which  pass  through  these  apertures. 
At  the  base  of  the  skull,  it  sends  a  fibrous  prolongation  into  the  foramen  caecum ; 
it  lines  the  olfactory  groove,  and  sends  a  series  of  tubular  prolongations  round 
the  filaments  of  the  olfactory  nerves  as  they  pass  through  the  cribriform  plate; 
a  prolongation  is  also  continued  through  the  sphenoidal  fissure  into  the  orbit, 
and  another  is  continued  into  the  same  cavity  through  the  optic  foramen,  form- 
ing a  sheath  for  the  optic  nerve,  which  is  continued  as  far  as  the  eyeball.  In 
certain  situations  in  the  skull  already  mentioned,  the  fibrous  layers  of  this 
membrane  separate,  to  form  sinuses,  for  the  passage  of  venous  blood.  Upon 
the  upper  surface  of  the  dura  mater,  in  the  situation  of  the  longitudinal  sinus, 
may  be  seen  numerous  small  whitish  bodies,  the  glandulse  Pacchioni. 

Structure.  The  dura  mater  consists  of  white  fibrous  and  elastic  tissues,  ar- 
ranged in  flattened  laminae,  which  intersect  one  another  in  every  direction. 

Its  arteries  are  very  numerous,  but  are  chiefly  distributed  to  the  bones.  Those 
found  in  the  anterior  fossa,  are  the  anterior  meningeal,  branches  of  the  anterior 
and  posterior  ethmoidal,  and  internal  carotid.  In  the  middle  fossa  are  the 
middle  and  small  meningeal,  branches  from  the  internal  maxillary,  and  a  third 
branch  from  the  ascending  pharyngeal,  which  enters  the  skull  through  the  fora- 
men lacerum  basis  cranii.  In  the  posterior  fossa,  are  the  meningeal  branch  of 
the  occipital,  which  enters  the  skull  through  the  jugular  foramen  ;  the  posterior 
meningeal,  from  the  vertebral ;  and  occasionally  meningeal  branches  from  the 
ascending  pharyngeal,  which  enter  the  skull,  one  at  the  jugular  foramen,  the 
other  at  the  anterior  condyloid  foramen. 

The  veins^  which  return  the  blood  from  the  dura  mater,  and  partly  from  the 
bones,  anastomose  with  the  diploic  veins.  These  vessels  terminate  in  the  various 
sinuses,  with  the  exception  of  two  which  accompany  the  middle  meningeal 
artery,  and  pass  out  of  the  skull  at  the  foramen  spinosum. 

The  nerves  of  the  dura  mater  are,  the  recurrent  branch  of  the  fourth,  and 
filaments  from  the  Casserian  ganglion,  from  the  ophthalmic  nerve,  and  from  the 
sympathetic. 

The  so-called  gland ulas  Pacchioni  are  numerous  small  whitish  granulations, 
usually  collected  into  clusters  of  variable  size,  which  are  found  in  the  following 
situations :  1.  Upon  the  outer  surface  of  the  dura  mater,  in  the  vicinity  of  the 
superior  longitudinal  sinus,  being  received  into  little  depressions  on  the  inner 
surface  of  the  calvarium.  2.  On  the  inner  surface  of  the  dura  mater.  3.  In 
the  superior  longitudinal  sinus.  4.  On  the  pia  mater  near  the  margin  of  the 
hemispheres. 

These  bodies  are  not  glandular  in  structure,  but  consist  of  a  fibro-cellular 
matrix,  originally  developed  from  the  pia  mater;  by  their  growth,  they  produce 
absorption  or  separation  of  the  fibres  of  the  dura  mater ;  in  a  similar  manner 
they  make  their  way  into  the  superior  longitudinal  sinus,  where  they  are  covered 
by  the  lining  membrane.  The  cerebral  layer  of  the  arachnoid  in  the  situation 
of  these  growths  is  usually  thickened  and  opaque,  and  adherent  to  the  parietal 
portion. 

These  bodies  are  not  found  in  infancy,  and  very  rarely  until  the  third  year. 
They  are  usually  found  after  the  seventh  year ;  and  from  this  period  they  in- 
crease in  number  as  age  advances.     Occasionally  they  are  wanting. 

Processes  of  the  Dura  Mater.     The  processes  of  the  dura  mater,  sent  inwards 
into  the  cavity  of  the  skull,  are  three  in  number,  the  falx  cerebri,  the  tentorium 
cerebelli,  and  the  falx  cerebelli. 
87 


57S  NERVOUS    SYSTEM. 

The/a?x  cerebri,  so  named  from  its  sickle-like  form,  is  a  strong  arched  process 
of  the  dura  mater,  which  descends  vertically  in  the  longitudinal  fissure  between 
the  two  hemispheres  of  the  brain.  It  is  narrow  in  front,  where  it  is  attached 
to  the  crista  galli  process  of  the  ethmoid  bone ;  and  broad  behind,  where  it  is 
connected  with  the  upper  surface  of  the  tentorium.  Its  upper  margin  is  con- 
vex, and  attached  to  the  inner  surface  of  the  skull  as  far  back  as  the  internal 
occipital  protuberance.  In  this  situation  it  is  broad,  and  contains  the  superior 
longitudinal  sinus.  Its  lower  margin  is  free,  concave,  and  presents  a  sharp 
curved  edge,  which  contains  the  inferior  longitudinal  sinus. 

The  tentorium  cerebeUi  is  an  arched  lamina  of  dura  mater,  elevated  in  the 
middle,  and  inclining  downwards  towards  the  circumference.  It  covers  the 
upper  surface  of  the  cerebellum,  supporting  the  posterior  lobes  of  the  brain, 
and  preventing  their  pressure  upon  it.  It  is  attached,  behind,  by  its  convex 
border,  to  the  transverse  ridges  upon  the  inner  surface  of  the  occipital  bone, 
and  there  incloses  the  lateral  sinuses ;  in  front,  to  the  superior  margin  of  the 
petrous  portion  of  the  temporal  bone,  inclosing  the  superior  petrosal  sinuses, 
and  from  the  apex  of  this  bone,  on  each  side,  is  continued  to  the  anterior  and 
posterior  clinoid  processes.  Along  the  middle  line  of  its  upper  surface,  the 
posterior  border  of  the  falx  cerebri  is  attached,  the  straight  sinus  being  placed 
at  their  point  of  junction.  Its  anterior  border  is  free  and  concave,  and  presents 
a  large  oval  opening  for  the  transmission  of  the  crura  cerebri. 

The  falx  cerebeUi  is  a  small  triangular  process  of  dura  mater,  received  into 
the  indentation  between  the  two  lateral  lobes  of  the  cerebellum  behind.  Its 
base  is  attached,  above,  to  the  under  and  back  part  of  the  tentorium ;  its  pos- 
terior margin,  to  the  lower  division  of  the  vertical  crest  on  the  inner  surface 
of  the  occipital  bone.  As  it  descends,  it  sometimes  divides  into  two  smaller 
folds,  which  are  lost  on  the  sides  of  the  foramen  magnum. 

Arachnoid  Membrane. 

The  Arachnoid  (dpa^vj?,  tUof,  like  a  spider^s  web),  so  named  from  its  extreme 
thinness,  is  the  serous  membrane  which  envelops  the  brain,  and  is  then  reflected 
on  the  inner  surface  of  the  dura  mater.  Like  other  serous  membranes,  it  is  a 
shut  sac,  and  consists  of  a  parietal  and  a  visceral  layer. 

The  parietal  layer  covers  the  inner  surface  of  the  dura  mater,'  and  gives  that 
membrane  its  smooth  and  polished  surface ;  it  is  also  reflected  over  those  pro- 
cesses which  separate  the  hemispheres  of  the  brain  and  cerebellum. 

The  visceral  layer  invests  the  brain  more  loosely,  being  separated  from  direct 
contact  with  the  cerebral  substance  by  the  pia  mater,  and  a  quantity  of  loose 
areolar  tissue,  the  subarachnoidean.  On  the  upper  surface  of  the  cerebrum,  the 
arachnoid  is  thin  and  transparent,  and  may  be  easily  demonstrated  by  injecting, 
a  stream  of  air  beneath  it  by  means  of  a  blowpipe;  it  passes  over  the  convolu- 
tions without  dipping  down  into  the  sulci  between  them.  At  the  base  of  the 
brain  the  arachnoid  is  thicker,  and  slightly  opaque  towards  the  central  part;  it 
covers  the  anterior  lobes,  and  is  extended  across  between  the  two  middle  lobes, 
so  as  to  leave  a  considerable  interval  between  it  and  the  brain,  the  anterior  sub- 
arachnoidean space ;  it  is  closely  adherent  to  the  pons  and  under  surface  of  the 
cerebellum;  but  between  the  hemispheres  of  the  cerebellum  and  the  medulla 
oblongata  another  considerable  interval  is  left  between  it  and  tlic  brain,  called 
the  posterior  subarachnoidean  space.  These  two  spaces  communicate  together 
across  the  crura  cerebri.  The  arachnoid  membrane  surrounds  the  nerves  which 
arise  from  the  brain,  and  incloses  them  in  loose  sheaths  as  far  as  their  point  of 
exit  from  the  skull,  where  it  becomes  continuous  with  the  parietal  layer. 

'  l?{>llikcr  denies  this;  and  states,  that  the  inner  surface  of  the  dura  mater  is  covered  with 
pavement  epithelium,  but  has  no  other  iovestment  which  can  be  regarded  as  a  parietal  layer  of 
the  arachnoid. 


1 

I 


I 


PIA    MATER  — THE    BRAIN.  579 

The  subarachnoid  space  is  the  interval  between  the  arachnoid  and  pia  mater: 
this  space  is  narrow  on  the  surface  of  the  hemispheres ;  but  at  the  base  of  the 
brain  a  wide  interval  is  left  between  the  two  middle  lobes,  and  behind,  between 
tbe  hemispheres  of  the  cerebellum  and  the  medulla  oblongata.  This  space  is 
the  seat  of  an  abundant  serous  secretion,  the  cerebro-spinal  fluid,  which  fills  up 
the  interval  between  the  arachnoid  and  pia  mater.  The  subarachnoid  space 
usually  communicates  with  the  general  ventricular  cavity  of  the  brain  by  means 
of  an  opening  in  the  inferior  boundary  of  the  fourth  ventricle. 

The  sac  of  the  arachnoid  also  contains  serous  fluid;  this  is,  however,  small 
in  quantity  compared  with  the  cerebro-spinal  fluid. 

Structure.  The  arachnoid  consists  of  bundles  of  white  fibrous  and  elastic 
tissues  intimately  blended  together.  Its  outer  surface  is  covered  with  a  layer 
of  scaly  epithelium.  It  is  destitute  of  vessels,  and  the  existence  of  nerves  in 
it  has  not  been  satisfactorily  demonstrated. 

The  cerebro-spinal  fluid  fills  up  the  subarachnoid  space,  keeping  the  opposed 
surfaces  of  the  arachnoid  membrane  in  contact.  It  is  a  clear,  limpid  fluid, 
having  a  saltish  taste,  and  a  slightly  alkaline  reaction.  According  to  Lassaigne, 
it  consists  of  98.5  parts  of  water,  the  remaining  1.5  per  cent,  being  solid  matters, 
animal  and  saline.  It  varies  in  quantity,  being  most  abundant  in  old  persons, 
and  is  quickly  reproduced.  Its  chief  use  is  probably  to  afford  mechanical 
protection  to  the  nervous  centres,  and  to  prevent  the  effects  of  concussions 
communicated  from  without. 

Pia  Mater. 

The  Pia  Mater  is  a  vascular  membrane,  and  derives  its  blood  from  the  internal 
carotid  and  vertebral  arteries.  It  consists  of  a  minute  plexus  of  bloodvessels, 
held  together  by  an  extremely  fine  areolar  tissue.  It  invests  the  entire  surface 
of  the  brain,  dipping  down  between  the  convolutions  and  laminae,  and  is  pro- 
longed into  the  interior,  forming  the  velum  interpositum  and  choroid  plexuses 
of  the  fourth  ventricle.  Upon  the  surfaces  of  the  hemispheres,  Avhere  it  covers 
the  gray  matter  of  the  convolutions,  it  is  very  vascular,  and  gives  off  from  its 
inner  surface  a  multitude  of  minute  vessels,  which  extend  perpendicularly  for 
some  distance  into  the  cerebral  substance.  At  the  base  of  the  brain,  in  the 
situation  of  the  substantia  perforata  and  locus  perforatus,  a  number  of  long 
straight  vessels  are  given  off*  which  pass  through  the  white  matter  to  reach  the 
gray  substance  in  the  interior.  On  the  cerebellum  the  membrane  is  more  deli- 
cate, and  the  vessels  from  its  inner  surface  are  shorter.  Upon  the  crura  cerebri 
and  pons  Varolii  its  characters  are  altogether  changed ;  it  here  presents  a  dense 
fibrous  structure,  marked  only  by  slight  traces  of  vascularity. 

According  to  Fohmann  and  Arnold,  this  membrane  contains  numerous  lym- 
phatic vessels.  Its  nerves  are  derived  from  the  sympathetic,  and  also  from  the 
third,  sixth,  seventh,  eighth,  and  spinal  accessory.  They  accompany  the  branches 
of  the  arteries. 

-The  Brain.- 

The  Brain  (encephalon)  is  that  .portion  of  the  cerebro-spinal  axis  that  is  con- 
tained in  the  cranial  cavity.  It  is  divided  into  four  principal  parts:  viz.,  the 
cerebrum,  the  cerebellum,  the  pons  Varolii,  and  medulla  oblongata. 

The  cerebrum  forms  the  largest  portion  of  the  encephalon,  and  occupies  a 
considerable  part  of  the  cavity  of  the  cranium,  resting  in  the  anterior  and  middle 
fossae  of  the  base  of  the  skull,  and  separated  posteriorly  from  the  cerebellum  by 
the  tentorium  cerebelli.  About  the  middle  of  its  under  surface  is  a  narrow 
constricted  portion,  part  of  which,  the  crura  cerebri,  is  continued  onwards  into 
the  ])ons  Varolii  below,  and  through  it  to  the  medulhi  oblongata  and  spinal  cord; 
whilst  another  portion,  the  crura  cerebelli,  passes  down  into  the  cerebellum. 


580  NERVOUS    SYSTEM. 

The  cerehellum  (little  brain  or  after  brain)  is  situated  in  the  inferior  occipital 
fossas,  being  separated  from  the  under  surface  of  the  posterior  lobes  of  the 
cerebrum  by  the  tentorium  cerebelli.  It  is  connected  to  the  rest  of  the  en- 
cephalon  by  means  of  connecting  bands,  called  crura:  of  these,  two  ascend  to 
the  cerebrum,  two  descend  to  the  medulla  oblongata,  and  two  blend  together 
in  front,  forming  the  pons  Varolii. 

The  pons  Varolii  is  that  portion  of  the  encephaloa  which  rests  upon  the 
upper  part  of  the  basilar  process.  It  constitutes  the  bond  of  union  of  the 
various  segments  above  named,  receiving,  above,  the  crura  from  the  cere- 
brum; at  the  sides,  the  crura  from  the  cerebellum;  and  below,  the  medulla 
oblongata. 

The  medulla  oblongata  extends  from  the  lower  border  of  the  pons  Varolii  to 
the  upper  part  of  the  spinal  cord.  It  lies  beneath  the  cerebellum,  resting  on 
the  lower  part  of  the  basilar  groove  of  the  occipital  bone. 

Weight  of  the  encephalon.  The  average  weight  of  the  brain,  in  the  adult  male, 
is  49.^  oz.,  or  little  more  than  3  lb.  avoirdupois;  that  of  the  female,  44  oz.;  the 
average  difference  between  the  two  being  from  5  to  6  oz.  The  prevailing 
weight  of  the  brain,  in  the  male,  ranges  between  46  oz.  and  53  oz. ;  and,  in  the 
female,  between  41  oz.  and  47  oz.  In  the  male,  the  maximum  weight  out  of 
278  cases  was  65  oz.,  and  the  minimum  weight  34  oz.  The  maximum  weight 
of  the  adult  female  brain,  out  of  191  cases,  was  56  oz.,  and  the  minimum  weight 
81  oz.  It  appears  that  the  weight  of  the  brain  increases  rapidly  up  to  the 
seventh  year,  more  slowly  to  between  sixteen  and  twentj'-,  and  still  more  slowly 
to  between  thirty  and  forty,  when  it  reaches  its  maximum.  Beyond  this  period, 
as  age  advances  and  the  mental  faculties  decline,  the  brain  diminishes  slowly 
in  weight,  about  an  ounce  for  each  subsequent  decennial  period.  These  results 
apply  alike  to  both  sexes. 

The  size  of  the  brain  appears  to  bear  a  general  relation  to  the  intellectual 
capacity  of  the  individual.  Cuvier's  brain  weighed  rather  more  than  64  oz., 
that  of  the  late  Dr.  Abercrombie  63  oz.,  and  that  of  Dupuytren  62 i  oz.  On 
the  other  hand,  the  brain  of  an  idiot  seldom  weighs  more  than  23  oz. 

The  human  brain  is  heavier  than  that  of  all  the  lower  animals  excepting  the 
elephant  and  whale.  The  brain  of  the  former  weighs  from  8  lb.  to  10  lb. ; 
and  that  of  the  whale,  in  a  specimen  seventy-five  feet  long,  weighed  rather 
more  than  5  lb. 

Medulla  Oblongata. 

The  Medulla  Oblongata  is  the  upper  enlarged  part  of  the  spinal  cord,  am 
extends  from  the  upper  border  of  the  atlas  to  the  lower  border  of  the  pons^ 
Varolii.  It  is  directed  obliquely  downwards  and  backwards;  its  anterior  sur-' 
face  rests  on  the  basilar  groove  of  the  occipital  bone,  its  posterior  surface  is 
received  into  the  fossa  between  the  hemispheres  of  the  cerebellum,  forming  the' 
floor  of  the  fourth  ventricle.  It  is  pyramidal  in  form,  its  broad  extremity 
directed  upwards,  its  lower  end  being  narrow  at  its  point  of  connection  with 
the  cord.  It  measures  an  inch  and  a  quarter  in  length,  three-quarters  of  an 
inch  in  breadth  at  its  widest  part,  and  half  an  inch  in  thickness.  Its  surface  is 
marked,  in  the  median  line,  in  front  and  behind,  by  an  anterior  and  posterior 
median  fissure,  which  are  continuous  with  those  of  the  spinal  cord.  The  an- 
terior fissure  contains  a  fold  of  pia  mater,  and  terminates  just  below  the  pons 
in  a  cul-de-saCy  the  foramen  caecum.  The  posterior  is  a  deep  but  narrow  fissure, 
continued  upwards  along  the  floor  of  the  fourth  ventricle,  where  it  is  finally 
lost.  These  two  fissures  divide  the  medulla  into  two  symmetrical  halves,  each 
lateral  half  being  subdivided  by  minor  grooves  into  four  columns,  which,  from 
before  backwards,  are  named  the  anterior  pyramid^  lateral  tract  and  olivary  body, 
the  resti/orm  body,  the  posterior  j^yramid. 


I 


MEDULLA    OBLONGATA. 


581 


Fig.  324. — Medulla  Oblongata  and 
Pons  Varolii.     Anterior  Surface. 


Fig.  32.0. — Posterior  Surface  of 
Medulla  Oblonofata. 


The  anterior  pyramids,  or  corpora  pyramidalia,  are  two  pyramidal-shaped 
bundles  of  whit^e  matter,  placed  one  on  either  side  of  the  anterior  median 
fissure,  and  separated  from  the  olivary  body, 
which  is  external  to  them,  by  a  slight  depres- 
sion. At  the  lower  border  of  the  pons  they 
are  somewhat  constricted ;  they  then  become 
enlarged,  and  taper  slightly  as  they  descend, 
being  continuous  below  with  the  anterior  co- 
lumns of  the  cord.  On  separating  the  pyra- 
mids below,  it  will  be  observed  that  their  in- 
nermost fibres  form  from  four  to  five  bundles  on 
each  side,  which  decussate  with  one  another ; 
this  decussation,  however,  is  not  formed  en- 
tirely of  fibres  from  the  pyramids,  but  mainly 
from  the  deep  portion  of  the  lateral  columns 
of  the  cord  which  pass  forwards  to  the  surface 
between  the  diverging  anterior  columns.  The 
outermost  fibres  do  not  decussate;  they  are  de- 
rived from  the  anterior  columns  of  the  cord, 
and  are  continued  directly  upwards  through  the 
pons  Varolii. 

Lateral  tract  and  olivary  body.     The   lateral 
tract  is  continuous  with  the  lateral  column  of 

the  cord.     Below,  it  is  broad,  and  includes  that  part  of  the  medulla  between 
the  anterior  pyramid  and  restiform  body ;  but,  above,  it  is  pushed  a  little  back- 
wards, and  narrowed  by  the  projection  forwards 
of  the  olivary  body. 

The  olivary  bodies  are  two  prominent,  oval  masses, 
situated  behind  the  anterior  pyramids,  from  which 
they  are  separated  by  slight  grooves.  They 
equal,  in  breadth,  the  anterior  pyramids,  are  a 
little  broader  above  than  below,  and  are  about 
half  an  inch  in  length,  being  separated,  above, 
from  the  pons  Varolii  by  a  slight  depression. 
Numerous  white  fibres  {fihrse  arci/ormes)  are  seen 
winding  round  the  lower  end  of  each  body  ;  some- 
times crossing  their  surface. 

The  restiform  bodies  (Fig.  325)  are  the  largest 
columns  of  the  medulla,  and  continuous,  below, 
with  the  posterior  columns  of  the  cord.  They 
are  two  rounded,  cord-like  eminences,  placed  be- 
tween the  lateral  tracts,  in  front,  and  the  posterior 
pyramids,  behind ;  from  both  of  which  they  are 
separated  by  slight  grooves.  As  they  ascend, 
they  diverge  from  each  other,  assist  in  forming 
the  lateral  boundaries  of  the  fourth  ventricle,  and 
then  enter  the  corresponding  hemisphere  of  the 
cerebellum,  forming  its  inferior  peduncle ;  it 
is  probable  that  some  fibres  are  continued  from 
the  restiform  bodies  into  the  cerebrum. 

The  posterior  pyramids  [fasciculi  graciles)  are  two  narrow,  white  cords,  placed 
one  on  each  side  of  the  posterior  median  fissure,  and  separated  from  the  resti- 
form bodies  by  a  narrow  groove.  They  consist  entirely  of  white  fibres,  and 
are  continuous  with  the  posterior  median  columns  of  the  spinal  cord.  These 
bodies  lie,  at  first,  in  close  contact.  Opposite  the  apex  of  the  fourth  ventricle 
they  form  an  enlargement  {processus  clavatus),  and  then,  diverging,  are  lost  in 


582  NERYOUS    SYSTEM. 

the  corresponding  restiform  body.     The  upper  part  of  the  posterior  pyramids 
forms  the  lateral  boundaries  of  the  calamus  scriptorius. 

The  poste)-ior  surface  of  the  medulla  oblongata  forms  part  of  the  floor  of  the 
fourth  ventricle.  It  is  of  a  triangular  form,  bounded  on  each  side  by  the  di- 
verging posterior  pyramids,  and  is  that  part  of  the  ventricle  which,  from  its 
resemblance  to  the  point  of  a  pen,  is  called  the  calavius  scrijHot'ius.  The  diver- 
gence of  the  posterior  pyramids  and  restiform  bodies,  opens  to  view  the  gray 
matter  of  the  medulla,  which  is  continuous,  below,  with  the  gray  commissure 
of  the  cord.  In  the  middle  line  is  seen  a  longitudinal  furrow,  continuous  with 
the  posterior  median  fissure  of  the  cord,  terminating,  below,  at  the  point  of  the 
ventricle,  in  a  cul-de-sac,  the  ventricle  of  Arantius,  which  descends  into  the 
medulla  for  a  slight  extent.  It  is  the  remains  of  a  canal,  which,  in  the  foetus, 
extends  throughout  the  entire  length  of  the  cord. 

Structure.  The  columns  of  the  cord  are  directly  continuous  with  those  of  the 
medulla  oblongata,  below  ;  but,  higher  up,  both  the  white  and  gray  constituents 
are  rearranged  before  they  are  continued  upwards  to  the  cerebrum  and  cere- 
bellum. 

The  anterior  pyramid  is  composed  of  fibres  derived  from  the  anterior  column 
of  the  cord  of  its  own  side,  and  from  the  lateral  column  of  the  opposite  half  of 
the  cord,  and  is  continued  upwards  into  the  cerebrum  and  cerebellum.  The 
cerebellar  fibres  form  a  superficial  and  deep  layer,  which  pass  beneath  the 
olivary  body  to  the  restiform  body,  and  spread  out  into  the  structure  of  the 
cerebellum.  A  deeper  fasciculus  incloses  the  olivary  body,  and,  receiving  fibres 
from  it,  enters  the  pons  as  the  olivary  fasciculus  or  fillet;  but  the  chief  mass 
of  fibres  from  the  pyramid,  the  cerebral  fibres,  enter  the  pons  in  their  passage 
upwards  to  the  cerebrum.     The  anterior  pyramids  contain  no  gray  matter. 

The  lateral  tract  is  continuous,  below,  with  the  lateral  column  of  the  cord. 
Its  fibres  pass  in  three  different  directions.  The  most  external  join  the  resti- 
form body,  and  pass  to  the  cerebellum.  The  internal,  more  numerous,  pass 
forwards,  pushing  aside  the  fibres  of  the  anterior  column,  and  form  part  of  the 
opposite  anterior  pyramid.  The  middle  fibres  ascend,  beneath  the  olivary  body, 
to  the  cerebrum,  passing  along  the  back  of  the  pons,  and  form,  together  with 

fibres  from  the   restiform    body,  the   fasciculi 
^^°'  ^^Ml'^l^'obl'^^a^'^^*^^"  °^      teretes,  in  the  floor  of  the  fourth  ventricle. 

'^!^^T,r»M  Olivary  body.     If  a  transverse  section  is  made 

fk,i,rttrr/.nr,^  ^  '^  tlirougli  cithcr  olivary  body,  it  will  be  found  to 

consist  of  a  small  ganglionic  mass,  deeply  im- 
bedded in  the  medulla,  partly  appearing  on  the 
surface  as  a  smooth,  olive-shaped  eminence  (Fig. 
326).  It  consists,  externally,  of  white  substance; 
j»t«-.«- xu^r^       ^  A^trrior F-jr,u,a       aud,  iutemally,  of  a  gray   nucleus,  the  corpus 

dentatum.  The  gray  matter  is  arranged  in  the 
form  of  a  hollow  capsule,  open  at  its  upper  and  inner  part,  and  presenting  a 
zigzag,  or  dentated  outline.  White  fibres  pass  into,  or  from  the  interior  of 
this  body,  by  the  aperture  in  the  posterior  part  of  the  capsule.  They  join  with 
those  fibres  of  the  anterior  column  which  ascend  on  the  outer  side,  and  beneath 
the  olivary  body,  to  form  the  olivary  fasciculus,  which  ascends  to  the  cerebrum. 
The  restiform.  body  is  formed  chiefly  of  fibres  from  the  posterior  column  of 
the  cord;  but  it  receives  some  from  the  lateral  column,  and  a  fasciculus  from 
the  anterior,  and  is  continued,  upwards,  to  the  cerebrum  and  cerebellum.  On 
entering  the  pons,  it  divides  into  two  fasciculi,  above  the  point  of  the  fourth 
ventricle.  Tlie  external  fasciculus  enters  the  cerebellum :  the  inner  fasciculus 
joins  the  posterior  pyramid,  is  continued  up  along  the  fourth  ventricle,  and  is 
traced  up  to  the  cerebrum  with  the  fasciculi  teretes. 

Septum  of  the  medulla  oblongata.  Above  the  decussation  of  the  anterior  pyra- 
mids, numerous  white  fibres  extend,  from  behind  forwards,  in  the  median  line, 
forming  a  septum,  which  subdivides  the  medulla  into  two  lateral  halves.  Some 


STRUCTURE  OF  THE  MEDULLA  OBLONGATA. 


583 


of  these  fibres  emerge  at  the  anterior  median  fissure,  and  form  a  band  which 
curves  round  the  lower  border  of  the  olivary  body,  or  passes  transversely  across 
it,  and  round  the  sides  of  the  medulla,  forming  the  arciform  fibres  of  Eolando. 
Others  appear  in  the  floor  of  the  fourth  ventricle,  issuing  from  the  posterior 
median  fissure,  and  form  the  white  striae  in  that  situation. 


Fig  327. 


-The  Columns  of  the  Medulla  Oblongata,  and  their  connection  with  the  Cerebrum 
and  Cerebellum. 


Gray  matter  of  the  medulla  oblongata.  The  gray  matter  of  the  medulla  is  a 
continuation  of  that  contained  in  the  interior  of  the  spinal  cord,  besides  a  series 
of  special  deposits  or  nuclei. 

In  the  lower  part  of  the  medulla,  the  gray  matter  is  arranged  as  in  the  cord, 
but  at  the  upper  part  it  becomes  more  abundant,  and  is  disposed  with  less  appa- 
rent regularity,  becoming  blended  with  all  the  white  fibres,  except  the  anterior 
pyramids.  The  part  corresponding  to  the  transverse  gray  commissure  of  the 
cord  is  exposed  to  view  in  the  floor  of  the  medulla  oblongata,  by  the  diverg- 
ence of  the  restiform  bodies,  and  posterior  pyramids,  becoming  blended  with 
the  ascending  fibres  of  the  lateral  column,  and  thus  forming  the  fasciculi  teretes. 
The  lateral  crescentic  portions,  but  especially  the  posterior  horns,  become  en- 
larged, blend  with  the  fibres  of  the  restiform  bodies,  and  form  the  tuberculo 
cinereo  of  Rolando. 

Special  deposits  of  gray  matter  are  found  both  in  the  anterior  and  posterior 
parts  of  the  medulla;  forming,  in  the  former  situation,  the  corpus  dentatum 
within  the  olivary  body,  and,  in  the  latter,  a  series  of  special  masses,  or  nuclei, 
connected  with  the  roots  of  origin  of  the  spinal  accessory,  vagus,  glosso-pharyn- 
geal,  and  hypoglossal  nerves.  It  thus  appears  that  the  closest  analogy  in  struc- 
ture, and  also  probably  in  general  endowments,  exists  between  the  medulla 
oblongata  and  the  spinal  cord.  The  larger  size  and  peculiar  form  of  the  me- 
dulla depends  on  the  enlargement,  divergence,  and  decussation  of  the  various 
columns ;  and  also  on  the  addition  of  special  deposits  of  gray  matter  in  the 
olivary  bodies  and  other  parts,  evidently  in  adaptation  to  the  more  extended 
range  of  function  which  this  part  of  the  cerebro-spinal  axis  possesses. 


584  NERVOUS    SYSTEM. 


PONS  VAROLII. 


The  Pons  Varolii  {mesocephale,  Chaussier)  is  the  bond  of  union  of  the  various 
segments  of  the  encephalon,  connecting  the  cerebrum  above,  the  medulla  ob- 
longata below,  and  the  cerebellum  behind.  It  is  situated  above  the  medulla 
oblongata,  below  the  crura  cerebri,  and  between  the  hemispheres  of  the  cere- 
bellum. 

Its  under  surface  presents  a  broad  transverse  band  of  white  fibres,  which 
arches  like  a  bridge  across  the  upper  part  of  the  medullxi,  extending  between 
the  two  hemispheres  of  the  cerebellum.  This  surface  projects  considerably 
beyond  the  level  of  these  parts,  is  of  a  quadrangular  form,  rests  upon  the 
basilar  groove  of  the  occipital  bone,  and  is  limited  before  and  behind  by  very 
prominent  margins.  It  presents  along  the  middle  line  a  longitudinal  groove, 
wider  in  front  than  behind,  which  lodges  the  basilar  artery ;  numerous  trans- 
verse strise  are  also  observed  on  each  side,  which  indicate  the  course  of  its 
superficial  fibres. 

Its  upper  surface  forms  part  of  the  floor  of  the  fourth  ventricle,  and  at  each 
side  it  becomes  contracted  into  a  thick  rounded  cord,  the  crus  cerebelli,  which 
enters  the  substance  of  the  cerebellum,  constituting  its  middle  peduncle. 

Structure.  The  pons  Varolii  consists  of  alternate  layers  of  transverse  and 
longitudinal  fibres  intermixed  with  gray  matter  (Fig.  327). 

The  transverse  fibres  connect  together  the  two  lateral  hemispheres  of  the  cere- 
bellum, and  constitute  its  great  transverse  commissure.  They  consist  of  a  super- 
ficial and  a  deep  layer.  The  superficial  layer  passes  uninterruptedly  across  the 
surface  of  the  pons,  forming  a  uniform  layer,  which  consists  of  fibres  derived 
from  the  crus  cerebelli  on  each  side,  meeting  in  the  median  line.  The  deep 
layer  of  transverse  fibres  decussates  with  the  longitudinal  fibres  continued  up 
from  the  medulla,  and  contains  much  gray  matter  between  its  fibres. 

The  longitudinal  fibres  are  continued  up  through  the  pons.  1.  From  the  an- 
terior pyramid.  2.  From  the  olivary  body.  3.  From  the  lateral  and  posterior 
columns  of  the  cord,  receiving  special  fibres  from  the  gray  matter  of  the  pons 
itself. 

1.  The  fibres  from  the  anterior  pyramid  ascend  through  the  pons,  imbedded 
between  two  layers  of  transverse  fibres,  being  subdivided  in  their  course  into 
smaller  bundles  ;  at  the  upper  border  of  the  pons  they  enter  the  crus  cerebri, 
forming  its  fasciculated  portion. 

2.  The  olivary  fasciculus  divides  in  the  pons  into  two  bundles,  one  of  which 
ascends  to  the  corpora  quadrigemina ;  the  other  is  continued  to  the  cerebrum 
with  the  fibres  of  the  lateral  column. 

3.  The  fibres  from  the  lateral  and  posterior  columns  of  the  cord,  with  a  bundle 
from  the  olivary  fasciculus,  are  intermixed  with  much  gray  matter,  and  appear 
in  the  floor  of  the  fourth  ventricle  as  the  fasciculi  teretes ;  they  ascend  to  the 
deep  or  cerebral  part  of  the  crus  cerebri. 

Foville  believes  that  a  few  fibres  from  each  of  the  longitudinal  tracts  of  the 
medulla  turn  forwards,  and  are  continuous  with  the  transverse  fibres  of  the  pons. 

Septum.  The  pons  is  subdivided  into  two  lateral  halves  by  a  median  septum, 
which  extends  through  its  posterior  half.  The  septum  consists  of  antero-pos- 
terior  and  transverse  fibres.  The  former  are  derived  from  the  floor  of  the  fourth 
ventricle  and  from  the  transverse  fibres  of  the  pons,  which  bend  backwards 
before  passing  across  to  the  opposite  side.  The  latter  are  derived  from  the  floor 
of  the  fourth  ventricle;  they  pierce  the  longitudinal  fibres,  and  are  then  con- 
tinued across  from  one  to  the  other  side  of  the  medulla,  piercing  the  antero- 
posterior fibres.  The  two  halves  of  the  pons,  in  front,  are  connected  together 
by  transverse  commissural  fibres. 


CEREBRUM. 


5g5 


CEREBRUM. 
Upper  Surface.    (Fig.  328.) 

The  Cerebrum,  in  man,  constitutes  the  largest  portion  of  tlie  encephalon.  Its 
upper  surface  is  of  an  ovoidal  form,  broader  behind  than  in  front,  convex  in  its 
general  outline,  and  divided  into  two  lateral  halves  or  hemispheres,  right  and 
left,  by  the  great  longitudinal  fissure,  which  extends  throughout  the  entire  length 
of  the  cerebrum  in  the  middle  line,  reaching  down  to  the  base  of  the  brain  in 
front  and  behind,  but  interrupted  in  the  middle  by  a  broad  transverse  commis- 
sure of  white  matter,  the  corpus  callosum,  which  connects  the  two  hemispheres 
together.  This  fissure  lodges  the  falx  cerebri,  and  indicates  the  original  de- 
velopment of  the  brain  by  two  lateral  halves. 

Fig.  328. — Upper  Surface  of  the  Brain,  the  Pia  Mater  haviog  been  removed. 

Great  ZonffituJlnaT  JYaSunt 


Bach  hemisphere  presents  an  outer  surface,  which  is  convex,  to  correspond 
with  the  vault  of  the  cranium  ;  an  inner  surface,  flattened,  and  in  contact  with 
the  opposite  hemisphere  (the  two  inner  surfaces  forming  the  sides  of  the  longi- 
tudinal fissure) ;  and  an  under  surface  or  base,  of  more  irregular  form,  which 
rests,  in  front,  on  the  anterior  and  middle  fossa  at  the  base  of  the  skull,  and 
behind,  upon  the  tentorium. 

Convolutions.  If  the  pia  mater  is  removed  with  the  forceps,  the  entire  surface 
of  each  hemisphere  will  be  seen  to  present  a  number  of  convoluted  eminences, 
the  convolutions  separated  from  each  other  by  depressions  (sulci)  of  various 
depths.     The  outer  surface  of  each  convolution,  as  well  as  the  sides  and  bottom 


586  NERVOUS    SYSTEM. 

of  the  sulci  between  them,  is  composed  of  gray  matter,  which  is  here  called 
the  cortical  substance.  The  interior  of  each  convolution  is  composed  of  white 
matter ;  and  white  fibres  also  blend  with  the  gray  matter  at  the  sides  and  bottom 
of  the  sulci.  By  this  arrangement  the  convolutions  are  adapted  to  increase  the 
amount  of  gray  matter  without  occupying  much  additional  space,  while  they 
also  afford  a  greater  extent  of  surface  for  the  termination  of  the  white  fibres  in 
gray  matter.  On  closer  examination,  however,  the  cortical  substance  is  found 
subdivided  into  four  layers,  two  of  which  are  composed  of  gray  and  two  of 
white  matter.  The  most  external  is  an  outer  white  stratum,  not  equally  thick 
over  all  parts  of  the  brain,  being  most  marked  on  the  convolutions  in  the  longi- 
tudinal fissure  and  on  the  under  part  of  the  brain,  especially  on  the  middle  lobe, 
near  the  descending  horn  of  the  lateral  ventricle.  Beneath  this  is  a'  thick 
reddish-gray  lamina,  and  then  another  thin  white  stratum ;  lastly,  a  thin  stratum 
of  gray  matter,  which  lies  in  close  contact  with  the  white  fibres  of  the  hemi- 
spheres; consequently  white  and  gray  laminae  alternate  with  one  another  in  the 
convolutions.  In  certaia  convolutions,  however,  the  cortical  substance  consists 
of  no  less  than  six  layers,  three-  gray  and  three  white,  an  additional  white 
stratum  dividing  the  most  superficial  gray  one  into  two  ;  this  is  especially 
marked  in  those  convolutions  which  are  situated  near  the  corpus  callosum. 

There  is  no  accurate  resemblance  between  the  convolutions  in  different  brains, 
nor  are  they  symmetrical  on  the  two  sides  of  the  same  brain.  Occasionally  the 
free  borders  or  the  sides  of  a  deep  convolution  present  a  fissured  or  notched 
appearance. 

The  sulci  are  generally  an  inch  in  depth ;  they  also  vary  in  different  brains, 
and  in  different  parts  of  the  same  brain;  they  are  usually  deepest  on  the  outer 
convex  surface  of  the  hemispheres ;  the  deepest  is  situated  on  the  inner  surface 
of  the  hemisphere,  on  a  level  with  the  corpus  callosum,  and  corresponds  to  the 
projection  in  the  posterior  horn  of  the  lateral  ventricle,  the  hippocampus  minor. 

The  number  and  extent  of  the  convolutions,  as  well  as  their  depth,  appear  to 
bear  a  close  relation  to  the  intellectual  power  of  the  individual,  as  is  shown  in 
their  increasing  complexity  of  arrangement  as  we  ascend  from  the  lowest  mam- 
malia up  to  man.  Thus  they  are  absent  in  some  of  the  lower  orders  of  mam- 
malia, and  they  increase  in  number  and  extent  through  the  higher  orders.  In 
man  they  present  the  most  complex  arrangement.  Again,  in  the  child  at  birth 
before  the  intellectual  faculties  are  exercised,  the  convolutions  have  a  very 
simple  arrangement,  presenting  few  undulations ;  and  the  sulci  between  them 
are  less  deep  than  in  the  adult.  In  old  age,  when  the  mental  faculties  have 
diminished  in  activity,  the  convolutions  become  much  less  prominently  marked. 

Those  convolutions  which  are  the  largest  and  most  constantly  present,  are 
the  convolution  of  the  corpus  callosum,  the  convolution  of  the  longitudinal 
fissure,  the  supraorbital  convolution,  and  the  convolutions  of  the  outer  surface 
of  the  hemisphere. 

The  convolution  of  the  corpus  callosum  {cfyrus  fomicatus)  is  always  well  marked. 
It  lies  parallel  with  the  free  surface  of  the  corpus  callosum,  commencing,  on 
the  under  surface  of  the  brain,  in  front  of  the  anterior  perforated  space;  it 
winds  round  the  curved  border  of  the  corpus  callosum,  and  passes  along  its 
upper  surface  as  far  as  its  posterior  extremity,  where  it  is  connected  with  the 
convolutions  of  the  posterior  lobe;  it  then  curves  downwards  and  forwards, 
embracing  the  cerebral  peduncle,  passes  into  the  middle  lobe,  forming  the  hip- 
pocampus major,  and  terminates  just  behind  the  point  from  whence  it  arose. 

The  supraorbital  convolution  on  the  under  surface  of  the  anterior  lobe  is  well 
marked. 

The  convolution  of  the  longitudinal  fissure  bounds  the  margin  of  the  fissure  on 
the  upper  surface  of  the  hemisphere.  It  commences  on  the  under  surface  of 
the  brain,  at  the  anterior  perforated  space,  passes  forwards  along  the  inner 
margin  of  the  anterior  lobe,  being  here  divided  by  a  deep  sulcus,  in  which  the 
olfactory  nerve  is  received;  it  then  curves  over  the  anterior  and  upper  surface 


BASE    OF    THE    BRAIN.  68t 

of  the  hemisphere,  along  the  margin  of  the  longitudinal  fissure,  to  its  posterior 
extremity,  where  it  curves  forwards  along  the  under  surface  of  the  hemisphere 
as  far  as  the  middle  lobe. 

The  convolutions  on  the  outer  convex  surface  of  the  hemisphere,  the  general 
direction  of  which  is  more  or  less  oblique,  are  the  largest  and  the  most  compli- 
cated convolutions  of  the  brain,  frequently  becoming  branched  like  the  letter 
Y  in  their  course  upwards  and  backwards  towards  the  longitudinal  fissure: 
these  convolutions  attain  their  greatest  development  in  man,  and  are  especially 
characteristic  of  the  human  brain.  They  are  seldom  symmetrical  on  the  two 
sides. 

Under  Surface  or  Base.    (Pig.  329.) 

The  under  surface  of  each  hemisphere  presents  a  subdivision,  as  already 
mentioned,  into  three  lobes,  named  from  their  position,  anterior,  middle,  and 
posterior. 

The  anterior  lohe,  of  a  triangular  form,  with  its  apex  backwards,  is  somewhat 
concave,  and  rests  upon  the  convex  surface  of  the  roof  of  the  orbit,  being 
separated  from  the  middle  lobe  by  the  fissure  of  Sylvius.  The  middle  lobe, 
which  is  more  prominent,  is  recieved  into  the  middle  fossa  of  the  base  of  the 
skull.  The  posterior  lobe  rests  upon  the  tentorium,  its  extent  forwards  being 
limited  by  the  anterior  margin  of  the  cerebellum. 

The  various  objects  exposed  to  view  on  the  under  surface  of  the  cerebrum, 
in  and  near  the  middle  line,  are  here  arranged  in  the  order  in  which  they  are 
met  with  from  before  backwards. 

Longitudinal  fissure.  Tuber  cinereum. 

Corpus  callosum  and  its  peduncles.  Infundibulum. 

Lamina  cinerea.  Pituitary  body. 

Olfactory  nerve.  Corpora  albicantia. 

Fissure  of  Sylvius.  Posterior  perforated  space 

Anterior  perforated  space.  Crura  cerebri. 
Optic  commissure. 

The  longitudinal  fissure  partially  separates  the  two  hemispheres  from  one 
another;  it  divides  the  two  anterior  lobes  in  front:  and  on  raising  the  cerebel- 
lum and  pons,  it  will  be  seen  completely  separating  the  two  posterior  lobes, 
the  intermediate  portioij  of  the  fissure  being  filled  up  by  the  great  transverse 
band  of  white  matter,  the  corpus  callosum.  Of  these  two  portions  of  the  lon- 
gitudinal fissure,  that  which  separates  the  posterior  lobes  is  the  longest.  In 
the  fissure  between  the  two  anterior  lobes  the  anterior  cerebral  arteries  may  be 
seen  ascending  to  the  corpus  callosum;  and  at  the  back  part  of  this  portion  of 
the  fissure,  the  anterior  curved  portion  of  the  corpus  callosum  descends  to  the 
base  of  the  brain. 

The  corpibs  callosum  terminates  at  the  base  of  the  brain  by  a  concave  margin, 
which  is  connected  with  the  tuber  cinereum  through  the  intervention  of  a  thin 
layer  of  gray  substance,  the  lamina  cinerea.  This  may  be  exposed  by  gently 
raising  and  drawing  back  the  optic  commissure.  A  broad  white  band  may  be 
observed  on  each  side,  passing  from  the  under  surface  of  the  corpus  callosum 
backwards  and  outwards,  to  the  commencement  of  the  fissure  of  Sylvius; 
these  bands  are  called  the  j)eduncles  of  the  corpus  callosum.  Laterally,  the 
corpus  callosum  extends  into  the  anterior  lobe. 

The  lamina  cinerea  is  a  thin  layer  of  gray  substance,  extending  backwards 
above  the  optic  commissure  from  the  termination  of  the  corpus  callosum  to  the 
tuber  cinereum;  it  is  continuous  on  either  side  with  the  gray  matter  of  the 
anterior  perforated  space,  and  forms  the  anterior  part  of  the  inferior  boundary 
of  the  third  ventricle. 

The  olfactory  nerve,  with  its  bulb,  is  seen  on  either  side  of  the  longitudinal 
fissure,  upon  the  under  surface  of  each  anterior  lobe. 


688 


NERVOUS    SYSTEM. 


Thejissure  of  Sylvius  separates  the  anterior  and  middle  lobes,  and  lodges  the 
middle  cerebral  artery.  At  its  commencement  is  seen  a  point  of  medullary 
substance,  corresponding  to  a  subjacent  band  of  white  fibres,  connecting  the 
anterior  and  middle  lobes,  and  called  i\iQ  fasciculv^  unciformis;  on  following 
this  fissure  outwards,  it  divides  into  two  branches,  which  inclose  a  triangular- 
shaped  prominent  cluster  of  isolated  convolutions,  the  island  of  Reil.  These 
convolutions,  from  being  covered  in  by  the  sides  of  the  fissure,  are  called  the 
gyri  operti. 

Fig.  329.— Base  of  the  Brain. 


The  anterior  perforated  space  is  situated  at  the  inner  side  of  the  fissure  of 
Sylvius.  It  is  of  a  triangular  shape,  bounded  in  front  by  the  convolution  of 
the  anterior  lobe  and  the  roots  of  the  olfactory  nerve ;  behind,  by  the  optic 
tract;  externally,  by  the  middle  lobe  and  commencement  of  the  fissure  of 
Sylvius;  internally,  it  is  continuous  with  the  lamina  cinerea,  and  crossed  by  the 
peduncle  of  the  corpus  callosum.  It  is  of  a  grayish  color,  and  corresponds  to 
the  under  surface  of  the  corpus  striatum,  a  large  mass  of  gray  matter,  situated 
in  the  interior  of  the  brain ;  it  has  received  its  name  from  being  perforated  by 
numerous  minute  apertures  for  the  transmission  of  small  straight  vessels  into 
the  substance  of  the  corpus  striatum. 

The  optic  commissure  is  situated  in  the  middle  line,  immediately  behind  the 
lamina  cinerea.     It  is  the  point  of  junction  between  the  two  optic  nerves. 

Immediately  behind  the  diverging  optic  tracts,  and  between  them  and  the 
peduncles  of  the  cerebrum  (crura  cerebri),  is  a  lozenge-shaped  interval,  the  inter- 


I 


BASE    OF    THE    BRAIX  68» 

peduncular  space,  in  which  are  found  the  following  parts,  arranged  in  the 
following  order  from  before  backwards:  the  tuber  cinereum,  infundibulum, 
pituitary  body,  corpora  albicantia,  and  the  posterior  perforated  space. 

The  tuber  cinereum  is  an  eminence  of  gray  matter,  situated  between  the  optic 
tracts  and  the  corpora  albicantia ;  it  is  connected  with  the  surrounding  parts  of 
the  cerebrum,  forms  part  of  the  floor  of  the  third  ventricle,  and  is  continuous 
with  the  gray  substance  in  that  cavity.  From  the  middle  of  its  under  surface 
a  conical  tubular  process  of  gray  matter,  about  two  lines  in  length,  is  continued 
downwards  and  forwards,  to  be  attached  to  the  posterior  lobe  of  the  pituitary 
body ;  this  is  the  infundibulum.  Its  canal,  which  is  funnel-shaped,  communi- 
cates with  the  third  ventricle. 

The  'pituitary  body  is  a  small  reddish-gray  vascular  mass,  weighing  from  five 
to  ten  grains,  and  of  an  oval  form,  situated  in  the  sella  Turcica,  in  connection 
with  which  it  is  retained  by  the  dura  mater  forming  the  inner  wall  of  the 
cavernous  sinus.  It  is  very  vascular,  and  consists  of  two  lobes,  separated  from 
one  another  by  a  fibrous  lamina.  Of  these,  the  anterior  is  the  larger,  of  an 
oblong  form,  and  somewhat  concave  behind,  where  it  receives  the  posterior 
lobe,  which  is  round.  The  anterior  lobe  consists  externally  of  firm  yellowish- 
gray  substance,  and  internally  of  a  soft  pulpy  substance  of  a  yellowish-white 
color.  The  posterior  lobe  is  darker  than  the  anterior.  In  the  foetus  it  is  larger 
proportionately  than  in  the  adult,  and  contains  a  cavity  which  communicates 
through  the  infundibulum  with  the  third  ventricle.  In  fhe  adult  it  is  firmer 
and  more  solid,  and  seldom  contains  any  cavity.  Its  structure,  especially  the 
anterior  lobe,  is  similar  to  that  of  the  ductless  glands. 

The  corpora  albicantia  are  two  small  round  white  masses,  each  about  the  size 
of  a  pea,  placed  side  by  side  immediately  behind  the  tuber  cinereum.  They 
are  formed  by  the  anterior  crura  of  the  fornix,  hence  called  the  bulbs  of  the 
fornix,  which,  after  descending  to  the  base  of  the  brain,  are  folded  upon  them- 
selves, before  passing  upwards  to  the  thalami  optici.  They  are  composed  ex- 
ternally of  white  substance,  and  internally  of  gray  matter;  the  gray  matter  of 
the  two  being  connected  by  a  transverse  commissure  of  the  same  material.  At 
an  early  period  of  foetal  life  they  are  blended  together  into  one  large  mass,  but 
become  separated  about  the  seventh  month. 

The  posterior  perforated  space  ( pons  Tarini)  corresponds  to  a  whitish-gray  sub- 
stance, placed  between  the  corpora  albicantia  in  front,  the  pons  Varolii  behind, 
and  the  crura  cerebri  on  either  side.  It  forms  the  back  part  of  the  floor  of  the 
third  ventricle,  and  is  perforated  by  numerous  small  orifices  for  the  passage  of 
bloodvessels  to  the  thalami  optici. 

The  crura  cerebri  {peduncles  of  the  cerebrum)  are  two  thick  cylindrical  bundles 
of  white  matter,  which  emerge  from  the  anterior  border  of  the  pons,  and  diverge 
as  they  pass  forwards  and  outwards  to  enter  the  under  part  of  either  hemisphere. 
Each  crus  is  about  three-quarters  of  an  inch  in  length,  and  somewhat  broader 
in  front  than  behind.  They  are  marked  upon  their  surface  with  longitudinal 
striie,  and  each  is  crossed,  just  before  entering  the  hemisphere,  by  a  flattened 
white  band,  the  optic  tract,  which  is  adherent  by  its  upper  border  to  the  peduncle. 
In  the  interior  of  the  crura  is  contained  a  mass  of  dark  gray  matter,  called  locus 
niger.  The  third  nerves  may  be  seen  emerging  from  the  inner  side  of  either 
crus;  and  the  fourth  nerve  winding  around  its  outer  side  from  above. 

Each  crus  consists  of  a  superficial  and  deep  layer  of  longitudinal  white  fibres, 
continued  upwards  from  the  pons;  these  layers  are  separated  from  each  other 
by  the  locus  niger. 

The  superficial  longitudinal  fibres  are  continued  upwards,  from  the  anterior 
pyramids  to  the  cerebrum.  They  consist  of  coarse  fasciculi,  which  form  the 
free  part  of  the  crus,  and  have  received  the  name  of  the  fasciculated  portion 
of  the  peduncle,  or  crust. 

The  deep  layer  of  longitudinal  fibres  are  continued  upwards,  to  the  cerebrum, 
from  the  lateral  and  posterior  columns  of  the  medulla,  and  from  the  olivary 


{)90  NERVOUS    SYSTEM. 

fasciculus,  these  filDres  consisting  of  some  derived  from  the  same,  and  others 
from  the  opposite  lateral  tract  of  the  medulla.  More  deeply,  are  a  layer  of 
finer  fibres,  mixed  with  gray  matter,  derived  from  the  cerebellum,  blended  with 
the  former.  The  cerebral  surface  of  the  eras  cerebri  is  formed  of  these  fibres, 
and  is  named  the  tegmentum. 

The  hcus  niger  is  a  mass  of  gray  matter,  situated  between  the  superficial  and 
deep  layer  of  fibres  above  described.  It  is  placed  nearer  the  inner  than  the 
outer  side  of  the  crus. 

The  posterior  lobes  of  the  cerebrum  are  concealed  from  view  by  the  upper 
surface  of  the  cerebellum,  and  pons  Varolii.  When  these  parts  are  removed, 
the  two  hemispheres  are  seen  to  be  separated  by  the  great  longitudinal  fissure, 
this  fissure  being  interrupted,  in  front,  by  the  posterior  rounded  border  of  the 
corpus  callosum. 

General  Arrangement  of  the  Parts  composing  the  Cerebrum. 

As  the  peduncles  of  the  cerebrum  enter  the  hemispheres,  they  diverge  from 
one  another,  so  as  to  leave  an  interval  between  them,  the  interpeduncular  space. 
As  they  ascend,  the  component  fibres  of  each  pass  through  two  large  masses 
of  gray  matter,  the  ganglia  of  the  brain,  called  the  thalamus  opticibs  and  corpus 
striatum^  which  project  as  rounded  eminences  from  the  upper  and  inner  side  of 
each  peduncle.  The  hemispheres  are  connected  together,  above  these  masses, 
by  the  great  transverse  commissure,  the  corpus  callosum,  and  the  interval  left 
between  its  under  surface,  the  upper  surface  of  the  ganglia,  and  the  parts 
closing  the  interpeduncular  space,  forms  the  general  ventricular  cavity.  The 
upper  part  of  this  cavity  is  subdivided  into  two,  by  a  vertical  septum,  the 
septum  lucidum;  and  thus  the  two  lateral  ventricles  are  formed.  The  lower 
part  of  the  cavity  forms  the  third  ventricle,  which  communicates  with  the  lateral 
ventricles,  above,  and  with  the  fourth  ventricle,  behind.  The  fifth  ventricle  is 
the  interval  left  between  the  two  layers  composing  the  septum  lucidum. 


Interior  of  the  Cerebrum. 


4 


If  the  upper  part  of  either  hemisphere  is  removed  with  a  scalpel,  about  half 
an  inch  above  the  level  of  the  corpus  callosum,  its  internal  white  matter  will 
be  exposed.  It  is  an  oval-shaped  centre,  of  white  substance,  surrounded  on  all 
sides  by  a  narrow,  convoluted  margin  of  gray  matter  which  presents  an  equal 
thickness  in  nearly  every  part.  This  white,  central  mass,  has  been  called  the 
centrum  -ovale  minus.  Its  surface  is  studded  with  numerous  minute  red  dots 
{puncta  vasculosa\  produced  by  the  escape  of  blood  from  divided  bloodvessels. 
In  inflammation,  or  great  congestion  of  the  brain,  these  are  very  numerous,  and 
of  a  dark  color.  If  the  remaining  portion  of  one  hemisphere  is  slightly  sepa- 
rated from  the  other,  a  broad  band  of  white  substance  will  be  observed  con- 
necting them,  at  the  bottom  of  the  longitudinal  fissure:  this  is  the  corpus 
callosum.  The  margins  of  the  hemispheres,  which  overlap  this  portion  of  the 
brain,  are  called  the  labia  cerebri.  Each  labium  is  part  of  the  convolution  of  the 
corpus  callosum  {gyrus  fornicattis)^  already  described;  and  the  space  between  it 
antl  the  upper  surface  of  the  corpus  callosum,  has  been  termed  the  ventricle  of 
the  corpus  callosum. 

The  hemispheres  should  now  be  sliced  off,  to  a  level  with  the  corpus  callosum, 
when  the  white  substance  of  that  structure  will  be  seen  connecting  together 
both  hemispheres.  The  large  expanse  of  medullary  matter  now  exposed,  sur- 
rounded by  the  convoluted  margin  of  gray  substance,  is  called  the  centrum  ovale 
majus  of  Vieussens. 

The  corpus  callosum  is  a  thick  stratum  of  transverse  fibres,  exposed  at  the 
bottom  of  the  longitudinal  fissure.  It  connects  the  two  hemispheres  of  the 
brain,  forming  their  great  transverse  commissure ;  and  forms  the  roof  of  a  space 
in  the  interior  of  each  hemisphere,  the  lateral  ventricle.     It  is  about  four  inches 


INTERIOR    OF    CEREBRUM. 


591 


in  length,  extending  to  within  an  inch  and  a  half  of  the  anterior,  and  to  within 
two  inches  and  a  half  of  the  posterior,  part  of  the  brain.  It  is  somewhat 
broader  behind  than  in  front,  and  is  thicker  at  either  end  than  in  its  central 
part,  being  thickest  behind.  It  presents  a  somewhat  arched  form,  from 
before  backwards,  terminating  anteriorly  in  a  rounded  border,  which  curves 
downwards  and  backwards,  between  the  anterior  lobes  to  the  base  of  the  brain. 
In  its  course,  it  forms  a  distinct  bend,  named  the  knee,  or  genu,  and  the  reflected 
portion,  named  the  leak  {rostrum)^  becoming  gradually  narrower,  is  attached  to 
the  anterior  cerebral  lobe,  and  is  connected  through  the  lamina  cinerea  with 
the  optic  commissure.  The  reflected  portion  of  the  corpus  collosum  gives  off, 
near  its  termination,  two  bundles  of  white  substance,  which,  diverging  from  one 
another,  pass  backwards,  across  the  anterior  perforated  space,  to  the  entrance 
of  the  fissure  of  Sylvius.     They  are  called  the  peduncles  of  the  corpus  callosum. 

Fig.  330.  —Section  of  the  Brain.     Made  on  a  level  with  the  Corpus  Callosum. 


Posteriorly,  the  corpus  callosum  forms  a  thick,  rounded  fold,  which  is  free  for 
a  little  distance,  as  it  curves  forwards,  and  is  then  continuous  with  the  fornix. 
On  its  upper  surface,  its  fibrous  structure  is  very  apparent  to  the  naked  eye, 
being  collected  into  coarse,  transverse  bundles.  Along  the  middle  line  is  a 
linear  depression,  the  raphe,  bounded  laterally  by  two  or  more  slightly  elevated 
longitudinal  bands,  called  the  striae  longitndinales,  or  nerves  of  Lancist;  and,  still 
more  externally,  other  longitudinal  strias  are  seen,  beneath  the  convolutions 
which  rest  on  the  corpus  callosum.  These  are  the  strise  lonqitudinales  laterales. 
The  under  surface  of  the  corpus  callosum  is  continuous  behind  with  the  fornix, 
being  separated  from  it  in  front  by  the  septum  lucidum,  which  forms  a  vertical 
partition  between  the  two  ventricles.     On  either  side,  the  fibres  of  the  corpus 


5y2 


NERYOUS    SYSTEM. 


callosum  penetrate  into  the  substance  of  the  hemispheres,  and  connect  together 
the  anterior,  middle,  and  part  of  the  posterior  lobes.  It  is  the  large  number 
of  fibres  derived  from  the  anterior  and  posterior  lobes  which  explains  the  great 
thickness  of  the  two  extremities  of  this  commissure. 

An  incision  should  now  be  made  through  the  corpus  callosum,  on  either  side  of  the  raphe,  when 
two  large  irregular-shaped  cavities  will  be  exposed,  which  extend  through  a  great  part  of  the 
length  of  each  hemisphere.     These  are  the  lateral  ventricles. 


The  lateral  ventricles  are  serous  cavities,  formed  by  the  upper  part  of  the 
general  ventricular  space  in  the  interior  of  the  brain.  They  are  lined  by  a  thin 
diaphanous  lining  membrane,  covered  with  ciliated  epithelium,  and  moistened 

Fig.  331.— The  Lateral  Ventricles  of  the  Brain. 


by  a  serous  fluid,  which  is  sometimes,  even  in  health,  secreted  in  considerable 
quantity.  These  cavities  are  two  in  number,  one  in  each  hemisphere,  and  they 
are  separated  from  each  other  by  a  vertical  septum,  the  septum  hickhim.  A1 

Each  lateral  ventricle  consists  of  a  central  cavity,  or  body,  and  three  smaller«l 
cavities  or  cornua,  which  extend  from  it  in  different  directions.     The  anterior 
cornu  curves  forwards  and  outwards,  into  the  substance  of  the  anterior  lobe. 
The  posterior  cornu,  called  the  digital  cavity,  curves  backwards  into  the  posterior 
lobe.     The  middle  cornu  descends  into  the  middle  lobe.  ^U 

The  ceyitral  cavity,  or  body  of  the  lateral  ventricle,  is  triangular  in  form.  ItU 
is  bounded,  above,  by  the  under  surface  of  the  corpus  callosum,  which  forms 
the  roof  of  the  cavity.  Internally,  is  a  vertical  partition,  the  septum  lucidum, 
which  separates  it  from  the  opposite  ventricle,  and  connects  the  under  surface 
of  the  corpus  callosum  with  the  fornix.  Its  floor  is  formed  by  the  following 
parts,  enumerated  in  their  order  of  position,  from  before  backwards:  the  corpus 


LATERAL    VENTRICLES.  693 

striatum,  tasnia  seraicircularis,  thalamus  opticus,  choroid  plexus,  corpus  fimbri- 
atum,  and  fornix. 

The  anterior  cornu  is  triangular  in  form,  passing  outwards  into  the  anterior 
lobe,  and  curving  round  the  anterior  extremity  of  the  corpus  striatum.  It  is 
bounded  above  and  in  front  by  the  corpus  callosum ;  behind,  by  the  corpus 
striatum. 

The  posterior  cornu^  or  digital  cavity,  curves  backwards  into  the  substance  of 
the  posterior  lobe,  its  direction  being  backwards  and  outwards,  and  then  inwards. 
On  its  floor  is  seen  a  longitudinal  eminence,  which  corresponds  with  a  deep 
sulcus  between  two  convolutions:  this  is  called  the  hippocampus  minor.  Be- 
tween the  middle  and  posterior  horns  a  smooth  eminence  is  observed,  which 
varies  considerably  in  size  in  different  subjects.  It  is  called  the  emineniia 
collateralis. 

The  corpus  striatum  has  received  its  name  from  the  striped  appearance  which 
its  section  presents,  in  consequence  of  diverging  white  fibres  being  mixed  with 
the  gray  matter  which  forms  the  greater  part  of  its  substance.  The  intraven- 
tricular portion  is  a  large  pear-shaped  mass,  of  a  gray  color  externally ;  its 
broad  extremity  is  directed  forwards,  into  the  fore  part  of  the  body,  and  anterior 
cornu  of  the  lateral  ventricle :  its  narrow  end  is  directed  outwards  and  back- 
wards, being  separated  from  its  fellow  by  the  thalami  optici :  it  is  covered  by 
the  serous  lining  of  the  cavity,  and  crossed  by  some  veins  of  considerable  size. 
The  extraventricular  portion  is  imbedded  in  the  white  substance  of  the  hemisphere. 

The  tsenia  semicircular  is  is  a  narrow,  whitish,  semitransparent  band  of  medul- 
lary substance,  situated  in  the  depression  between  the  corpus  striatum  and  tha- 
lamus opticus.  Anteriorly,  it  descends  in  connection  with  the  anterior  pillar  of 
the  fornix;  behind,  it  is  continued  into  the  descending  horn  of  the  ventricle, 
where  it  becomes  lost.  Its  surface,  especially  at  its  fore  part,  is  transparent,  and 
dense  in  structure,  and  this  was  called  by  Tarinus  the  horny  hand.  It  consists 
of  longitudinal  white  fibres,  the  deepest  of  which  run  between  the  corpus 
striatum  and  thalamus  opticus.  Beneath  it  is  a  large  vein  {vena  corporis  striati)^ 
which  receives  numerous  smaller  veins  from  the  surface  of  the  corpus  striatum 
and  thalamus  opticus,  and  joins  the  vense  Galeni. 

The  choroid  plexus  is  a  highly  vascular,  fringe-like  membrane,  occupying  the 
margin  of  the  fold  of  pia  mater  {velum  interpositum)^  in  the  interior  of  tiie  i)rain. 
It  extends,  in  a  curved  direction,  across  the  floor  of  the  lateral  ventricle.  In 
front,  where  it  is  small  and  tapering,  it  communicates  with  the  choroid  plexus 
of  the  opposite  side,  through  a  large  oval  aperture,  the  foramen  of  Monro. 
Posteriorly,  it  descends  into  the  middle  horn  of  the  lateral  ventricle,  where  it 
joins  with  the  pia  mater  through  the  transverse  fissure.  In  structure,  it  consists 
of  minute  and  highly  vascular  villous  processes,  the  villi  being  covered  by  a 
single  layer  of  epithelium,  composed  of  large,  round  corpuscles,  containing, 
besides  a  central  nucleus,  a  bright  yellow  spot.  The  arteries  of  the  choroid 
plexus  enter  the  ventricle  at  the  descending  cornu,  and,  after  ramifying  through 
its  substance,  send  branches  into  the  substance  of  the  brain.  The  veins  of  the 
choroid  plexus  terminate  in  the  venae  Galeni. 

Tlie  corpus  fimhriatum  {tsenia  hippocampi)  is  a  narrow,  white,  tape-like  band, 
situated  immediately  behind  the  choroid  plexus.  It  is  the  lateral  edge  of  the 
posterior  pillar  of  the  fornix,  and  is  attached  along  the  inner  border  of  the 
hippocampus  major  as  it  descends  into  the  middle  horn  of  the  lateral  ventricle. 
It  may  be  traced  as  far  as  the  pes  hippocampi. 

The  thalami  optici  2kVL(\.  fornix  will  be  described  when  more  completely  ex- 
posed, in  a  later  stage  of  the  dissection  of  the  brain. 

The  middle  cornu  should  now  be  exposed,  throuf^hout  its  entire  extent,  by  introducing  the 
little  finger  gently  into  it,  and  cutting  outwards,  along  the  P.nger  through  the  subatan(;e  of  the 
hemisphere,  which  should  be  removed,  to  an  extent  sufficient  to  expose  the  entire  cavity. 

The  middle,  or  descending  cornu,  the  largest  of  the  three,  traverses  the  middle 
lobe  of  the  brain,  forming  in  its  course  a  remarkable  curve  round  the  back  of 
38 


594 


NERYOUS    SYSTEM. 


the  optic  thalamus.  It  passes,  at  first,  backwards,  outwards,  and  downwards, 
and  then  curves  round  the  crus  cerebri,  forwards  and  inwards,  nearly  to  the 
point  of  the  middle  lobe,  close  to  the  fissure  of  Sylvius.  Its  upper  boundary 
is  formed  by  the  medullary  substance  of  the  middle  lobe,  and  the  under  surface 
of  the  thalamus  opticus.  Its  lower  boundary,  or  floor,  presents  for  examination 
the  following  parts  :  the  hippocampus  major,  pes  hippocampi,  pes  accessorius, 
corpus  fimbriatum,  choroid  plexus,  fascia  dentata,  transverse  fissure. 

The  hijypocampus  major,  or  cornu  Ammonis,  so  called  from  its  resemblance  to 
a  ram's  horn,  is  a  white  eminence,  of  a  curved  elongate  form,  extending  along 

Fig.  332. — The  Fornix,  Yelum  Tnterpositnm,  and  Middle  or  Descending  Cornu  of  the 

Lateral  Ventricle. 


N 


the  entire  length  of  the  floor  of  the  middle  horn  of  the  lateral  ventricle.  At 
its  lower  extremity  it  becomes  enlarged,  and  presents  a  number  of  rounded 
elevations  with  intervening  depressions,  whicli,  from  presenting  some  resem- 
blance to  the  paw  of  an  animal,  is  called  the  pes  hijypocampi.  If  a  transverse 
section  is  made  through  the  hippocampus  major,  it  will  be  seen  that  this  emi- 
nence is  the  inner  surface  of  the  convolution  of  the  corpus  callosum,  doubled 
upon  itself  like  a  horn,  the  white  convex  portion  projecting  into  the  cavity  of 
the  ventricle ;  the  gray  portion  being  on  the  surface  of  the  cerebrum,  the  edge 
of  which,  slightly  indented,  forms  the  fascia  dentata.  The  white  matter  of  the 
hippocampus  major  is  continuous  through  the  corpus  fimbriatum,  with  the 
fornix  ana  corpus  callosam. 

The  ptes  accessorins,  or  enfiinentia  coUatcrah's,  has  been  already  mentioned,  as 
a  white  eminence,  varying  in  size,  placed  between  the  hippocampus  major  and 


MIDDLE    CORNTJ.  595 

minor,  at  the  junction  of  the  posterior  with  the  descending  cornu.  Like  the 
hippocampi,  it  is  formed  of  wliite  matter  corresponding  to  one  of  the  sulci, 
between  two  convolutions  protruding  into  the  cavity  of  the  ventricle. 

The  corpus  fimhriaium  is  a  continuation  of  the  posterior  pillar  of  the  fornix, 
prolonged,  as  already  mentioned,  from  the  central  cavity  of  the  lateral  ventricle. 

Fascia  dentata.  On  separating  the  inner  border  of  the  corpus  fimbriatum  from 
the  choroid  plexus,  and  raising  the  edge  of  the  former,  a  serrated  band  of  gray 
substance,  the  edge  of  the  gray  substance  of  the  middle  lobe,  will  be  seen  be- 
neath it :  this  is  the  fascia  dentata.  Correctly  speaking,  it  is  placed  external 
to  the  cavity  of  the  descending  cornu. 

The  transverse  fissure  is  seen  on  separating  the  corpus  fimbriatum  from  the 
thalamus  opticus.  It  is  situated  beneath  the  fornix,  extending  from  the  middle 
line  behind,  downwards  on  either  side,  to  the  end  of  the  descending  cornu, 
being  bounded  on  one  side  by  the  fornix  and  the  hemisphere,  and  on  the  other 
by  the  thalamus  opticus.  Through  this  fissure  the  pia  mater  passes  from  the 
exterior  of  the  brain  into  the  ventricles,  to  form  the  choroid  plexuses.  Where 
the  pia  mater  projects  into  the  lateral  ventricle,  beneath  the  edge  of  the  fornix, 
it  is  covered  by  a  prolongation  of  the  lining  membrane,  which  excludes  it  from 
the  cavity. 

The  seiitum  lucidum  (Fig.  331)  forms  the  internal  boundary  of  the  lateral  ven- 
tricle. It  is  a  thin,  semi-transparent  septum,  attached,  above,  to  the  under 
surface  of  the  corpus  callosum ;  below,  to  the  anterior  part  of  the  fornix,  and, 
in  front  of  this,  to  the  prolonged  portion  of  the  corpus  callosum.  It  is  trian- 
gular in  form,  broad  in  front,  and  narrow  behind,  its  surfaces  looking  towards 
the  cavities  of  the  ventricles.  The  septum  consists  of  two  laminae,  separated 
by  a  narrow  interval,  the  fifth  ventricle. 

Fifth  Ventricle.  Each  lamina  of  the  septum  lucidum  consists  of  an  internal 
layer  of  white  substance,  covered  by  the  lining  membrane  of  the  fifth  ventricle; 
and  an  outer  layer  of  gray  matter,  covered  by  the  lining  membrane  of  the  late- 
ral ventricle.  The  cavity  of  the  fifth  ventricle  is  lined  by  a  serous  membrane, 
covered  with  epithelium,  and  contains  fluid.  In  the  foetus,  and  in  some  animals, 
this  cavity  communicates,  below,  with  the  third  ventricle;  but  in  the  adult,  it 
forms  a  separate  cavity.  In  cases  of  serous  effusion  into  the  ventricles,  the 
septum  is  often  found  softened  and  partially  broken  down. 

The  fifth  ventricle  may  be  exposed  by  cutting  through  the  septum,  and  attached  portion  of 
the  corpus  callosum,  with  scissors ;  after  examining  which,  the  corpus  callosum  should  be  cut 
across,  towards  its  anterior  part,  and  the  two  portions  carefully  dissected,  the  one  forwards,  the 
other  backwards,  when  the  fornix  will  be  exposed. 

The/om^x  (Figs.  331,  332)  is  a  longitudinal  lamella  of  white  fibrous  matter, 
situated  beneath  the  corpus  callosum,  with  which  it  is  continuous  behind,  but 
separated  from  it  in  front  by  the  septum  lucidum.  It  may  be  described  as  con- 
sisting of  two  symmetrical  halves,  one  for  either  hemisphere.  These  two  por- 
tions are  joined  together  in  the  middle  line,  where  they  form  the  body,  but  are 
separated  from  one  another  in  front  and  behind ;  forming  the  anterior  and  pos- 
terior crura. 

The  body  of  the  fornix  is  triangular ;  narrow  in  front,  broad  behind.  Its 
upper  surface  is  connected,  in  the  median  line,  to  the  septum  lucidum  in  front, 
and  the  corpus  callosum  behind.  Its  under  surface  rests  upon  the  velum  inter- 
positum,  which  separates  it  from  the  third  ventricle,  and  the  inner  portion  of 
the  optic  thalami.  Its  lateral  edges  form,  on  each  side,  part  of  the  floor  of  the 
lateral  ventricles,  and  are  in  contact  with  the  choroid  plexuses. 

The  anterior  crura  arch  downwards  towards  the  base  of  the  brain,  separated 
from  each  other  by  a  narrow  interval.  They  are  composed  of  white  fibres, 
which  descend  through  a  quantity  of  gray  matter  in  the  lateral  walls  of  the 
third  ventricle,  and  are  placed  immediately  behind  the  anterior  commissure. 
At  the  base  of  the  brain,  the  white  fibres  of  each  crus  form  a  sudden  curve  upon 
themselves,  spread  out  and  form  the  outer  part  of  the  corresponding  corpus 


59fi  NERVOUS    SYSTEM. 

albicans,  from  which  point  they  may  be  traced  upwards  into  the  substance  of 
the  corresponding  thalamus  opticus.  The  anterior  crura  of  the  fornix  are  con- 
nected in  their  course  with  the  optic  commissure,  the  white  fibres  covering  the 
optic  thalamus,  the  peduncle  of  the  pineal  gland,  and  the  superficial  fibres  of 
the  taenia  semicircularis. 

The  posttrior  crura,  at  their  commencement,  are  intimately  connected  by  their 
upper  surfaces  with  the  corpus  callosum;  diverging  from  one  another,  they  pass 
downwards  into  the  descending  horn  of  the  lateral  ventricle,  being  continuous 
with  the  concave  border  of  the  hippocampus  major.  The  lateral  thin  edges  of 
the  posterior  crura  have  received  the  name  corpus  Jimbriatiim,  already  described. 
On  the  under  surface  of  the  fornix,  towards  its  posterior  part,  between  the 
diverging  posterior  crura,  may  be  seen  some  transverse  lines,  and  others  longi- 
tudinal or  oblique.  This  appearance  has  been  termed  the  lyra,  from  the  fancied 
resemblance  it  bears  to  the  strings  of  a  harp. 

Between  the  anterior  pillars  of  the  fornix  and  the  anterior  extremities  of  the 
thalami  optici,  an  oval  aperture  is  seen  on  each  side,  the  foramen  of  Monro.  The 
two  openings  descend  towards  the  middle  line,  and  joining  together,  lead  into 
the  upper  part  of  the  third  ventricle.  These  openings  communicate  with  the 
lateral  ventricles  on  each  side,  and  below  with  the  third  ventricle.    • 

Divide  the  fornix  across  anteriorly,  and  reflect  the  two  portions,  the  one  forwards,  the  other 
backwards,  when  the  velura  interpositum  will  be  exposed. 

The  velum  interpositum  (Fig.  332)  is  a  vascular  membrane,  reflected  from  the 
pia  mater  into  the  interior  of  the  brain  through  the  transverse  fissure,  passing 
beneath  the  posterior  rounded  border  of  the  corpus  callosum  and  fornix,  and 
above  the  corpora  quadrigemina,  pineal  gland,  and  optic  thalami.  It  is  of  a 
triangular  form,  and  separates  the  under  surface  of  the  body  of  the  fornix  from 
the  cavity  of  the  third  ventricle.  Its  posterior  border  forms  an  almost  com-f  I 
plete  investment  for  the  pineal  gland.  Its  anterior  extremity,  or  apex,  is  bifid; 
each  bifurcation  being  continued  into  the  corresponding  lateral  ventricle,  behind 
the  anterior  crura  of  the  fornix,  forming  the  anterior  extremity  of  the  choroi(^| 
plexus.  On  its  under  surface  are  two  vascular  fringes,  which  diverge  fron^l 
each  other  behind,  and  project  into  the  cavity  of  the  third  ventricle.  These 
are  the  choroid  plexuses  of  the  third  ventricle.  To  its  lateral  margins  are  con- 
nected the  choroid  plexuses  of  the  lateral  ventricles.  The  arteries  of  the 
velum  interpositum  enter  from  behind,  beneath  the  corpus  callosum.  Its  veins, 
the  venas  Galeni,  two  in  number,  run  along  its  under  surface ;  they  are  formed 
by  the  venae  corporis  striati  and  the  veins  of  the  choroid  plexuses;  the  venae 
Galeni  unite  posteriorly  into  a  single  trunk,  which  terminates  in  the  straight 
sinus. 

The  velum  interpositum  should  now  be  removed.  This  must  be  efTected  carefully,  especially 
at  its  posterior  part,  where  it  invests  the  pineal  gland  ;  the  thalami  optici  will  then  be  exposed 
with  the  cavity  of  the  third  ventricle  between  them  (Fig.  333). 

The  thalami  optici  are  two  large  oblong  masses,  placed  between  the  diverging 
portions  of  the  corpora  striata;    they  are  of  a  white  color  superficially;  in- 
ternally, they  are  composed  of  white  fibres  intermixed  with  gray  matter.  Each.™ 
thalamus  rests  upon  its  corresponding  crus  cerebri,  which  it  embraces,      •^■^'fl 
ternalhj,  it  is  bounded  by  the  corpus  striatum,  and  taenia  semicircularis;  and  is 
continuous  with  the  hemisphere.     Internally,  it  forms  the  lateral  boundary  of 
the  third  ventricle;  and  running  along  its  upper  border  is  seen  the  peduncle 
of  the  pineal  gland.     Its  upper  surface  is  free,  being  partly  seen  in  the  lateral-, 
ventricle;  it  is  partly  covered  by  the  fornix,  and  marked  in  front  by  an  enii.J| 
nence,  the  anterior  tubercle.     Its  under  surface  forms  the  roof  of  the  descend- 
ing  cornu  of  the  lateral  ventricle;  into  it  the  crus  cerebri  passes.     Its  posterior 
and  inferior  part,  which  projects  into  the  descending  horn  of  the  lateral  ven- 
tricle, presents  two  small  round  eminences,  the  internal  and  external  genwidate 
bodies.     Its  anterior  extremity,  which  is  narrow,  forms  the  posterior  boundary 
of  the  foramen  of  Monro. 


THIRD    VENTRICLE.  697 

The  third  ventricle  is  the  narrow  oblong  fissure  placed  between  the  thalami 
optici,  and  extending  to  the  base  of  the  brain.  It  is  bounded,  above,  by  the 
under  surface  of  the  velum  interpositurn,  from  which  are  suspended  the  choroid 
plexuses  of  the  third  ventricle;    and,  laterally,  by  two  white  tracts,  one  on 

Fig.  333.— The  Third  and  Fourth  Veatricles. 


either  side,  the  peduncles  of  the  pineal  gland.  Its  floor,  somewhat  oblique  in 
its  direction,  is  formed,  from  before  backwards,  by  the  parts  which  close  the 
interpeduncular  space,  viz.,  the  lamina  cinerea,  the  tuber  cinereum  and  infun- 
dibulum,  the  corpora  albicantia,  and  the  locus  perforatus  posticus;  its  sides,  by 
the  optic  thalami ;  it  is  bounded,  in  front,  by  the  anterior  crura  of  the  fornix, 
and  part  of  the  anterior  commissure;  behind,  by  the  posterior  commissure,  and 
the  iter  a  tertio  ad  quartunn  ventriculum. 

The  cavity  of  the  third  ventricle  is  crossed  by  three  commissures,  named, 
from  their  position,  anterior,  middle,  and  posterior. 

The  anterior  commissure  is  a  rounded  cord  of  white  fibres,  placed  in  front  of 
the  anterior  crura  of  the  fornix.  It  perforates  the  corpus  striatum  on  either 
side,  and  spreads  out  into  the  substance  of  the  hemispheres,  over  the  roof  of 
the  descending  horn  of  each  lateral  ventricle. 

The  middle  or  soft  commissure  consists  almost  entirely  of  gray  matter.  It 
connects  together  the  thalami  optici,  and  is  continuous  with  the  gray  matter 
lining  the  anterior  part  of  the  third  ventricle.  It  is  frequently  broken  in 
examining  the  brain,  and  might  then  be  supposed  to  have  been  wanting. 


598  NERVOUS    SYSTEM. 

The  posterior  commissure,  smaller  than  the  anterior,  is  a  flattened  white  band 
of  fibres,  connecting  together  the  two  thalami  optici  posteriorly.  It  bounds 
the  third  ventricle  posteriorly,  and  is  placed  in  front  of  and  beneath  the  pineal 
gland,  above  the  opening  leading  to  the  fourth  ventricle. 

The  third  ventricle  has  four  openings  connected  with  it.  In  front  are  the 
two  oval  apertures  of  the  foramen  of  Monro,  one  on  either  side,  through  which 
the  third  communicates  with  the  lateral  ventricles.  Behind  is  a  third  opening 
leading  into  the  fourth  ventricle  by  a  canal,  the  aquaiduct  of  Sylvius,  or  iter  a 
tertio  ad  quartum  ventriculum.  The  fourth,  situated  in  the  anterior  part  of  the 
floor  of  the  ventricle,  is  a  deep  pit,  which  leads  downwards  to  the  funnel- 
shaped  cavity  of  the  infundibulum  {iter  ad  infundihulum). 

The  lining  membrane  of  the  lateral  ventricles  is  continued  through  the 
foramen  of  Monro  into  the  third  ventricle,  and  extends  along  the  iter  a  tertio 
into  the  fourth  ventricle;  at  the  bottom  of  the  iter  ad  infundibulum  it  ends  in 
a  cul-de-sac. 

Gray  matter  of  the  third  ventricle.  A  layer  of  gray  matter  covers  the  greater 
part  of  the  surface  of  the  third  ventricle.  In  the  floor  of  this  cavity  it  exists  in 
great  abundance,  and  is  prolonged  upwards  on  the  sides  of  the  thalami,  extend- 
ing across  the  cavity  as  the  soft  commissure;  below,  it  enters  into  the  corpora 
albicantia,  and  surrounds  in  part  the  anterior  pillars  of  the  fornix. 

Behind  the  third  ventricle,  and  in  front  of  the  cerebellum,  are  the  corpora 
quadrigemina;  and  resting  upon  these,  the  pineal  gland. 

The  pineal  gland  (conarium),  so  named  from  its  peculiar  shape  {pinus,  a  fir- 
cone), is  a  small  reddish-gray  body,  conical  in  form,  placed  immediately  behind 
the  posterior  commissure,  and  between  the  nates,  upon  which  it  rests.  It  is 
retained  in  its  position  by  a  duplicature  of  pia  matter,  derived  from  the  under 
surface  of  the  velum  interpositura,  which  almost  completely  invests  it.  The 
pineal  gland  is  about  four  lines  in  length,  and  from  two  to  three  in  width  at  its  .j 
base,  and  is  said  to  be  larger  in  the  child  than  in  the  adult,  and  in  the  female 
than  in  the  male.  Its  base  is  connected  with  the  cerebrum  by  some  transverse 
commissural  fibres,  derived  from  the  posterior  commissure;  and  by  four  slender 
peduncles,  formed  of  medullary  fibres.  Of  these  the  two  superior  pass  forwards 
upon  the  upper  and  inner  margin  of  the  optic  thalami  to  the  anterior  crura  of 
the  fornix,  with  which  they  become  blended.  The  inferior  peduncles  pass 
vertically  downwards  from  the  base  of  the  pineal  gland,  along  the  back  part  of 
the  inner  surface  of  the  thalami,  and  are  only  seen  on  a  vertical  section  through 
the  gland.  The  pineal  gland  is  very  vascular,  and  consists  chiefly  of  gray 
matter,  with  a  few  medullary  fibres.  In  its  base  is  a  small  cavity,  said  by  some 
to  communicate  with  that  of  the  third  ventricle.  It  contains  a  transparent 
viscid  fluid,  and  occasionally  a  quantity  of  sabulous  matter,  named  accrvulus 
cerebri,  composed  of  phosphate  and  carbonate  of  lime,  phosphate  of  magnesia 
and  ammonia,  with  a  little  animal  matter.  These  concretions  are  almost 
constant  in  their  existence,  and  are  found  at  all  periods  of  life.  When  this  body 
is  solid,  the  sabulous  matter  is  found  upon  its  surface,  and  occasionally  upon 
its  peduncles. 

On  the  removal  of  the  pineal  gland  and  adjacent  portion  of  pia  tnater,  the  corpora  qnadri- 
gcmina  are  exposed. 

The  corpora  or  tiiberoula  quadrigemina  {optic  lobes)  are  four  rounded  eminences 
placed  in  pairs,  two  in  front,  and  two  behind,  and  separated  from  one  another 
by  a  crucial  depression.  They  are  situated  immediately  behind  the  third  ven- 
tricle and  posterior  commissure,  beneath  the  posterior  border  of  the  corpus 
callosum,  and  above  the  iter  a  tertio  ad  quartum  ventriculum.  The  anterior  pair, 
the  nates,  are  the  larger,  oblong  from  before  backwards,  and  of  a  gray  color. 
The  posterior  pair,  the  testes,  are  hemispherical  in  form,  and  lighter  in  color 
than  the  preceding.  They  are  connected  on  each  side  with  the  thalamus  opti- 
cus, and  commencement  of  the  optic  tracts,  by  means  of  two  white  prominent 
bands,  termed  hrachia.     Those  connecting  the  nates  with  the  thalamus  (brachia 


STRUCTURE  OF  THE  CEREBRUM.  599 

anteriora)  are  the  larger,  and  pass  obliquely  outwards.  Those  connecting  the 
testes  with  the  thalamus,  are  called  the  hrachia  posteriora.  Both  pairs,  in  the 
adult,  are  quite  solid,  being  composed  of  white  matter  externally,  and  gray 
matter  within.  These  bodies  are  larger  in  the  lower  animals  than  in  man.  In 
fishes,  reptiles,  and  birds,  they  are  only  two  in  number,  are  called  the  optic  lobes, 
from  their  connection  with  the  optic  nerves,  and  are  hollow  in  their  interior; 
but  in  mammalia,  they  are  four  in  number,  as  in  man,  and  quite  solid.  In  the 
human  foetus,  they  are  developed  at  a  very  early  period,  and  form  a  large  pro- 
portion of  the  cerebral  mass ;  at  first,  they  are  only  two  in  number,  as  in  the 
lower  mammalia,  and  hollow  i»n  their  interior. 

These  bodies  receive,  from  below,  white  fibres  from  the  olivary  fasciculus  or 
fillet;  they  are  also  connected  with  the  cerebellum,  by  means  of  a  large  white 
cord  on  each  side,  the  processus  ad  testes,  or  superior  peduncles  of  the  cerebel- 
lum, which  pass  up  to  the  thalami  from  the  tubercula  quadrigemina. 

The  valve  of  Vieussens  is  a  thin  translucent  lamina  of  medullary  substance, 
stretched  between  the  two  processus  e  cerehello  ad  testes  ;  it  covers  in  the  canal 
leading  from  the  third  to  the  fourth  ventricle,  forming  part  of  the  roof  of  the 
latter  cavity.  It  is  narrow  in  front,  where  it  is  connected  with  the  testes;  and 
broader  behind,  at  its  connection  with  the  vermiform  process  of  the  cerebellum. 
A  slight  elevated  ridge,  the  frenulum,  descends  upon  the  upper  part  of  the 
valve  from  the  corpora  quadrigemina,  and  on  either  side  of  it  may  be  seen  the 
fibres  of  origin  of  the  fourth  nerve.  Its  lower  half  is  covered  by  a  thin  trans- 
versely grooved  lobule  of  gray  matter  prolonged  from  the  anterior  border  of 
the  cerebellum;  this  is  called  by  the  Italian  anatomists  the  linguetta  lamwosa. 

The  corpora  geniculata  are  two  small  flattened,  oblong  masses,  placed  on  the 
outer  side  of  the  corpora  quadrigemina,  and  on  the  under  and  back  part  of 
each  optio  thalamus,  and  named  from  their  position,  corpus  geniculatum  exter- 
num and  intermim.  They  are  placed  one  on  the  outer  and  one  on  the  inner 
side  of  each  opic  tract.  In  this  situation,  the  opic  tract  may  be  seen  dividing 
into  two  bands,  one  of  which  is  connected  with  the  external  geniculate  body 
and  nates,  the  other  being  connected  with  the  internal  geniculate  body  and  testis. 

Structure  of  the  Cerebrum.  The  white  matter  of  each  hemisphere  consists  of 
three  kinds  of  fibres.  1.  Diverging  or  peduncular  fibres,  which  connect  the 
hemisphere  with  the  cord  and  medulla  oblongata.  2.  Transverse  commissural 
fibres,  which  connect  together  the  two  hemispheres.  3.  Longitudinal  commis- 
sural fibres,  which  connect  distant  parts  of  the  same  hemisphere. 

The  diverging  or  peduncular  fibres  consist  of  a  main  body,  and  of  certain 
accessory  fibres.  The  main  body  originate  in  the  columns  of  the  cord  and 
medulla  oblongata,  and  enter  the  cerebrum  through  the  crus  cerebri,  where 
they  are  arranged  in  two  bundles,  separated  by  the  locus  niger.  Those  fibres 
which  form  the  inferior  or  fasciculated  portion  of  the  crus,  are  derived  from 
the  anterior  pyramid,  and,  ascending,  pass  mainly  through  the  centre  of  the 
striated  body;  those  on  the  opposite  surface  of  the  crus,  which  form  the 
tegmentum,  are  derived  from  the  posterior  pyramid  and  fasciculi  teretes;  as 
they  ascend,  they  pass,  some  through  the  under  part  of  the  thalamus,  and 
others  through  both  thalamus  and  corpus  striatum,  decussating  in  these  bodies 
with  each  other,  and  with  the  fibres  of  the  corpus  callosum.  The  optic  thalami 
also  receive  accessory  fibres  from  the  processus  ad  testes,  the  olivary  fasciculus, 
the  corpora  quadrigemina,  and  corpora  geniculata.  Some  of  the  diverging 
fibres  end  in  the  cerebral  ganglia,  whilst  others  pass  through  and  receive  addi- 
tional fibres  from  them,  and  as  they  emerge,  radiate  into  the  anterior,  middle, 
and  posterior  lobes  of  the  hemisphere,  decussating  again  with  the  fibres  of  the 
corpus  callosum,  before  passing  to  the  convolutions.  These  fibres  have  received 
the  name  of  corona  radiata. 

The  transverse  commissural  fibres  connect  together  the  two  hemispheres  across 
the  middle  line.  They  are  formed  by  the  corpus  callosum,  and  the  anterior  and 
posterior  commissures. 


600 


NERVOUS    SYSTEM. 


The  longitudinal  commissural  fibres  connect  together  distant  parts  of  the  same 
hemisphere,  the  fibres  being  disposed  in  a  longitudinal  direction.  They  form 
the  fornix,  the  taenia  semicircularis,  and  peduncles  of  the  pineal  gland,  the  striaB 
longitudinalea,  the  fibres  of  the  gyrus  fornicatus,  and  the  fasciculus  unciformis. 

The  Cerebellum. 

The  Cerebellum,  or  little  brain,  is  that  portion  of  the  encephalon  which  is 
contained  in  the  inferior  occipital  fossae.  It  is  situated  beneath  the  posterior 
lobes  of  the  cerebrum,  from  which  it  is  separated  by  the  tentorium.  Its  average 
weight  in  the  male  is  5  oz.  4  drs.  It  attains  its  maximum  weight  between  the 
twenty-fifth  and  fortieth  year;  its  increase  in  weight  after  the  fourteenth  year 
being  relatively  greater  in  the  female  than  in  the  male.  The  proportion 
between  the  cerebellum  and  cerebrum  is,  in  the  male,  as  1  to  8^;  and  in  the 
female,  as  1  to  8  J.  In  the  infant,  the  cerebellum  is  proportionally  much  smaller 
than  in  the  adult,  the  relation  between  it  and  the  cerebrum  being,  according  to 
Chaussier,  between  1  to  13,  and  1  to  26;  by  Cruveilhier  the  proportion  was 
found  to  be  1  to  20.  In  form,  the  cerebellum  is  oblong,  and  flattened  from 
above  downwards,  its  greatest  diameter  being  from  side  to  side.  It  measures 
from  three  and  a  half  to  four  inches  transversely,  and  from  two  to  two  and  a 
half  inches  from  before  backwards,  being  about  two  inches  thick  in  the  centre, 
and  about  six  lines  at  the  circumference,  which  is  the  thinnest  part.  It  consists 
of  gray  and  white  matter:  the  former,  darker  than  that  of  the  cerebrum,  occu- 
pies the  surface;  the  latter  the  interior.  The  surface  of  the  cerebellum  is  not 
convoluted  like  the  cerebrum,  but  traversed  by  numerous  curved  furrows  or 
sulci,  which  vary  in  depth  at  different  parts,  and  separate  the  laminae  of  which 
its  exterior  is  composed. 

Its  upper  stirface  (Fig.  334)  is  somewhat  elevated  in  the  median  line,  and 
depressed  towards  its  circumference;  it  consists  of  two  lateral  hemispheres,  con- 
nected together  by  an  elevated  median  portion  or  lobe,  the  superior  vermiform 
process.     The  median  lobe  is  the  fundamental  part,  and  in  some  animals,  as 

Fig.  334. — Upper  Surface  of  the  Cerebellum. 


fishes  and  reptiles,  tlie  only  part  which  exists;  the  hemispheres  being  additions, 
and  attaining  their  maximum  size  in  man.  The  hemispheres  are  separated,  in 
front,  by  a  deep  notch,  the  incisura  cerehelU  anterior^  which  encircles  the  corpora 
quadrigemina  behind;  they  are  also  separated  by  a  similar  notch  behind,  the 
incisura  cerebelli  posterior,  in  which  is  received  the  upper  part  of  the  falx  cere- 
belli.  The  superior  vermiform  process  (upper  part  of  the  median  lobe  of  the 
cerebellum)  extends  from  the  notch  on  the  anterior  to  that  on  the  posterior 


CEREBELLUM. 


601 


border.  It  is  divided  into  three  lobes:  the  lohulns  centralis^  a  small  lobe, 
situated  in  the  incisura  anterior;  the  7won/ic?«^Ms  cereieZ/i,  the  central  projecting 
part  of  the  process;  and  the  commissura  simplex,  a  small  lobe  near  the  incisura 
posterior. 

The  under  surface  of  the  cerebellum  (Fig.  335)  is  subdivided  into  two  lateral 
hemispheres  by  a  depression,  the  valley,  which  extends  from  before  backwards 
in  the  middle  line.  The  lateral  hemispheres  are  lodged  in  the  inferior  occipital 
fossee;  the  median  depression,  or  valley,  receives  the  back  part  of  the  medulla 

Fig.  335. —  Under  Surface  of  the  Cerebellum. 


oblongata,  is  broader  in  tlie  centre  than  at  either  extremity,  and  has,  projecting 
from  its  floor,  part  of  the  median  lobe  of  the  cerebellum,  called  the  inferior 
vermiform  process.  The  parts  entering  into  the  composition  of  this  body  are, 
from  behind  forwards,  the  commissura  brevis,  situated  in  the  incisura  posterior; 
in  front  of  this,  a  laminated  conical  projection,  the  pjjramid;  more  anteriorly,  a 
larger  eminence,  the  uvula,  which  is  placed  between  the  two  rounded  lobes 
which  occupy  the  sides  of  the  valley,  the  a.mygdalse  or  tonsils,  and  is  connected 
with  them  by  a  commissure  of  gray  matter,  indented  on  the  surface,  called  the 
furrowed  hand.  In  front  of  the  uvula  is  the  nodule;  it  is  the  anterior  pointed 
termination  of  the  inferior  vermiform  process,  and  projects  into  the  cavity  of 
the  fourth  ventricle;  it  has  been  named  by  Malacarne  the  laminated  tubercle. 
On  each  side  of  the  nodule  is  a  thin  layer  of  white  substance,  attached  exter- 
nally to  the  flocculus,  and  internally  to  the  nodule;  these  form  together  the 
posterior  medidlary  velum,  or  commissure  of  the  flocculus.  It  is  usually  covered 
in  and  concealed  by  the  amygdalae,  and  cannot  be  seen  until  they  are  drawn 
aside.  This  band  is  of  a  semilunar  form  on  each  side,  its  anterior  margin  being 
free  and  concave,  its  posterior  attached  just  in  front  of  the  furrowed  band. 
Between  it  and  the  nodulus  and  uvula  behind,  is  a  deep  fossa,  called  the  sival- 
low^s  nest  {nidus  hirundinis). 

Lobes  of  the  cerebellum.  Each  hemisphere  is  divided  into  an  upper  and  a 
lower  portion  by  the  great  horizontal  fissure,  which  commences  in  front  at  the 
pons,  and  passes  horizontally  round  the  free  margin  of  either  hemisphere, 
backwards  to  the  middle  line.  From  this  primary  fissure  numerous  secondary 
fissures  proceed,  which  separate  the  cerebellum  into  lobes. 

Upon  the  upper  surface  of  either  hemisphere  there  are  two  lobes,  separated 
from  each  other  by  a  fissure.  These  are  the  anterior  or  square  lobe,  which 
extends  as  far  back  as  the  posterior  edge  of  the  vermiform  process,  and  the 
posterior  or  semilunar  lobe,  which  passes  from  the  termination  of  the  preceding 
to  the  great  horizontal  fissure. 

Upon  the  under  surface  of  either  hemisphere  there  are  five  lobes,  separated 
by  sulci;  these  are  from  before  backwards;  i\\Q  flocculus  or  sub-peduncular  lobe, 


G02 


NERVOUS    SYSTEM. 


a  prominent  tuft,  situated  behind  and  below  the  middle  peduncle  of  the  cere- 
bellum; its  surface  is  composed  of  gray  matter,  subdivided  into  a  few  small 
laminae:  it  is  sometimes  called  the  pneumogastric  lobule^  from  being  situated 
behind  the  pneumogastric  nerve.  The  amygdala  or  tonsil  is  situated  on  either 
side  of  the  great  median  fissure  or  valley,  and  projects  into  the  fourth  ventricle. 
The  digastric  lobe  is  situated  on  the  outside  of  the  tonsil,  being  connected  in 
part  with  the  pyramid.  Behind  the  digastric  is  the  slender  lobe,  which  is  con- 
nected with  the  back  part  of  the  pyramid  and  the  commissura  brevis:  and 
more  posteriorly  is  the  inferior  posterior  lobe,  which  also  joins  the  commissura 
brevis  in  the  valley. 

Striicture.  If  a  vertical  section  is  made  through  either  hemisphere  of  the 
cerebellum,  midway  between  its  centre  and  the  superior  vermiform  process,  the 
interior  will  be  found  to  consist  of  a  central  stem  of  white  matter,  which  con 
tains  in  its  interior  a  dentate  body.  From  the  surface  of  this  central  stem,  a 
series  of  plates  of  medullary  matter  are  detached,  which,  covered  with  gray 
matter,  form  the  laminse ;  and  from  the  anterior  part  of  each  hemisphere  arise 
three  large  processes  or  peduncles,  superior,  middle  and  inferior,  by  which  the 
cerebellum  is  connected  with  the  rest  of  the  encephalon. 

The  laminse  are  about  ten  or  twelve  in  number,  including  those  on  both  sur- 
faces of  the  cerebellum,  those  in  front  being  detached  at  aright  angle,  and  those 
behind  at  an  acute  angle  ;  as  each  lamina  proceeds  outwards,  other  secondary 
laminae  are  detached  from  it,  and,  from  these,  tertiary  laminae.  The  arrange- 
ment thus  described  gives  to  the  cut  surface  of  the  organ  a  foliated  appearance, 
to  which  the  name  arbor  vitse  has  been  given.  Each  lamina  consists  of  white 
matter,  covered  externally  by  a  layer  of  gray  substance.  The  white  matter  of 
each  lamina  is  derived  partly  from  the  central  stem ;  in  addition  to  which  white 
fibres  pass  from  one  lamina  to  another.     The  gray  matter  resembles  somewhat 

the  cortical  substance  of  the 
Fig.  336.— Vertical  Section  of  the  Cerebellum.  convolutions.     It  consists  of 

two  layers :  the  external  one, 
soft  and  of  a  grayish  color ; 
the  internal  one,  firmer,  and 
of  a  rust  color. 

The  corpus  dentatum,  or  gan- 
glion of  the  cerebellum,  is  situ- 
ated a  little  to  the  inner  side 
of  the  centre  of  the  stem  of 
white  matter.  It  consists  of 
an  open  bag  or  capsule  of 
gray  matter,  the  section  of 
which  presents  a  gray  den- 
tated  outline,  open  at  its  an- 
terior part.  It  is  surrounded 
by  white  fibres;  white  fibres 
are  also  contained  in  its  in- 
terior, which  issue  from  it  to 
join  the  superior  peduncles. 
H\\Q  peduncles  of  the  cerebellum,  superior,  middle,  and  inferior,  serve  to  con- 
nect it  with  the  rest  of  the  encephalon. 

^\\Q  superior  peduncles  (^processus  e  cerebello  ad  testes)  connect  the  cerebellum 
with  the  cerebrum;  they  pass  forwards  and  upwards  to  the  testes,  beneath  whicli 
they  ascend  to  the  crura  cerebri  and  optic  tlialami,  forming  part  of  the  diverging 
cerebral  fibres;  each  peduncle  forms  jiart  of  the  lateral  boundary  of  the  fourth 
ventricle,  and  isxjonnected  with  its  fellow  of  the  opposite  side  by  the  valve  of 
Vieussens.  The  peduncles  are  continuous  behind  with  the  folia  of  the  inferior 
vermiform  process,  and  with  the  white  fibres  in  the  interior  of  the  corpus  den- 


FOURTH    VENTRICLE.  603 

tatum.  Beneath  the  corpora  quadrigemina,  the  innermost  fibres  of  each  peduncle 
decussate  with  each  other,  so  that  some  fibres  from  the  right  half  of  the  cere- 
bellum are  continued  to  the  left  half  of  the  cerebrum. 

1}]\Q  inferior  peduncles  [processus  ad  medullam)  connect  the  cerebellum  with 
the  medulla  oblongata.  They  pass  downwards,  to  the  back  part  of  the  medulla, 
and  form  part  of  the  restiforra  bodies.  Above,  the  fibres  of  each  process  are 
connected  chiefly  with  the  laminae,  on  the  upper  surface  of  the  cerebellum;  and 
below,  they  are  connected  with  all  three  tracts  of  one  half  of  the  medulla,  and, 
through  these,  with  the  corresponding  half  of  the  cord,  excepting  the  posterior 
median  columns. 

The  middle  peduncles  [processus  ad  pontem\  the  largest  of  the  three,  connect 
together  the  two  hemispheres  of  the  cerebellum,  forming  their  great  transverse 
commissure.  They  consist  of  a  mass  of  curved  fibres,  which  arise  in  the  lateral 
parts  of  the  cerebellum,  and  pass  across  to  the  same  points  on  the  opposite  side 
They  form  the  transverse  fibres  of  the  pons  Varolii. 

Fourth  Venteicle.    (Fig.  833.) 

The  Fourth  Ventricle,  or  ventricle  of  the  cerebellum,  is  the  space  between 
the  posterior  surface  of  the  medulla  oblongata  and  pons  in  front,  and  the  cere- 
bellum behind.  It  is  lozenge-shaped,  being  contracted  above  and  below,  and 
broadest  across  its  central  part.  It  is  bounded  laterally  by  the  processws  e  cere- 
bello  ad  testes  above,  and  by  the  diverging  posterior  pyramids  and  restiforra 
bodies  below. 

The  roof  is  arched ;  it  is  formed  by  the  valve  of  Vieussens  and  the  under 
surface  of  the  cerebellum,  which  presents,  in  this  situation,  four  small  eminences 
or  lobules,  the  nodulus,  uvula,  and  amygdalas. 

The  anterior  boundary,  or  fioor^  is  formed  by  the  posterior  surface  of  the 
medulla  oblongata  and  pons.  In  the  median  line  is  seen  the  posterior  median 
fissure,  which  becomes  gradually  obliterated  above,  and  terminates  below  in  the 
point  of  the  calamus  scriptorius,  formed  by  the  convergence  of  the  posterior 
pyramids.  At  this  point  is  the  orifice  of  a  short  canal  terminating  in  a  cul-de- 
sac^  the  remains  of  the  canal  which  extends  in  foetal  life  through  the  centre  of 
the  cord.  On  each  side  of  the  median  fissure  are  two  slightly  convex  longi- 
tudinal eminences,  the  fasciculi  teretes ;  they  extend  the  entire  length  of  the 
floor,  being  indistinct  below  and  of  a  grayish  color,  but  well  marked  and  whitish 
above.  Each  eminence  consists  of  fibres  derived  from  the  lateral  tract  and 
restiforra  body,  which  ascend  to  the  cerebrura.  Opposite  the  crus  cerebelli,  on 
the  outer  side  of  the  fasciculi  teretes,  is  a  small  eminence  of  dark  gray  sub- 
stance, which  presents  a  bluish  tint  through  the  thin  stratura  covering  it;  this 
is  called  the  hcus  coendeus]  and  a  thin  streak  of  the  sarae  color  continued  up 
from  this  on  either  side  of  the  fasciculi  teretes,  as  far  as  the  top  of  the  ventricle, 
is  called  the  tsenia  violacea.  The  lower  part  of  the  floor  of  the  ventricle  is 
crossed  by  several  white  transverse  lines,  lineoe  transversve ;  they  emerge  from 
the  posterior  median  fissure ;  some  enter  the  crus  cerebelli,  others  enter  the 
roots  of  origin  of  the  auditory  nerve,  whilst  some  pass  upwards  and  outwards 
on  the  floor  of  the  ventricle. 

The  lining  membrane  of  the  fourth  ventricle  is  continuous  with  that  of  the 
third,  through  the  aquaeduct  of  Sylvius,  and  its  cavity  communicates  below  with 
the  sub-arachnoid  space  of  the  brain  and  cord  through  an  aperture  in  the  layer 
of  pia  mater  extending  between  the  cerebellum  and  medulla  oblongata.  Later- 
ally, this  membrane  is  reflected  outwards  a  short  distance  between  the  cere- 
bellum and  medulla. 

The  choroid  plexuses  of  the  fourth  ventricle  are  two  in  number;  they  are  deli- 
cate vascular  fringes,  which  project  into  the  ventricle  on  each  side,  passing  from 
the  point  of  the  inferior  vermiform  process  to  the  outer  margin  of  the  resti- 
forra bodies. 


604  NERVOUS    SYSTEM. 

The  gray  matter  in  the  floor  of  the  ventricle  consists  of  a  tolerably  thick 
stratum,  continuous  below  with  the  gray  commissure  of  the  cord,  and  extending 
up  as  high  as  the  aquaeduct  of  Sylvius,  besides  some  special  deposits  connected 
with  the  roots  of  origin  of  certain  nerves.  In  the  upper  half  of  the  ventricle 
is  a  projection  situated  over  the  nucleus,  from  which  the  sixth  and  facial  nerves 
take  a  common  origin.  In  the  lower  half  are  three  eminences  on  each  side  for 
the  roots  of  origin  of  the  eighth  and  ninth  nerves. 


For  further  information  on  the  Descriptive  Anatomy  of  the  Nervous  Centres,  consult :  Crn- 
veilhier's  "Anatomic  Descriptive;"  'I'odd's  "Descriptive  Anatomy  of  the  Brain.  Spinal  Cord, 
and  Ganglions;"  Herbert  M aye's  "  Plates  of  the  Brain  and  Spinal  Cord ;"  and  Arnold's  "  Tabnlae 
Anatomicae,  Fascic.  1.    Icoues  Cerebri  et  MeduUae  Spinalis." 


Cranial   Nerves. 

The  Cranial  Nerves,  nine  in  number  on  each  side,  arise  from  some  part  of 
the  cerebro-spinal  centre,  and  are  transmitted  through  foramina  in  the  base  of 
the  cranium.  They  have  been  named  numerically,  according  to  the  order  in 
which  they  pass  out  of  the  cranial  cavity.  Other  names  are  also  given  to  them 
derived  from  the  parts  to  which  they  are  distributed,  or  from  their  functions. 
Taken  in  their  order,  from  before  backwards,  they  are  as  follows : — 

1st.  Olfactory.  ^.■,  J  Facial  (Portio  Dura). 

2d.  Optic.  *^'^'  I  Auditory  (Portio  Mollis). 

8d.  Motor  Oculi.  I  Glosso-pharyngeal. 

4th.  Pathetic.  8th.  <  Pneumogastric  (Par  Vagum). 

5th.  Trifacial  (Trigeminus).  (  Spinal  Accessory. 

6th.  Abducens.  9th.      Hypoglossal. 

If,  however,  the  7th  pair  be  considered  as  two,  and  the  8th  pair  as  three 
distinct  nerves,  then  their  number  will  be  increased  to  twelve,  which  is  the 
arrangement  adopted  by  Scimmering. 

The  cranial  nerves  may  be  subdivided  into  four  groups,  according  to  the 
peculiar  function  possessed  by  each,  viz.,  nerves  of  special  sense;  nerves  of 
common  sensation  ;  nerves  of  motion ;  and  mixed  nerves.  These  groups  may 
be  thus  arranged  : — 

Nerves  of  Special  Sense.  Nerves  of  Motion. 

Olfactory.  Motor  Oculi. 

Optic.  Pathetic. 

Auditory.  Part  of  Third  Division  of  Fifth. 

Part  of  Glosso-pharyngeal.  Abducens. 

Lingual  or  Gustatory  Branch  of  Fifth.  Facial. 

Hypoglossal. 

Nerves  of  Common  Sensation.  Mixed  Nerves. 

Fifth  (greater  portion).  Pneumogastric. 

Part  of  Glosso-pharyngeal.  Spinal  Accessory. 

All  the  cranial  nerves  are  connected  to  some  part  of  the  surface  of  the  brain. 
This  is  termed  their  superficial^  or  apparent  origin.  But  their  fibres  may,  in  all 
cases,  be  traced  deeply  into  the  substance  of  the  organ.  This  part  is  called  their 
deep,  or  real  origin. 

/  -^       Olfactory  Nerve.    (Fig.  329.) 

The  First,  or  Olfactory  Nerve,  the  special  nerve  of  the  sense  of  smell,  may 
be  regarded  as  a  lobe,  or  portion  of  the  cerebral  substance,  pushed  forward  in 
direct  relation  with  the  organ  to  which  it  is  distributed.  It  arises  by  three 
roots. 

The  external,,  or  long  root,  is  a  narrow,  white,  medullary  band,  which  passes 
outwards  across  the  fissure  of  Sylvius,  into  the  substance  of  the  middle  lobe  of 
the  cerebrum.  Its  deep  origin  has  been  traced  to  the  corpus  striatum,'  the 
superficial  fibres  of  the  optic  thalamus,^  the  anterior  commissure,^  and  the  con- 
volutions of  the  island  of  Reil. 

'  Vieussens,  Winslow,  Monro,  Mayo.  '  Valentin.  ■  Cruveilhicr. 

605 


606 


CRANIAL    NERVES. 


The  middle^  or  gray  root,  arises  from  a  papilla  of  gray  matter  (caruncnla  mam- 
millaris),  imbedded  in  the  anterior  lobe.  This  root  is  prolonged  into  the  nerve 
from  the  adjacent  part  of  the  brain,  and  contains  white  fibres  in  its  interior, 
which  are  connected  with  the  corpus  striatum. 

The  internal^  or  short  root,  is  composed  of  white  fibres,  which  arise  from  the 
inner  and  back  part  of  the  anterior  lobe,  being  connected,  according  to  Foville, 
with  the  longitudinal  fibres  of  the  gyrus  fornicatus. 

These  three  roots  unite,  and  form  a  flat  band,  narrower  in  the  middle  than  at 
either  extremity,  and  of  a  somewhat  prismoid  form  on  section.  It  is  soft  in 
texture,  and  contains  a  considerable  amount  of  gray  matter  in  its  substance. 
As  it  passes  forwards,  it  is  contained  in  a  deep  sulcus,  between  two  convolutions, 
lying  on  the  under  surface  of  the  anterior  lobe,  on  either  side  of  the  longitudinal 
fissure,  and  is  retained  in  position  by  the  arachnoid  membrane  which  covers  it. 
On  reaching  the  cribriform  plate  of  the  ethmoid  bone,  it  expands  into  an  oblong 
mass  of  grayish-white  substance,  the  olfactory  bulb.  From  the  under  part  of 
this  bulb  are  given  off  numerous  filaments,  about  twenty  in  number,  which  pass 
through  the  cribriform  foramina,  and  are  distributed  to  the  mucous  membrane 
of  the  nose.  Each  filament  is  surrounded  by  a  tubular  prolongation  from  the 
dura  mater,  and  pia  mater;  the  former  being  lost  on  the  periosteum  lining  the 
nose;  the  latter,  in  the  neurilemma  of  the  nerve.  The  filaments,  as  they  enter 
the  nares,  are  divisible  into  three  groups;  an  inner  group,  larger  than  those  on 
the  outer  wall,  spread  out  over  the  upper  third  of  the  septum ;  a  middle  set, 
confined  to  the  roof  of  the  nose ;  and  an  outer  set,  which  are  distributed  over  the 
superior  and  middle  turbinated  bones,  and  the  surface  of  the  ethmoid  in  front 
of  them.  As  the  filaments  descend,  they  unite  in  a  plexiform  network,  and 
become  gradually  lost  in  the  lining  membrane.  Their  mode  of  termination  is 
unknown. 

The  olfactory  differs  in  structure  from  other  nerves,  in  containing  gray  matter 
in  its  interior,  and  being  soft  and  pulpy  in  structure.  Its  filaments  are  deficient 
in  the  white  substance  of  Schwann,  are  not  divisible  into  fibrillae,  and  resemble 
the  gelatinous  fibres,  in  being  nucleated,  and  of  a  finely-granular  texture. 

Optic  Nerve. 

The  Second,  or  Optic  Nerve,  the  special  nerve  of  the  sense  of  sight,  is  dis- 
tributed exclusively  to  the  eyeball.    The  nerves  of  opposite  sides  are  connected 

together  at  the  commissure;  and  from  the 
back  of  the  commissure,  they  may  be  traced 
to  the  brain,  under  the  name  of  the  optic 
tracts. 

The  optic  tract,  at  its  connection  with  the 
brain,  is  divided  into  two  bands  which  arise 
from  the  optic  thalami,  the  corpora  geniculata, 
and  the  corpora  quadrigemina.  The  fibres 
of  origin  from  the  thalamus  may  be  traced 
partly  from  its  surface,  and  partly  from  its 
interior.  From  this  origin,  the  tract  winds 
obliquely  across  the  under  surface  of  the  crus 
cerebri,  in  the  form  of  a  flattened  band,  desti- 
tute of  neurilemma,  and  is  attached  to  the 
crus  by  its  anterior  margin.  It  now  assumes 
a  cylindrical  form,  and,  as  it  passes  forwards, 
is  connected  with  the  tuber  cinereum,  and 
lamina  cinerea,  from  both  of  which  it  receives 
fibres.  According  to  Foville,  it  is  also  con- 
nected with  the  taenia  semicircularis,  and  the 
anterior  termination  of  ttie  gyrus  fornicatus.  It  finally  joins  with  the  nerve  of 
the  opposite  side  to  form  the  optic  commissure. 


I 


Fig.  337.— The  Optic  Nerves  and  Optic 
Tract. 


AUDITORY.  COT 

The  commissure^  or  chiasma,  somewhat  quadrilateral  in  form,  rests  upon  the 
olivary  process  of  the  sphenoid  bone,  being  bounded,  in  front,  by  the  lamina 
cinerea;  behind,  by  the  tuber  cinereum;  on  either  side  by  the  anterior  perfo- 
rated space.  Within  the  commissure,  the  optic  nerves  of  the  two  sides  undergo 
a   partial  decussation.      The  fibres  which  form  the 

inner  margin  of  each  tract,  are  continued  across  from  Fig.  338.— Course  of  the 
one  to  the  other  side  of  the  brain,  and  have  no  con-  Fibres  in  the  Optic  Com- 
nection  with  the  optic  nerves.  These  may  be  regarded  ™^^^"''^- 
as  commissural  fibres  (inter-cerebral)  between  the 
thalami  of  opposite  sides.  Some  fibres  are  continued 
across  the  anterior  border  of  the  chiasma,  and  connect 
the  optic  nerves  of  the  two  sides,  having  no  relatioji 
with  the  optic  tracts.  They  may  be  regarded  as  com- 
missural fibres  between  the  two  retinte  (inter-retinal 
fibres).  The  outer  fibres  of  each  tract  are  continued  into  the  optic  nerve  of  the 
same  side.  The  central  fibres  of  each  tract  are  continued  into  the  optic  nerve 
of  the  opposite  side,  decussating  in  the  commissure  with  similar  fibres  of  the 
opposite  tract.' 

The  optic  nerves  arise  from  the  fore  part  of  the  commissure,  and,  diverging 
from  one  another,  become  rounded  in  form  and  firm  in  texture,  and  are  inclosed 
in  a  sheath  derived  from  the  arachnoid.  As  each  nerve  passes  through  the 
corresponding  optic  foramen,  it  receives  a  sheath  from  the  dura  mater ;  and  as 
it  enters  the  orbit,  this  sheath  subdivides  into  two  layers,  one  of  which  becomes 
continuous  with  the  periosteum  of  the  orbit ;  the  other  forms  a  sheath  for  the 
nerve,  and  surrounds  it  as  far  as  the  sclerotic.  The  nerve  passes  through  the 
cavity  of  the  orbit,  pierces  the  sclerotic  and  choroid  coats  at  the  back  part  of 
the  eyeball,  a  little  to  the  nasal  side  of  its  centre,  and  expands  into  the  retina. 
A  small  artery,  the  arteria  centralis  retinae,  perforates  the  optic  nerve  a  little 
behind  the  globe,  and  runs  along  its  interior  in  a  tubular  canal  of  fibrous  tissue. 
It  supplies  the  inner  surface  of  the  retina,  and  is  accompanied  by  corresponding 
veins. 

Auditory  Nerve. 

The  Auditory  Nerve  (poriio  mollis  of  the  seventh  pair)  is  the  special  nerve 
of  the  sense  of  hearing,  being  distributed  exclusively  to  the  internal  ear.  The 
portio  dura  of  the  seventh  pair,  or  facial  nerve,  is  the  motor  nerve  of  the  mus- 
cles of  the  face.     It  will  be  described  with  the  cranial  motor  nerves. 

The  auditory  nerve  arises  by  numerous  white  striae,  the  linese  transversse,  which 
emerge  from  the  posterior  median  fissure  in  the  anterior  wall,  or  floor,  of  the 
fourth  ventricle.  It  is  also  connected  with  the  gray  matter  of  the  medulla, 
corresponding  to  the  locus  caeruleus.  According  to  Foville,  the  roots  of  this 
nerve  are  connected,  on  the  under  surface  of  the  middle  peduncle,  with  the 
gray  substance  of  the  cerebellum,  with  the  flocculus,  and  with  the  gray  matter 
at  the  borders  of  the  calamus  scriptorius.  The  nerve  winds  round  the  restiform 
body,  from  which  it  receives  fibres,  and  passes  forwards  across  the  posterior 
border  of  the  crus  cerebelli,  in  company  with  the  facial  nerve,  from  which  it  is 
partially  separated  by  a  small  artery.  It  then  enters  the  meatus  auditorius,  in 
company  with  the  facial  nerve,  and,  at  the  bottom  of  the  meatus,  divides  into 
two  branches,  cochlear  and  vestibular,  which  are  distributed,  the  former  to  the 
cochlea,  the  latter  to  the  vestibule  and  semicircular  canals.  The  auditory  nerve 
is  very  soft  in  texture  (hence  the  name,  portio  mollis),  destitute  of  neurilemma, 
and,  within  the  meatus,  receives  one  or  two  filaments  from  the  facial. 

(The  other  nerves  of  special  sense  must  be  described  with  the  glosso-pharyn- 
geal  and  fifth  nerves,  of  which  they  are  parts.) 

'  A  specimen  of  congenital  absence  of  the  optic  commissure  is  to  be  found  in  the  Museum  of 
the  Wcstmiuster  Hospital. 


608 


CRANIAL    NERVES. 


tl:^  raJInthUmP 


Third  Nerve.    (Figs.  339,  340.) 

The  Third  Nerve  {motor  oculi)  supplies  all  the  muscles  of  the  eyeball  except 
the  Superior  Oblique  and  External  Rectus ;  it  also  sends  nnotor  filaments  to  the 
iris.  It  is  a  rather  large  nerve,  of  rounded  form  and  firm  texture,  having  its 
apparent  origin  from  the  inner  surface  of  the  crus  cerebri,  immediately  in  front 
of  the  pons  Varolii. 

The  deep  origin  may  be  traced  into  the  substance  of  the  crus,  where  some  of 
its  fibres  are  connected  with  the  locus  niger;  others  run  downwards,  among  the 

longitudinal  fibres  of  the  pons; 
Fig.  339.— Nerves  of  the  Orbit.  Seen  from  above.  whilst  others  ascend,  to  be  con- 
nected with  the  tubercula  quad- 
rigemina,  and  valveof  Vieussens. 
According  the  Stilling,  the  fibres 
of  the  nerve  pierce  the  peduncle 
and  locus  niger,  and  arise  from 
a  gray  nucleus  in  the  floor  of  the 
aquaeduct  of  Sylvius.  One  merg- 
ing from  the  brain,  the  nerve  is 
invested  with  a  sheath  of  pia 
mater,  and  inclosed  in  a  prolon- 
gation from  the  arachnoid.  It 
then  pierces  the  dura  mater  on 
the  outer  side  of  the  anterior 
clinoid  process,  where  its  serous 
covering  is  reflected  from  it,  and 
it  passes  along  the  outer  wall  of 
the  cavernous  sinus,  above  the 
other  orbital  nerves,  receiving  in 
its  course  one  or  two  filaments 
from  the  cavernous  plexus  of  the 
sympathetic.  It  then  divides 
into  two  branches,  which  enter 
the  orbit  through  the  sphenoidal 
fissure,  between  the  two  heads 
of  the  External  Rectus  muscle. 
On  passing  through  the  fissure, 
the  nerve  is  placed  below  the 
fourth,  and  the  frontal  and  lach- 
rymal branches  of  the  ophthal* 
mic  nerve. 

^riie  snperior  division,  the 
smaller,  passes  inwards  across  the  optic  nerve,  and  supplies  the  Superior  Rectus 
and  Levator  Palpebrae. 

The  inferior  division,  the  larger,  divides  into  three  branches.  One  passes 
beneath  the  optic  nerve  to  the  Internal  Rectus;  another  to  the  Inferior  Rectus; 
and  the  third,  the  largest  of  the  three,  passes  forwards  between  the  Liferior 
and  External  Recti,  to  the  Inferior  Oblique.  From  the  latter,  a  short  thick 
branch  is  given  off  to  the  lower  part  of  the  lenticular  ganglion,  forming  its 
inferior  root,  as  well  as  two  filaments  to  the  Inferior  Rectus.  All  these  branches 
enter  the  muscles  on  their  ocular  surface. 

Fourth  Nerve.    (Fig.  339.)   'Tik^  ^'^^^ 

The  Fourth,  or  Trochlear  Nerve,  the  smallest  of  the  cranial  nerves,  supplies 
the  Superior  Oblique  muscle.  It  arises  from  the  upper  part  of  the  valve  of 
Vieussens,  immediately  behind  the  testis,  and  divides,  beneath  the  corpora 
quadrigemina,  into  two  fasciculi ;  the  anterior  one  arising  from  a  nucleus  of 


S*M*arv  ^"tl 


II 
I 
I 

I 


SIXTH. 


609 


gray  matter,  close  to  the  middle  line  of  the  floor  of  the  Sylvian  aquaeduct ;  the 
posterior  one  from  a  gray  nucleus,  at  the  upper  part  of  the  floor  of  the  fourth 
ventricle,  close  to  the  origin  of  the  fifth  nerve.  The  two  nerves  are  connected 
together  at  their  origin,  by  a  transverse  band  of  white  fibres,  which  crosses  the 
surface  of  the  valve  of  Vieussens.  The  nerve  winds  round  the  outer  side  of 
the  crus  cerebri,  immediately  above  the  pons  Varolii,  pierces  the  dura  mater 
in  the  free  border  of  the  tentorium  cerebelli,  near  the  posterior  clinoid  process, 
above  the  oval  opening  for  the  fifth  nerve,  and  passes  forwards  through  the 
outer  wall  of  the  cavernous  sinus,  below  the  third ;  but,  as  it  enters  the  orbit, 
through  the  sphenoidal  fissure,  it  becomes  the  highest  of  all  the  nerves.  In 
the  orbit,  it  passes  inwards,  above  the  origin  of  the  Levator  Palpebrse,  and 
finally  enters  the  orbital  surface  of  the  Superior  Oblique  muscle. 

In  the  outer  wall  of  the  cavernous  sinus,  this  nerve  receives  some  filaments 
from  the  carotid  plexus  of  the  sympathetic.  It  is  not  unfrequently  blended 
with  the  ophthalmic  division  of  the  fifth ;  and  occasionally  gives  off  a  branch 
to  assist  in  the  formation  of  the  lachrymal  nerve.     It  also  gives  off  a  recurrent 

Fig.  340.— Nerves  of  the  Orbit  and  Ophthalmic  GanglioQ.    Side  View. 


InltmaZ  Cajvtc'd  A3. 
&  Ccurotid  Plecciu., 


Stmt 


branch,  which  passes  backwards  between  the  layers  of  the  tentorium,  dividing 
into  two  or  three  filaments,  which  may  be  traced  as  far  back  as  the  wall  of  the 
lateral  sinus. 

Sixth  Nerve. 

The  Sixth  Nerve  {ahducens)  supplies  the  External  Rectus  muscle.  Its 
apparent  origin  is  by  several  filaments  from  the  constricted  part  of  the  corpus 
pyramidale,  close  to  the  pons,  or  from  the  lower  border  of  the  pons  itself. 

The  deep  origin  of  this  nerve  has  been  traced,  by  Mayo,  between  the  fasciculi 
of  the  corpus  pyramidale,  to  the  posterior  part  of  the  medulla,  where  Stilling 
has  shown  its  connection  with  a  gray  nucleus  in  the  floor  of  the  fourth  ven- 
tricle. The  nerve  pierces  the  dura  mater,  immediately  below  the  posterior 
clinoid  process,  lying  in  a  groove  by  the  side  of  the  body  of  the  sphenoid  bone. 
It  passes  forwards  through  the  cavernous  sinus,  lying  on  the  outer  side  of  the 
internal  carotid  artery,  where  it  is  joined  by  several  filaments  from  the  carotid 
plexus,  by  one  from  Meckel's  ganglion  (Bock),  and  another  from  the  ophthal- 
mic nerve.  It  enters  the  orbit  through  the  sphenoidal  fissure,  and  lies  above 
the  ophthalmic  vein,  from  which  it  is  separated  by  a  lamina  of  dura  mater.    It 

a9 


610  CRANIAL    NERVES. 

then  passes  between  the  two  heads  of  the  External  Rectus,  and  is  distributed 
to  that  muscle  on  its  ocular  surface. 

The  above-mentioned  nerves,  as  well  as  the  ophthalmic  division  of  the  fifth, 
as  they  pass  to  the  orbit,  bear  a  certain  relation  to  each  other  in  the  cavernous 
sinus,  at  the  sphenoidal  fissure,  and  in  the  cavity  of  the  orbit,  which  will  be  now 
described. 

In  the  cavernous ^inus,  the  third,  fourth,  and  ophthalmic  division  of  the  fifth, 
are  placed  in  the  dura  mater  of  the  outer  wall  of  the  sinus,  in  their  numerical 
order,  both  from  above  downwards,  and  from  within  outwards.  The  sixth  nerve 
lies  at  the  outer  side  of  the  internal  carotid  artery.  As  these  nerves  pass  for- 
wards to  the  sphenoidal  fissure,  the  third  and  fifth  nerves  become  divided  into 
branches,  and  the  sixth  approaches  the  rest ;  so  that  their  relative  position  be- 
comes considerably  changed. 

In  the  sphenoidal  fissure,  the  fourth,  and  the  frontal  and  lachrymal  divisions 
of  the  ophthalmic,  lie  upon  the  same  plane,  the  former  being  most  internal,  the 
latter  external ;  and  they  enter  the  cavity  of  the  orbit  above  the  muscles.  The 
remaining  nerves  enter  the  orbit  between  the  two  heads  of  the  External  Rectus. 

The  superior  division  of  the  third  is  the  highest  of  these ;  beneath  this  lies 
the  nasal  branch  of  the  fifth ;  then  the  inferior  division  of  the  third ;  and  the 
sixth  lowest  of  all. 

In  the  orhit,  the  fourth,  and  the  frontal  and  lachrymal  divisions  of  the  oph- 
thalmic, lie  on  the  same  plane  immediately  beneath  the  periosteum,  the  fourth 
nerve  being  internal  and  resting  on  the  Superior  Oblique,  the  frontal  resting 
on  the  Levator  PalpebraB,  and  the  lachrymal  on  the  External  Rectus.  Next  in 
order  comes  the  superior  division  of  the  third  nerve  lying  immediately  beneath 
the  Superior  Rectus,  and  then  the  nasal  division  of  the  fifth  crossing  the  optic 
nerve  from  the  outer  to  the  inner  side  of  the  orbit.  Beneath  these  is  found  the 
optic  nerve,  surrounded  in  front  by  the  ciliary  nerves,  and  having  the  lenticular 
ganglion  on  its  outer  side,  between  it  and  the  External  Rectus.  Below  the  optic 
is  the  inferior  division  of  the  third,  and  the  sixth,  which  lies  on  the  outer  side 
of  the  orbit. 

Facial  Nerve. 

The  Facial  Nerve  {portio  dura  of  the  seventh  pair)  is  the  motor  nerve  of  all 
the  muscles  of  expression  in  the  face,  and  of  the  Platysma  and  Buccinator.     It 

supplies  also  the  muscles  of  the 

Fig.  341. — The  Course  and  Connection  of  the  Facial      external  ear,  the  posterior  belly 

Nerve,  in  the  Temporal  Bone-  of  the  Digastric,  and  the  Stylo- 

ripv-^    ji  hyoid.  Through  the  chorda  tym- 

E:ct».ai  rrAr..a/ '  ^"^^Jv ^^^%7; ^  ■  "'  \        P^^^  ^^  suppHcs  thc  Liugualis ; 

s.,,nn  Pef,os«i — rV^=raEl^iife>^^---^''''-'-^    \       bv  its  tympanic  branch,  the  Sta- 

T7^F7!!^k  pedius  and  Laxator  Tympani; 

""  \>iiii/1^'''''r  '      through  the  otic  ganglion,  the 

,  „_./J?Sir:  \l  Tensor  Tympani;  and  through 

the  connection  of  its  trunk  with 
the  Vidian  nerve,  by  the  petrosal 
nerves,  it  probably  supplies  the 
Levator  Palati  and  Azygos  UvuIsb.  It  arises  from  the  lateral  tract  of  the 
medulla  oblongata,  in  the  groove  between  the  olivary  and  restiforra  bodies. 
Its  deep  origin  may  be  traced  to  the  floor  of  the  fourth  ventricle,  where  it  is 
connected  with  the  same  nucleus  as  the  sixth  nerve.  This  nerve  is  situated  a 
little  nearer  to  the  middle  line  than  the  portio  mollis,  close  to  the  lower  border 
of  the  pons  Varolii,  from  which  some  of  its  fibres  are  derived. 

Connected  with  this  nerve,  and  lying  between  it  and  the  portio  mollis,  is  a 
small  fasciculus  {2)ortio  inter  duram  et  mollem  of  Wrisberg,  or  i^oriio  intermedia). 
This  accessory  portion  arises  from  the  lateral  column  of  the  cord. 

The  nerve  passes  forwards  and  outwards  upon  the  crus  cerebelli,  and  enters 


; 


FACIAL.  611 

the  internal  auditory  meatus  with  the  auditory  nerve.  Within  the  meatus,  the 
facial  nerve  lies  first  to  the  inner  side  of  the  auditory,  and  then  in  a  groove  upon 
that  nerve,  and  is  connected  to  it  by  one  or  two  filaments. 

At  the  bottom  of  the  meatus,  it  enters  the  aquaeductus  Fallopii,  and  follows 
the  serpentine  course  of  that  canal  through  the  petrous  portion  of  the  temporal 
bone,  from  its  commencement  at  the  internal  meatus  to  its  termination  at  the 
stylo-mastoid  foramen.  It  is  at  first  directed  outwards  towards  the  hiatus  Fal- 
lopii, where  it  forms  a  reddish  gangliform  swelling  (intumescentia  ganglioformis), 
and  is  joined  by  several  nerves ;  then  bending  suddenly  backwards,  it  runs  in 
the  internal  wall  of  the  tympanum,  above  the  fenestra  ovalis,  and  at  the  back 
of  that  cavity  passes  vertically  downwards  to  the  stylo-mastoid  foramen. 

On  emerging  from  this  aperture,  it  runs  forwards  in  the  substance  of  the 
parotid  gland,  crosses  the  external  carotid  artery,  and  divides  behind  the  ramus 
of  the  lower  jaw  into  two  primary  branches,  temporo-facial  and  cervico-facial, 
from  which  numerous  offsets  are  distributed  over  the  side  of  the  head,  face, 
and  upper  part  of  the  neck,  supplying  the  superficial  muscles  in  these  regions. 
As  the  primary  branches  and  their  offsets  diverge  from  each  other,  they  present 
somewhat  the  appearance  of  a  bird's  claws ;  hence  the  name  of  pes  anserinus  is 
given  to  the  divisions  of  the  facial  nerve  in  and  near  the  parotid  gland. 

The  communications  of  the  facial  nerve  may  be  thus  arranged : — 

In  the  internal  auditory  meatus  .       With  the  auditory  nerve. 

f  With  Meckel's  ganglion  by  the  large 
petrosal  nerve. 
With  the  otic  ganglion  by  the  small 
In  the  aquaeductus  Fallopii         .   -|      petrosal  nerve. 

With  the  sympathetic  on  the  middle 
meningeal  by  the  external  petrosal 
nerve. 
With  the  pneumogastric. 
"         glosso-pharyngeal. 
"        carotid  plexus. 
"         auricularis  magnus. 
"        auriculo-temporal. 
On  the  face         ....       With  the  three  divisions  of  the  fifth. 

In  the  internal  auditory  meatus,  some  minute  filaments  pass  between  the 
facial  and  auditory  nerves. 

Opposite  the  hiatus  Fallopii,  the  gangliform  enlargement  on  the  facial  nerve 
communicates  by  means  of  the  large  petrosal  nerve,  with  Meckel's  ganglion, 
forming  its  motor  root ;  by  a  filament  from  the  small  petrosal,  with  the  otic 
ganglion ;  and  by  the  external  petrosal,  with  the  sympathetic  filaments  accom- 
panying the  middle  meningeal  artery  (Bidder).  From  the  gangliform  enlarge- 
ment, according  to  Arnold,  a  twig  is  sent  back  to  the  auditory  nerve. 

At  its  exit  from  the  stylo-mastoid  foramen,  it  sends  a  twig  to  the  pneumo- 
gastric, another  to  the  glosso-pharyngeal  nerve,  and  communicates  with  the 
carotid  plexus  of  the  sympathetic,  with  the  great  auricular  branch  of  the  cer- 
vical plexus,  with  the  auriculo-temporal  branch  of  the  mferior  maxillary  nerve 
in  the  parotid  gland,  and  on  the  face  with  the  terminal  branches  of  the  three 
divisions  of  the  fifth. 

Branches  of  Distributiox. 

Within  aqu£eductus  Fallopii  \  n7"^5^"'°' 

^  ^     (  Uhorda  tympani. 

At  exit  from  stylo-mastoid     Posterior  auricular. 

foramen    .         .         .         •iP/^fT''--^ 

(  otylo-hyoid. 


At  its  exit  from  the  stylo-mastoid 
foramen 


61S 


CRANIAL    NERVES. 


{Temporal. 
Malar. 
Infraorbital. 
On  the  face  ....-{  (  Buccal. 

I  Cervico-facial      <  Supramaxillary. 
[,  (  Inframaxillary. 

The  tympanic  branch  arises  from  the  nerve  opposite  the  pyramid ;  it  is  a 
small  filament,  which  supplies  the  Stapedius  and  Laxator  Tympani  muscles. 

The  chorda  tympani  is  given  off  from  the  facial  as  it  passes  vertically  down- 
wards at  the  back  of  the  tympanum,  about  a  quarter  of  an  inch  before  its  exit 
from  the  stylo-mastoid  foramen.  It  ascends  from  below  upwards  in  a  distinct 
canal,  parallel  with  the  aquaeductus  Fallopii,  and  enters  the  cavity  of  the  tym- 
panum through  an  opening  between  the  base  of  the  pyramid  and  the  attach- 

Fig.  342.— The  Nerves  of  the  Scalp,  Face,  and  Side  of  the  Neck. 


TerminatiBtiit 
Supra  -  troe/ilra  r 
tf  Infra  -  trocJilear 
if  ^atal 


ment  of  the  membrana  tympani,  and  becomes  invested  with  mucous  membrane. 
It  passes  forwards  through  the  cavity  of  the  tympanum,  between  the  handle 
of  the  malleus  and  vertical  ramus  of  the  incus,  to  its  anterior  inferior  angle, 
and  emerges  from  that  cavity  through  a  foramen  (the  canal  of  Huguier)  at  the 
inner  side  of  the  Glaserian  fissure.  It  then  descends  between  the  two  Pterygoid 
muscles,  and  meets  the  gustatory  nerve  at  an  acute  angle,  after  communicating 


FACIAL.  613 

with  wliich,  it  accompanies  it  to  the  submaxillary  gland ;  it  then  joins  the  sub- 
maxillary ganglion,  and  terminates  in  the  Lingualis  muscle. 

The  posterior  auricular  nerve  arises  close  to  the  stylo-mastoid  foramen,  and 
passes  upwards  in  front  of  the  mastoid  process,  where  it  is  joined  by  a  filament 
from  the  auricular  branch  of  the  pneumogastric,  and  communicates  with  the 
deep  branch  of  the  auricularis  magnus;  as  it  ascends  between  the  meatus  and 
mastoid  process  it  divides  into  two  branches.  The  auricular  branch  supplies  the 
Retraheas  Aurem.  The  occipital  branch,  the  larger,  passes  backwards  along  the 
superior  curved  line  of  the  occipital  bone,  and  supplies  the  occipital  portion  of 
the  Occipito-frontalis. 

The  stylo-hyoid  is  a  long  slender  branch,  which  passes  inwards,  entering  the 
Stylo-hyoid  muscle  about  its  middle ;  it  communicates  with  the  sympathetic  fila- 
ments on  the  external  carotid  artery. 

The  digastric  branch  usually  arises  by  a  common  trunk  with  the  preceding ; 
it  divides  into  several  filaments,  which  supply  the  posterior  belly  of  the  Digas- 
tric ;  one  of  these  perforates  that  muscle  to  join  the  glosso-pharyngeal  nerve. 

The  Temporo-facial,  the  larger  of  the  two  terminal  branches,  passes  upwards 
and  forwards  through  the  parotid  gland,  crosses  the  neck  of  the  condyle  of  the 
jaw,  being  connected  in  this  situation  with  the  auriculo-temporal  branch  of  the 
inferior  maxillary  nerve,  and  divides  into  branches,  which  are  distributed  over 
the  temple  and  upper  part  of  the  face ;  these  are  divided  into  three  sets,  tem- 
poral, malar,  and  infraorbital. 

The  temporal  branches  cross  the  zygoma  to  the  temporal  region,  supplying 
the  Attrahens  Aurem  muscle,  and  join  with  the  temporal  branch  of  the  supe- 
rior maxillary,  and  with  the  auriculo-temporal  branch  of  the  inferior  maxillary. 
The  more  anterior  branches  supply  the  frontal  portion  of  the  Occipito-frontalis, 
and  the  Orbicularis  Palpebrarum  muscle,  joining  with  the  supraorbital  branch 
of  the  ophthalmic. 

The  malar  branches  pass  across  the  malar  bone  to  the  outer  angle  of  the  orbit, 
where  they  supply  the  Orbicularis  and  Corrugator  Supercilii  muscles,  joining 
with  filaments  from  the  lachrymal  and  supraorbital  nerves ;  others  supply  the 
lower  eyelid,  joining  with  filaments  of  the  malar  branches  of  the  superior 
maxillary  nerve. 

The  infraorbital,  of  larger  size  than  the  rest,  pass  horizontally  forwards  to  be 
distributed  between  the  lower  margin  of  the  orbit  and  the  mouth.  The  super- 
ficial branches  run  beneath  the  skin  and  above  the  superficial  muscles  of  the 
face,  which  they  supply ;  some  supply  the  lower  eyelid  and  Pyramidalis  Nasi, 
joining  at  the  inner  angle  of  the  orbit,  with  the  infratrochlear  and  nasal  branches 
of  the  ophthalmic.  The  deep  branches  pass  beneath  the  Levator  Labii  Superi- 
oris,  supply  it  and  the  Levator  Anguli  Oris,  and  form  a  plexus  (infraorbital)  by 
joining  with  the  infraorbital  branch  of  the  superior  maxillary  nerve. 

The  Gervico-facial  division  of  the  facial  nerve  passes  obliquely  downwards 
and  forwards  through  the  parotid  gland,  where  it  is  joined  by  branches  from 
the  great  auricular  nerve ;  opposite  the  angle  of  the  lower  jaw  it  divides  into 
branches  which  are  distributed  on  the  lower  half  of  the  face  and  upper  part  of 
the  neck.  These  may  be  divided  into  three  sets :  buccal,  supramaxillary,  and 
inframaxillary. 

The  buccal  branches  cross  the  Masseter  muscle,  join  the  infraorbital  branches 
of  the  temporo-facial  division  of  the  nerve,  and  with  filaments  of  the  buccal 
branch  of  the  inferior  maxillary  nerve.  They  supply  the  Buccinator  and 
Orbicularis  Oris. 

The  siq^ramaxillary  branches  pass  forwards  beneath  the  Platysma  and  Depres- 
sor Anguli  Oris,  supplying  the  muscles  of  the  lip  and  chin,  and  anastomosing 
with  the  mental  branch  of  the  inferior  dental  nerve. 

The  inframaxillary  branches  run  forwards  beneath  the  Platysma,  and  form  a 
series  of  arches  across  the  side  of  the  neck  over  the  supra-hyoid  region.  One 
of  these  branches  descends  vertically  to  join  with  the  superficial  cervical  nerve 
from  the  cervical  plexus  ;  others  supply  the  Platysma. 


614 


CRANIAL    NERVES. 


Ninth,  or  Hypoglossal  Nerve. 

The  Ninth,  or  Hypoglossal  Nerve,  is  the  motor  nerve  of  the  tongue.  It  arises 
by  several  filaments,  from  ten  to  fifteen  in  number,  from  the  groove  between 
the  pyraniidal  and  olivary  bodies,  in  a  continuous  line  with  the  anterior  roots 
of  the  spinal  nerves.  According  to  Stilling,  these  roots  may  be  traced  to  a 
gray  nucleus  in  the  floor  of  the  medulla  oblongata,  between  the  posterior 
median  furrow  and  the  nuclei  of  the  glosso-pharyngeal  and  vagus  nerves.  The 
filaments  ot  this  nerve  are  collected  into  two  bundles,  which  perforate  the  dura 
mater  separately,  opposite  the  anterior  condyloid  foramen,  and  unite  together 
after  their  passage  through  it.     In  those  cases  in  which  the  anterior  condyloid 

Fig.  343. — ITypoglossal  Nerve,  Cervical  Plexus,  and  their  Branches. 


foramen  in  the  occipital  bone  is  double,  these  two  portions  of  the  nerve  are  sepa- 
rated by  a  small  piece  of  bone,  which  divides  the  foramen.  The  nerve  descends 
almost  vertically  to  a  point  corresponding  with  the  angle  of  the  jaw.  It  is  at 
first  deeply  seated  beneath  the  internal  carotid  and  internal  jugular  vein,  and 
intimately  connected  with  the  pneumogastrio  nerve ;  it  then  passes  forwards 
between  the  vein  and  artery,  and  at  a  lower  part  of  the  neck  becomes  super- 
ficial below  the  Digastric  muscle.  The  nerve  then  loops  round  the  occipital 
artery,  and  crosses  the  external  carotid  below  the  tendon  of  the  Digastric 
muscle.  It  passes  beneath  the  Mylo-hyoid  muscle,  lying  between  it  and  the 
Hyo-glossus,  and  is  connected  at  the  anterior  border  of  the  latter  muscle  with 
the  gustatory  nerve;  it  is  then  continued  forwards  into  the  Genio-hyo-glossus 
musclo  as  far  as  the  tip  of  the  tongue,  distributing  branches  to  its  substance. 


/      FIFTH.  615 

Branches  of  this  nerve  communicate  with  the 

Pneumogastric.  First  and  second  cervical  nerves. 

Sympathetic.  Gustatory. 

The  communication  with  the  pneumogastric  takes  place  close  to  the  exit  of 
the  nerve  from  the  skull,  numerous  filaments  passing  between  the  hypoglossal 
and  second  ganglion  of  the  pneumogastric,  or  both  being  united  so  as  to  form 
one  mass. 

The  communication  with  the  sympathetic  takes  place  opposite  the  atlas,  by 
branches  derived  from  the  superior  cervical  ganglion,  and  in  the  same  situation 
the  ninth  is  joined  by  a  filament  derived  from  the  loop  connecting  the  first  two 
cervical  nerves. 

The  communication  with  the  gustatory  takes  place  near  the  anterior  border 
of  the  Hyo-glossus  muscle  by  numerous  filaments  which  ascend  upon  it. 
The  branches  of  distribution  are  the 

Descendens  noni.  Thyro-hyoid. 

Muscular. 

The  descendens  noni  is  a  long  slender  branch,  which  quits  the  hypoglossal 
where  it  turns  round  the  occipital  artery.  It  descends  obliquely  across  the 
sheath  of  the  carotid  vessels,  and  joins  just  below  the  middle  of  the  neck,  to 
form  a  loop  with  the  communicating  branches  from  the  second  and  third  cervi- 
cal nerves.  From  the  convexity  of  this  loop  branches  pass  forwards  to  supply 
the  Sterno-hyoid,  Sterno-thyroid,  and  both  bellies  of  the  Omo-hyoid,  According 
to  Arnold,  another  filament  descends  in  front  of  the  vessels  into  the  chest, 
which  joins  the  cardiac  and  phrenic  nerves.  The  descendens  noni  is  occasion- 
ally contained  in  the  sheath  of  the  carotid  vessels,  being  sometimes  placed  over 
and  sometimes  beneath  the  internal  jugular  vein. 

The  thyro-hyoid  is  a  small  branch,  arising  from  the  hypoglossal  near  the  pos- 
terior border  of  the  Hyo-glossus ;  it  passes  obliquely  across  the  great  cornu  of 
the  hyoid  bone,  and  supplies  the  Thyro-hyoid  muscle. 

The  muscular  branches  are  distributed  to  the  Stylo-glossus,  Hyo-glossus,  Genio- 
hj^oid,  and  Genio-hyo-glossus  muscles.  At  the  under  surface  of  the  tongue, 
numerous  slender  branches  pass  upwards  into  the  substance  of  the  organ. 

Fifth  Nerve. 

The  Fifth  Nerve  {trifacial,  trigeminus)  is  the  largest  cranial  nerve,  and  re- 
sembles a  spinal  nerve,  in  its  origin  by  two  roots,  and  in  the  existence  of  a 
ganglion  on  its  posterior  root.  The  functions  of  this  nerve  are  various.  It  is 
a  nerve  of  special  sense,  of  common  sensation,  and  of  motion.  It  is  the  great 
sensitive  nerve  of  the  head  and  face,  the  motor  nerve  of  the  muscles  of  masti- 
cation, and  its  lingual  branch  is  one  of  the  nerves  of  the  special  sense  of  taste. 
It  arises  by  two  roots,  a  posterior  larger  or  sensory,  and  an  anterior  smaller  or 
motor  root.  Its  superficial  origin  is  from  the  side  of  the  pons  Varplii,  a  little 
nearer  to  the  upper  than  the  lower  border.  The  smaller  root  consists  of  three 
or  four  bundles  ;  in  the  larger,  the  bundles  are  more  numerous,  varying  in  num- 
ber from  seventy  to  a  hundred  ;  the  two  roots  are  separated  from  one  another 
by  a  few  of  the  transverse  fibres  of  the  pons.  The  deep  origin  of  the  larger 
or  sensory  root  may  be  traced  between  the  transverse  fibres  of  the  pons  Varolii 
to  the  lateral  tract  of  the  medulla  oblongata,  immediately  behind  the  olivary 
body.  According  to  some  anatomists,  it  is  connected  with  the  gray  nucleus  at 
the  back  part  of  the  medulla,  between  the  fasciculi  teretes  and  restiform  col- 
umns. By  others,  it  is  said  to  be  continuous  with  the  fasciculi  teretes  and 
lateral  column  of  the  cord ;  and,  according  to  Foville,  some  of  its  fibres  are 
connected  with  the  transverse  fibres  of  the  pons ;  whilst  others  enter  the  cere- 
bellum, spreading  out  on  the  surface  of  its  middle  peduncle.  The  motor  root 
has  been  traced  by  Bell  and  Retzius  to  be  connected  with  the  pyramidal  body. 
The  two  roots  of  the  nerve  pass  forwards  through  an  oval  opening  in  the  dura 


616  CRANIAL    NERVES. 

mater,  at  the  apex  of  the  petrous  portion  of  the  temporal  bone ;  here  the  fibres 
of  the  larger  root  enter  a  large  semilunar  ganglion  (Casserian),  while  the  smaller 
root  passes  beneath  the  ganglion  without  having  any  connection  with  it,  and 
joins  outside  the  cranium  with  one  of  the  trunks  derived  from  it. 

The  Casserian,  or  Semilunar  Ganglion,  is  lodged  in  a  depression  near  the  apex 
of  the  petrous  portion  of  the  temporal  bone.  It  is  of  a  somewhat  crescentic 
form,  with  its  convexity  turned  forwards.  Its  upper  surface  is  intimately 
adherent  to  the  dura  mater. 

Branches.  This  ganglion  receives,  on  its  inner  side,  filaments  from  the  carotid 
plexus  of  the  sympathetic ;  and  from  it  some  minute  branches  are  given  off  to 
the  tentorium  cerebelli,  and  the  dura  mater,  in  the  middle  fossa  of  the  cranium. 
From  its  anterior  border,  which  is  directed  forwards  and  outwards,  three  large 
branches  proceed:  the  ophthalmic,  superior  maxillary,  and  inferior  maxillary. 
The  ophthalmic  and  superior  maxillary  consist  exclusively  of  fibres  derived 
from  the  larger  root  and  ganglion,  and  are  solely  nerves  of  common  sensation. 
The  third  division,  or  inferior  maxillary,  is  composed  of  fibres  from  both  roots. 
This,  therefore,  strictly  speaking,  is  the  only  portion  of  the  fifth  nerve  which 
can  be  said  to  resemble  a  spinal  nerve. 

Ophthalmic  Nerve.    (Fig.  339.) 

The  Ophthalmic,  or  first  division  of  the  fifth,  is  a  sensory  nerve.  It  supplies 
the  eyeball,  the  lachrymal  gland,  the  mucous  lining  of  the  eye  and  nose,  and 
the  integument  and  muscles  of  the  eyebrow  and  forehead.  It  is  the  smallest 
of  the  three  divisions  of  the  fifth,  arising  from  the  upper  part  of  the  Casserian 
ganglion.  It  is  a  short,  flattened  band,  about  an  inch  in  length,  which  passes 
forwards  along  the  outer  wall  of  the  cavernous  sinus,  below  the  other  nerves, 
and  just  before  entering  the  orbit,  through  the  sphenoidal  fissure,  divides  into 
three  branches,  lachrymal,  frontal,  and  nasal.  The  ophthalmic  nerve  is  joined 
by  filaments  from  the  cavernous  plexus  of  the  sympathetic,  and  gives  off  recur- 
rent filaments  which  pass  between  the  layers  of  the  tentorium,  with  a  branch 
from  the  fourth  nerve. 

Its  branches  jutg,  the 

Lachrymal.  Frontal.  Nasal. 

The  Lachrymal  is  the  smallest  of  the  three  branches  of  the  ophthalmic.  Not 
unfrequently  it  arises  by  two  filaments,  one  from  the  ophthalmic,  the  other 
from  the  fourth,  and  this  Swan  considers  to  be  its  usual  condition.  It  passes 
forwards  in  a  separate  tube  of  dura  mater,  and  enters  the  orbit  through  the 
narrowest  part  of  the  sphenoidal  fissure.  In  the  orbit,  it  runs  along  the 
upper  border  of  the  External  Rectus  muscle,  with  the  lachrymal  artery,  and 
is  connected  with  the  orbital  branch  of  the  superior  maxillary  nerve.  Within 
the  lachrymal  gland  it  gives  off  several  filaments,  which  supply  the  gland  and 
the  conjunctiva.  Finally  it  pierces  the  palpebral  ligament,  and  terminates  in 
the  integument  of  the  upper  eyelid,  joining  with  filaments  of  the  facial  nerve. 

"The  Frontal  is  the  largest  division  of  the  ophthalmic,  and  may  be  regarded, 
both  from  its  size  and  direction,  as  the  continuation  of  this  nerve.  It  enters 
the  orbit  above  the  muscles,  through  the  highest  and  broadest  part  of  the  sphe- 
noidal fissure,  and  runs  forwards  along  tlie  middle  line,  between  the  Levator 
palpebraa  and  the  periosteum.  Midway  between  the  apex  and  base  of  the  orbit 
it  divides  into  two  branches,  supratrochlear  and  supraorbital. 

The  supratrochlear  branch,  the  smaller  of  the  two,  passes  inwards,  above  the 
pulley  of  the  Superior  Oblique  muscle,  and  gives  off  a  descending  filament, 
which  joins  with  the  infratrochlear  branch  of  the  nasal  nerve.  It  then  escapes 
from  the  orbit  between  the  pulley  of  the  Superior  Oblique  and  the  supraorbital 
foramen,  curves  up  on  to  the  forehead  close  to  the  bone,  and  ascends  behind 
the  Corrugator  Supercilii,  and  Occipito-frontalis  muscles,  to  both  of  which  it  is 
distributed;  finally,  it  is  lost  in  the  integument  of  the  forehead. 


OPHTHALMIC.  617 

The  supraorbital  branch  passes  forwards  through  the  supraorbital  foramen, 
and  gives  off,  in  this  situation,  palpebral  Jilaments  to  the  upper  eyelid.  It  then 
ascends  upon  the  forehead,  and  terminates  in  muscular,  cutaneous,  and  peri- 
cranial branches.  The  muscular  branches  supply  the  Corrugator  Supercilii, 
Occipito-frontalis,  and  Orbicularis  Palpebrarum,  furnishing  these  muscles  with 
common  sensation,  and  joining  in  the  substance  of  the  latter  lAuscle  with  the 
facial  nerve.  The  cutaneous  branches,  two  in  number,  an  inner  and  an  outer, 
supply  the  integument  of  the  cranium  as  far  back  as  the  occiput.  They  are  at 
first  situated  beneath  the  Occipito-Yrontalis,  the  inner  branch  perforating  the 
frontal  portion  of  the  muscle,  the  outer  branch  its  tendinous  aponeurosis.  The 
pericranial  branches  are  distributed  to  the  pericranium  over  the  frontal  and 
parietal  bones.  They  are  derived  from  the  cutaneous  branches  whilst  beneath 
the  muscle. 

The  Nasal  nerve  is  intermediate  in  size  between  the  frontal  and  lachrymal, 
and  more  deeply  placed  than  the  other  branches  of  the  ophthalmic.  It  enters 
the  orbit  between  the  two  heads  of  the  External  Eectus,  and  passes  obliquely 
inwards  across  the  optic  nerve,  beneath  the  Levator  Palpebrae  and  Superior 
Eectus  muscles,  to  the  inner  wall  of  the  orbit,  where  it  enters  the  anterior 
ethmoidal  foramen,  immediately  below  the  Superior  Oblique.  It  then  enters 
the  cavity  of  the  cranium,  traverses  a  shallow  groove  on  the  front  of  the  cribri- 
form plate  of  the  ethmoid  bone,  and  passes  down,  through  the  slit  by  the  side 
of  the  crista  galli,  into  the  nose,  where  it  divides  into  two  branches,  an  internal 
and  an  external.  The  internal  branch  supplies  the  mucous  membrane  near  the 
fore  part  of  the  septum  of  the  nose.  The  external  branch  descends  in  a  groove 
on  the  inner  surface  of  the  nasal  bone,  and  supplies  a  few  filaments  to  the 
mucous  membrane  covering  the  fore  part  of  the  outer  wall  of  the  nares  as  far 
as  the  inferior  spongy  bone;  it  then  leaves  the  cavity  of  the  nose,  between  the 
lower  border  of  the  nasal  bone  and  the  upper  lateral  cartilage  of  the  nose,  and, 
passing  down  beneath  the  Compressor  Nasi,  supplies  the  integument  of  the  ala 
and  tip  of  the  nose,  joining  with  the  facial  nerve. 

The  branches  of  the  nasal  nerve  are,  the  ganglionic,  ciliary,  and  infratrochlear. 

The  ganglionic  is  a  long,  slender  branch,  about  half  an  inch  in  length,  which 
usually  arises  from  the  nasal,  between  the  two  heads  of  the  external  rectus.  It 
passes  forwards  on  the  outer  side  of  the  optic  nerve,  and  enters  the  superior 
and  posterior  angle  of  the  ciliary  ganglion,  forming  its  superior,  or  long  root. 
It  is  sometimes  joined  by  a  filament  from  the  cavernous  plexus  of  the  sympa- 
thetic, or  from  the  superior  division  of  the  third  nerve. 

The  long  ciliary  nerves,  two  or  three  in  number,  are  given  off  from  the  nasal 
as  it  crosses  the  optic  nerve.  They  join  the  short  ciliary  nerves  from  the  ciliary 
ganglion,  pierce  the  posterior  part  of  the  sclerotic,  and,  running  forwards 
between  it  and  the  choroid,  are  distributed  to  the  ciliary  muscle  and  iris. 

The  infratrochlear  branch  is  given  off  just  as  the  nasal  nerve  passes  through 
the  anterior  ethmoidal  foramen.  It  runs  forwards  along  the  upper  border  of 
the  Internal  Rectus,  and  is  joined,  beneath  the  pulley  of  the  Superior  Oblique, 
by  a  filament  from  the  supratrochlear  nerve.  It  then  passes  to  the  inner  angle 
of  the  eye,  and  supplies  the  Orbicularis  Palpebrarum,  the  integument  of  the 
eyelids,  and  side  of  the  nose,  the  conjunctiva,  lachrymal  sac,  and  caruncula 
lachrymalis. 

Connected  with  the  three  divisions  of  the  fifth  nerve  are  four  small  Ganglia, 
which  form  the  whole  of  the  cephalic  portion  of  the  sympathetic.  With  the 
first  division  is  connected  the  ophthalmic  ganglion ;  with  the  second  division, 
the  spheno-palatine,  or  Meckel's  ganglion;  and  with  the  third,  the  otic  and  sub- 
maxillary ganglia.  All  the  four  receive  sensitive  filaments  from  the  fifth,  and 
motor  and  sympathetic  filaments  from  various  sources;  these  filaments  are 
called  the  roots  of  the  ganglia.  The  ganglia  are  also  connected  with  each  other, 
and  with  the  cervical  portion  of  the  sympathetic. 


618  CRANIAL    NERVES.        ' 

Ophthalmic  Ganglion.    (Fig.  340.) 

The  Ophthalmic,  Lenticular,  or  Ciliary  Ganglion,  is  a  small,  quadrangular,  flat- 
tened ganglion,  of  a  reddish-gray  color,  and  about  the  size  of  a  pin's  head  situ- 
ated at  the  back  part  of  the  orbit  between  the  optic  nerve  and  the  External 
Rectus  muscle,  lying  generally  on  the  outer  side  of  the  ophthalmic  artery.  It 
is  inclosed  in  a  quantity  of  loose  fat,  which  makes  its  dissection  somewhat 
difl&cult. 

Its  branches  of  communication,  or  roots,  are  three,  all  of  which  enter  its  posterior 
border.  One,  the  long  root,  is  derived  from  the  nasal  branch  of  the  ophthalmic, 
and  joins  its  superior  angle.  Another  branch,  the  short  root,  is  a  short  thick 
nerve,  occasionally  divided  into  two  parts,  which  is  derived  from  the  branch  of 
the  third  nerve  or  the  Inferior  Oblique  muscle,  and  is  connected  with  the  in- 
ferior angle  of  the  ganglion.  A  third  branch,  the  sympathetic  root,  is  a  slender 
filament  from  the  cavernous  plexus  of  the  sympathetic.  This  is  occasionally 
blended  with  the  long  root,  and  sometimes  passes  to  the  ganglion  separately. 
According  to  Tiedemann,  this  ganglion  receives  a  filament  of  communication 
from  the  spheno-palatine  ganglion. 

Its  branches  of  distribution  are  the  short  ciliary  nerves.  These  are  delicate 
filaments  from  ten  to  twelve  in  number,  which  arise  from  the  fore  part  of  the 
ganglion  in  two  bundles,  connected  with  its  superior  and  inferior  angles  ;  the 
upper  bundle  consisting  of  four  filaments,  and  the  lower  of  six  or  seven.  They 
run  forwards  with  the  ciliary  arteries  in  a  wavy  course,  one  set  above  and  the 
other  below  the  optic  nerve,  pierce  the  sclerotic  at  the  back  part  of  the  globe, 
pass  forwards  in  delicate  grooves  on  its  inner  surface,  and  are  distributed  to  the 
ciliary  muscle  and  iris.  A  small  filament  is  described  by  Tiedemann  pene- 
trating the  optic  nerve  with  the  arteria  centralis  retinae. 

Superior  Maxillary  Nerve.    (Fig.  344.) 

The  Superior  Maxillary,  or  second  division  of  the  fifth,  is  a  sensory  nerve. 
It  is  intermediate,  both  in  position  and  size,  between  the  ophthalmic  and  inferior 
maxillary.  It  commence  at  the  middle  of  the  Casserian  ganglion  as  a  flattened 
plexiform  band,  and  passes  forwards  through  the  foramen  rotundura,  where  it 
becomes  more  cylindrical  in  form,  and  firmer  in  texture.  It  then  crosses  the 
spheno-maxillary  fossa,  traverses  the  infraorbital  canal  in  the  floor  of  tlie  orbit, 
and  appears  upon  the  face  at  the  infraorbital  foramen.  At  its  termination,  the 
nerve  lies  beneath  the  Levator  Labii  Superioris  muscle,  and  divides  into  a  leash 
of  branches,  which  spread  out  upon  the  side  of  the  nose,  the  lower  eyelid,  and 
upper  lip,  joining  with  filaments  of  the  facial  nerve. 

The  branches  of  this  nerve  may  be  divided  into  three  groups:  1.  Those  given 
off  in  the  spheno-maxillary  fossa.  2.  Those  in  the  infraorbital  canal.  3.  Those 
on  the  face. 

i  Orbital. 

Spheno-maxillary  fossa  I  Spheno-palatine.  

(  Posterior  dental. 
Infraorbital  canal     .     .     Anterior  dental. 

{Palpebral. 
Nasal. 
Labial. 

The  orbital  branch  arises  in  the  spheno-maxillary  fossa,  enters  the  orbit  by 
tlie  spheno-maxillary  fissure,  and  divides  at  the  back  of  that  cavity  into  two 
branches,  temporal  and  malar. 

The  temporal  braiich  runs  in  a  groove  along  the  outer  wall  of  the  orbit  (in  the 
malar  bone),  receives  a  branch  of  communication  from  the  lachrymal,  and, 
passing  through  a  foramen  in  the  malar  bone,  enters  the  temporal  fossa.  It 
ascends  between  the  bone  and  substance  of  the  Temporal  muscles,  pierces  this 


SUPERIOR    MAXILLARY. 


619 


muscle  and  the  temporal  fascia  about  an  inch  above  the  zygoma,  and  is  dis- 
tributed to  the  integument  covering  the  temple  and  side  of  the  forehead,  com- 
municating with  the  facial  and  auriculo-temporal  branch  of  the  inferior  maxil- 
lary nerve. 

The  malar  branch  passes  along  the  external  inferior  angle  of  the  orbit, 
emerges  upon  the  face  through  a  foramen  in  the  malar  bone,  and  perforating 
the  Orbicularis  Palpebrarum  muscle  on  the  prominence  of  the  cheek,  joins  with 
the  facial. 

The  spheno-palatine  branches,  two  in  number,  descend:  to  the  spheno-palatine 
ganglion. 

The  posterior  dental  branches  arise  from  the  trunk  of  the  nerve  just  as  it  is 
about  to  enter  the  infraorbital  canal ;  they  are  two  in  number,  posterior  and 
anterior. 


Fig.  344. — Distribution  of  the  Second  and  Third  Divisions  of  the  Fifth  Nerve 
and  Sub-maxillary  Ganglion. 


Mirtor  Jlfot 


The  posterior  branch  passes  from  behind  forwards  in  the  substance  of  the 
superior  maxillary  bone,  and  joins  opposite  the  canine  fossa  with  the  anterior 
dental.  Numerous  filaments  are  given  off  from  the  lower  border  of  this  nerve, 
which  form  a  minute  plexus  in  the  outer  wall  of  the  superior  maxillary  bone, 
immediately  above  the  alveolus.  From  this  plexus  filaments  are  distributed  to 
the  pulps  of  the  molar  and  second  bicuspid  teeth,  the  lining  membrane  of  the 
antrum,  and  corresponding  portion  of  the  gums. 

The  anterior  branch  is  distributed  to  the  gums  and  Buccinator  muscle. 

The  anterior  dental,  of  large  size,  is  given  off  from  the  superior  maxillary 
nerve  just  before  its  exit  from  the  infraorbital  foramen  ;  it  enters  a  special  canal 
in  the  anterior  wall  of  the  antrum,  and  anastomoses  with  the  posterior  dental. 
From  this  nerve  some  filaments  are  distributed  to  the  incisor,  canine,  and  first 


620 


CRANIAL    NERVES. 


bicuspid  teeth ;  others  are  lost  upon  the  lining  membrane  covering  the  fore  part 
of  the  inferior  meatus. 

The  palpebral  branches  pass  upwards  beneath  the  Orbicularis  Palpebrarum. 
They  supply  this  muscle,  the  integument,  and  conjunctiva  of  the  lower  eyelid 
with  sensation,  joining  at  the  outer  angle  of  the  orbit  with  the  facial  nerve  and 
malar  branch  of  the  orbital. 

The  nasal  branches  pass  inwards ;  they  supply  the  muscles  and  integument  of 
the  side  of  the  nose,  and  join  with  the  nasal  branch  of  the  ophthalmic. 

The  labial  branches,  the  largest  and  most  numerous,  descend  beneath  the 
Levator  labii  superioris,  and  are  distributed  to  the  integument  and  muscles  of 
the  upper  lip,  the  mucous  membrane  of  the  mouth,  and  labial  glands. 

All  these  branches  are  joined,  immediately  beneath  the  orbit,  by  filaments 
from  the  facial  nerve,  forming  an  intricate  plexus,  the  infraorbital. 

Spheno-palatine  Ganglion. 

The  Spheno-palatine  Ganglion  (Meckel's)  (Fig.  345),  the  largest  of  the  cranial 
ganglia,  is  deeply  placed  in  the  spheno-maxillary  fossa,  close  to  the  spheno- 
palatine foramen.  It  is  triangular,  or  heart-shaped  in  form,  of  a  reddish-gray 
color,  and  placed  mainly  behind  the  palatine  branches  of  the  superior  maxillary 
nerve,  at  the  point  where  the  sympathetic  root  joins  the  ganglion.  It  conse- 
quently does  not  involve  those  nerves  which  pass  to  the  palate  and  nose.  Like 
the  other  ganglia  of  the  fifth  nerve,  it  possesses  a  motor,  a  sensory,  and  a  sym- 
pathetic root.  Its  motor  root  is  derived  from  the  facial,  through  the  Vidian ; 
its  sensory  rootfrom  the  fifth  ;  and  its  sympathetic  root  from  the  carotid  plexus, 
through  the  Vidian.  Its  branches  are  divisible  into  four  groups ;  ascending, 
which  pass  to  the  orbit ;  descending,  to  the  palate ;  internal,  to  the  nose ;  and 
posterior  branches,  to  the  pharynx. 

Fig.  345. — The  Spheno-palatine  Ganglion  and  its  Branches. 


Trr-m'  <>f 


The  ascending  branches  are  two  or  three  delicate  filaments,  which  enter  the 
orbit  by  the  spheno-maxillary  fissure,  and  supply  the  periosteum.  Arnold 
describes  and  delineates  these  branches  as  ascending  to  the  optic  nerve;  one,  to 
the  sixth  nerve  (Bock) ;  and  one,  to  the  ophthalmic  ganglion  (Tiedemann). 


SPHENO-PALATINE    GANGLION.  621 

The  descending  or  'palatine  branches  are  distributed  to  the  roof  of  the  mouth, 
the  soft  palate,  tonsil,  and  lining  membrane  of  the  nose.  They  are  almost  a 
direct  continuation  of  the  spheno-palatine  branches  of  the  superior  maxillary 
nerve,  and  are  three  in  number :  anterior,  middle,  and  posterior. 

The  anterior,  or  large  palatine  nerve,  descends  through  the  posterior  palatine 
canal,  emerges  upon  the  hard  palate,  at  the  posterior  palatine  foramen,  and 
passes  forwards  through  a  groove  in  the  hard  palate,  nearly  as  far  as  the  incisor 
teeth.  It  supplies  the  gums,  the  mucous  membrane  and  glands  of  the  hard 
palate,  and  communicates  in  front  with  the  termination  of  the  naso-palatine 
nerve.  While  in  the  posterior  palatine  canal,  it  gives  off  inferior  nasal  branches, 
which  enter  the  nose  through  openings  in  the  palate  bone,  and  ramify  over  the 
middle  meatus,  and  the  middle  and  inferior  spongy  bones ;  and  at  its  exit  from 
the  canal,  a  palatine  branch  is  distributed  to  both  surfaces  of  the  soft  palate. 

The  middle,  or  external  palatine  nerve,  descends  in  the  same  canal  as  the 
preceding,  to  the  posterior  palatine  foramen,  distributing  branches  to  the  uvula, 
tonsil,  and  soft  palate.     It  is  occasionally  wanting. 

The  posterior,  or  small  palatine  nerve,  descends  with  a  small  artery  through, 
the  small  posterior  palatine  canal,  emerging  by  a  separate  opening  behind  the 
posterior  palatine  foramen.  It  supplies  the  Levator  Palati  and  Azygos  Uvulse 
muscles,  the  soft  palate,  tonsil,  and  uvula. 

The  internal  branches  are  distributed  to  the  septum,  and  outer  wall  of  the  nasal 
fossae.     They  are  the  superior  nasal  (anterior),  and  the  naso-palatine. 

The  superior  nasal  branches  (anterior),  four  or  five  in  number,  enter  the  back 
part  of  the  nasal  fossa  by  the  spheno-palatine  foramen.  They  supply  the  mucous 
membrane  covering  the  superior  and  middle  spongy  bones,  and  that  lining  the 
posterior  ethmoidal  cells,  a  few  being  prolonged  to  the  upper  and  back  part  of 
the  septum. 

The  naso-palatine  nerve  (Cotunnius)  enters  the  nasal  fossa  with  the  other 
nasal  nerves,  and  passes  inwards  across  the  roof  of  the  nose,  below  the  orifice 
of  the  sphenoidal  sinus,  to  reach  the  septum ;  it  then  runs  obliquely  downwards 
and  forwards  along  the  lower  part  of  the  septum,  to  the  anterior  palatine  fora- 
men, lying  between  the  periosteum  and  mucous  membrane.  It  descends  to  the 
roof  of  the  mouth  by  a  distinct  canal,  which  opens  below  in  the  anterior  pala- 
tine fossa ;  the  right  nerve,  also  in  a  separate  canal,  being  posterior  to  the  left 
one.  In  the  mouth,  they  become  united,  supply  the  mucous  membrane  behind 
the  incisor  teeth,  and  join  with  the  anterior  palatine  nerve.  The  naso-palatine 
nerve  occasionally  furnishes  a  few  small  filaments  to  the  mucous  membrane  of 
the  septum. 

The  posterior  branches  are  the  Vidian  and  pharyngeal  (pterygo-palatine). 

The  Vidian  nerve,  if  traced /ro?n  Meckel's  ganglion,  may  be  said  to  arise  from 
the  back  part  of  the  spheno-palatine  ganglion,  and  then  passes  through  the 
Vidian  canal,  enters  the  cartilage  filling  in  the  foramen  lacerum  basis  cranii, 
and  divides  into  two  branches,  the  large  petrosal,  and  the  carotid.  In  its  course 
along  the  Vidian  canal,  it  distributes  a  few  filaments  to  the  lining  membrane  at 
the  back  part  of  the  roof  of  the  nose  and  septum,  and  that  covering  the  end  of 
the  Eustachian  tube.     These  are  upper  posterior  nasal  branches. 

The  large  petrosal  branch  [nervus  j)etrosus  swperjicialis  major)^  enters  the  cra- 
nium through  the  foramen  lacerum  basis  cranii,  having  pierced  the  cartilaginous 
substance  which  fills  in  this  aperture.  It  runs  beneath  the  Casserian  ganglion 
and  dura  mater  contained  in  a  groove  in  the  anterior  surface  of  the  petrous 
portion  of  the  temporal  bone,  enters  the  hiatus  Fallopii,  and,  being  continued 
through  it  into  the  aquseductus  Fallopii,  joins  the  gangliform  enlargement  on 
the  facial  nerve.  Properly  speaking,  this  nerve  passes  from  the  facial  to  the 
spheno-palatine  ganglion,  forming  its  motor  root. 

The  carotid  branch  is  shorter,  but  larger  than  the  petrosal,  of  a  reddish-gray 
color,  and  soft  in  texture.     It  crosses  the  foramen  lacerum,  surrounded  by  the 


CRANIAL    NERVES. 

cartilaginous  substance  whicli  fills  in  that  aperture,  and  enters  the  carotid  canal 
on  the  outer  side  of  the  carotid  artery,  to  join  the  carotid  plexus. 

This  description  of  the  Vidian  nerve  as  a  branch  from  the  ganglion,  is  the 
more  convenient  anatomically,  inasmuch  as  the  nerve  is  generally  dissected 
from  the  ganglion,  as  a  single  trunk  dividing  ioto  two  branches.  But  it  is  more 
correct,  physiologically,  to  describe  the  Vidian  as  being  formed  by  the  union 
of  the  two  branches  (great  petrosal  and  carotid)  from  the  facial  and  the  sympa- 
thetic, and  as  running  into  the  ganglion.  The  filaments,  which  are  described 
above  as  given  off  from  the  Vidian  nerve,  would  then  be  regarded  as  branches 
from  the  ganglion  which  are  merely  inclosed  in  the  same  sheath  as  the  Vidian. 

The  pharyngeal  nerve  (pterygo-palatine)  is  a  small  branch  arising  from  the 
back  part  of  the  ganglion,  occasionally  together  with  the  Vidian  nerve.  It 
passes  through  the  pterygo-palatine  canal  with  the  pterygo-palatine  artery, 
and  is  distributed  to  the  lining  membrane  of  the  pharynx,  behind  the  Eusta- 
chian tube. 

Inferior  Maxillary  Nerve.    (Fig.  344.) 

The  Inferior  Maxillary  Nerve  distributes  branches  to  the  teeth  and  gums  of 
the  lower  jaw,  the  integument  of  the  temple  and  external  ear,  the  lower  part 
of  the  face  and  lower  lip,  and  the  muscles  of  mastication;  it  also  supplies  the 
tongue  with  one  of  its  special  nerves  of  the  sense  of  taste.  It  is  the  largest 
of  the  three  divisions  of  the  fifth,  and  consists  of  two  portions,  the  large  or 
sensory  root  proceeding  from  the  inferior  angle  of  the  Casserian  ganglion ;  and 
the  small  or  motor  root,  which  passes  beneath  the  ganglion,  and  unites  with  the 
inferior  maxillary  nerve,  just  after  its  exit  through  the  foramen  ovale.  Imme- 
diately beneath  the  base  of  the  skull  this  nerve  divides  into  two  trunks, 
anterior  and  posterior. 

The  anterior,  and  smaller  division,  which  receives  nearly  the  whole  of  the 
motor  root,  divides  into  five  branches,  which  supply  the  muscles  of  mastication. 
They  are  the  masseteric,  deep  temporal,  buccal,  and  two  pterygoid. 

The  masseteric  branch  passes  outwards,  above  the  External  Pterygoid  muscle, 
in  front  of  the  temporo-maxillary  articulation,  and  crosses  the  sigmoid  notch, 
with  the  masseteric  artery,  to  the  Masseter  muscle,  in  which  it  ramifies  nearly 
as  far  as  its  anterior  border.  It  occasionally  gives  a  branch  to  the  Temporal 
muscle,  and  a  filament  to  the  articulation  of  the  jaw. 

The  deep  temporal  branches,  two  in  number,  anterior  and  posterior,  supply  the 
deep  surface  of  the  Temporal  muscle.  The  posterior  branch,  of  small  size,  is 
placed  at  the  back  of  the  temporal  fossa.  It  is  sometimes  joined  with  the  mas- 
seteric branch.  The  anterior  branch  is  reflected  upwards,  at  the  pterygoid  ridge 
of  the  sphenoid,  to  the  front  of  the  temporal  fossa.  It  is  occasionally  joined 
with  the  buccal  nerve. 

The  buccal  branch  pierces  the  External  Pterygoid,  and  passes  downwards 
beneath  the  inner  surface  of  the  coronoid  process  of  the  lower  jaw,  or  through 
the  fibres  of  the  Temporal  muscle  to  reach  the  surface  of  the  Buccinator,  upon 
which  it  divides  into  a  superior  and  an  inferior  branch.  It  gives  a  branch  to 
the  External  Pterygoid  during  its  passage  through  that  muscle,  and  a  few 
ascending  filaments  to  the  Temporal  muscle,  one  of  which  occasionally  joins 
with  the  anterior  branch  of  the  deep  temporal  nerve.  The  tipper ^  branch  sup- 
plies the  integument  and  upper  part  of  the  Buccinator  muscle,  joining  with  the 
facial  nerve  round  the  facial  vein.  The  loiver  branch  passes  forwards  to  the 
angle  of  the  mouth ;  it  supplies  the  integument  and  Buccinator  muscle,  as  well 
as  the  mucous  membrane  lining  the  inner  surface  of  that  muscle,  and  joins  the 
facial  nerve. 

The  pterygoid  branches  are  two  in  number,  one  for  each  Pterygoid  muscle. 
The  branch  to  the  Internal  Pterygoid  is  long  and  slender,  and  passes  inwards 
to  enter  the  deep  surface  of  the  muscle.  This  nerve  is  intimately  connected  at 
its  origin  with  the  otic  ganglion.     The  branch  to  the  External  Pterygoid  is 


INFERIOR    MAXILLARY.  623 

most  frequently  derived  from  the  buccal,  but  it  may  be  given  oif  separately 
from  the  anterior  trunk  of  the  nerve. 

The  posterior  and  larger  division  of  the  inferior  maxillary  nerve  also  receives 
a  few  filaments  from  the  motor  root.  It  divides  into  three  branches,  auriculo- 
temporal, gustatory,  and  inferior  dental. 

The  Auriculo-temporal  nerve  generally  arises  by  two  roots,  between  which  the 
middle  meningeal  artery  passes.  It  runs  backwards  beneath  the  External 
Pterygoid  muscle  to  the  inner  side  of  the  articulation  of  the  lower  jaw.  It 
then  turns  upwards  with  the  temporal  artery,  between  the  external  ear  and 
condyle  of  the  jaw,  under  cover  of  the  parotid  gland,  and  escaping  from 
beneath  this  structure,  divides  into  two  temporal  branches.  The  posterior  tem- 
poral, the  smaller  of  the  two,  is  distributed  to  the  upper  part  of  the  pinna  and 
the  neighboring  tissues.  The  anterior  temporal  accompanies  the  temporal  artery 
to  the  vertex  of  the  skull,  and  supplies  the  integument  of  the  temporal  region, 
communicating  with  the  facial  nerve. 

The  auriculo-temporal  nerve  has  branches  of  communication  with  the  facial 
and  otic  ganglion.  Those  joining  the  facial  nerve,  usually  two  in  number,  pass 
forwards  behind  the  neck  of  the  condyle  of  the  jaw,  and  join  this  nerve  at  the 
posterior  border  of  the  Masseter  muscle.  They  form  one  of  the  principal 
branches  of  communication  between  the  facial  and  the  fifth  nerve.  The  fila- 
ments of  communication  with  the  otic  ganglion  are  derived  from  the  commence- 
ment of  the  auriculo-temporal  nerve. 

The  auricular  branches  are  two  in  number,  inferior  and  superior.  The  inferior 
auricular  arises  behind  the  articulation  of  the  jaw,  and  is  distributed  to  the  ear 
below  the  external  meatus ;  other  filaments  twine  round  the  internal  maxillary 
artery,  and  communicate  with  the  sympathetic.  The  superior  atiricular  arises 
in  front  of  the  external  ear,  and  supplies  the  integument  covering  the  tragus 
and  pinna. 

Branches  to  the  meatus  auditorius^  two  in  number,  arise  from  the  point  of 
communication  between  the  auriculo-temporal  and  facial  nerves,  and  are  dis- 
tributed to  the  meatus. 

The  branch  to  the  temporo -maxillary  articulation  is  usually  derived  from  the 
auriculo-temporal  nerve. 

The  parotid  branches  supply  the  parotid  gland. 

The  Gustatory  or  Lingual  Nerve,  one  of  the  special  nerves  of  the  sense  of 
taste,  supplies  the  papillae  and  mucous  membrane  of  the  tongue.  It  is  deeply 
placed  throughout  the  whole  of  its  course.  It  lies  at  first  beneath  the  External 
Pterygoid  muscle,  together  with  the  inferior  dental  nerve,  being  placed  to  the 
inner  side  of  the  latter  nerve,  and  is  occasionally  joined  to  it  by  a  branch  which 
crosses  the  internal  maxillary  artery.  The  chorda  tympani  also  joins  it  at  an 
acute  angle  in  this  situation.  The  nerve  then  passes  between  the  Internal 
Pterygoid  muscle  and  the  inner  side  of  the  ramus  of  the  jaw,  and  crosses 
obliquely  to  the  side  of  the  tongue  over  the  Superior  Constrictor  muscle  of  the 
pharynx,  and  beneath  the  Stylo-glossus  muscle  and  deep  part  of  the  submax- 
illary gland ;  the  nerve  lastly  runs  across  Wharton's  duct,  and  along  the  side 
of  the  tongue  to  its  apex,  being  covered  by  the  mucous  membrane  of  the  mouth. 

Its  branches  of  communication  are  with  the  submaxillary  ganglion  and  hypo- 
glossal nerve.  The  branches  of  the  submaxillary  ganglion  are  two  or  three  in 
number;  those  connected  with  the  hypoglossal  nerve  form  a  plexus  at  the 
anterior  margin  of  the  Hyo-glossus  muscle. 

Its  branches  of  distribution  are  few  in  number.  They  supply  the  mucous 
membrane  of  the  mouth,  the  gums,  the  sublingual  gland,  the  conical  and  fungi- 
form papillae  and  mucous  membrane  of  the  tongue,  the  terminal  filaments  anas- 
tomosing at  the  tip  of  the  tongue  with  the  hypoglossal  nerve. 

The  Inferior  Dental  is  the  largest  of  the  three  branches  of  the  inferior  max- 
illary nerve.  It  passes  downwards  with  the  inferior  dental  artery,  at  first  be- 
neath the  External  Pterygoid  muscle,  and  then  between  the  internal  lateral 


624 


CRANIAL    NERVES. 


ligament  and  t"he  ramus  of  the  jaw  to  the  dental  foramen.  It  then  passes 
forwards  in  the  dental  canal  in  the  inferior  maxillary  bone,  lying  beneath  the 
teeth,  as  far  as  the  mental  foramen,  where  it  divides  into  two  terminal  branches, 
incisor  and  mental.  The  incisor  branch  is  continued  onwards  within  the  bone 
to  the  middle  line,  and  supplies  the  canine  and  incisor  teeth.  The  mental  branch 
emerges  from  the  bone  at  the  mental  foramen,  and  divides  beneath  the  Depres- 
sor Anguli  Oris  into  an  external  branch,  which  supplies  that  muscle,  the  Orbi 
cularis  Oris,  and  the  integument,  communicating  with  the  facial  nerve ;  and  an 
inner  branch,  which  ascends  to  the  lower  lip  beneath  the  Quadratus  Menti ;  it 
supplies  that  muscle  and  the  mucous  membrane  and  integument  of  the  lip, 
communicating  with  the  facial  nerve. 

The  branches  of  the  inferior  dental  are,  the  mylo-hyoid,  and  dental. 

The  mylo-hyoid  is  derived  from  the  inferior  dental  just  as  that  nerve  is  about 
to  enter  the  dental  foramen.  It  descends  in  a  groove  on  the  inner  surface  of 
the  ramus  of  the  jaw,  in  which  it  is  retained  by  a  process  of  fibrous  membrane. 
It  supplies  the  cutaneous  surface  of  the  Mylo-hyoid  muscle,  and  the  anterior 
belly  of  the  Digastric,  occasionally  sending  one  or  two  filaments  to  the  sub- 
maxillary gland. 

The  dental  branches  supply  the  molar  and  bicuspid  teeth.  They  correspond 
in  number  to  the  fangs  of  those  teeth ;  each  nerve  entering  the  orifice  at  the 
point  of  the  fang,  and  supplying  the  pulp  of  the  tooth. 

Two  small  ganglia  are  connected  with  the  inferior  maxillary  nerve:  the  otic, 
with  the  trunk  of  the  nerve ;  and  the  submaxillary  with  its  lingual  branch,  the 
gustatory. 

Otic  Ganglion. 

The  Otic  Ganglion  (Arnold's)  (Fig.  346),  is  a  small,  oval-shaped,  flattened 
ganglion,  of  a  reddish-gray  color,  situated  immediately  below  the  foramen 

Fig.  346. — The  Otic  Ganplion  and  its  Branches. 


ovale,  on  the  inner  surface  of  the  inferior  maxillary  nerve,  and  round  the  origin 
of  the  internal  pterygoid  nerve.  It  is  in  relation,  externally,  with  the  truuk  of 
the  inferior  maxillary  nerve,  at  the  point  where  the  motor  root  joins  the  sensory 
portion;  internally,  with  the  cartilaginous  part  of  the  Eustachian  tube,  and  the 
origin  of  the  Tensor  Palati  muscle ;  behind  it,  is  the  middle  meningeal  artery. 


SUBMAXILLARY    GANGLIOI!^.  625 

Branches  of  communication.  This  ganglion  is  connected  with  the  inferior 
maxillary  nerve,  and  its  internal  pterygoid  branch,  by  two  or  three  short,  deli- 
cate filaments,  and  also  with  the  auriculo-temporal  nerve :  from  the  former  it 
obtains  its  motor ;  from  the  latter,  its  sensory  root ;  its  communication  with 
the  sympathetic  being  effected  by  a  filament  from  the  plexus  surrounding  the 
middle  meningeal  artery.  This  ganglion  also  communicates  with  the  glosso- 
pharyngeal and  facial  nerves,  through  the  small  petrosal  nerve  continued  from 
the  tympanic  plexus. 

Its  branches  of  distribution  are  a  filament  to  the  Tensor  Tympani,  and  one  to 
the  Tensor  Palati.  The  former  passes  backwards,  on  the  outer  side  of  the 
Eustachian  tube;  the  latter  arises  from  the  ganglion,  near  the  origin  of  the  in- 
ternal pterygoid  nerve,  and  passes  forwards. 

Submaxillary  Ganglion. 

The  Submaxillary  Ganglion  (Fig.  844)  is  of  small  size,  circular  in  form,  and 
situated  above  the  deep  portion  of  the  submaxillary  gland,  near  the  posterior 
border  of  the  Mylo-hyoid  muscle,  being  connected  by  filaments  with  the  lower 
border  of  the  gustatory  nerve. 

Branches  of  communication.  This  ganglion  is  connected  with  the  gustatory 
nerve  by  a  few  filaments  which  join  it  separately,  at  its  fore  and  back  part.  It 
also  receives  a  branch  from  the  chorda  tympani,  by  which  it  communicates  with 
the  facial ;  and  communicates  with  the  sympathetic  by  filaments  from  the  nervi 
molles — the  sympathetic  plexus  around  the  facial  artery. 

Branches  of  distribution.  These  are  five  or  six  in  number ;  they  arise  from 
the  lower  part  of  the  ganglion,  and  supply  the  mucous  membrane  of  the  mouth 
and  Wharton's  duct,  some  being  lost  in  the  submaxillary  gland.  According  to 
Meckel,  a  branch  from  this  ganglion  occasionally  descends  in  front  of  the  Hyo- 
glossus  muscle,  and,  after  joining  with  one  from  the  hypoglossalj  passes  to  the 
Genio-hyo-glossus  muscle. 

EiG-HTH  Pair. 

The  Eighth  Pair  consists  of  three  nerves,  the  glosso-pharyngeal,  pneumogas- 
tric,  and  spinal  accessory. 

The  Glosso-2)haryngeal  Nerve  is  distributed,  as  its  name  implies,  to  the  tongue 

and  pharynx,  being  the  nerve  of  sensation  to  the  mucous  membrane  of  the 

pharynx,  fauces,  and  tonsil ;    of    motion  to    the 

pharyngeal  muscles ;  and  a  special  nerve  of  taste    ^%  ?*'^;-^^'''^^«  of  *^^«  ,^^8'^*5 
•        iwf  i.       r-  xi?     ^  \.         X,-  \     -4.  •     A-  .-  ■  Pair,  their  Origin,  Ganglia,  and 

in  all  the  parts  or  the  tongue  to  which  it  is  distri-        Communicatious. 

buted.     It  is  the  smallest  of  the  three  divisions  of  ^    ,   ^    , 

the  eighth  pair,  and  arises  by  three  or  four  fila-  i    ^^,„„^  ^^^  ^ 

ments,  closely  connected  together,  from  the  upper        CtTTl^feJ     I     ^•7'^'"' 
part  of  the  medulla  oblongata,  immediately  behind 
the  olivary  body. 

Its  deep  origin  may  be  traced  through  the  fasci- 
culi of  the  lateral  tract,  to  a  nucleus  of  gray  matter 
at  the  lower  part  of  the  floor  of  the  fourth  ven- 
tricle, external  to  the  fasciculi  teretes.     From  its 

superficial  origin,  it  passes  outwards  across  the  pmuJ^at^t, 

flocculus,  and  leaves  the  skull  at  the  central  part 
of  the  jugular  foramen,  in  a  separate  sheath  of  the  dura  mater  and  arachnoid, 
in  front  of  the  pneumogastric  and  spinal  accessory  nerves.  In  its  passage 
through  the  jugular  foramen,  it  grooves  the  lower  border  of  the  petrous  por- 
tion of  the  temporal  bone ;  and,  at  its  exit  from  the  skull,  passes  forwards 
between  the  jugular  vein  and  internal  carotid  artery,  and  descends  in  front  of 
the  latter  vessel,  and  beneath  the  styloid  process  and  the  muscles  connected 
with  it,  to  the  lower  border  of  the  Stylo-pharyngeus.  The  nerve  now  curves 
40 


626 


CRANIAL    NERYES. 


Spinal  Armt*99ry 


inwards,  forming  an  arch  on  the  side  of  thfi  neck,  and  lying  upon  the  Stvlo- 
pharyngeus  and  the  Middle  Constrictor  of  the  pharynx,  above  the  superior 

laryngeal  nerve.  It  then  passes 
Fig.  348.— Course  and  Distribution  of  the  Eighth  Pair      beneath  the  Ilyo-glossus,  and 
""^  ^'^'■''^^-  is  finally  distributed  to  the  mu- 

cous  membrane  of  the  fauces, 
and  base  of  the  tongue,  the 
mucous  glands  of  the  mouth 
and  tonsil. 

In  passing  through  the  jugu- 
lar foramen,  the  nerve  presents, 
in  succession,  two  gangliform 
enlargements.  The  superior, 
the  smaller,  is  called  i\\Qjxi<jU' 
lar  ganglion^  the  inferior  and 
larger  the  petrous  ganglion,  or 
the  ganglion  of  Andersch. 

The  superior,  or  J7igular  gan- 
glion, is  situated  in  the  upper 
part  of  the  groove  in  which 
the  nerve  is  lodged  during  its 
passage  through  the  jugular 
foramen.  It  is  of  very  small 
size,  and  involves  only  the 
outer  side  of  the  trunk  of  the 
nerve,  a  small  fasciculus,  pass- 
ing beyond  it,  which  is  not 
connected  directly  with  it. 

The  inferior,  or  petrous  gan- 
glion, is  situated  in  a  depres- 
sion in  the  lower  border  of  the 
petrous  portion  of  the  temporal 
bone;  it  is  larger  than  the  for- 
mer, and  involves  the  whole 
of  the  fibres  of  the  nerve.  From 
this  ganglion  arise  those  fila- 
ments which  connect  the  glosso- 
pharyngeal with  other  nerves 
at  the  base  of  the  skull. 

Its  branches  of  comimmicaiion 
are  with  the  pneumogastric, 
sympathetic,  and  facial,  and  the 
tympanic  branch. 

The  branches  to  the  pneumo- 
gastric are  two  filaments,  one 
to  its  auricular  branch,  and  one 
to  the  upper  ganglion  of  the 
pneumogastric. 

The  branch  to  the  sympa- 
thetic is  connected  with  the 
superior  cervical  ganglion. 

The  branch  of  communica- 
tion with  the  facial  perforates 
the  posterior  belly  of  the  Digastric.  It  arises  from  the  trunk  of  the  nerve  below 
the  petrous  ganglion,  and  joins  the  facial  just  after  its  exit  from  the  stylo-mas- 
toid  foramen. 

The  tympanic  branch  (Jacobson's  nerve)  arises  from  the  petrous  ganglion,  and 


SPINAL    ACCESSORY.  627 

enters  a  small  bony  canal  at  the  base  of  the  petrous  portion  of  the  temporal 
bone ;  the  lower  opening  of  which  is  situated  on  the  bony  ridge  which  sepa- 
rates the  carotid  canal  from  the  jugular  fossa.  Jacobson's  nerve  ascends  to  the 
tympanum,  enters  that  cavity  by  an  aperture  in  its  floor  close  to  the  inner  wall, 
and  divides  into  three  branches,  which  are  contained  in  grooves  upon  the  sur- 
face of  the  promontory. 

Its  branches  of  distribution  are,  one  to  the  fenestra  rotunda,  one  to  the  fenestra 
ovalis,  and  one  to  the  lining  membrane  of  the  Eustachian  tube  and  tympanum. 

Its  branches  of  communication  are  three,  and  occupy  separate  grooves  on  the 
surface  of  the  promontory.  One  of  these  arches  forwards  and  downwards  to 
the  carotid  canal  to  join  the  carotid  plexus.  A  second  runs  vertically  upwards 
to  join  the  greater  superficial  petrosal  nerve,  as  it  lies  in  the  hiatus  Fallopii. 
The  third  branch,  the  lesser  petrosal,  runs  upwards  and  forwards  towards  the 
anterior  surface  of  the  petrous  bone,  and  passes  through  a  small  aperture  in 
the  sphenoid  and  temporal  bones,  to  the  exterior  of  the  skull,  where  it  joins  the 
otic  ganglion.  This  nerve,  in  its  course  through  the  temporal  bone,  passes  by 
the  ganglionic  enlargement  of  the  facial,  and  has  a  connecting  filament  with  it. 

The  branches  of  the  glosso-pharyngeal  nerve  are  the  carotid,  pharyngeal, 
muscular,  tonsillar,  and  lingual. 

The  carotid  branches  descend  along  the  trunk  of  the  internal  carotid  artery  as 
far  as  its  point  of  bifurcation,  communicating  with  the  pharyngeal  branch  of 
the  pneumogastric,  and  with  branches  of  the  sympathetic. 

The  pharyngeal  branches  are  three  or  four  filaments  whicb  unite  opposite  the 
Middle  Constrictor  of  the  pharynx  with  the  pharyngeal  branches  of  the  pneu- 
mogastric, superior  laryngeal,  and  sympathetic  nerves,  to  form  the  pharyngeal 
plexus,  branches  from  which  perforate  the  muscular  coat  of  the  pharynx  to 
supply  the  mucous  membrane. 

The  muscular  branches  are  distributed  to  the  Stylo-pharyngeus. 

The  tonsillar  branches  supply  the  tonsil,  forming  a  plexus  (circulus  tonsil- 
laris) around  this  body,  from  which  branches  are  distributed  to  the  soft  palate 
and  fauces,  where  they  anastomose  with  the  palatine  nerves. 

The  lingual  branches  are  two  in  number ;  one  supplies  the  mucous  membrane 
covering  the  surface  of  theljase  of  the  tongue,  the  other  perforates  its  substance, 
and  supplies  the  mucous  membrane  and  papillae  of  the  side  of  the  organ. 

The  Sjnnal  Accessory  Nerve  consists  of  two  parts ;  one,  the  accessory  part  to 
the  vagus,  and  the  other  the  spinal  portion. 

The  accessory  part^  the  smaller  of  the  two,  arises  by  four  or  five  delicate  fila- 
ments from  the  lateral  tract  of  the  cord  below  the  roots  of  the  vagus ;  these 
filaments  may  be  traced  to  a  nucleus  of  gray  matter  at  the  back  of  the  medulla, 
below  the  origin  of  the  vagus.  It  joins,  in  the  jugular  foramen,  with  the  upper 
ganglion  of  the  vagus  by  one  or  two  filaments,  and  is  continued  into  the  vagus 
below  the  second  ganglion.  It  gives  branches  to  the  pharyngeal  and  superior 
laryngeal  branches  of  the  vagus. 

The  s^jinal  jwrtion,  firm  in  texture,  arises  by  several  filaments  from  the  lateral 
tract  of  the  cord,  as  low  down  as  the  sixth  cervical  nerve ;  the  fibres  pierce  the 
tract,  and  are  connected  with  the  anterior  horn  of  the  gray  matter  of  the  cord. 
This  portion  of  the  nerve  ascends  between  the  ligamentum  denticulatum  and 
the  posterior  roots  of  the  spinal  nerves,  enters  the  skull  through  the  foramen 
magnum,  and  is  then  directed  outwards  to  the  jugular  foramen,  through  which 
it  passes,  lying  in  the  same  sheath  as  the  pneumogastric,  separated  from  it  by 
a  fold  of  the  arachnoid,  and  is  here  connected  with  the  accessory  portion.  At 
its  exit  from  the  jugular  foramen,  it  passes  backwards  behind  the  internal  jugu- 
lar vein,  and  descends  obliquely  behind  the  Digastric  and  Stylo-hyoid  muscles 
to  the  upper  part  of  the  Sterno-mastoid.  It  pierces  that  muscle,  and  passes 
obliquely  across  the  suboccipital  triangle,  to  terminate  in  the  deep  surface  of 
the  Trapezius.  This  nerve  gives  several  branches  to  the  Sterno-mastoid  during 
its  passage  through  it,  and  joins  in  its  substance  with  branches  from  the  third 


628  CRANIAL    NERVES. 

cervical.  In  the  occipital  triangle  it  joins  with  the  second  and  third  cervical 
nerves,  and  assists  in  the  formation  of  the  cervical  plexus,  and  occasionally  of 
the  great  auricular  nerve.  On  the  front  of  the  Trapezius,  it  is  reinforced  bv 
branches  from  the  third,  fourth,  and  fifth  cervical  nerves,  joins  with  the  poste- 
rior branches  of  the  spinal  nerves,  and  is  distributed  to  the  Trapezius,  some 
filaments  ascending  and  others  descending  in  the  substance  of  the  muscle  as  far 
as  its  inferior  angle. 

The  Pneumogastric  Nerve  {nervus  vagus,  or  par  vagum),  one  of  the  three 
divisions  of  the  eighth  pair,  has  a  more  extensive  distribution  than  any  of  the 
other  cranial  nerves,  passing  through  the  neck  and  thorax  to  the  upper  part  of 
the  abdomen.  It  is  composed  of  both  motor  and  sensitive  filaments.  It  sup- 
plies the  organs  of  voice  and  respiration  with  motor  and  sensitive  fibres ;  and 
the  pharynx,  oesophagus,  stomach,  and  heart  with  motor  influence.  Its  super- 
ficial  origin  is  by  eight  or  ten  filaments  from  the  lateral  tract  immediately 
behind  the  olivary  body  and  below  the  glosso-pharyngeal ;  its  fibres  may,  how- 
ever, be  traced  deeply  through  the  fasciculi  of  the  medulla,  to  terminate  in  a 
gray  nucleus  near  the  lower  part  of  the  floor  of  the  fourth  ventricle.  The 
filaments  become  united,  and  form  a  flat  cord,  which  passes  outwards  across 
the  flocculus  to  the  jugular  foramen,  through  which  it  emerges  from  the  cranium. 
In  passing  through  this  opening,  the  pneumogastric  accompanies  the  spinal 
accessory,  being  contained  in  the  same  sheath  of  djira  mater  with  it,  a  mem- 
branous septum  separating  it  from  the  glosso-pharyngeal,  which  lies  in  front. 
The  nerve  in  this  situation  presents  a  well-marked  ganglionic  enlargement, 
which  is  called  ganglion  jugulare,  or  the  ganglion  of  the  root  of  the  pneumogastric ; 
to  it  the  accessory  part  of  the  spinal  accessory  nerve  is  connected.  After  the 
exit  of  the  nerve  from  the  jugular  foramen,  a  second  gangliform  swelling  is 
formed  upon  it,  called  the  ganglion  inferius,  or  the  ganglion  of  the  trunk  of  the  nerve ; 
below  which  it  is  again  joined  by  filaments  from  the  accessory  nerve.  The 
nerve  passes  vertically  down  the  neck  within  the  sheath  of  the  carotid  vessels, 
lying  between  the  internal  carotid  artery  and  internal  jugular  vein  as  far  as 
the  thyroid  cartilage,  and  then  between  the  same  vein  and  the  common  carotid 
to  the  root  of  the  neck.  Here  the  course  of  the  nerve  becomes  different  on  the 
two  sides  of  the  body. 

On  the  right  side,  the  nerve  passes  across  the  subclavian  artery  between  it 
and  the  subclavian  vein,  and  descends  by  the  side  of  the  trachea  to  the  back 
part  of  the  root  of  the  lung,  where  it  spreads  out  in  a  plexiform  network 
(posterior  pulmonary),  from  the  lower  part  of  which  two  cords  descend  upon 
the  oesophagus,  on  which  they  divide,  forming,  with  branches  from  the  opposite 
nerve,  the  oesophageal  plexus ;  below,  these  branches  are  collected  into  a  single 
cord,  which  runs  along  the  back  part  of  the  oesophagus,  enters  the  abdomen, 
and  is  distributed  to  the  posterior  surface  of  the  stomach,  joining  the  left  side 
of  the  coeliac  plexus,  and  the  splenic  plexus. 

On  the  left  side,  the  pneumogastric  nerve  enters  the  chest  between  the  left 
carotid  and  subclavian  arteries,  behind  the  left  innominate  vein.  It  crosses  the 
arch  of  the  aorta,  and  descends  behind  the  root  of  the  left  lung  and  along  the 
anterior  surface  of  the  oesophagus  to  the  stomach,  distributing  branches  over 
its  anterior  surface,  some  extending  over  the  great  cul-(k-sac,  and  others  along 
the  lesser  curvature.  Filaments  from  these  latter  branches  enter  the  gastro- 
hepatic  omentum,  and  join  the  left  hepatic  plexus. 

The  gfinglion  of  the  root  is  of  a  grayish  color,  circular  in  form,  about  two 
lines  in  diameter,  and  resembles  the  ganglion  on  the  large  root  of  the  fifth  nerve. 
Connecting  branches.  To  this  ganglion  the  accessory  portion  of  the  spinal 
accessory  nerve  is  connected  by  several  delicate  filaments;  it  also  has  an  anas- 
tomotic twig  with  the  petrous  ganglion  of  the  glosso-pharyngeal,  with  the  facial 
nerve  by  means  of  the  auricular  branch,  and  with  the  sympathetic  by  means 
of  an  ascending  filament  from  the  superior  cervical  ganglion. 

The  ganglion  of  the  trunk  (inferior)  is  a  plexiform  cord,  cylindrical  in  form. 


PNEUMOGASTRIC.  629 

of  a  reddish  color,  and  about  an  inch  in  length ;  it  involves  the  whole  of  the 
fibres  of  the  nerve,  except  the  portion  of  the  nerve  derived  from  the  spinal 
accessory,  which  blends  with  the  nerve  beyond  the  ganglion. 

Connecting  branches.  This  ganglion  is  connected  with  the  hypoglossal,  the 
superior  cervical  ganglion  of  the  sympathetic,  and  the  loop  between  the  first 
and  second  cervical  nerves. 

The  branches  of  the  pneumogastric  are — • 

In  the  jugular  fossa         .         .         Auricular. 

r  Pharyngeal. 
In  the  neck  \  Superior  laryngeal 

I   Recurrent  laryngeal. 

[  Cervical  cardiac. 

(  Thoracic  cardiac. 

T     ,1     ,1  Anterior  pulmonary. 

in  the  thorax         .         .         .     ^  -n    ^    •  i 

.1   Posterior  pulmonary. 


(Esophageal. 
In  the  abdomen      .        .         .  Gastric. 

The  auricular  branch  (Arnold's)  arises  from  the  ganglion  of  the  root,  and  is 
joined  soon  after  its  origin  by  a  filament  from  the  glosso-pharyngeal ;  it  crosses 
the  jugular  fossa  to  an  opening  near  the  root  of  the  styloid  process.  Travers- 
ing the  substance  of  the  temporal  bone,  it  crosses  the  aquaeductus  Fallopii 
about  two  lines  above  its  termination  at  the  stylo-mastoid  foramen;  it  here 
gives  off  an  ascending  branch,  which  joins  the  facial,  and  a  descending  branch, 
which  anastomoses  with  the  posterior  auricular  branch  of  the  same  nerve :  the 
continuation  of  the  nerve  reaches  the  surface  between  the  mastoid  process  and 
the  external  auditory  meatus,  and  supplies  the  integument  at  the  back  part  of 
the  pinna. 

The  pharyngeal  branch,  the  principal  motor  nerve  of  the  pharynx  and  soft 
palate,  arises  from  the  upper  part  of  the  inferior  ganglion  of  the  pneumogastric, 
receiving  a  filament  from  the  accessory  portion  of  the  spinal  accessory ;  it 
passes  across  the  internal  carotid  artery  (in  front  or  behind),  to  the  upper  border 
of  the  Middle  Constrictor,  where  it  divides  into  numerous  filaments,  which 
anastomose  with  those  from  the  glosso-pharyngeal,  superior  laryngeal,  and 
sympathetic,  to  form  the  pharyngeal  plexus,  from  which  branches  are  distributed 
to  the  muscles  and  mucous  membrane  of  the  pharynx.  As  this  nerve  crosses 
the  internal  carotid,  some  filaments  are  distributed,  together  with  those  from 
the  glosso-pharyngeal,  upon  the  wall  of  this  vessel. 

The  superior  laryngeal  is  the  nerve  of  sensation  to  the  larynx.  It  is  larger 
than  the  preceding,  and  arises  from  the  middle  of  the  inferior  ganglion  of  the 
pneumogastric.  It  descends,  by  the  side  of  the  pharynx,  behind  the  internal 
carotid,  where  it  divides  into  two  branches,  the  external  and  internal  laryngeal. 

The  external  laryngeal  branch,  the  smaller,  descends  by  the  side  of  the 
larynx,  beneath  the  Sterno-thyroid,  to  supply  the  Crico-thyroid  muscle  and  the 
thyroid  gland.  It  gives  branches  to  the  pharyngeal  plexus,  and  the  Inferior 
Constrictor,  and  communicates  with  the  superior  cardiac  nerve,  behind  the 
common  carotid. 

The  internal  laryngeal  branch  descends  to  the  opening  in  the  thyro-hyoid 
membrane,  through  which  it  passes  with  the  superior  laryngeal  artery,  and  is 
distributed  to  the  mucous  membrane  of  the  larynx,  and  the  Arytenoid  muscle, 
anastomosing  with  the  recurrent  laryngeal. 

The  branches  to  the  mucous  membrane  are  distributed,  some  in  front,  to  the 
epiglottis,  the  base  of  the  tongue  and  the  epiglottidean  glands;  while  others 
pass  backwards,  in  the  aryteno-epiglottidean  fold,  to  supply  the  mucous  mem- 
brane surrounding  the  superior  orifice  of  the  larynx,  as  well  as  the  membrane 
which  lines  the  cavity  of  the  larynx  as  low  down  as  the  vocal  chord. 


630  CRANIAL    NERYES. 

The  filament  to  the  Arytenoid  muscle  is  distributed  partly  to  it,  and  partly 
to  the  mucous  lining  of  the  larynx. 

The  filament  which  joins  with  the  recurrent  laryngeal,  descends  beneath  the 
mucous  membrane  on  the  posterior  surface  of  the  larynx,  behind  the  lateral 
part  of  the  thyroid  cartilage,  where  the  two  nerves  become  united. 

The  inferior  or  recurrent  laryngeal^  so  called  from  its  reflected  course,  is  the 
motor  nerve  of  the  larynx.  It  arises  on  the  right  side,  in  front  of  the  sub- 
clavian artery:  winds  from  before  backwards  round  that  vessel,  and  ascends 
obliquely  to  the  side  of  the  trachea,  behind  the  common  carotid  and  inferior 
thyroid  arteries.  On  the  left  side,  it  arises  in  front  of  the  arch  of  the  aorta, 
and  winds  from  before  backwards  round  the  aorta  at  the  point  where  the 
obliterated  remains  of  the  ductus  arteriosus  are  connected  with  it,  and  then 
ascends  to  the  side  of  the  trachea.  The  nerves  on  both  sides  ascend  in  the 
groove  between  the  trachea  and  oesophagus,  and,  passing  under  the  lower 
border  of  the  Inferior  Constrictor  muscle,  enter  the  larynx  behind  the  articu- 
lation of  the  inferior  cornu  of  the  thyroid  cartilage  with  the  cricoid,  being 
distributed  to  all  the  muscles  of  the  larynx,  excepting  the  Crico-thyroid,  and 
joining  with  the  superior  laryngeal. 

The  recurrent  laryngeal,  as  it  winds  round  the  subclavian  artery  and  aorta, 
gives  off  several  cardiac  filaments,  which  unite  with  cardiac  branches  from  the 
pneumogastric  and  sympathetic.  As  it  ascends  in  the  neck,  it  gives  off'  oeso- 
phageal branches,  more  numerous  on  the  left  than  on  the  right  side,  which 
supply  the  mucous  membrane  and  muscular  coat  of  the  oesophagus;  tracheal 
branches  to  the  mucous  membrane  and  muscular  fibres  of  the  trachea;  and  some 
pharyngeal  filaments  to  the  Inferior  Constrictor  of  the  pharynx. 

The  cervical  cardiac  branches^  two  or  three  in  number,  arise  from  the  pneumo- 
gastric, at  the  upper  and  lower  part  of  the  neck. 

The  superior  branches  are  small,  and  communicate  with  the  cardiac  branches 
of  the  sympathetic,  and  with  the  great  cardiac  plexus. 

The  inferior  cardiac  branches,  one  on  each  side,  arise  at  the  lower  part  of  the 
neck,  just  above  the  first  rib.  On  the  right  side,  this  branch  passes  in  front 
of  the  arteria  innominata,  and  anastomoses  with  the  superior  cardiac  nerve. 
On  the  left  side,  it  passes  in  front  of  the  arch  of  the  aorta,  and  anastomoses 
either  with  the  superior  cardiac  nerve,  or  with  the  cardiac  plexus. 

The  thoracic  cardiac  branches,  on  the  right  side,  arise  from  the  trunk  of  the 
pneumogastric,  as  it  lies  by  the  side  of  the  trachea:  passing  inwards,  they 
terminate  in  the  deep  cardiac  plexus.  On  the  left  side,  they  arise  from  the  left 
recurrent  laryngeal  nerve. 

The  anterior  pulmonary  branches,  two  or  three  in  number,  and  of  small  size, 
are  distributed  on  the  anterior  aspect  of  the  root  of  the  lungs.  They  join  with 
filaments  from  the  sympathetic,  and  form  the  anterior  pulmonary  plexus. 

The  posterior  jmhnonary  branches,  more  numerous  and  larger  than  the  ante- 
rior, are  distributed  on  the  posterior  aspect  of  the  root  of  the  lung:  they  are 
joined  by  filaments  from  the  third  and  fourth  thoracic  ganglia  of  the  sympa- 
thetic, and  form  the  posterior  pulmonary  plexus.  Branches  from  both  })lexusea 
accompany  the  ramifications  of  the  air-tubes  through  the  substance  of  the  lungs. 

The  oesophageal  branches  are  given  off  from  the  pneumogastric  both  above  and 
below  the  pulmonary  branches.  The  latter  are  the  more  numerous  and  largest. 
They  form,  together  with  branches  from  the  opposite  nerve,  the  oesophageal 
plexus. 

The  gastric  branches  are  the  terminal  filaments  of  the  pneumogastric  nerve. 
The  nerve  on  the  right  side  is  distributed  to  the  posterior  surface  of  the 
stomach,  and  joins  the  left  side  of  the  coeliao  plexus,  and  tlie  splenic  plexus. 
The  nerve  on  the  left  side  is  distributed  over  the  anterior  surface  of  the 
stomach,  some  filaments  passing  across  the  great  ctd-de-sac,  and  others  along  the 
lesser  curvature.  They  unite  with  branches  of  the  right  nerve  and  sympathetic, 
some  filaments  passing  through  the  lesser  omentum  to  the  left  hepatic  plexus. 


CRANIAL    NERYES.  631 

For  the  following  brief  account  of  the  most  recent  views  relating  to  the  origin 
of  the  cranial  nerves,  the  editor  is  indebted  to  his  friend  Mr.  Lockhart  Clarke : — 

The  third  cerebral  nerve  arises  chiefly  from  two  large  masses  of  gray  sub- 
stance at  the  floor  of  the  iter  e  tertio  ad  quartum  ventriculum  beneath  the 
corpora  quadrigeraina. 

The  fourth  arises  from  two  nuclei  at  the  floor  of  the  iter  e  tertio  ad  quartum 
ventriculum,  and  from  the  valve  of  Vieussens,  where  the  opposite  nerves  decus- 
sate each  other. 

"The  large  roots  of  the  fifth  or  trigeminal  arise  chiefly  from  the  gray  tubercles 
of  Rolando,  or  the  upper  expanded  extremities  of  the  posterior  gray  horns  of 
the  spinal  cord;  the  small  or  motor  roots  arise  from  two  masses  of  large,  multi- 
polar cells  situated  each  on  the  inner  side,  and  close  to  the  gray  tubercle,  and 
intimately  connected  with  it. 

The  sixth  nerve  arises  in  common  with  the  facial  from  the  gray  substance 
of  the  fasciculus  teres  on  the  floor  of  the  fourth  ventricle. 

The  facial  nerve  has  two  origins:  1.  From  the  gray  substance  of  the  fasci- 
culus teres  on  the  floor  of  the  fourth  ventricle.  2.  From  the  nucleus  of  the 
motor  root  of  the  trigeminus ;  between  these  two  origins  it  forms  a  loop  along 
the  floor  of  the  ventricle. 

The  auditory  nerve  has  three  origins:  1.  From  the  superior  vermiform 
process  of  the  cerebellum;  2  and  3.  From  the  inner  and  outer  auditory  nuclei 
formed  chiefly  by  the  gray  substance  of  the  posterior  pyramid  and  restiform 
body. 

The  vagus  and  glossop-haryngeal  nerves  have  each  two  origins:  1.  From  a 
special  nucleus  in  the  floor  of  the  fourth  ventricle.  2.  From  the  anterior  or 
motor  part  of  the  medulla. 

The  spinal  accessory  nerve  has  three  origins:  1.  The  lower  roots  from  the 
anterior  gray  horn  of  the  spinal  cord  in  common  with  the  motor  roots  of  the 
cervical  nerves.  2,  From  the  gray  nucleus  of  the  hypoglossal  nerve.  3.  From 
a  special  nucleus  behind  the  central  canal  of  the  medulla  oblongata. 


For  further  information  on  the  origin  of  these  nerves,  and  on  the  connection  between  their 
several  nuclei,  see  Mr.  Lockhart  Clarke's  memoir  "  On  the  Intimate  Structure  of  the  Brain,"  1st 
and  2d  Ser.  Phil.  Trans.  1858  and  1868. 

For  fuller  detail  concerning  the  Cranial  Nerves,  the  student  may  refer  to  F.  Arnold's  "  Icones 
Nervorum  Capitis." 


The  Spinal  Nerves. 


The  Spinal  .Nerves  Are  so  called,  because  thej  take  their  origin  from  the 
spinal  cord,  and  are  transmitted  through  the  intervertebral  foramina  on  either 
side  of  the  spinal  column.  There  are  thirty-one  pairs  of  spinal  nerves,  which 
are  arranged  into  the  following  groups,  corresponding  to  the  region  of  the  spine 
through  which  they  pass  : — 

Cervical  ...  8  pairs. 

Dorsal  .        .  12     " 

Lumbar  .         .         .  5     " 

Sacral  .        .        .  5     " 

Coccygeal  .        .        .  1      " 

It  will  be  observed,  that  each  group  of  nerves  corresponds  in  number  with 
the  vertebra  in  that  region,  except  the  cervical  and  coccygeal. 

Each  spinal  nerve  arises  by  two  roots,  an  anterior,  or  motor  root,  and  a  pos- 
terior, or  sensory  root. 

EOOTS   OF   THE   SpINAL  NeRVES. 

The  anterior  roots  arise  somewhat  irregularly  from  a  linear  series  of  foramina, 
on  the  antero-lateral  column  of  the  spinal  cord,  gradually  approaching  towards 
ihe  anterior  median  fissure  as  they  descend. 

The  fibres  of  the  anterior  roots,  according  to  the  researches  of  Mr.  Lockhart 
Clarke,  are  attached  to  the  anterior  part  of  the  antero-lateral  column  ;  and,  after 
penetrating  horizontally  through  the  longitudinal  fibres  of  this  tract,  enter  the 
gray  substance,  where  their  fibrils  cross  each  other  and  diverge  in  all  directions, 
like  the  expanded  hairs  of  a  brush,  some  of  them  running  more  or  less  longi- 
tudinally upwards  and  downwards,  and  others  decussating  with  those  of  the 
opposite  side  through  the  anterior  commissure  in  front  of  the  central  canal. 
Kolliker  states  that  many  fibres  of  the  anterior  root  enter  the  lateral  column  of 
the  same  side,  where,  turning  ^ipwanls^  they  pursue  their  course  as  longitudinal 
fibres.  In  other  respects,  the  description  of  the  origin  of  the  anterior  roots  by 
these  observers  is  very  similar. 

The  posterior  roots  are  all  attached  immediately  to  the  posterior  white  columns 
only ;  but  some  of  them  pass  through  the  gray  substance  into  both  the  lateral 
and  anterior  white  columns.  Within  the  gray  substance,  they  run,  longi- 
tudinally, upwards  and  downwards,  transversely,  through  the  posterior  com- 
missure to  the  opposite  side,  and  into  the  anterior  column  of  their  own  side. 

The  posterior  roots  of  the  nerves  are  larger,  but  the  individual  filaments  are 
finer  and  more  delicate  than  those  of  the  anterior.  As  their  component  fibrils 
jiass  outwards,  towards  the  aperture  in  the  dura  mater,  they  coalesce  into  two 
bundles,  receive  a  tubular  sheath  from  that  membrane,  and  enter  the  ganglion 
which  is  developed  upon  each  root. 

The  posterior  root  of  the  first  cervical  nerve  forms  an  exception  to  these 
characters.  It  is  smaller  than  the  anterior,  has  frequently  no  ganglion  de- 
veloped upon  it,  and,  when  the  ganglion  exists,  it  is  often  situated  within  the 
dura  mater. 

The  anterior  roots  are  the  smaller  of  the  two,  devoid  of  any  ganglionic  en- 
largement, and  their  component  fibrils  are  collected  into  two  bundles,  near  the 
intervertebral  foramina. 
632 


GANGLIA  — CERVICAL    NERVES.  633 

Ganglia  of  the  Spinal  Nekves. 

A  Ganglion  is  developed  upon  the  posterior  root  of  each  of  the  spinal  nerves. 
These  ganglia  are  of  an  oval  form,  and  of  a  reddish  color ;  they  bear  a  pro- 
portion in  size  to  the  nerves  upon  which  they  are  formed,  and  are  placed  in  the 
intervertebral  foramina,  external  to  the  point  where  the  nerves  perforate  the 
dura  mater.  Each  ganglion  is  bifid  internally,  where  it  is  joined  by  the  two 
bundles  of  the  posterior  root,  the  two  portions  being  united  into  a  single  mass 
externally.  The  ganglia  upon  the  first  and  second  cervical  nerves  form  an  ex- 
ception to  these  characters,  being  placed  on  the  arches  of  the  vertebrae  over 
which  the  nerves  pass.  The  ganglia,  also,  of  the  sacral  nerves  are  placed  within 
the  spinal  canal ;  and  that  on  the  coccygeal  nerve,  also  in  the  canal  about  the 
middle  of  its  posterior  root.  Immediately  beyond  the  ganglion,  the  two  roots 
coalesce,  their  fibres  intermingle,  and  the  trunk  thus  formed  passes  out  of  the 
intervertebral  foramen,  and  divides  into  an  anterior  branch,  for  the  supply  of 
the  anterior  part  of  the  body ;  and  a  posterior  branch  for  the  posterior  part, 
each  branch  containing  fibres  from  both  roots. 

The  anterior  branches  of  the  spinal  nerves  supply  the  parts  of  the  body  in  front 
of  the  spine,  including  the  limbs.  They  are  for  the  most  part  larger  than  the 
posterior  branches ;  this  increase  of  size  being  proportioned  to  the  larger  ex- 
tent of  structures  they  are  required  to  supply.  Each  branch  is  connected  by 
slender  filaments  with  the  sympathetic.  In  the  dorsal  region,  the  anterior 
branches  of  the  spinal  nerves  are  completely  separate  from  each  other,  and  are 
uniform  in  their  distribution  ;  but  in  the  cervical,  lumbar,  and  sacral  regions, 
they  form  intricate  plexuses  previous  to  "their  distribution. 

The  posterior  branches  of  the  spinal  nerves  are  generally  smaller  than  the  an- 
terior ;  they  arise  from  the  trunk,  resulting  from  the  union  of  the  roots  in  the 
intervertebral  foramina,  and,  passing  backwards,  divide  into  external  and  in- 
ternal branches,  which  are  distributed  to  the  muscles  and  integument  behind 
the  spine.  The  first  cervical  and  lower  sacral  nerves  are  exceptions  to  these 
characters. 

Cervical  Nerves. 

The  roots  of  the  cervical  nerves  increase  in  size  from  the  first  to  the  fifth,  and 
then  maintain  the  same  size  to  the  eighth.  The  posterior  roots  bear  a  proportion 
to  the  anterior  as  3  to  1,  which  is  much  greater  than  in  any  other  region,  the 
individual  filaments  being  also  much  larger  than  those  of  the  anterior  roots.  In 
direction,  the  roots  of  the  cervical  are  less  oblique  than  those  of  the  other  spinal 
nerves.  The  first  cervical  nerve  is  directed  a  little  upwards  and  outwards ;  the 
second  is  horizontal;  the  others  are  directed  obliquely  downwards  and  outwards, 
the  lowest  being  the  most  oblique,  and  consequently  longer  than  the  upper,  the 
distance  between  their  place  of  origin  and  their  point  of  exit  from  the  spinal 
canal  never  exceeding  the  depth  of  one  vertebra. 

The  truyik  of  the  first  cervical  nerve  {suboccipital)  leaves  the  spinal  canal, 
between  the  occipital  bone  and  the  posterior  arch  of  the  atlas ;  the  second  be- 
tween the  posterior  arch  of  the  atlas  and  the  lamina  of  the  axis;  and  the  eighth 
(the  last),  between  the  last  cervical  and  first  dorsal  vertebrae. 

Each  nerve,  at  its  exit  from  the  intervertebral  foramen,  divides  into  an  ante- 
rior and  a  posterior  branch.  The  anterior  branches  of  the  four  upper  cervical 
nerves  form  the  cervical  plexus.  The  anterior  branches  of  the  four  lower  cer- 
vical nerves,  together  with  the  first  dorsal,  form  the  brachial  plexus. 

Anterior  Branches  of  the  Cervical  Nerves. 

The  anterior  branch  of  the  first,  or  suboccipital  nerve,  is  of  small  size.  It  escapes 
from  the  spinal  canal,  through  a  groove  upon  the  posterior  arch  of  the  atlas. 
In  this  groove  it  lies  beneath  the  vertebral  artery,  to  the  inner  side  of  the  Rec- 


634 


SPINAL    NERVES. 


tus  Lateralis.  As  it  crosses  the  foramen  in  the  transverse  process  of  the  atlas 
it  receives  a  filament  from  the  sympathetic.  It  then  descends,  in  front  of  this 
process,  to  communicate  with  an  ascending  branch  from  the  second  cervical 
nerve. 

Communicating  filaments  from  this  nerve  join  the  pneumogastric,  the  hypo- 
glossal and  sympathetic,  and  some  branches  are  distributed  to  the  Rectus  Late- 
ralis, and  the  two  Anterior  Recti.  According  to  Valentin,  the  anterior  branch 
of  the  suboccipital  also  distributes  filaments  to  the  occipito-atloid  articulation, 
and  mastoid  process  of  the  temporal  bone. 

The  anterior  branch  of  the  second  cervical  nerve  escapes  from  the  spinal  canal, 
between  the  posterior  arch  of  the  atlas  and  the  lamina  of  the  axis,  and,  passing 
forwards  on  the  outer  side  of  the  vertebral  artery,  divides  in  front  of  the  Inter- 
transverse muscle,  into  an  ascending  branch,  which  joins  the  first  cervical;  and 
two  descending  branches  which  join  the  third. 

The  anterior  branch  of  the  third  cervical  nerve  is  double  the  size  of  the  preced- 
ing. At  its  exit  from  the  intervertebral  foramen,  it  passes  downwards  and  out- 
wards beneath  the  Sterno-mastoid,  and  divides  into  two  branches.  The  ascending 
branch  joins  the  anterior  division  of  the  second  cervical,  communicates  with  the 
sympathetic  and  spinal  accessory  nerves,  and  subdivides  into  the  superficial  cer- 
vical, and  great  auricular  nerves.  The  descending  branch  passes  down  in  front 
of  the  Scalenus  Anticus,  anastomoses  with  the  fourth  cervical  nerve,  and  be- 
comes continuous  with  the  clavicular  nerves. 

The  anterior  branch  of  the  fourth  cervical  is  of  the  same  size  as  the  preceding. 
It  receives  a  branch  from  the  third,  sends  a  communicating  branch  to  the  fifth 
cervical,  and,  passing  downwards  and  outwards,  divides  into  numerous  fila- 
ments, which  cross  the  posterior  triangle  of  the  neck,  towards  the  clavicle  and 
acromion.  It  usually  gives  a  branch  to  the  phrenic  nerve,  whilst  it  is  contained 
in  the  inter-transverse  space. 

The  anterior  branches  of  the  ffth^  sixth,  seventh,  and  eighth  cervical  nerves,  are 
remarkable  for  their  large  size.  They  are  much  larger  than  the  preceding 
nerves,  and  are  of  equal  size.  They  assist  in  the  formation  of  the  brachial 
plexus. 

Cervical  Plexus. 

The  Cervical  Plexus  (Fig.  343)  is  formed  by  the  anterior  branches  of  the 
four  upper  cervical  nerves.  It  is  situated  in  front  of  the  four  upper  vertebrae, 
resting  upon  the  Levator  Anguli  Scapulae,  and  Scalenus  Medius  muscles,  and 
covered  in  by  the  Sterno-mastoid. 

Its  branches  may  be  divided  into  two  groups,  superficial  and  deep,  which 
may  be  thus  arranged  : — 

{Superficialis  colli. 
Auricularis  magnus. 
Occipitalis  minor. 


Superficial 


^  Descending.     Supra-clavicular 


Sternal. 

Clavicular. 

Acromial. 


Deep 


r  Internal 


External 


'  Communicating. 

Muscular. 

Coramunicans  noni. 

Phrenic. 

Communicating. 
I  Muscular. 


Superficial  Branches  op  the  Cervical  Plexus. 

The  Superficialis  Colli  arises  from  the  second  and  third  cervical  nerves,  turns 
round  the  posterior  border  of  the  Sterno-mastoid  about  its  middle,  and  passing 


SUPERFICIAL    BRANCHES    OF    CERVICAL    PLEXUS.    635 

obliquely  forwards  behind  tlie  external  jugular  vein  to  tbe  anterior  border  of 
that  muscle,  perforates  the  deep  cervical  fascia,  and  divides  beneath  the  Pla- 
tysma  into  two  branches,  which  are  distributed  to  the  anterior  and  lateral  parts 
of  the  neck. 

The  ascending  branch  gives  a  filament,  which  accompanies  the  external  jugu- 
lar vein ;  it  then  passes  upwards  to  the  submaxillary  region,  and  divides  into 
branches,  some  of  which  form  a  plexus  with  the  cervical  branches  of  the  facial 
nerve  beneath  the  Platysma ;  others  pierce  that  muscle,  supply  it,  and  are  dis- 
tributed to  the  integument  of  the  upper  half  of  the  neck,  at  its  fore  part,  as  high 
as  the  chin. 

The  descending  branch  pierces  the  Platysma,  and  is  distributed  to  the  integu- 
ment of  the  side  and  front  of  the  neck,  as  low  as  the  sternum.  • 

This  nerve  is  occasionally  represented  by  two  or  more  filaments. 

The  Auricularis  Magnus  is  the  largest  of  the  ascending  branches.  It  arises 
from  the  second  and  third  cervical  nerves,  winds  round  the  posterior  border  of 
the  Sterno-mastoid,  and  after  perforating  the  deep  fascia,  ascends  upon  that 
muscle  beneath  the  Platysma  to  the  parotid  gland,  where  it  divides  into  nume- 
rous branches. 

l}\iQ  facial  branches  pass  across  the  parotid,  and  are  distributed  to  the  integu- 
ment of  the  face ;  others  penetrate  the  substance  of  the  gland,  and  communicate 
with  the  facial  nerve. 

The  posterior  or  auricular  branches  ascend  vertically  to  supply  the  integument 
of  the  back  part  of  the  pinna,  communicating  with  the  auricular  branches  of 
the  facial  and  pneumogastric  nerves. 

The  mastoid  branch  joins  the  posterior  auricular  branch  of  the  facial,  and 
crossing  the  mastoid  process,  is  distributed  to  the  integument  behind  the  ear. 

The  Occipitalis  Minor  arises  from  the  second  cervical  nerve ;  it  curves  round 
the  posterior  border  of  the  Sterno-mastoid  above  the  preceding,  and  ascends 
vertically  along  the  posterior  border  of  that  muscle  to  the  back  part  of  the  side 
of  the  head.  Near  the  cranium  it  perforates  the  deep  fascia,  and  is  continued 
upwards  along  the  side  of  the  head  behind  the  ear,  supplying  the  integument 
and  Occipito-frontalis  muscle,  and  communicating  with  the  occipitalis  major, 
auricularis  magnus,  and  posterior  auricular  branch  of  the  fascial. 

This  nerve  gives  off  an  auricular  branchy  which  supplies  theAttollens  Aurem 
and  the  integument  of  the  upper  and  back  part  of  the  auricle.  This  branch  is 
occasionally  derived  from  the  great  occipital  nerve.  The  occipitalis  minor  varies 
in  size  ;  it  is  occasionally  double. 

The  Descending  or  supra-clavicular  branches  arise  from  the  third  and  fourth 
cervical  nerves ;  emerging  beneath  the  posterior  border  of  the  Sterno-mastoid, 
they  descend  in  the  interval  between  that  muscle  and  the  Trapezius,  and  divide 
into  branches,  which  are  arranged,  according  to  their  position,  into  three  groups. 

The  inner  or  sternal  branch  crosses  obliquely  over  the  clavicular  and  sternal 
attachments  of  the  Sterno-mastoid,  and  supplies  the  integument  as  far  as  the 
median  line. 

The  middle  or  clavicular  branch  crosses  the  clavicle,  and  supplies  the  integu- 
ment over  the  Pectoral  and  Deltoid  muscles,  communicating  with  the  cutaneous 
branches  of  the  upper  intercostal  nerves.  Not  unfrequently,  the  clavicular 
branch  passes  through  a  foramen  in  the  clavicle,  at  the  junction  of  the  outer 
with  the  middle  third  of  the  bone. 

The  external  or  acromial  branch  passes  obliquely  across  the  outer  surface  of 
the  Trapezius  and  the  acromion,  and  supplies  the  integument  of  the  upper  and 
back  part  of  the  shoulder. 

Deep  Branches  of  the  Cervical  Plexus.     Intern-al  Series. 

The  communicating  branches  consist  of  several  filaments,  which  pass  from  the 
loop  between  the  first  and  second  cervical  nerves  in  front  of  the  atlas  to  the 
pneumogastric,  hypoglossal,  and  sympathetic. 


636  SPINAL    NERVES. 

Muscular  branches  supply  the  Anterior  Recti  and  Rectus  Lateralis  muscles: 
they  proceed  from  the  first  cervical  nerve,  and  from  the  loop  formed  between 
it  and  the  second. 

The  Communicans  Noni  (Fig.  343)  consists  usually  of  two  filaments,  one  being 
derived  from  the  second,  and  the  other  from  the  third  cervical.  These  filaments 
pass  vertically  downwards  on  the  outer  side  of  the  internal  jugular  vein,  cross 
in  front  of  the  vein  a  little  below  the  middle  of  the  neck,  and  form  a  loop  with 
the  descendens  noni  in  front  of  the  sheath  of  the  carotid  vessels.  Occasionally, 
the  junction  of  these  nerves  takes  place  within  the  sheath. 

The  Phrenic  Nerve  {internal  respiratory  of  Bell)  arises  from  the  third  and  fourth 
cervical  nerves,  and  receives  a  communicating  branch  from  the  fifth.  It  de- 
scends to  the  root  of  the  neck,  lying  obliquely  across  the  front  of  the  Scalenus 
Anticus,  passes  over  the  first  part  of  the  subclavian  artery,  between  it  and  the 
subclavian  vein,  and,  as  it  enters  the  chest,  crosses  the  internal  mammary 
artery  near  its  root.  Within  the  chest,  it  descends  nearly  vertically  in  front 
of  the  root  of  the  lung,  and  by  the  side  of  the  pericardium,  between  it  and 
the  mediastinal  portion  of  the  pleura,  to  the  Diaphragm,  where  it  divides  into 
branches,  which  separately  pierce  that  muscle,  and  are  distributed  to  its  under 
surface. 

The  two  phrenic  nerves  differ  in  their  length,  and  also  in  their  relations  at 
the  upper  part  of  the  thorax. 

The  right  ryrve  is  situated  more  deeply,  and  is  shorter  and  more  vertical  in 
direction  than  the  left;  it  lies  on  the  outer  side  of  the  right  vena  innominata 
and  superior  vena  cava. 

The  left  nerve  is  rather  longer  than  the  right,  from  the  inclination  of  the  heart 
to  the  left  side,  and  from  the  Diaphragm  being  lower  on  this  than  on  the  opposite 
side.  At  the  upper  part  of  the  thorax,  it  crosses  in  front  of  the  arch  of  the 
aorta  to  the  root  of  the  lung. 

Each  nerve  supplies  filaments  to  the  pericardium  and  pleura,  and  near  the 
chest  is  joined  by  a  filament  from  the  sympathetic,  by  another  derived  from  the 
fifth  and  sixth  cervical  nerves,  and,  occasionally,  by  one  from  the  union  of  the 
descendens  noni  with  the  spinal  nerves;  this  filament  is  found,  according  to 
Swan,  only  on  the  left  side. 

From  the  right  nerve.,  one  or  two  filaments  pass  to  join  in  a  small  ganglion 
with  phrenic  branches  of  the  solar  plexus ;  and  branches  ffom  this  ganglion 
are  distributed  to  the  hepatic  plexus,  the  suprarenal  capsule,  and  inferior  vena 
cava.  From  the  left  nerve.,  filaments  pass  to  join  the  phrenic  plexus,  but  with- 
out any  ganglionic  enlargement. 

Deep  Branches  of  the  Cervical  Plexus.    External  Series. 

Communicating  branches.  The  cervical  plexus  communicates  with  the  spinal 
accessory  nerve,  in  the  substance  of  the  Sterno-mastoid  muscle,  in  the  occipital 
triangle,  and  beneath  the  Trapezius. 

Mtiscular  branches  are  distributed  to  the  Sterno-mastoid,  Levator  Anguli 
Scapulae,  Scalenus  Medius,  and  Trapezius. 

The  branch  for  the  Sterno-mastoid  is  derived  from  the  second  cervical,  the 
Levator  Anguli  Scapulae  receiving  branches  from  the  third,  and  the  Trapezius 
branches  from  the  third  and  fourth. 

Posterior  Branches  of  the  Cervical  Nerves. 

The  posterior  branches  of  the  cervical  nerves,  with  the  exception  of  those  of 
the  first  two,  pass  backwards,  and  divide,  behind  the  posterior  Intertransverse 
muscles,  into  external  and  internal  branches. 

The  external  branches  supply  the  muscles  at  the  side  of  the  neck,  viz.,  the 
Cervicalis  Ascendcns,  Transversalis  Colli,  and  Trachelo-mastoid. 

The  external  branch  of  the  second  cervical  nerve  is  the  largest ;  it  is  often 


BRACHIAL    PLEXUS.  637 

joined  witli  the  third,  and  supplies  the  Complexus,  Splenius,  and  Trachelo- 
niastoid  muscles. 

The  internal  branches,  the  larger,  are  distributed  differently  in  the  upper  and 
lower  part  of  the  neck.  Those  derived  from  the  third,  fourth,  and  fifth  nerves 
pass  between  the  Semispinalis  and  Complexus  muscles,  and  having  reached  the 
spinous  processes,  perforate  the  aponeurosis  of  the  Splenius  and  Trapezius,  and 
are  continued  outwards  to  the  integument  over  the  Trapezius;  whilst  those 
derived  from  the  three  lowest  cervical  nerves  are  the  smallest,  and  are  placed 
beneath  the  Semispinalis,  which  they  supply,  and  do  not  furnish  any  cutaneous 
filaments.  These  internal  branches  supply  the  Complexus,  Semispinalis  Colli, 
Interspinales,  and  Multifidus  Spinae. 

The  posterior  branches  of  the  three  first  cervical  nerves  require  a  separate 
description. 

The  posterior  branch  of  the  first  cervical  nerve  {suboccipital)  is  larger  than  the 
anterior,  and  escapes  from  the  spinal  canal  between  the  occipital  bone  and  the 
posterior  arch  of  the  atlas,  lying  behind  the  vertebral  artery.  It  enters  the 
triangular  space  formed  by  the  Eectus  Posticus  Major,  the  Obliquus  Superior, 
and  Obliquus  Inferior,  and  supplies  the  Eecti  and  Obliqui  muscles,  and  the 
Complexus.  From  the  branch  which  supplies  the  Inferior  Oblique  a  filament 
is  given  off",  which  joins  the  second  cervical  nerve.  This  nerve  also  occasionally 
gives  off  a  cutaneous  filament,  which  accompanies  the  occipital  artery,  and 
communicates  with  the  occipitalis  major  and  minor  nerves. 

The  posterior  division  of  the  first  cervical  has  no  branch  analogous  to  the 
external  branch  of  the  other  posterior  cervical  nerves. 

The  posterior  branch  of  the  second  cervical  nerve  is  three  or  four  times  greater 
than  the  anterior  branch,  and  the  largest  of  all  the  posterior  cervical  nerves. 
It  emerges  from  the  spinal  canal  between  the  posterior  arch  of  the  atlas  and 
lamina  of  the  axis,  below  the  Inferior  Oblique.  It  supplies  this  muscle,  and 
receives  a  communicating  filament  from  the  first  cervical.  It  then  divides  into 
an  external  and  an  internal  branch. 

The  internal  branch,  called,  from  its  size  and  distribution,  the  occipitalis  major, 
ascends  obliquely  inwards  between  the  Inferior  Oblique  and  Complexus,  and 
pierces  the  latter  muscle  and  the  Trapezius  near  their  attachments  to  the  cranium. 
It  is  now  joined  by  a  filament  from  the  third  cervical  nerve,  and  ascending  on 
the  back  part  of  the  head  with  the  occipital  artery,  divides  into  two  branches, 
which  supply  the  integument  of  the  scalp  as  far  forwards  as  the  vertex,  com- 
municating with  the  occipitalis  minor.  It  gives  off'  an  auricular  branch  to  the 
back  part  of  the  ear,  and  muscular  branches  to  the  Complexus. 

The  posterior  branch  of  the  third  cervical  is  smaller  than  the  preceding,  but 
larger  than  the  fourth ;  it  differs  from  the  posterior  branches  of  the  other  cervi- 
cal nerves  in  its  supplying  an  additional  filament  to  the  integument  of  the 
occiput.  This  occipital  branch  arises  from  the  internal  or  cutaneous  branch 
beneath  the  Trapezius ;  it  pierces  that  muscle,  and  supplies  the  skin  on  the 
lower  and  back  part  of  the  head.  It  lies  to  the  inner  side  of  the  occipitalis 
major,  with  which  it  is  connected. 

The  internal  branches  of  the  posterior  divisions  of  the  first  three  cervical 
nerves  are  occasionally  joined  beneath  the  Complexus  by  communicating 
branches.  This  communication  is  described  by  Cruveilhier  as  the  posterior 
cervical  plexus. 

The  Brachial  Plexus.    (Fig.  349.) 

The  Brachial  Plexus  is  formed  by  the  union  of  the  anterior  branches  of  the 
four  lower  cervical  and  first  dorsal  nerves.  It  extends  from  the  lower  part  of 
the  side  of  the  neck  to  the  axilla.  It  is  very  broad,  and  presents  little  of  a 
plexiform  arrangement  at  its  commencement,  is  narrow  opposite  the  clavicle, 
becomes  broad,  and  forms  a  more  dense  interlacement  in  the  axilla,  and  divides 
opposite  the  coracoid  process  into  numerous  branches  for  the  supply  of  the 


638 


SPINAL    NERYES. 


upper  limb.  The  nerves  which  form  the  plexus  are  all  smaller  in  size,  and 
their  mode  of  communication  is  the  following.  The  fifth  and  sixth  nerves 
unite  near  their  exit  from  the  spine  into  a  common  trunk ;  the  seventh  nerve 

joins  this  trunk  near  the  outer 


Fig.  349.— Plan  of  the  Brachial  Plexus. 


Crrvtca/Jirs^ 


CetHmttnientiny  u>i&  PhrClUO 


C      '^^ — S"p  »•«  -Seapular 
-      '•■'•»  sT  CiavicU, 


border  of  the  Middle  Scalenus; 
and  the  three  nerves  thus  form 
one  large  single  cord.  The 
eighth  cervical  and  first  dorsal 
nerves  unite  behind  the  Ante- 
rior Scalenus  into  a  common 
trunk.  Thus  two  large  trunks 
are  formed,  the  upper  one  by 
the  union  of  the  fifth,  sixth,  and 
seventh  cervical ;  and  the  lower 
one  by  the  eighth  cervical  and 
first  dorsal.  These  two  trunks 
accompany  the  subclavian  ar- 
tery to  the  axilla,  lying  upon 
its  outer  side,  the  trunk  formed 
by  the  union  of  the  last  cervical 
and  first  dorsal  being  nearest 
to  the  vessel.  Opposite  the 
clavicle,  and  sometimes  in  the 
axilla,  each  of  these  cords  gives 
off  a  fasciculus,  by  the  union 
of  which  a  third  trunk  is  formed, 
so  that  in  the  middle  of  the 
axilla  three  cords  are  found, 
one  lying  on  the  outer  side  of 
the  axillary  artery,  one  on  its 
inner  side,  and  one  behind.^ 
The  brachial  plexus  communi- 
cates with  the  cervical  plexus  by  a  branch  from  the  fourth  to  the  fifth  nerve, 
and  with  the  phrenic  nerve  by  a  branch  from  the  fifth  cervical,  which  joins 
that  nerve  on  the  Anterior  Scalenus  muscle.  The  cervical  and  first  dorsal 
nerves  are  also  joined  by  filaments  from  the  middle  and  inferior  cervical  ganglia 
of  the  sympathetic,  close  to  their  exit  from  the  intervertebral  foramina. 

Relations.  In  the  neck,  the  brachial  plexus  lies  at  first  between  the  Anterior 
and  Middle  Scaleni  muscles,  and  then  above  and  to  the  outer  side  of  the  sub- 
clavian artery ;  it  then  passes  behind  the  clavicle  and  Subclavius  muscle,  lying 
upon  the  first  serration  of  the  Serratus  Magnus  and  the  Subscapularis  milscles. 
In  the  axilla,  it  is  placed  on  the  outer  side  of  the  first  portion  of  the  axillary 
artery ;  it  surrounds  the  artery  in  the  second  part  of  its  course,  one  cord  lying 
upon  the  outer  side  of  that  vessel,  one  on  the  inner  side,  and  one  behind  it ; 
and  at  the  lower  part  of  the  axillary  space  gives  off  its  terminal  branches  to 
the  upper  extremity. 

Branches.  The  branches  of  the  brachial  plexus  are  arranged  into  two  groups, 
viz.,  those  given  off  above  the  clavicle,  and  those  below  that  bone. 

Branches  above  the  Clavicle. 
Communicating.  Posterior  thoracic. 

Muscular.  Suprascapular. 

The  communicating/  branch  with  the  phrenic  is  derived  from  the  fifth  cervical 
nerve ;  it  joins  the  phrenic  on  the  Anterior  Scalenus  muscle. 

'  This  is  the  most  common  mode  of  formation  of  the  plexus  ;  but  it  is  also  very  common  for 
the  third,  or  posterior,  cord  to  be  formed  by  the  seventh  cervical  nerve,  running  undivided,  and 
receiving  a  branch  from  each  of  the  other  cords. 


BRANCHES    BELOW    THE    CLAVICLE  639 

The  miiscular  branches  supply  the  Longus  Colli,  Scaleni,  Ehomboidei,  and 
Subclavius  muscles.  Those  for  the  Scaleni  and  Longus  Colli  arise  from  the 
lower  cervical  nerves  at  their  exit  from  the  intervertebral  foramina.  The 
rhomboid  branch  arises  from  the  fifth  cervical,  pierces  the  Scalenus  Medius, 
and  passes  beneath  the  Levator  Anguli  Scapulae,  which  it  occasionally  supplies, 
to  the  Rhomboid  muscles.  The  nerve  to  the  Subclavius  is  a  small  filament, 
Which  arises  from  the  trunk  formed  by  the  junction  of  the  fifth  and  sixth 
cervical  nerves ;  it  descends  in  front  of  the  subclavian  artery  to  the  Subclavius 
muscle,  and  is  usually  connected  by  a  filament  with  the  phrenic  nerve. 

The  posterior  thoracic  nerve  (long  thoracic,  external  respiratory  of  Bell),  (Fig. 
352)  supplies  the  Serratus  Magnus,  and  is  remarkable  for  the  length  of  its 
course.  It  arises  by  two  roots,  from  the  fifth  and  sixth  cervical  nerves,  imme- 
diately after  their  exit  from  the  intervertebral  foramina.  These  unite  in  the 
substance  of  the  Middle  Scalenus  muscle,  and,  after  emerging  from  it,  the  nerve 
passes  down  behind  the  brachial  plexus  and  the  axillary  vessels,  resting  on  the 
outer  surface  of  the  Serratus  Magnus.  It  extends  along  the  side  of  the  chest 
to  the  lower  border  of  that  muscle,  and  supplies  it  with  numerous  filaments. 

The  suprascajndar  nerve  (Fig.  353)  arises  from  the  cord  formed  by  the  fifth, 
sixth,  and  seventh  cervical  nerves;  passing  obliquely  outwards  beneath  the 
Trapezius,  it  enters  the  supraspinous  fossa,  through  the  notch  in  the  upper 
border  of  the  scapula;  and,  passing  beneath  the  Supraspinatus  muscle,  curves 
in  front  of  the  spine  of  the  scapula  to  the  infraspinous  fossa.  In  the  supra- 
spinous fossa,  it  gives  off'  two  branches  to  the  Supraspinatus  muscle,  and  an 
articular  filament  to  the  shoulder-joint ;  and  in  the  infraspinous  fossa,  it  gives 
off  two  branches  to  the  Infraspinatus  muscle,  besides  some  filaments  to  the 
shoulder-joint  and  scapula. 

Branches  below  the  Clavicle. 
To  chest       ....  Anterior  thoracic 

To  shoulder         .        .        .      |   Subscapular. 

\   Circumflex. 
Musculo-cutaneous. 
Internal  cutaneous. 
Lesser  internal  cutaneous. 
Median. 
Ulnar. 
^  Musculo-spiral. 

The  branches  given  off  below  the  clavicle,  are  derived  from  the  three  cords 
of  the  brachial  plexus,  in  the  following  manner. 

Fro7n  the  outer  cord,  arises  the  external  of  the  two  anterior  thoracic  nerves, 
the  musculo-cutaneous  nerve,  and  the  outer  head  of  the  median. 

From  the  inner  cord,  arises  the  internal  of  the  two  anterior  thoracic  nerves, 
the  internal  cutaneous,  the  lesser  internal  cutaneous  (nerve  of  Wrisberg),  the 
ulnar  and  inner  head  of  the  median. 

From  the  posterior  cord,  arise  the  three  subscapular  nerves ;  and  the  cord  then 
divides  into  the  musculo-spiral  and  circumflex  nerves. 

The  Anterior  Thoracic  Nerves  (Fig.  352),  two  in  number,  supply  the  Pectoral 
muscles. 

The  external,  or  superficial  branch,  the  larger  of  the  two,  arises  from  the  outer 
cord  of  the  brachial  plexus,  passes  inwards,  across  the  axillary  artery  and  vein; 
and  is  distributed  to  the  under  surface  of  the  Pectoralis  Major.  It  sends  down 
a  communicating  filament  to  join  the  internal  branch. 

The  internal,  or  deep  branch,  arises  from  the  inner  cord,  and  passes  upwards 
between  the  axillary  artery  and  vein  (sometimes  perforates  the  vein),  and  joins 
with  the  filament  from  the  superficial  branch.  From  the  loop  thus  formed, 
branches  are  distributed  to  the  under  surface  of  the  Pectoralis  Minor  and 
Pectoralis  Major  muscles. 


To  arm,  forearm,  and  hand 


640 


SPINAL    NERVES. 


Fig.  350. — Cutaneous  Nerves  of 
Riffht  Upper  Extremity.  Anterior 
View. 


The  Subscaplular  Nerves^  three  in  number,  supply  the  Subscapularis,  Teres 
Major,  and  Latissimus  Dorsi  muscles. 

The  upper  subscapular  nerve^  the  smallest,  enters  the  upper  part  of  the  Sub- 
scapularis muscle. 

The  lower  suhscajmlar  nerve  enters  the  axillary  border  of  the  Subscapularis, 
and  terminates  in  the  Teres  Major.  The  latter  muscle  is  sometimes  supplied 
by  a  separate  branch. 

The  long  subscapular,  the  largest  of  the  three,  descends  along  the  lower  border 

of  the  Subscapularis  to  the  Latissimus  Dorsi, 
through  which  it  may  be  traced  as  far  as  its 
lower  border. 

The  Circumfiex  Nerve  (Fig.  353)  supplies  some 
of  the  muscles,  and  the  integument  of  the  shoul- 
der, and  the  shoulder-joint.  It  arises  from  the 
posterior  cord  of  the  brachial  plexus,  in  common 
with  the  musculo-spiral  nerve.  It  passes  down 
behind  the  axillary  artery,  and  in  front  of  the 
Subscapularis;  and,  at  the  lower  border  of  that 
muscle,  passes  backwards,  and  divides  into  two 
branches. 

The  upper  branch  winds  round  the  neck  of  the 
humerus,  beneath  the  Deltoid,  with  the  posterior 
circumflex  vessels,  as  far  as  the  anterior  border 
of  the  muscle,  supplying  it,  and  giving  off  cuta- 
neous branches,  which  pierce  it  to  ramify  in  the 
integument  covering  its  lower  part. 

The  lower  branch,  at  its  origin,  distributes  fila- 
ments to  the  Teres  Minor  and  back  part  of  the 
Deltoid  muscles.  Upon  the  filament  to  the  for- 
mer muscle  a  gangliform  enlargement  usually 
exists.  The  nerve  then  pierces  the  deep  fascia, 
and  supplies  the  integument  over  the  lower  two- 
thirds  of  the  posterior  surface  of  the  Deltoid,  as 
well  as  that  covering  the  long  head  of  the 
Triceps. 

The  circumflex  nerve,  before  its  division,  gives 
off  an  articular  filament,  which  enters  the  shoul- 
der-joint below  the  Subscapularis. 

The  Mxiscuh-cutaneous  Nerve  (Fig.  352)  (exter- 
nal cutaneous,  perforans  Casserii),  supplies  some 
of  the  muscles  of  the  arm,  and  the  integument  of 
the  forearm.  It  arises  from  the  outer  cord  of  the 
brachial  plexus,  opposite  the  lower  border  of  the 
Pectoralis  Minor.  It  then  perforates  the  Coraco- 
brachialis  muscle,  and  passes  obliquely  between 
the  Biceps  and  Brachialis  Anticus,  to  the  outer 
side  of  the  arm,  a  little  above  the  elbow,  where  it 
perforates  the  deep  fascia  and  becomes  cutaneous. 
This  nerve,  in  its  course  through  the  arm,  sup- 
plies the  Coraco-brachialis,  Biceps,  and  Brachialis 
Anticus  muscles,  besides  sending  some  filaments 
to  the  elbow-joint  and  humerus. 

The  cutaneous  portion  of  the  nerve  passes  be- 
hind the  median  cephalic  vein,  and  divides,  opposite  the  elbow-joint,  into  an 
anterior  and  a  posterior  branch. 

The  anterior  branch  descends  along  the  radial  border  of  the  forearm  to  the 
wrist.     It  is  here  placed  in  front  of  the  radial  artery,  and,  piercing  the  deep 


INTERNAL    CUTANEOUS    NERYE. 


641 


Fig.  351. — Cutaneous  Nerves  of 
Right  Upper  Extremity.  Poste- 
rior View. 


fascia,  accompanies  that  vessel  to  the  back  of  the  wrist.  It  communicates  with 
a  branch  from  the  radial  nerve,  and  distributes  filaments  to  the  integument  of 
the  ball  of  the  thumb. 

The  posterior  branch  is  given  off  about  the  middle  of  the  forearm,  and  passes 
downwards,  along  the  back  part  of  its  radial  side  to  the  wrist.  It  supplies  the 
integument  of  the  lower  third  of  the  forearm, 
communicating  with  the  radial  nerve,  and  the 
external  cutaneous  branch  of  the  musculo-spiral. 

The  Internal  Cutaneous  Nerve  (Fig.  352)  is  one 
of  the  smallest  branches  of  the  brachial  plexus. 
It  arises  from  the  inner  cord,  in  common  with 
the  ulnar  and  internal  head  of  the  median,  and, 
at  its  commencement,  is  placed  on  the  inner  side 
of  the  brachial  artery.  It  passes  down  the  inner 
side  of  the  arm,  pierces  the  deep  fascia  with  the 
basilic  vein,  about  the  middle  of  the  limb,  and, 
becoming  cutaneous,  divides  into  two  branches. 

This  nerve  gives  off,  near  the  axilla,  a  cuta- 
neous filament,  which  pierces  the  fascia,  and  sup- 
plies the  integument  covering  the  Biceps  muscle, 
nearly  as  far  as  the  elbow.  This  filament  lies  a 
little  external  to  the  common  trunk  from  which 
it  arises. 

The  anterior  branch,  the  larger  of  the  two, 
passes  usually  in  front  of,  but  occasionally  be- 
hind, the  median  basilic  vein.  It  then  descends 
on  the  anterior  surface  of  the  ulnar  side  of  the 
forearm,  distributing  filaments  to  the  integument 
as  far  as  the  wrist,  and  communicating  with  a 
cutaneous  branch  of  the  ulnar  nerve. 

The  posterior  branch  passes  obliquely  down- 
wards on  the  inner  side  of  the  basilic  vein,  winds 
over  the  internal  condyle  of  the  humerus  to  the 
back  of  the  forearm,  and  descends,  on  the  poste- 
rior surface  of  its  ulnar  side,  to  a  little  below  the 
middle,  distributing  filaments  to  the  integument. 
It  anastomoses  above  the  elbow,  with  the  lesser 
internal  cutaneous,  and  above  the  wrist,  with  the 
dorsal  branch  of  the  ulnar  nerve  (Swan). 

The  Lesser  Internal  Cutaneous  Nerve  (nerve  of 
Wrisberg)  (Fig.  352),  is  distributed  to  the  in- 
tegument on  the  inner  side  of  the  arm.  It  is  the 
smallest  of  the  branches  of  the  brachial  plexus, 
and  usually  arises  from  the  inner  cord,  with  the 
internal  cutaneous  and  ulnar  nerves.  It  passes 
through  the  axillary  space,  at  first  lying  behind, 
and  then  on  the  inner  side  of  the  axillary  vein, 
and  communicates  with  the  intercosto-humeral 
nerve.  It  then  descends  along  the  inner  side  of 
the  brachial  artery,  to  the  middle  of  the  arm, 
where  it  pierces  the  deep  fascia,  and  is  distri- 
buted to  the  integument  of  the  back  part  of  the 
lower  third  of  the  arm,  extending  as  far  as  the 
elbow,  where  some  filaments  are  lost  in  the  integument  in  front  of  the  inner 
condyle,  and  others  over  the  olecranon.  It  communicates  with  the  inner 
branch  of  the  internal  cutaneous  nerve. 

In  some  cases  the  nerve  of  Wrisberg  and  intercosto-humeral  are  connected 
41 


642 


SPINAL    NERVES. 


by  two  or  three  filaments,  which  form  a  plexus  at  the  back  part  of  the  axilla. 
In  other  cases,  the  intercosto- humeral  is  of  large  size,  and  takes  the  place  of 


Fig.  352. — Nerves  of  the  Left  Upper  Extremity.     Front  View. 


'Anterior  Z7tora^e 


fnftrnnf 
'Anterior  TAonaet* 


Culnneeu* 


Mtelimn 


>Iutcii7o  Spiml 

Po.tter^'or 
Interosseous 


ylnttn'or 
2utereatto44» 


MEDIAN.  643 

the  nerve  of  Wrisberg,  receiving  merely  a  filament  of  communication  from  the 
brachial  plexus,  which  represents  the  latter  nerve.  In  other  cases,  this  filament 
is  wanting,  the  place  of  the  nerve  of  Wrisberg  being  supplied  entirely  from 
the  intercosto-humeral. 

The  Median  Nerve  (Fig.  352)  has  received  its  name  from  the  course  it  takes 
along  the  middle  of  the  arm  and  forearm  to  the  hand,  lying  between  the  ulnar 
and  the  musculo-spiral  and  radial  nerves.  It  arises  by  two  roots,  one  from  the 
outer,  and  one  from  the  inner  cord  of  the  brachial  plexus ;  these  embrace  the 
lower  part  of  the  axillary  artery,  uniting  either  in  front  or  on  the  outer  side  of 
that  vessel.  As  it  descends  through  the  arm,  it  lies  at  first  on  the  outer  side 
of  the  brachial  artery,  crosses  that  vessel  in  the  middle  of  its  course,  usually 
in  front,  but  occasionally  behind  it,  and  lies  on  its  inner  side  to  the  bend  of  the 
elbow,  where  it  is  placed  beneath  the  bicipital  fascia,  and  is  separated  from  the 
elbow-joint  by  the  Brachialis  Anticus.  In  the  forearm^  it  passes  between  the 
two  heads  of  the  Pronator  Eadii  Teres,  and  descends  beneath  the  Flexor  Sub- 
limis,  to  within  two  inches  above  the  annular  ligament,  where  it  becomes  more 
superficial,  lying  between  the  Flexor  Sublimis  and  Flexor  Carpi  Eadialis, 
covered  by  the  integument  and  fascia.  It  then  passes  beneath  the  annular  liga- 
ment into  the  hand. 

Branches.  No  branches  are  given  off  from  the  median  nerve  in  -the  arm. 
In  the  forearm  its  branches  are,  muscular,  anterior  interosseous,  and  palmar 
cutaneous. 

The  muscular  branches  supply  all  the  superficial  muscles  on  the  front  of  the 
forearm,  except  the  Flexor  Carpi  Ulnaris.  These  branches  are  derived  from 
the  nerve  near  the  elbow.  The  branch  furnished  to  the  Pronator  Kadii  Teres 
often  arises  above  the  joint. 

The  anterior  interosseous  supplies  the  deep  muscles  on  the  front  of  the  fore- 
arm, except  the  Flexor  Carpi  Ulnaris  and  inner  half  of  the  Flexor  Profundus 
Digitorum.  It  accompanies  the  anterior  interosseous  artery  along  the  inter- 
osseous membrane,  in  the  interval  between  the  Flexor  Longus  Pollicis  and 
Flexor  Profundus  Digitorum  muscles,  both  of  which  it  supplies,  and  terminates 
below  in  the  Pronator  Quadratus. 

The  palmar  cutaneous  branch  arises  from  the  median  nerve  at  the  lower  part 
of  the  forearm.  It  pierces  the  fascia  above  the  annular  ligament,  and  divides 
into  two  branches ;  of  which  the  outer  supplies  the  skin  over  the  ball  of  the 
thumb,  and  communicates  with  the  external  cutaneous  nerve;  andthetwzer  sup- 
plies the  integument  of  the  palm  of  the  hand,  anastomosing  with  the  cutaneous 
branch  of  the  ulnar.  Both  nerves  cross  the  annular  ligament  previous  to  their 
distribution. 

In  the  jjalm  of  the  hand,  the  median  nerve  is  covered  by  the  integument  and 
palmar  fascia,  and  rests  upon  the  tendons  of  the  flexor  muscles.  In  this  situation 
it  becomes  enlarged,  somewhat  flattened,  of  a  reddish  color,  and  divides  into 
two  branches.  Of  these,  the  external  supplies  a  muscular  branch  to  some  of 
the  muscles  of  the  thumb,  and  digital  branches  to  the  thumb  and  index-finger; 
the  internal  branch  supplying  digital  branches  to  the  contiguous  sides  of  the 
index  and  middle,  and  of  the  middle  and  ring  fingers. 

The  branch  to  the  muscles  of  the  thumb  is  a  short  nerve,  which  subdivides  to 
supply  the  Abductor,  Opponens,  and  outer  head  of  the  Flexor  Brevis  Pollicis 
muscles  ;  the  remaining  muscles  of  this  group  being  supplied  by  the  ulnar  nerve. 

The  digital  branches  are  five  in  number.  The  first  and  second  pass  along  the 
borders  of  the  thumb,  the  external  branch  communicating  with  branches  of  the 
radial  nerve.  The  third  passes  along  the  radial  side  of  the  index-finger,  and 
supplies  the  first  Lumbrical  muscle.  The/owW/i  subdivides  to  supply  the  adja- 
cent sides  of  the  index  and  middle  fingers,  and  sends  a  branch  to  the  second 
Lumbrical  muscle.  The  fifth  supplies  the  adjacent  sides  of  the  middle  and  ring 
fingers,  and  communicates  with  a  branch  from  the  ulnar  nerve. 

Each  digital  nerve,  opposite  the  base  of  the  first  phalanx,  gives  oflf  a  dorsal 


644  SPIXAL    NERYES. 

branch,  -whicli  joins  the  dorsal  digital  nerve,  and  runs  along  the  side  of  the 
dorsum  of  the  finger,  ending  in  the  integument  over  the  last  phalanx.  At  the 
end  of  the  finger,  the  digital  nerve  divides  into  a  palmar  and  a  dorsal  brancli ; 
the  former  of  which  supplies  the  extremity  of  the  finger,  and  the  latter  ramifies 
round  and  beneath  the  nail.  The  digital  nerves,  as  they  run  along  the  fingers, 
are  placed  superficial  to  the  digital  arteries. 

The  Ulnar  Nerve  (Fig.  852)  is  placed  along  the  inner  or  ulnar  side  of  the 
upper  limb,  and  is  distributed  to  the  muscles  and  integument  of  the  forearm 
and  hand.  It  is  smaller  than  the  median,  behind  which  it  is  placed,  diverging 
from  it  in  its  course  down  the  arm.  It  arises  from  the  inner  cord  of  the 
brachial  plexus,  in  common  with  the  inner  head  of  the  median  and  the  internal 
cutaneous  nerve.  At  its  commencement,  it  lies  at  the  inner  side  of  the  axillary 
artery,  and  holds  the  same  relation  with  the  brachial  artery  to  the  middle  of  the 
arm.  From  this  point,  it  runs  obliquely  across  the  internal  head  of  the  Triceps, 
pierces  the  internal  intermuscular  septum,  and  descends  to  the  groove  between 
the  internal  condyle  and  olecranon,  accompanied  by  the  inferior  profunda 
artery.  At  the  elhow^  it  rests  upon  the  back  of  the  inner  condyle,  and  passes 
into  the  forearm  between  the  two  heads  of  the  Flexor  Carpi  Ulnaris.  In  the 
forearm,  it  descends  in  a  perfectly  straight  course  along  its  ulnar  side,  lying 
upon  the  Flexor  Profundus  Digitorum,  its  upper  half  being  covered  by  the 
Flexor  Carpi  Ulnaris,  its  lower  half  lying  on  the  outer  side  of  the  muscle, 
covered  by  the  integument  and  fascia.  The  ulnar  artery,  in  the  upper  part  of 
its  course,  is  separated  from  the  ulnar  nerve  by  a  considerable  interval ;  but  in 
the  rest  of  its  extent,  the  nerve  lies  to  its  inner  side.  At  the  wrist,  the  ulnar 
nerve  crosses  the  annular  ligament  on  the  outer  side  of  the  pisiform  bone,  a 
little  behind  the  ulnar  artery,  and  immediately  beyond  this  bone  divides  into 
two  branches,  superficial  and  deep  palmar. 

The  branches  of  the  ulnar  nerve  are: — 

'Articular  (elbow). 

Muscular.  /  c         a  '  ^       ^^ 

-r    n  ri  i.  T    1.     J     Superficial  palmar. 

In  forearm  ■{  Cutaneous.  In  hand  <  -n  ^        i     ^ 
I  T^        1      i.  Deep  palmar. 

Dorsal  cutaneous.  '■         ^  ^ 

[  Articular  (wrist). 

The  articular  branches  distributed  to  the  elbow-joint  consist  of  several  small 
filaments.  They  arise  from  the  nerve  as  it  lies  in  the  groove  between  the  inner 
condyle  and  olecranon. 

The  muscular  branches  are  two  in  number;  one  supplying  the  Flexor  Carpi 
Ulnaris;  the  other,  the  inner  half  of  the  Flexor  Profundus  Digitorum.  They 
arise  from  the  trunk  of  the  nerve  near  the  elbow. 

The  cutaneous  branch  arises  from  the  ulnar  nerve  about  the  middle  of  the 
forearm,  and  divides  into  a  superficial  and  deep  branch. 

The  superficial  branch  (frequently  absent)  pierces  the  deep  fascia  near  the 
wrist,  and  is  distributed  to  the  integument,  communicating  with  a  branch  of 
the  internal  cutaneous  nerve. 

The  deep  branch  lies  on  the  ulnar  artery,  which  it  accompanies  to  the  hand, 
some  filaments  entwining  round  the  vessel,  which  end  in  the  integument  of  the 
palm,  communicating  with  branches  of  the  median  nerve. 

The  dorsal -cutaneous  branch  arises  about  two  inches  above  the  wrist;  it  passes 
backwards  beneath  the  Flexor  Carpi  Ulnaris,  perforates  the  deep  fascia,  and 
running  .along  the  ulnar  side  of  the  wrist  and  hand,  supplies  the  inner  side 
of  the  little  finger,  and  the  adjoining  sides  of  the  little  and  ring  fingers;  it  also 
sends  a  communicating  filament  to  that  branch  of  the  radial  nerve  which  sup- 
plies the  adjoining  sides  of  the  middle  and  ring  fingers. 

The  articular  filaments  to  the  wrist  are  also  sii])plied  by  the  ulnar  nerve. 

The  superficial  palmar  branch  supplies  the  Palmaris  Brevis,  and  the  integu- 
ment on  tfie  inner  side  of  the  hand,  and  terminates  in  two  digital  branches. 


MUSCtJLO-SPIRAL. 


645 


353. — The  Suprascapular,  Circumflex,  and  Musculo- 
spiral  Nerves. 


Supra-Seapula. 


Oircumfleao 


Spiral' 


whicli  are  distributed,  one  Fig. 
to  the  ulnar  side  of  the  little 
finger,  the  other  to  the  ad- 
joining sides  of  the  little  and 
ring  fingers,  the  latter  com- 
munica.ting  with  a  branch 
from  the  median. 

The  deep  palmar  branch 
passes  between  the  Abductor 
and  Flexor  Brevis  Minimi 
Digiti  muscles,  and  follows 
the  course  of  the  deep  pal- 
mar arch  beneath  the  flexor 
tendons.  At  its  origin,  it 
supplies  the  muscles  of  the 
little  finger.  As  it  crosses 
the  deep  part  of  the  hand  it 
sends  two  branches  to  each 
interosseous  space,  one  for 
the  Dorsal  and  one  for  the 
Palmar  Interosseous  muscle, 
the  branches  to  the  second 
and  third  Palmar  Interossei 
supplying  filaments  to  the 
two  inner  Lumbricales  mus- 
cles. At  its  termination  be- 
tween the  thumb  and  index 
finger,  it  supplies  the  Ad- 
ductor Pollicis  and  the  inner 
head  of  the  Flexor  Brevis 
Pollicis. 

The  Musculo-spiral  Nerve 
(Fig.  853),  the  largest  branch 
of  the  brachial  plexus,  sup- 
plies the  muscles  of  the  back 
part  of  the  arm  and  forearm, 
and  the  integument  of  the 
same  parts,  as  well  as  that 
of  the  hand.  It  arises  from 
the  posterior  cord  of  the  bra- 
chial plexus  by  a  common 
trunk  with  the  circumflex 
nerve.  At  its  commence- 
ment it  is  placed  behind  the 
axillary  and  upper  part  of 
the  brachial  arteries,  passing 
down  in  front  of  the  tendons 
of  the  Latissimus  Dorsi  and  Teres  Major.  It  winds  round  the  humerus  in  the 
spiral  groove  with  the  superior  profunda  artery,  passing  from  the  inner  to  the 
outer  side  of  the  bone,  beneath  the  Triceps  muscle.  At  the  outer  side  of  the 
arm,  it  descends  between  the  Brachialis  Anticus  and  Supinator  Longus  to  the 
front  of  the  external  condyle,  where  it  divides  into  the  radial  and  posterior 
interosseous  nerves. 

The  branches  of  the  musculo-spiral  nerve  are : — 


\nterioT-IattKitteotu 


Muscular. 
Cutaneous. 


Radial. 

Posterior  interosseous. 


6A6  SPINAL    NERVES. 

The  muscular  branches  supply  the  Triceps,  Anconeus,  Supinator  Longus,  Ex. 
tensor  Carpi  Radialis  Longior,  and  Brachialis  Anticus.  These  branches  are 
derived  from  the  nerve,  at  the  inner  side,  back  part,  and  outer  side  of  the  arm. 

The  internal  muscular  branches  supply  the  inner  and  middle  heads  of  the 
Triceps  muscle.  That  to  the  inner  head  of  the  Triceps,  is  a  long,  slender  fila- 
ment, which  lies  close  to  the  ulnar  nerve,  as  far  as  the  lower  third  of  the  arm. 

The  posterior  muscular  branch,  of  large  size,  arises  from  the  nerve  in  the 
groove  between  the  Triceps  and  the  humerus.  It  divides  into  branches  which 
supply  the  outer  head  of  the  Triceps  and  Anconeus  muscles.  The  branch  for 
the  latter  muscle  is  a  long,  slender  filament,  which  descends  in  the  substance  of 
the  Triceps  to  the  Anconeus  in  the  same  course  with  the  posterior  articular 
branch  from  the  superior  profunda  artery. 

The  external  muscular  branches  supply  the  Supinator  Longus,  Extensor  Carpi 
Kadialis  Longior,  and,  usually,  the  Brachialis  Anticus. 

The  cutaneous  branches  are  three  in  number,  one  internal  and  two  external. 

The  internal  cutaneous  branch  arises  in  the  axillary  space,  with  the  inner 
muscular  branch.  It  is  of  small  size,  and  passes  across  the  axilla  to  the  inner 
side  of  the  arm,  supplying  the  integument  on  its  posterior  aspect  nearly  as  far 
as  the  olecranon. 

The  two  external  cutaneous  branches  perforate  the  outer  head  of  the  Triceps, 
at  its  attachment  to  the  humerus.  The  upper  and  smaller  one  follows  the  course 
of  the  cephalic  vein  to  the  front  of  the  elbow,  supplying  the  integument  of  the 
lower  half  of  the  upper  arm  on  its  anterior  aspect.  The  lower  branch  pierces 
the  deep  fascia  below  the  insertion  of  the  Deltoid,  and  passes  down  along  the 
outer  side  of  the  arm  and  elbow,  and  along  the  back  part  of  the  radial  side  of 
the  forearm  to  the  wrist,  supplying  the  integument  in  its  course,  and  joining, 
near  its  termination,  with  a  branch  of  the  external  cutaneous  nerve. 

The  radial  nerve  passes  along  the  front  of  the  radial  side  of  the  forearm,  to 
the  commencement  of  its  lower  third.  It  lies  at  first  a  little  to  the  outer  side 
of  the  radial  artery,  concealed  beneath  the  Supinator  Longus.  In  the  middle 
third  of  the  forearm,  it  lies  beneath  the  same  muscle,  in  close  relation  with  the 
outer  side  of  the  artery.  It  quits  the  artery  about  three  inches  above  the  wrist, 
passes  beneath  the  tendon  of  the  Supinator  Longus,  and,  piercing  the  deep  fascia 
at  the  outer  border  of  the  forearm,  divides  into  two  branches. 

The  external  branch,  the  smaller  of  the  two,  supplies  the  integument  of  the 
radial  side  and  ball  of  the  thumb,  joining  with  the  posterior  branch  of  the 
external  cutaneous  nerve. 

The  internal  branch  communicates,  above  the  wrist,  with  a  branch  from  the 
external  cutaneous,  and,  on  the  back  of  the  hand,  forms  an  arch  with  the  dorsal 
branch  of  the  ulnar  nerve.  It  then  divides  into  four  digital  nerves,  which  are 
distributed  as  follows;  The  first  supplies  the  ulnar  side  of  the  thumb ;  the  second, 
the  radial  side  of  the  index  finger;  the  third,  the  adjoining  sides  of  the  index 
and  middle  fingers;  and  the  fourth,  the  adjacent  borders  of  the  middle  and  ring 
fingers.  The  latter  nerve  communicates  with  a  filament  from  the  dorsal  branch 
of  the  ulnar  nerve. 

^\xQ posterior  interosseous  nerve  pierces  the  Supinator  Brevis,  winds  to  the  back 
of  the  forearm,  in  the  substance  of  that  muscle,  and,  emerging  from  its  lower 
border,  passes  down  between  the  superficial  and  deep  layer  of  muscles,  to  the 
middle  of  the  forearm.  Considerably  diminished  in  size,  it  descends  on  the 
interosseous  membrane,  beneath  the  Extensor  Sccundi  Internodii  Pollicis,  to 
the  back  of  the  carpus,  where  it  presents  a  gangliform  enlargement,  from  which 
filaments  are  distributed  to  the  ligaments  and  articulations  of  the  carpus.  It 
supplies  all  the  muscles  of  tlie  radial  and  posterior  brachial  regions,  excepting 
the  Anconeus,  Supinator  Longus,  and  Extensor  Carpi  Kadialis  Longior. 


DORSAL— INTERCOSTAL.  647 


Dorsal  Nerves. 


The  Dorsal  Nerves  are  twelve  in  number  on  each  side.  The  first  appears 
between  the  first  and  second  dorsal  vertebrae,  and  the  last  between  the  last  dorsal 
and  first  lumbar. 

The  roots  of  origin  of  the  dorsal  nerves  are  few  in  number,  of  small  size,  and 
vary  but  slightly  from  the  second  to  the  last.  Both  roots  are  very  slender ;  the 
posterior  roots  only  slightly  exceeding  the  anterior  in  thickness.  These  roots 
gradually  increase  in  length  from  above  downwards,  and  remain  in  contact  with 
the  spinal  cord  for  a  distance  equal  to  the  height  of,  at  least,  two  vertebrae,  in 
the  lower  part  of  the  dorsal  region.  They  then  join  in  the  intervertebral  fora- 
men, and,  at  their  exit,  divide  into  two  branches,  a  posterior,  or  dorsal,  and  an 
anterior,  or  intercostal  branch. 

The  first  and  last  dorsal  nerves  are  peculiar  in  several  respects  (see  next  page). 

The  posterior  hranches  of  the  dorsal  nerves,  which  are  smaller  than  the  inter- 
costal, pass  backwards  between  the  transverse  processes,  and  divide  into  external 
and  internal  branches. 

The  external  hranches  increase  in  size  from  above  downwards.  They  pass 
through  the  Longissimus  Dorsi,  corresponding  to  the  cellular  interval  between 
it  and  the  Sacro-lumbalis,  and  supply  those  muscles,  as  well  as  their  continua- 
tions upwards  to  the  head,  and  the  Levatores  Costarum;  the  five  or  six  lower 
nerves  also  give  off  cutaneous  filaments. 

The  internal  hranches  of  the  six  upper  nerves  pass  inwards  to  the  interval 
between  the  Multifidus  Spinee,  and  Semispinalis  Dorsi  muscles,  which  they 
supply  ;  and  then,  piercing  the  origin  of  the  Ehomboidei  and  Trapezius,  become 
cutaneous  by  the  side  of  the  spinous  processes.  The  internal  branches  of  the 
six  lower  nerves  are  distributed  to  the  Multifidus  Spin^,  without  giving  off  any 
cutaneous  filaments. 

The  cutaneous  hranches  of  the  dorsal  nerves  are  twelve  in  number,  the  six 
upper  being  derived  from  the  internal  branches,  and  the  six  lower  from  the 
external  branches.  The  former  pierce  the  Rhomboid  and  Trapezius  muscles, 
close  to  the  spinous  processes,  and  ramify  in  the  integument.  They  are  fre- 
quently furnished  with  gangliform  enlargements.  The  six  lower  cutaneous 
branches  pierce  the  Serratus  Posticus  Inferior,  and  Latissimus  Dorsi,  in  a  line 
with  the  angles  of  the  ribs. 

Intercostal  Nerves. 

The  Intercostal  Nerves  (anterior  branches  of  the  dorsal  nerves),  are  twelve 
in  number  on  each  side.  They  are  distributed  to  the  parietes  of  the  thorax 
and  abdomen,  separately  from  each  other,  without  being  joined  in  a  plexus ;  in 
which  respect  they  differ  from  the  other  spinal  nerves.  Each  nerve  is  connected 
with  the  adjoining  ganglia  of  the  sympathetic  by  one  or  two  filaments.  The 
intercostal  nerves  may  be  divided  into  two  sets,  from  the  difference  they  present 
in  their  distribution.  The  six  upper,  with  the  exception  of  the  first,  are  limited 
in  their  distribution  to  the  parietes  of  the  chest.  The  six  lower  supply  the 
parietes  of  the  chest  and  abdomen. 

The  Upper  Intercostal  Nerves  pass  forwards  in  the  intercostal  space's  with  the 
intercostal  vessels,  being  situated  below  them.  At  the  back  of  the  chest  they 
lie  between  the  pleura  and  the  External  Intercostal  muscle,  but  are  soon  placed 
between  the  two  planes  of  Intercostal  muscles  as  far  as  the  costal  cartilages, 
where  they  lie  between  the  pleura  and  the  Internal  Intercostal  muscles.  Near 
the  sternum,  they  cross  the  internal  mammary  artery,  and  Triangularis  Sterni, 
pierce  the  Internal  Intercostal  and  Pectoralis  Major  muscles,  and  supply  the 
integument  of  the  mamma  and  front  of  the  chest,  forming  the  anterior  cuta- 
neous nerves  of  the  thorax ;  the  branch  from  the  second  nerve  becoming 
joined  with  the  clavicular  nerve. 


648  SPINAL    NERVES. 

Branches.  Numerous  slender  muscular  filaments  supply  the  Intercostal  and 
Triangularis  Sterni  muscles.  Some  of  these  branches,  at  the  front  of  the  chest, 
cross  the  costal  cartilages  from  one  to  another  intercostal  space. 

Lateral  cutaneoibs  nerves.  These  are  derived  from  the  intercostal  nerves, 
midway  between  the  vertebrae  and  sternum ;  they  pierce  the  External  Inter- 
costal and  Serratus  Magnus  muscles,  and  divide  into  two  branches,  anterior 
and  posterior. 

The  anterior  branches  are  reflected  forwards  to  the  side  and  the  fore  part  of 
the  chest,  supplying  the  integument  of  the,  chest  and  mamma,  and  the  upper 
digitations  of  the  External  Oblique. 

The  posterior  branches  are  reflected  backward  to  supply  the  integument  over 
the  scapula  and  over  the  Latissimus  Dorsi. 

The  first  intercostal  nerve  has  no  lateral  cutaneous  branch.  The  lateral 
cutaneous  branch  of  the  second  intercostal  nerve  is  of  large  size,  and  named, 
from  its  origin  and  distribution,  the  iniercosto -humeral  nerve  (E'lg.  352).  It  pierces 
the  External  Intercostal  muscle,  crosses  the  axilla  to  the  inner  side  of  the  arm, 
and  joins  with  a  filament  from  the  nerve  of  Wrisberg.  It  then  pierces  the 
fascia,  and  supplies  the  skin  of  the  upper  half  of  the  inner  and  back  part  of 
the  arm,  communicating  with  the  internal  cutaneous  branch  of  the  musculo- 
spiral  nerve.  The  size  of  this  nerve  is  in  inverse  proportion  to  the  size  of  the 
other  cutaneous  nerves,  especially  the  nerve  of  Wrisberg.  A  second  intercosto- 
humeral  nerve  is  frequently  given  off  from  the  third  intercostal.  It  supplies 
filaments  to  the  armpit  and  inner  side  of  the  arm. 

The  Lower  Intercostal  Nerves  (excepting  the  last)  have  the  same  arrangement 
as  the  upper  ones  as  far  as  the  anterior  extremities  of  the  intercostal  spaces, 
where  they  pass  behind  the  costal  cartilages,  and  between  the  Internal  Oblique 
and  Transversalis  muscles,  to  the  sheath  of  the  Eectus,  which  they  perforate. 
They  supply  the  Rectus  muscle,  and  terminate  in  branches  which  become  sub- 
cutaneous near  the  linea  alba.  These  branches,  which  are  named  the  anterior 
cutaneous  nerves  of  the  abdomen,  supply  the  integument  of  the  front  of  the 
belly ;  they  are  directed  outwards  as  far  as  the  lateral  cutaneous  nerves.  The 
lower  intercostal  nerves  supply  the  Intercostal  and  abdominal  muscles,  and, 
about  the  middle  of  their  course,  give  off  lateral  cutaneous  branches,  which 
pierce  the  External  Intercostal  and  External  Oblique  muscles,  and  are  dis- 
tributed to  the  integument  of  the  abdomen,  the  anterior  branches  passing 
nearly  as  far  forwards  as  the  margin  of  the  Rectus ;  the  posterior  branches 
passing  to  supply  the  skin  over  the  Latissimus  Dorsi,  where  they  join  the 
dorsal  cutaneous  nerves. 

Peculiar  Dorsal  Nerves. 

First  dorsal  nerve.  Its  roots  of  origin  are  similar  to  those  of  a  cervical  nerve. 
Its  posterior  or  dorsal  branch  resembles,  in  its  mode  of  distribution,  the  dorsal 
branches  of  the  cervical  nerves.  Its  anterior  branch  enters  almost  wholly  into 
the  formation  of  the  brachial  plexus,  giving  off,  before  it  leaves  the  thorax,  a 
small  intercostal  branch,  which  runs  along  the  first  intercostal  space,  and  ter- 
minates on  the  front  of  the  chest,  by  forming  the  first  anterior  cutaneous 
nerve  of  the  thorax.  The  first  intercostal  nerve  gives  off  no  lateral  cutaneous 
branch. 

The  last  dorsal  is  larger  than  the  other  dorsal  nerves.  Its  anterior  branch 
runs  along  the  lower  border  of  the  last  rib  in  front  of  the  Quadratus  Lumbo- 
rum,  perforates  the  aponeurosis  of  the  Transversalis,  and  passes  forwards  be- 
tween it  and  the  Internal  Oblique,  to  be  distributed  in  the  same  manner  as  the 
preceding  nerves.  It  communicates  with  the  ilio-hypogastric  branch  of  the 
lumbar  plexus,  and  is  occasionally  connected  with  the  first  lumbar  nerve  by  a 
slender  branch,  the  dorsi-lurabar  nerve,  which  descends  in  the  substance  of  the 
Quadratus  Lumborum. 


LTMBAR    PLEXUS.  649 

The  lateral  cvtaneous  branch  of  the  last  dorsal  is  remarkable  for  its  large  size; 
it  perforates  the  Internal  and  External  Oblique  muscles,  passes  downwards 
over  the  crest  of  the  ilium,  and  is  distributed  to  the  integument  of  the  front 
of  the  hip,  some  of  its  filaments  extending  as  low  down  as  the  trochanter  major. 

Lumbar  Nerves. 

The  Lumbar  Nerves  are  five  in  number  on  each  side ;  the  first  appears  between 
the  first  and  second  lumbar  vertebras,  and  the  last  between  the  last  lumbar  and 
the  base  of  the  sacrum. 

The  roots  of  the  lumbar  nerves  are  the  largest,  and  their  filaments  the  most 
numerous,  of  all  the  spinal  nerves,  and  they  are  closely  aggregated  together 
upon  the  lower  end  of  the  cord.  The  anterior  roots  are  the  smaller ;  but  there 
is  not  the  same  disproportion  between  them  and  the  posterior  roots  as  in  the 
cervical  nerves.  The  roots  of  these  nerves  have  a  vertical  direction,  and  are 
of  considerable  length,  more  especially  the  lower  ones,  since  the  spinal  cord 
does  not  extend  beyond  the  first  lumbar  vertebra.  The  roots  become  joined 
in  the  intervertebral  foramina ;  and  the  nerves,  so  formed,  divide  at  their  exit 
into  two  branches,  anterior  and  posterior. 

The  j30sterior  branches  of  the  lumbar  nerves  diminish  in  size  from  above 
downwards ;  they  pass  backwards  between  the  transverse  processes,  and  divide 
into  external  and  internal  branches. 

The  external  branches  supply  the  Erector  Spinas  and  Intertransverse  mus- 
cles. From  the  three  upper  branches,  cutaneous  nerves  are  derived,  which 
pierce  the  Sacro-lumbalis  and  Latissimus  Dorsi  muscles,  and  descend  over  the 
back  part  of  the  crest  of  the  ilium,  to  be  distributed  to  the  integument  of  the 
gluteal  region,  some  of  the  filaments  passing  as  far  as  the  trochanter  major. 

The  internal  branches,  the  smaller,  pass  inwards  close  to  the  articular  pro- 
cesses of  the  vertebrae,  and  supply  the  Multifidus  Spinse  and  Interspinales 
muscles. 

The  anterior  branches  of  the  lumbar  nerves  increase  in  size  from  above  down- 
wards. At  their  origin,  they  communicate  with  the  lumbar  ganglia  of  the 
sympathetic  by  long  slender  filaments,  which  accompany  the  lumbar  arteries 
round  the  sides  of  the  bodies  of  the  vertebrae,  beneath  the  Psoas  muscle.  The 
nerves  pass  obliquely  outwards  behind  the  Psoas  Magnus,  or  between  its  fasci- 
culi, distributing  filaments  to  it  and  the  Quadratus  Lumborum.  The  anterior 
branches  of  the  four  upper  nerves  are  connected  together  in  this  situation  by 
anastomotic  loops,  and  form  the  lumbar  plexus.  The  anterior  branch  of  the 
fifth  lumbar,  joined  with  a  branch  from  the  fourth,  descends  across  the  base  of 
the  sacrum  to  join  the  anterior  branch  of  the  first  sacral  nerve,  and  assist  in 
the  formation  of  the  sacral  plexus.  The  cord  resulting  from  the  union  of  these 
two  nerves,  is  called  the  lumbo-sacral  nerve. 

Lumbar  Plexus. 

The  Lumbar  Plexus  is  formed  by  the  loops  of  communication  between  the 
anterior  branches  of  the  four  upper  lumbar  nerves.  The  plexus  is  narrow 
above,  and  occasionally  connected  with  the  last  dorsal  by  a  slender  branch,  the 
dorsi-lumbar  nerve ;  it  is  broad  below,  where  it  is  joined  to  the  sacral  plexus 
by  the  lumbo-sacral  cord.  It  is  situated  in  the  substance  of  the  Psoas  muscle 
near  its  posterior  part,  in  front  of  the  transverse  processes  of  the  lumbar, 
vertebrae. 

The  mode  in  which  the  plexus  is  formed  is  the  following:  The  first  lumbar 
nerve  gives  off  the  ilio-hypogastric  and  ilio-inguinal  nerves,  and  a  communi- 
cating branch  to  the  second  lumbar  nerve.  The  second  gives  off  the  external 
cutaneous  and  genito-crural,  and  a  communicating  branch  to  the  third  nerve. 
The  third  nerve  gives  a  descending  filament  to  the  fourth,  and  divides  into  two 
branches,  which  assist  in  forming  the  anterior  crural  and  obturator  nerves; 


650 


SPINAL    NERVES. 


sometimes,  also,  it  furnishes  a -part  of  the  accessory  obturator.  The  fourth 
nerve  completes  the  formation  of  the  anterior  crural,  and  the  obturator,  and 
gives  off  a  communicating  branch  to  the  fifth  lumbar ;  sometimes  it  also  fur- 
nishes part  of  the  accessory  obturator. 

The  branches  of  the  lumbar  plexus  are  the 


Ilio-hypogastric. 
Ilio-inguinal. 
Genito-crural. 
External  cutaneous. 


Obturator. 

Accessory  obturator. 
Anterior  crural. 


These  branches  may  be  divided  into  two  groups,  according  to  their  mode  of 
distribution.  One  group,  including  the  ilio-hypogastric,  ilio-inguinal,  and  part 
of  the  genito-crural  nerves,  supplies  the  lower  part  of  the  parietes  of  the  abdo- 

■  Fig.  354. — The  Lumbar  Plexus  and  its  Branches. 


men ;  the  other  group,  which  includes  the  remaining  nerves,  supplies  the  fore 
part  of  the  thigh  and  inner  side  of  the  leg. 

The  Ilio-hypogastric  Nerve  {superior  muscuh-cutaneotis)  arises  from  the  first 
lumbar  nerve.  It  pierces  the  outer  border  of  the  Psoas  muscle  at  its  upper 
part,  and  crosses  obliquely  in  front  of  the  Quadratus  Lumborum  to  the  crest 
of  the  ilium.  It  then  perforates  the  Transversalis  muscle  at  its  back  part,  and 
divides  between  it  and  the  Internal  Oblique  into  two  branches,  iliac  and  hypo- 
gastric. 

The  iliac  branch  pierces  the  Internal  and  External  Oblique  muscles  imme- 
diately above  the  crest  of  the  ilium,  and  is  distributed  to  the  integument  of  the 


« 


NERVES    OF    LOWER    EXTREMITY.  «»!• 

gluteal  region,  behind  the  lateral  cutaneous  branch  of  the  last  dorsal  nerve 
(Fig.  357).  The  size  of  this  nerve  bears  an  inverse  proportion  to  that  of  the 
cutaneous  branch  of  the  last  dorsal  nerve. 

The  hypogastric  branch  (Fig.  355)  continues  onwards  between  the  Internal 
Oblique  and  Transversalis  muscles.  It  first  pierces  the  Internal  Oblique,  and 
near  the  middle  line  perforates  the  External  Oblique  above  the  external  abdomi- 
nal ring,  and  is  distributed  to  the  integument  covering  the  hypogastric  region. 

The  llio-inguinal  Nerve  {inferior  muscuh-cidaneous)^  smaller  than  the  preced- 
ing, arises  with  it  from  the  first  lumbar  nerve.  It  pierces  the  outer  border  of 
the  Psoas  just  below  the  ilio-hypogastric,  and,  passing  obliquely  across  the 
Quadratus  Lumborum  and  Iliacus  muscles,  perforates  the  Transversalis,  near 
the  fore  part  of  the  crest  of  the  ilium,  and  communicates  with  the  Ilio-hypogas- 
tric nerve  between  that  muscle  and  the  Internal  Oblique.  The  nerve  then 
pierces  the  Internal  Oblique,  distributing  filaments  to  it,  and,  accompanying  the 
spermatic  cord,  escapes  at  the  external  abdominal  ring,  and  is  distributed  to  the 
integument  of  the  scrotum  and  upper  and  inner  part  of  the  thigh  in  the  male, 
and  to  the  labium  in  the  female.  The  size  of  this  nerve  is  in  inverse  propor- 
tion to  that  of  the  ilio-hypogastric.  Occasionally  it  is  very  small,  and  ends  by 
joining  the  ilio-hypogastric  ;  in  such  cases,  a  branch  from  the  ilio-hypogastric 
takes  the  place  of  the  ilio-inguinal,  or  the  latter  nerve  may  be  altogether  absent. 

The  Ge7iito-crural  Nerve  arises  from  the  second  lumbar,  and  by  a  few  fibres 
from  the  cord  of  communication  between  it  and  the  first.  It  passes  obliquely 
through  the  substance  of  the  Psoas,  descends  on  its  surface  to  near  Poupart's 
ligament,  and  divides  into  a  genital  and  a  crural  branch. 

The  genital  branch  descends  on  the  external  iliac  artery,  sending  a  few  fila- 
ments round  that  vessel ;  it  then  pierces  the  fascia  transversalis,  and,  passing 
through  the  internal  abdominal  ring,  descends  along  the  back  part  of  the  sper- 
matic cord  to  the  scrotum,  and  supplies,  in  the  male,  the  Cremaster  muscle.  .In 
the  female,  it  accompanies  the  round  ligament,  .and  is  lost  upon  it. 

The  crural  branch  passes  along  the  inner  margin  of  the  Psoas  muscle,  beneath 
Poupart's  ligament,  into  the  thigh,  where  it  pierces  the  fascia  lata,  and  is  dis- 
tributed to  the  integument  of  the  upper  and  anterior  aspect  of  the  thigh,  com- 
municating with  the  middle  cutaneous  nerve. 

A  few  filaments  from  this  nerve  may  be  traced  on  to  the  femoral  artery  ; 
they  are  derived  from  the  nerve  as  it  passes  beneath  Poupart's  ligament. 

The  External  Cutaneous  Nerve  arises  from  the  second  lumbar,  or  from  the 
loop  between  it  and  the  third.  It  perforates  the  outer  border  of  the  Psoas 
muscle  about  its  middle,  and  crosses  the  Iliacus  muscle  obliquely,  to  the  notch 
immediately  beneath  the  anterior  superior  spine  of  the  ilium,  where  it  passes 
beneath  Poupart's  ligament  into  the  thigh,  and  divides  into  two  branches  of 
nearly  equal  size. 

The  anterior  branch  descends  in  an  aponeurotic  canal  formed  in  the  fascia 
lata,  becomes  superficial  about  four  inches  below  Poupart's  ligament,  and  divides 
into  branches,  which  are  distributed  to  the  integument  along  the  anterior  and 
outer  part  of  the  thigh,  as  far  down  as  the  knee.  This  nerve  occasionally  com- 
municates with  the  long  saphenous  nerve. 

H\iQ  posterior  branch  pierces  the  fascia  lata,  and  subdivides  into  branches  which 
pass  across  the  outer  and  posterior  surface  of  the  thigh,  supplying  the  integu- 
ment as  far  as  the  middle  of  the  thigh. 

The  Obturator  Nerve  supplies  the  Obturator  Externus  and  Adductor  muscles 
of  the  thigh,  the  articulations  of  the  hip  and  knee,  and  occasionally  the  integu- 
ment of  the  thigh  and  leg.  It  arises  by  two  branches :  one  from  the  third,  the 
other  from  the  fourth  lumbar  nerve.  It  descends  through  the  inner  fibres  of 
the  Psoas  muscle,  and  emerges  from  its  inner  border  near  the  brim  of  the 
pelvis ;  it  then  runs  along  the  lateral  wall  of  the  pelvis,  above  the  obturator 
vessels,  to  the  upper  part  of  the  obturator  foramen,  where  it  enters  the  thigh, 


652 


SPINAL    NERVES. 


Fig.  355.— Cutaneous  Nerves  of  Lower  Fig.  356. — Nerves  of  the  Lower  Extremity. 

Extremity.    Front  View.  Front  View. 


A 


A 


vi- 


Tii.ffafXtnta*. 


.  Alt.  Tih(A 


Anterior 
Crural 


An  ter/orD/vhi'en 
of  OittcTator 


NERVES    OF    LOWER    EXTREMITIES.  653 

and  divides  into  an  anterior  and  a  posterior  branch,  separated  by  tbe  Adductor 
Brevis  muscle. 

The  anterior  branch  (Fig.  356)  passes  down  in  front  of  the  Adductor  Brevis, 
being  covered  bj  the  Pectineus  and  Adductor  Longus;  and  at  the  lower  border 
of  the  latter  muscle,  communicates  with  the  internal  cutaneous  and  internal 
saphenous  nerves,  forming  a  kind  of  plexus.  It  then  descends  upon  the  femo- 
ral artery,  upon  which  it  is  finally  distributed. 

This  nerve,  near  the  obturator  foramen,  gives  off  an  articular  branch  to  the 
hip-joint.  Behind  the  Pectineus,  it  distributes  muscular  branches  to  the  Ad- 
ductor Longus  and  Gracilis,  and  occasionally  to  the  Adductor  Brevis  and  Pec- 
tineus, and  receives  a  communicating  branch  from  the  accessory  obturator 
nerve. 

Occasionally  this  communicating  branch  is  continued  down,  as  a  cutaneous 
branch,  to  the  thigh  and  leg.  This  occasional  cutaneous  branch  emerges  from 
the  1-ower  border  of  the  Adductor  Longus,  descends  along  the  posterior  margin, 
of  the  Sartor ius  to  the  inner  side  of  the  knee,  where  it  pierces  the  deep  fascia, 
communicates  with  the  long  saphenous  nerve,  and  is  distributed  to  the  integu- 
ment of  the  inner  side  of  the  leg,  as  low  down  as  its  middle.  When  this 
branch  is  small,  its  place  is  supplied  by  the  internal  cutaneous  nerve. 

The  posterior  branch  of  the  obturator  nerve  pierces  the  Obturator  Bxternus, 
and  passes  behind  the  Adductor  Brevis  to  the  front  of  the  Adductor  Magnus, 
where  it  divides  into  numerous  muscular  branches,  which  Supply  the  Obturator 
Externus,  the  Adductor  Magnus,  and,  occasionally,  the  Adductor  Brevis. 

The  articular  branch  for  the  knee-joint  perforates  the  lower  part  of  the  Adductor 
Magnus,  and  enters  the  popliteal  space ;  it  then  descends  upon  the  popliteal  ar- 
tery, as  far  as  the  back  part  of  the  knee-joint,  where  it  perforates  the  posterior 
ligament,  and  is  distributed  to  the  synovial  membrane.  It  gives  filaments  to 
the  artery  in  its  course. 

The  Accessory  Obturator  Nerve  (Fig.  354)  is  of  small  size,  and  arises  either 
from  the  obturator  nerve  near  its  origin,  or  by  separate  filaments  from  the 
third  and  fourth  lumbar  nerves.  It  descends  along  the  inner  border  of  the 
Psoas  muscle,  crosses  the  body  of  the  pubes,  and  passes  beneath  the  Pectineus 
muscle,  where  it  divides  into  numerous  branches.  One  of  these  supplies  the 
Pectineus,  penetrating  its  under  surface ;  another  is  distributed  to  the  hip-joint ; 
while  a  third  communicates  with  the  anterior  branch  of  the  obturator  nerve. 
This  branch,  when  of  large  size,  is  prolonged  (as  already  mentioned),  as  a 
cutaneous  branch,  to  the  leg.  The  accessory  obturator  nerve  is  not  constantly 
found :  when  absent,  the  hip-joint  receives  branches  from  the  obturator  nerve. 
Occasionally  it  is  very  small,  and  becomes  lost  in  the  capsule  of  the  hip-joint. 

The  Anterior  Crural  Nerve  (Figs.  354,  356)  is  the  largest  branch  of  the  lumbar 
plexus.  It  supplies  muscular  branches  to  the  Iliacus,  Pectineus,  and  all  the 
muscles  on  the  front  of  the  thigh,  excepting  the  Tensor  Vaginae  Femoris  ;  cuta- 
neous filaments  to  the  front  and  inner  side  of  the  thigh,  and  to  the  leg  and  foot ; 
and  articular  branches  to  the  knee.  It  arises  from  the  third  and  fourth  lumbar 
nerves,  receiving  also  a  fasciculus  from  the  second.  It  descends  through  the 
fibres  of  the  Psoas  muscle,  emerging  from  it  at  the  lower  part  of  its  outer  bor- 
der ;  and  passes  down  between  it  and  the  Iliacus,  and  beneath  Poupart's  liga- 
ment, into  the  thigh,  where  it  becomes  somewhat  flattened,  and  divides  into  an 
anterior  or  cutaneous,  and  a  posterior  or  muscular  part.  Beneath  Poupart's 
ligament,  it  is  separated  from  the  femoral  artery  by  the  Psoas  muscle,  and  lies 
beneath  the  iliac  fascia. 

Within  the  pelvis^  the  anterior  crural  nerve  gives  off  from  its  outer  side  some 
small  branches  to  the  Iliacus,  and  a  branch  to  the  femoral  artery,  which  is  dis- 
tributed upon  the  upper  part  of  that  vessel.  The  origin  of  this  branch  varies; 
it  occasionally  arises  higher  than  usual,  or  it  may  arise  lower  down  in  the 
thigh. 


654  SPINAL    NERVES. 

External  to  the  pelvis,  the  following  branches  are  given  off: — • 

From  the  Anterior  Division.  From  the  Posterior  Division. 

Middle  cutaneous.  Muscular. 

Internal  cutaneous.  Articular. 

Long  saphenous. 

The  middle  cutaneous  nerve  (Fig.  855)  pierces  the  fascia  lata  (occasionally  the 
Sartorius  also),  about  three  inches  below  Poupart's  ligament,  and  divides  into 
two  branches,  which  descend  in  immediate  proximity  along  the  fore  part  of 
the  thigh,  distributing  numerous  branches  to  the  integument  as  low  as  the  front 
of  the  knee,  where  the  middle  cutaneous  communicates  with  a  branch  of  the 
internal  saphenous  nerve.  Its  outer  branch  communicates,  above,  with  the 
crural  branch  of  the  genito-crural  nerve;  and  the  inner  branch  with  the  inter- 
nal cutaneous  nerve  below.  The  Sartorius  muscle  is  supplied  by  this  or  the 
following  nerve. 

The  internal  cutaneous  nerve  passes  obliquely  across  the  upper  part  of  the 
sheath  of  the  femoral  artery,  and  divides  in  front,  or  at  the  inner  side,  of  that 
vessel,  into  two  branches,  anterior  and  internal. 

The  anterior  branch  perforates  the  fascia  lata  at  the  lower  third  of  the  thigh, 
and  divides  into  two  branches,  one  of  which  supplies  the  integument  as  low 
down  as  the  inner  side  of  the  knee;  the  other  crosses  the  patella  to  the  outer 
side  of  the  joint,  communicating  in  its  course  with  the  long  saphenous  nerve. 
A  cutaneous  filament  is  occasionally  given  off  from  this  nerve,  which  accom- 
panies the  long  saphenous  vein ;  and  it  sometimes  communicates  with  the  inter- 
nal branch  of  the  nerve. 

The  inner  branch  descends  along  the  posterior  border  of  the  Sartorius  muscle 
to  the  knee,  where  it  pierces  the  fascia  lata,  communicates  with  the  long  saphe- 
nous nerve,  and  gives  off  several  cutaneous  branches.  The  nerve  then  passes 
down  the  inner  side  of  the  leg,  to  the  integument  of  which  it  is  distributed. 
This  nerve,  beneath  the  fascia  lata,  joins  in  a  plexiform  network,  by  uniting 
with  branches  of  the  long  saphenous  and  obturator  nerves  (Fig.  356).  When 
the  communicating  branch  from  the  latter  nerve  is  large,  and  continued  to  the 
integument  of  the  leg,  the  inner  branch  of  the  internal  cutaneous  is  small,  and 
terminates  at  the  plexus,  occasionally  giving  off"  a  few  cutaneous  filaments. 

This  nerve,  before  subdividing,  gives  off  a  few  filaments,  which  pierce  th 
fascia  lata,  to  supply  the  integument  of  the  inner  side  of  the  thigh,  accompany- 
ing the  long  saphenous  vein.  One  of  these  filaments  passes  through  the  saphe- 
nous opening;  a  second  becomes  subcutaneous  about  the  middle  of  the  thigh; 
and  a  third  pierces  the  fascia  at  its  lower  third. 

The  long,  or  internal  saphenous  nerve,  is  the  largest  of  the  cutaneous  branch 
of  the  anterior  crural.  It  approaches  the  femoral  artery  where  this  vess' 
passes  beneath  the  Sartorius,  and  lies  on  its  outer  side,  beneath  the  aponeuroti 
covering,  as  far  as  the  opening  in  the  lower  part  of  the  Adductor  Magnus.  It 
then  quits  the  artery,  and  descends  vertically  along  the  inner  side  of  the  knee 
beneath  the  Sartorius,  pierces  the  deep  fascia  between  the  tendons  of  the  Sar 
tori  us  and  Gracilis,  and  becomes  subcutaneous.  The  nerve  then  passes  along 
the  inner  side  of  the  leg,  accompanied  by  the  internal  saphenous  vein,  descend 
behind  the  internal  border  of  the  tibia,  and,  at  the  lower  third  of  the  leg,  divid 
into  two  branches:  one  continues  its  course  along  the  margin  of  the  tibia,  ter- 
minating at  the  inner  ankle;  the  other  passes  in  front  of  the  ankle,. and  is  distri 
buted  to  the  integument  along  the  inner  side  of  the  foot,  as  far  as  the  great  to 

Branches.     The  long  saphenous  nerve,  about  the  middle  of  the  thigh,  gives  o 
a  communicating  branch,  which  joins  the  plexus  formed  by  the  obturator  an' 
internal  cutaneous  nerves. 

At  the  inner  side  of  the  knee,  it  gives  off  a  large  branch  {n.  cutaneus  patellse), 
which  pierces  the  Sartorius  and  fascia  lata,  and  is  distributed  to  the  integument 
in  front  of  the  patella.     This  nerve  communicates  above  the  knee  with  the  ante- 


11 


% 


SACRAL    AND    COCCYGEAL  655 

rior  brancli  of  the  internal  cutaneous;  helow  the  knee,  with  other  branches  of  the 
long  saphenous;  and,  on  the  outer  side  of  the  joint,  with  brandies  of  the  middle 
and  external  cutaneous  nerves,  forming  a  plexiform  network,  the  plexus  2>atellse. 
The  cutaneous  nerve  of  the  patella  is  occasionally  small,  and  terminates  by 
joining  the  internal  cutaneous,  which  supplies  its  place  in  front  of  the  knee. 

Below  the  knee^  the  branches  of  the  long  saphenous  nerve  are  distributed  to 
the  integument  of  the  front  and  inner  side  of  the  leg,  communicating  with  the 
cutaneous  branches  from  the  internal  cutaneous,  or  obturator  nerve. 

The  Deep  Group  of  branches  of  the  anterior  crural  nerve  are  muscular  and 
articular. 

The  muscular  branches  supply  the  Pectineus,  and  all  the  muscles  on  the  front 
of  the  thigh,  except  the  Tensor  Yaginge  Femoris,  which  is  supplied  from  the 
superior  gluteal  nerve,  and  the  Sartorius,  which  is  supplied  by  filaments  from 
the  middle  or  internal  cutaneous  nerves. 

The  branches  to  the  Pectineus,  usually  two  in  number,  pass  inwards  behind 
the  femoral  vessels,  and  enter  the  muscle  on  its  anterior  surface. 

The  branch  to  the  Rectus  muscle  enters  its  under  surface  high  up. 

The  branch  to  the  Vastus  Externus,  of  large  size,  follows  the  course  of  the 
descending  branch  of  the  external  circumflex  artery,  to  the  lower  part  of  the 
muscle.     It  gives  off  an  articular  filament. 

The  branches  to  the  Vastus  Internus  and  Grureus  enter  the  middle  of  those 
muscles. 

The  articular  branches,  two  in  number,  supply  the  knee-joint.  One,  a  long 
slender  filament,  is  derived  from  the  nerve  to  the  Vastus  Externus.  It  pene- 
trates the  capsular  ligament  of  the  joint  on  its  anterior  aspect.  The  other  is 
derived  from  the  nerve  to  the  Vastus  Internus.  It  descends  along  the  internal 
intermuscular  septum,  accompanying  the  deep  branch  of  the  anastomotica 
magna  artery,  pierces  the  capsular  ligament  of  the  joint  on  its  inner  side,  and 
supplies  the  synovial  membrane. 

The  Sacral  and  Coccygeal  Neeves. 

The  sacral  nerves  are  five  in  number  on  each  side.  The  four  upper  ones  pass 
from  the  sacral  canal,  through  the  sacral  foramina;  the  fifth  through  the  fora- 
men between  the  sacrum  and  coccyx. 

The  roots  of  origin  of  the  upper  sacral  (and  lumbar)  nerves  are  the  largest  of 
all  the  spinal  nerves;  whilst  those  of  the  lowest  sacral  and  coccygeal  nerve  are 
the  smallest. 

The  roots  of  these  nerves  are  of  very  considerable  length,  being  longer  than 
those  of  any  of  the  other  spinal  nerves,  on  account  of  the  spinal  cord  not 
extending  beyond  the  first  lumbar  vertebra.  From  their  great  length,  and  the 
appearance  they  present  in  connection  with  the  spinal  cord,  the  roots  of  origin 
of  these  nerves  are  called  collectively  the  cauda  equina.  Each  sacral  and 
coccygeal  nerve  divides  into  two  branches,  anterior  and  posterior. 

The  2^osterior  sacral  nerves  are  small,  diminish  in  size  from  above  down- 
wards, and  emerge,  except  the  last,  from  the  sacral  canal  by  the  posterior  sacral 
formina. 

The  three  upper  ones  are  covered,  at  their  exit  from  the  sacral  canal,  by  the 
Multifidus  spinae,  and  divide  into  external  and  internal  branches. 

The  internal  branches  are  small,  and  supply  the  Multifidus  Spinae. 

The  external  branches  communicate  with  one  another,  and  with  the  last 
lumbar  and  fourth  sacral  nerves,  by  means  of  anastomosing  loops.  These 
branches  pass  outwards,  to  the  outer  surface  of  the  great  sacro-sciatic  ligament, 
where  they  form  a  second  series  of  loops  beneath  the  Gluteus  Maximus.  Cuta- 
neous branches  from  this  second  series  of  loops,  usually  three  in  number,  pierce 
the  Gluteus  Maximus,  one  near  the  posterior  inferior  spine  of  the  ilium;  another 
opposite  the  end  of  the  sacrum;  and  the  third,  midway  between  the  other  twoi 
They  supply  the  integument  over  the  posterior  part  of  the  gluteal  region. 


656  SPINAL    NERVES. 

The  two  lower  posterior  sacral  nerves  are  situated  below  the  Multifidus  Spinse. 
They  are  of  small  size,  and  join  with  each  other,  and  with  the  coccygeal  nerve, 
so  as  to  form  loops  on  the  back  of  the  sacrum,  filaments  from  which  supply 
the  integument  over  the  coccyx. 

The  coccygeal  nerve  divides  into  its  anterior  and  posterior  branch  in  the  spinal 
canal.  The  posterior  branch  is  the  smaller.  It  receives,  as  already  mentioned, 
a  communicating  branch  from  the  last  sacral,  and  is  lost  in  the  fibrous  struc- 
ture on  the  back  of  the  coccyx. 

The  anterior  sacral  nerves  diminish  in  size  from  above  downwards.  The  four 
upper  ones  emerge  from  the  anterior  sacral  foramina;  the  anterior  branch  of 
the  fifth,  together  with  the  coccygeal  nerve,  between  the  sacrum  and  the  coccyx. 
All  the  anterior  sacral  nerves  communicate  with  the  sacral  ganglia  of  the  sym- 
pathetic, at  their  exit  from  the  sacral  foramina.  1l\\q  first  nerve,  of  large  size, 
unites  with  the  lumbo-sacral  nerve.  The  second  equals  in  size  the  preceding, 
with  which  it  joins.  The  third^  about  one-fourth  the  size  of  the  second,  unites 
with  the  preceding  nerves,  to  form  the  sacral  plexus, 

^\iQ  fourth  anterior  sacral  nerve  sends  a  branch  to  join  the  sacral  plexus.  The 
remaining  portion  of  the  nerve  divides  into  visceral  and  muscular  branches ; 
and  a  communicating  filament  descends  to  join  the  fifth  sacral  nerve.  The  vis- 
ceral branches  are  distributed  to  the  viscera  of  the  pelvis,  communicating  witli 
the  sympathetic  nerve.  These  branches  ascend  upon  the  rectum  and  bladder  ; 
in  the  female,  upon  the  vagina  and  bladder,  communicating  with  branches  of 
the  sympathetic  to  form  the  hypogastric  plexus.  The  muscular  branches  are 
distributed  to  the  Levator  Ani,  Coccygeus,  and  Sphincter  Ani.  Cutaneous  fila- 
ments arise  from  the  latter  branch,  which  supply  the  integument  between  the 
anus  and  coccyx. 

^he  fifth  anterior  sacral  nerve,  after  passing  from  the  lower  end  of  the  sacral 
canal,  pierces  the  Coccygeus  muscle,  and  descends  upon  its  anterior  surface  to 
the  tip  of  the  coccyx,  where  it  perforates  that  muscle,  to  be  distributed  to  the 
integument  over  the  back  part  and  side  of  the  coccyx.  This  nerve  commu- 
nicates above  with  the  fourth  sacral,  and  below  with  the  coccygeal  nerve,  and 
supplies  the  Coccygeus  muscle. 

The  anterior  branch  of  the  coccygeal  nerve  is  a  delicate  filament  which  escapes 
at  the  termination  of  the  sacral  canal.  It  pierces  the  sacro-sciatic  ligament  and 
Coccygeus  muscle,  is  joined  by  a  branch  from  the  fifth  anterior  sacral,  and  be 
comes  lost  in  the  integument  at  the  back  part  and  side  of  the  coccyx. 


I 


II 


Sacral  Plexus. 

The  Sacral  Plexus  is  formed  by  the  lumbo-sacral,  the  anterior  branches  of 
the  three  upper  sacral  nerves,  and  part  of  that  of  the  fourth.  These  nerves 
proceed  in  different  directions;  the  upper  ones  obliquely  outwards,  the  lower || 
one  nearly  horizontally,  and  they  all  unite  into  a  single,  broad,  flat  cord.  The 
sacral  plexus  is  triangular  in  form,  its  base  corresponding  with  the  exit  of  the 
nerves  from  the  sacrum,  its  apex  with  the  lower  part  of  the  great  sacro-sciatic 
foramen.  It  rests  upon  the  anterior  surface  of  the  Pyriformis,  and  is  covered 
in  front  by  the  pelvic  fascia,  which  separates  it  from  the  sciatic  and  pudic 
branches  of  the  internal  iliac  artery,  and  from  the  viscera  of  the  pelvis. 

The  branches  of  the  sacral  plexus  are  :-;- 

Muscular.  Pudic. 

Superior  gluteal.  Small  sciatic. 

Great  sciatic. 

The  muscular  branches  supply  the  Pyriformis,  Obturator  Internus,  the  two 
Gemelli,  and  the  Quadratus  Femoris.  The  branch  to  the  Pyriformis  arises 
either  from  the  plexus,  or  from  the  upper  sacral  nerves  ;  the  branch  to  the  Ob- 
turator Internus  arises  at  the  junction  of  the  lumbo-sacral  and  first  sacral  nerves; 
it  crosses  behind  the  spine  of  the  ischium,  and  passes  through  the  lesser  sacro- 


SACRAL    PLEXUS.  657 

sciatic  foramen  to  the  inner  surface  of  the  Obturator  Internus ;  the  branch  to 
the  Gemellus  Superior  arises  from  the  lower  part  of  the  plexus,  near  the  pudic 
nerve ;  the  small  branch  to  the  Gemellus  Inferior  and  Quadratus  Femoris  also 
arises  from  the  lower  part  of  the  plexus;  it  passes  beneath  the  Gemelli  and 
tendon  of  the  Obturator  Internus,  and  supplies  an  articular  branch  to  the  hip- 
joint.  This  branch  is  occasionally  derived  from  the  upper  part  of  the  great 
sciatic  nerve. 

The  Superior  Gluteal  Nerve  (Fig.  858)  arises  from  the  back  part  of  the  lumbo- 
sacral ;  it  passes  from  the  pelvis  through  the  great  sacro-sciatic  foramen  above 
the  Pyriformis  muscle,  accompanied  by  the  gluteal  vessels,  and  divides  into  a 
superior  and  an  inferior  branch. 

The  superior  branch  follows  the  line  of -origin  of  the  Gluteus  Minimus,  and 
supplies  it  and  the  Gluteus  Medius. 

The  inferior  hrayich  crosses  obliquely  between  the  Gluteus  Minimus  and  Glu- 
teus Medius,  distributing  filaments  to  both  these  muscles,  and  terminates  in  the 
Tensor  Vaginae  Femoris,  extending  nearly  to  its  lower  end. 

The  Pudic  Nerve  arises  from  the  lower  part  of  the  sacral  plexus,  and  leaves 
the  pelvis,  through  the  great  sacro-sciatic  foramen,  below  the  Pyriformis.  It 
then  crosses  the  spine  of  the  ischium,  and  re-enters  the  pelvis  through  the 
lesser  sacro-sciatic  foramen. "  It  accompanies  the  pudic  vessels  upwards  and  for- 
wards, along  the  outer  wall  of  the  ischio-rectal  fossa,  being  covered  by  the 
obturator  fascia,  and  divides  into  two  terminal  branches,  the  perineal  nerve, 
and  the  dorsal  nerve  of  the  penis.  Near  its  origin,  it  gives  off  the  inferior 
htemorrhoidal  nerve. 

The  inferior  hsemorrhoidal  nerve  is  occasionally  derived  from  the  sacral  plexus. 
It  passes  across  the  ischio-rectal  fossa,  with  its  accompanying  vessels,  towards 
the  lower  end  of  the  rectum,  and  is  distributed  to  the  External  Sphincter  and 
the  integument  round  the  anus.  Branches  of  this  nerve  communicate  with  the 
inferior  pudendal  and  superficial  perineal  nerves  on  the  inner  margin  of  the  thigh. 

li:h.Q  perineal  nerve,  the  inferior  and  larger  of  the  two  terminal  branches  of 
the  pudic,  is  situated  below  the  pudic  artery.  It  accompanies  the  superficial 
perineal  artery  in  the  periaeum,  dividing  into  cutaneous  and  muscular  branches. 

The  cutaneous  branches  (superficial  perineal)  are  two  in  number,  posterior 
and  anterior.  The  posterior  branch  passes  to  the  back  part  of  the  ischio-rectal 
fossa,  distributing  filaments  to  the  Sphincter  Ani  and  integument  in  front  of 
the  anus,  which  communicate  with  the  inferior  hsemorrhoidal  nerve;  it  then 
passes  forwards,  with  the  anterior  branch,  to  the  back  of  the  scrotum,  communi- 
cating with  the  anterior  branch  and  with  the  inferior  pudendal.  The  anterior 
branch  passes  to  the  fore  part  of  the  ischio-rectal  fossa,  in  front  of  the  preceding, 
and  accompanies  it  to  the  scrotum  and  under  part  of  the  penis.  This  branch 
gives  one  or  two  filaments  to  the  Levator  Ani. 

The  muscular  branches  are  distributed  to  the  Transversus  Perinei,  Accele- 
rator Urinas,  Erector  Penis,  and  Compressor  Urethrae.  The  nerve  of  the  bulb 
supplies  the  corpus  spongiosum ;  some  of  its  filaments  run  for  some  distance 
on  the  surface,  before  penetrating  to  the  interior. 

The  dorsal  nerve  of  the  penis  is  the  superior  division  of  the  pudic  nerve ;  it 
accompanies  the  pudic  artery  along  the  ramus  of  the  ischium,  and  between  the 
two  layers  of  the  deep  perineal  fascia ;  it  then  pierces  the  suspensory  ligament 
of  the  penis,  and  accompanies  the  arteria  dorsalis  penis  to  the  glans,  to  which 
it  is  distributed.  On  the  penis,  this  nerve  gives  oft'  a  cutaneous  branch,  which 
runs  along  the  side  of  the  organ  ;  it  is  joined  with  branches  of  the  sympathetic, 
and  supplies  the  integument  of  the  upper  surface  and  sides  of  the  penis  and 
prepuce,  giving  a  large  branch  to  the  corpus  cavernosum. 

In  the  female,  the  pudic  nerve  is  distributed  to  the  parts  analogous  to  those 
in  the  male ;  its  superior  division  terminating  in  the  clitoris,  its  inferior  in  the 
external  labia  and  perineum. 

The  Small  Sciatic  Nerve  (Fig.  358)  supplies  the  integument  of  the  perineum 
42 


668 


SPINAL    NERVES. 


Fig.  357. — Cutaneous  Nerve  of  Lower 
Extremity.     Posterior  View. 


Fig.  358. — Nerves  of  the  Lower  Extremity. 
Posterior  View. 


ii 


\ 


X.ti  earuRAroR  int. 


Xmall  Seiatie 


Cemmnnii-nns 


GREAT    SCIATIC.  659 

and  back  part  of  the  thigh  and  leg,  and  one  muscle,  the  Gluteus  Maximus.  It 
is  usually  formed  by  the  union  of  two  branches,  which  arise  from  the  lower 
part  of  the  sacral  plexus.  It  issues  from  the  pelvis  below  the  Pyriformis  mus- 
cle, descends  beneath  the  Gluteus  Maximus  with  the  sciatic  artery,  and  at  the 
lower  border  of  that  muscle  passes  along  the  back  part  of  the  thigh,  beneath 
the  fascia  lata,  to  the  lower  part  of  the  popliteal  region,  where  it  pierces  the 
fascia  and  becomes  cutaneous.  It  then  accompanies  the  external  saphenous 
vein  below  the  middle  of  the  leg,  its  terminal  filaments  communicating  with 
the  external  saphenous  nerve. 

The  branches  of  the  small  sciatic  nerve  are  muscular  (inferior  gluteal)  and 
cutaneous. 

The  inferior  gluteal  consist  of  several  large  branches  given  off  to  the  under 
surface  of  the  Gluteus  Maximus,  'near  its  lower  part. 

The  aUaneous  branches  consist  of  two  groups,  internal  and  ascending. 

The  internal  cutaneous  branches  are  distributed  to  the  skin  at  the  upper  and 
inner  side  of  the  thigh,  on  its  posterior  aspect.  One  branch,  longer  than  the 
rest,  the  inferior  pudendal,  curves  forward  below  the  tuber  ischii,  pierces  the 
fascia  lata  on  the  outer  side  of  the  ramus  of  the  ischium,  and  is  distributed  to 
the  integument  of  the  scrotum,  communicating  with  the  superficial  perineal 
nerve. 

The  ascending  cutaneous  branches  consist  of  two  or  three  filaments,  which  turn 
upwards  round  the  lower  border  of  the  Gluteus  Maximus,  to  supply  the  integu- 
ment covering  its  surface.  One  or  two  filaments  occasionally  descend  along 
the  outer  side  of  the  thigh,  supplying  the  integument  as  far  as  the  middle  of 
that  region. 

Two  or  three  branches  are  given  off  from  the  lesser  sciatic  nerve  as  it  de- 
scends beneath  the  fascia  of  the  thigh ;  they  supply  the  integument  of  the  back 
part  of  the  thigh,  popliteal  region,  and  upper  part  of  the  leg. 

The  Great  Sciatic  Nerve  (Fig.  358)  supplies  nearly  the  whole  of  the  integu- 
ment of  the  leg,  the  muscles  of  the  back  of  the  thigh,  and  those  of  the  leg  and 
foot.  It  is  the  largest  nervous  cord  in  the  body,  measuring  three-quarters  of 
an  inch  in  breadth,  and  is  the  continuation  of  the  lower  part  of  the  sacral 
plexus.  It  passes  out  of  the  pelvis  through  the  great  sacro-sciatic  foramen, 
below  the  Pyriformis  muscle.  It  descends  between  the  trochanter  major  and 
tuberosity  of  the  ischium,  along  the  back  part  of  the  thigh  to  about  its  lower 
third,  where  it  divides  into  two  large  branches,  the  internal  and  external  popli- 
teal nerves. 

This  division  may  take  place  at  any  point  between  the  sacral  plexus  and  the 
lower  third  of  the  thigh.  When  the  division  occurs  at  the  plexus,  the  two 
nerves  descend  together,  side  by  side ;  or  they  may  be  separated,  at  their  com- 
mencement, by  the  interposition  of  part  or  the  whole  of  the  Pyriformis  muscle. 
As  the  nerve  descends  along  the  back  of  the  thigh,  it  rests  at  first  upon  the 
external  rotator  muscles,  together  with  the  small  sciatic  nerve  and  artery,  being 
covered  by  the  Gluteus  Maximus ;  lower  down,  it  lies  upon  the  Adductor  Mag- 
nus, and  is  covered  by  the  long  head  of  the  Biceps. 

The  branches  of  the  nerve,  before  its  division,  are  articular  and  muscular. 

The  articular  branches  arise  from  the  upper  part  of  the  nerve ;  they  supply 
the  hip-joint,  perforating  its  fibrous  capsule  posteriorly.  These  branches  are 
sometimes  derived  from  the  sacral  plexus. 

The  muscular  branches  are  distributed  to  the  flexors  of  the  leg ;  viz.,  the 
Biceps,  Semitendinosus,  and  Semimembranosus,  and  a  branch  to  the  Adductor 
Magnus.     These  branches  are  given  off"  beneath  the  Biceps  muscle. 

The  Internal  Popliteal  Nerve,  the  larger  of  the  two  terminal  branches  of  the 
great  sciatic,  descends  along  the  back  part  of  the  thigh  through  the  middle  of 
the  popliteal  space,  to  the  lower  part  of  the  Popliteus  muscle,  where  it  passes 
with  the  artery  beneath  the  arch  of  the  Soleus,  and  becomes  the  posterior  tibial. 
It  lies  at  first  very  superficial,  and  at  the  outer  side  of  the  popliteal  vessels; 


660 


SPINAL    NERVES. 


Fig.  359.— The  Plantar  Nerves. 


opposite  the  knee-joint,  it  is  in  close  relation  with  the  vessels,  and  crosses  the 
artery  to  its  inner  side. 

The  branches  of  this  nerve  are  articular,  muscular,  and  a  cutaneous  branch, 
the  external  or  short  saphenous  nerve. 

The  articular  branches,  usually  three  in  number,  supply  the  knee-joint ;  two 
of  these  branches  accompany  the  superior  and  inferior  internal  articular  arteries ; 
and  a  third,  the  azygos. 

The  muscular  branches,  four  or  five  in  number,  arise  from  the  nerve  as  it  lies 
between  the  two  heads  of  the  Gastrocnemius  muscle;  they  supply  that  muscle, 
the  Plantaris,  Soleus,  and  Popliteus. 

The  external  or  short  saphenous  nerve  (Fig.  357)  descends  between  the  two 
heads  of  the  Gastrocnemius  muscle,  and,  about  the  middle  of  the  back  of  the 
leg,  pierces  the  deep  fascia,  and  receives  a  communicating  branch  {communicans 
peronei)  from  the  external  popliteal  nerve.  The  nerve  then  continues  its  course 
down  the  leg  near  the  outer  margin  of  the  tendo  Achillis,  in  company  with  the 
external  saphenous  vein,  winds  round  the  outer  malleolus,  and  is  distributed  to 
the  integument  along  the  outer  side  of  the  foot  and  little  toe,  communicating 
on  the  dorsum  of  the  foot  with  the  musculo-cutaneous  nerve. 

The  posterior  tibial  nerve  (Fig.  358)  commences  at  the  lower  border  of  the  Pop- 
liteus muscle,  and  passes  along  the  back  part  of  the  leg  with  tlie  posterior 

tibial  vessels  to  the  interval  between  the 
inner  malleolus  and  the  heel,  where  it  divides 
into  the  external  and  internal  plantar  nerves. 
It  lies  upon  the  deep  muscles  of  the  leg,  and 
is  covered  by  the  deep  fascia,  the  superficial 
muscles,  and  integument.  In  the  upper  part 
of  its  course,  it  lies  to  the  inner  side  of  the 
posterior  tibial  artery;  but  it  soon  crosses 
that  vessel,  and  lies  to  its  outer  side  as  far 
as  the  ankle.  In  the  lower  third  of  the  leg, 
it  is  placed  parallel  with  the  inner  margin  of 
the  tendo  Achillis. 

The  branches  of  the  posterior  tibial  nerve 
are  the  muscular  and  plantar  cutaneous. 

The  muscular  branches  arise  either  sepa- 
rately or  by  a  common  trunk  from  the  upjier 
part  of  the  nerve.  They  supj)ly  the  Tibialis 
Posticus,  Flexor  Longus  l)igitorum,  and 
Flexor  Longus  Pollicis  muscles  ;  the  branch 
to  the  latter  muscle  accompanying  the  pero- 
neal artery. 

The  plaritar  cutaneous  branch  perforates  the 
internal  annular  ligament,  and  supplies  the 
integument  of  the  heel  and  inner  side  of  the 
sole  of  the  foot. 

The  internal  plantar  nerve  (Fig.  359),  the 
larger  of  the  two  terminal  branches  of  the 
posterior  tibial,  accompanies  the  internal 
plantar  artery  along  the  inner  side  of  the 
foot.  From  its  origin  at  the  inner  ankle  it 
passes  forwards  between  the  Abductor  Pollicis  and  Flexor  Brevis  Digitorum, 
ilivides  opposite  the  bases  of  the  metatarsal  bones  into  four  digital  branches, 
and  communicates  with  the  external  plantar  nerve. 

Branches.  In  its  course,  the  internal  plantar  nerve  gives  off  cutaneous 
branches,  which  pierce  the  plantar  fascia,  and  supply  the  integument  of  the 
sole  of  the  foot;  muscular  branches,  which  supply  the  Abductor  Pollicis  and 
Flexor  Brevis  Digitorum ;  articular  branches  to  the  articulations  of  the  tarsus 


EXTERNAL    POPLITEAL.  661 

and  metatarsus ;  aiad  foicr  digital  branches.  These  pierce  the  plantar  fascia  in 
the  clefts  between  the  toes,  and  are  distributed  in  the  following  manner :  The 
first  supplies  the  inner  border  of  the  great  toe,  and  sends  a  filament  to  the 
Flexor  Brevis  Pollicis  muscle ;  the  second  bifurcates,  to  supply  the  adjacent 
sides  of  the  great  and  second  toes,  sending  a  filament  to  the  first  Lumbrical 
muscle ;  the  third  digital  branch  supplies  the  adjacent  sides  of  the  second  and 
third  toes,  and  the  second  Lumbrical  muscle ;  the  fourth  supplies  the  corre- 
sponding sides  of  the  third  and  fourth  toes,  and  receives  a  communicating 
branch  from  the  external  plantar  nerve.  It  will  be  observed,  that  the  distri- 
bution of  these  branches  is  precisely  similar  to  that  of  the  median  nerve  in 
the  hand.  Each  digital  nerve  gives  off  cutaneous  and  articular  filaments ;  and 
opposite  the  last  phalanx  sends  a  dorsal  branch,  which  supplies  the  structures 
round  the  nail,  the  continuation  of  the  nerve  being  distributed  to  the  ball  of 
the  toe. 

The  external  plantar  nerve,  the  smaller  of  the  two,  completes  the  nervous 
supply  to  the  structures  of  the  foot,  being  distributed  to  the  little  toe  and  one- 
half  of  the  fourth,  as  well  as  to  most  of  the  deep  muscles,  its  distribution  being 
similar  to  that  of  the  ulnar  in  the  hand.  It  passes  obliquely  forwards  with  the 
external  plantar  artery  to  the  outer  side  of  the  foot,  lying  between  the  Flexor 
Brevis  Digitorum  and  Flexor  Accessorius;  and,  in  the  interval  between  the 
former  muscle  and  Abductor  Minimi  Digiti,  divides  into  a  superficial  and  a 
deep  branch.  Before  its  division,  it  supplies  the  Flexor  Accessorius  and 
Abductor  Minimi  Digiti. 

The  superficial  branch  separates  into  two  digital  nerves ;  -one,  the  smaller  of 
the  two,  supplies  the  outer  side  of  the  little  toe,  the  Flexor  Brevis  Minimi 
Digiti,  and  the  two  interosseous  muscles  of  the  fourth  metatarsal  space;  the 
other,  and  larger  digital  branch,  supplies  the  adjoining  sides  of  the  fourth  and 
fifth  toes,  and  communicates  with  the  internal  plantar  nerve. 

The  deep  or  muscular  branch  accompanies  the  external  plantar  artery  into  the 
deep  part  of  the  sole  of  the  foot,  beneath  the  tendons  of  the  flexor  muscles  and 
Adductor  Pollicis,  and  supplies  all  the  Interossei  (except  those  in  the  fourth 
metatarsal  space),  the  two  outer  Lumbricales,  the  Adductor  Pollicis,  and  the 
Transversus  Pedis. 

The  Exte.riial  Popliteal  or  Peroneal  Nerve  (Fig.  858),  about  one-half  the  size 
of  the  internal  popliteal,  descends  obliquely  along  the  outer  side  of  the  popliteal 
space  to  the  fibula,  close  to  the  margin  of  the  Biceps  muscle.  It  is  easily  felt 
beneath  the  skin  behind  the  head  of  the  fibula,  at  the  inner  side  of  the  tendon 
of  the  Biceps.  About  an  inch  below  the  head  of  the  fibula  it  pierces  the  origin 
of  the  Peroneus  Longus,  and  divides  beneath  that  muscle  into  the  anterior 
tibial  and  musculo-cutaneous  nerves. 

The  branches  of  the  peroneal  nerve,  previous  to  its  division,  are  articular  and 
cutaneous. 

The  articular  branches,  two  in  number,  accompany  the  superior  and  inferior 
external  articular  arteries  to  the  outer  side  of  the  knee.  The  upper  one  occa- 
sionally arises  from  the  great  sciatic  nerve  before  its  bifurcation,  A  third 
(recurrent)  articular  nerve  is  given  off  at  the  point  of  division  of  the  peroneal 
nerve ;  it  ascends  with  the  tibial  recurrent  artery  through  the  Tibialis  Anticus 
muscle  to  the  front  of  the  knee,  which  it  supplies. 

The  cutaneous  branches,  two  or  three  in  number,  supply  the  integument  along 
the  back  part  and  outer  side  of  the  leg,  as  far  as  its  middle  or  lower  part ;  one 
of  these,  larger  than  the  rest,  the  communicans  j^eronei,  arises  near  the  head  of 
the  fibula,  crosses  the  external  head  of  the  Gastrocnemius  to  the  middle  of  the 
leg,  and  joins  with  the  external  saphenous.  This  nerve  occasionally  exists  as 
a  separate  branch,  which  is  continued  down  as  far  as  the  heel. 

The  Anterior  Tibial  Nerve  (Fig.  So^)  commences  at  the  bifurcation  of  the 
peroneal  nerve,  between  the  fibula  and  upper  part  of  the  Peroneus  Longus, 
passes  obliquely  forwards  beneath  the  Extensor  Longus  Digitorum  to  the  fore 


662  SPINAL    NERVES. 

part  of  the  interosseous  membrane,  and  reaolies  the  outer  side  of  the  anterior 
tibial  arterj  above  the  middle  of  the  leg ;  it  then  descends  with  the  artery  to 
the  front  of  the  ankle-joint,  where  it  divides  into  an  external  and  an  internal 
branch.  This  nerve  lies  at  first  on  the  outer  side  of  the  anterior  tibial  artery, 
then  in  front  of  it,  and  again  at  its  outer  side  at  the  ankle-joint. 

The  branches  of  the  anterior  tibial  nerve,  in  its  course  through  the  leg,  are 
the  muscular  nerves  to  the  Tibialis  Anticus,  Extensor  Longus  Bigitorum,  and 
Extensor  Proprius  Pollicis  muscles. 

The  external  or  tarsal  branch  of  the  anterior  tibial,  passes  outwards  across  the 
tarsus,  beneath  the  Extensor  Brevis  Digitorum,  and,  having  become  ganglionic, 
like  the  posterior  interosseous  nerve  at  the  wrist,  supplies  the  Extensor  Brevis 
Digitorum  and  the  articulations  of  the  tarsus  and  metatarsus. 

The  internal  branch,  the  continuation  of  the  nerve,  accompanies  the  dorsalis 
pedis  artery  along  the  inner  side  of  the  dorsum  of  the  foot,  and,  at  the  first 
interosseous  space,  divides  into  two  branches,  which  supply  the  adjacent  sides 
of  the  great  and  second  toes,  communicating  with  the  internal  division  of  the 
musculo-cutaneous  nerve. 

The  Musculo-  Cutaneous  Nerve  (Fig.  856)  supplies  the  muscles  on  the  fibular 
side  of  the  leg,  and  the  integument  of  the  dorsum  of  the  foot.  It  passes  for- 
wards between  the  Peronei  muscles  and  the  Extensor  Longus  Digitorum,  pierces 
the  deep  fascia  at  the  lower  third  of  the  leg,  on  its  front  and  outer  side,  and 
divides  into  two  branches.  This  nerve,  in  its  course  between  the  muscles, 
gives  off  muscular  branches  to  the  Peroneus  Longus  and  Peroneus  Brevis,  and 
cutaneous  filaments  to  the  integument  of  the  lower  part  of  the  leg. 

The  internal  branch  of  the  musculo-cutaneous  nerve,  passes  in  front  of  the 
ankle-joint,  and  along  the  dorsum  of  the  foot,  supplying  the  inner  side  of  the 
great  toe,  and  the  adjoining  sides  of  the  second  and  third  toes.  It  also  supplies 
the  integument  of  the  inner  ankle  and  inner  side  of  the  foot,  communicating 
with  the  internal  saphenous  nerve,  and  joins  with  the  anterior  tibial  nerve, 
between  the  great  and  second  toes. 

The  external  branch,  the  larger,  passes  along  the  outer  side  of  the  dorsum  of 
the  foot,  to  be  distributed  to  the  adjoining  sides  of  the  third,  fourth,  and  fifth 
toes.  It  also  supplies  the  integument  of  the  outer  ankle  and  outer  side  of  the 
foot,  communicating  with  the  short  saphenous  nerve. 

The  distribution  of  these  branches  of  the  musculo-cutaneous  nerve  will  be 
found  to  vary;  together,  they  supply  all  the  toes  excepting  the  outer  side  of  the 
little  toe,  and  the  adjoining  sides  of  the  great  and  second  toes. 


The  Sympathetic  Nerve. 

The  Sympathetic  Nerve  is  eo  called  from  the  opinion  entertained  that  through 
it  is  produced  a  sympathy  between  the  affections  of  distant  organs.  It  consists 
of  a  series  of  ganglia,  connected  together  by  intervening  cords,  extending  on 
each  side  of  the  vertebral  column  from  the  base  of  the  skull  to  the  coccyx.  It 
may,  moreover,  be  traced  up  into  the  head,  where  the  ganglia  (which  are  all  in 
connection  with  the  fifth  cranial  nerve)  occupy  spaces  between  the  cranial  and 
facial  bones.  These  two  gangliated  cords  lie  parallel  with  one  another  as  far 
as  the  sacrum,  on  which  bone  they  converge,  communicating  together  through 
a  single  ganglion  {ganglion  impar\  placed  in  front  of  the  coccyx.  Some 
anatomists  also  state  that  the  two  cords  are  joined  at  their  cephalic  extremity, 
through  a  small  ganglion  (the  ganglion  of  Ribes),  situated  upon  the  anterior 
communicating  artery.  Moreover,  the  chains  of  opposite  sides  communicate 
between  these  two  extremities  in  several  parts,  by  means  of  the  nervous  cords 
that  arise  from  them. 

The  ganglia  are  somewhat  less  numerous  than  the  vertebrse:  thus  there  are 
only  three  in  the  cervical  region,  twelve  in  the  dorsal,  four  in  the  lumbar,  five 
in  the  sacral,  and  one  in  the  coccygeal. 

The  sympathetic  nerve,  for  convenience  of  description,  may  be  divided  into 
several  parts,  according  to  the  position  occupied  by  each;  and  the  number 
of  ganglia  of  which  each  part  is  composed,  may  be  thus  arranged: — 

Cephalic  portion 
Cervical         " 
Dorsal  " 


4 

ganglia. 

3 

12 

4 

5 

1 

Lumbar  " 

Sacral  " 

Coccygeal       " 

Each  ganglion  may  be  regarded  as  a  distinct  centre,  from  or  to  which 
branches  pass  in  various  directions.  These  branches  may  be  thus  arranged: 
1.  Branches  of  communication  between  the  ganglia.  2.  Branches  of  commu- 
nication with  the  cerebral  or  spinal  nerves.  3.  Primary  branches  passing  to  be 
distributed  to  the  arteries  in  the  vicinity  of  the  ganglia,  and  to  the  viscera,  or 
proceeding  to  other  ganglia  placed  in  the  thorax,  abdomen,  or  pelvis. 

1.  The  branches  of  communication  between  the  ganglia  are  composed  of  gray 
and  white  nerve-fibres,  the  latter  being  continuous  with  those  fibres  of  the 
spinal  nerves  which  pass  to  the  ganglia. 

2.  The  branches  of  communication  between  the  ganglia  and  the  cerebral  or 
spinal  nerves  also  consist  of  a  white  and  a  gray  portion ;  the  former  proceeding 
from  the  spinal  nerve  to  the  ganglion,  the  latter  passing  from  the  ganglion  to 
the  spinal  nerve. 

3.  The  primary  branches  of  distribution  also  consist  of  two  kinds  of  nerve- 
fibres,  the  sympathetic  and  spinal.  They  have  a  remarkable  tendency  to  form 
intricate  plexuses,  which  encircle  the  bloodvessels,  and  are  conducted  by  them 
to  the  viscera.  The  greater  number,  however,  of  these  branches  pass  to  a  series 
of  visceral  ganglia:  these  are  ganglionic  masses,  of  variable  size,  situated  in  the 
large  cavities  of  the  trunk,  the  thorax,  and  abdomen ;  and  are  connected  with 
the  roots  of  the  great  arteries  of  the  viscera.  These  ganglia  are  single  and 
unsymmetrical,  and  are  called  the  cardiac  and  semilunar.  From  these  visceral 
ganglia  numerous  plexuses  of  nerves  are  derived,  which  entwine  round  the 
bloodvessels,  and  are  conducted  by  them  to  the  viscera. 

663 


664 


SYMPATHETIC    NERVE. 


Fig.  360. — The  Sympathetic  Nerve. 


StgMfitr  Carviumf  OmtgUon 

fuddle  Ctrvieal  BatyJto 

/ 
Inferior  Omical  Ganglion 


Jinryniftat   Branektt 
Cardine    Bri 

trp    Cardiac  Plexus 

Superficial  Cardiac  Flexui. 


Solar  Pleikuu- 


Aoriic  FkxuM 


JJypnifattrie  /".*.»«# 


Sticral  GanyttQ 


G^uijlion  Jmjti^r 


CAVERNOUS    PLEXUS.  665 

The  cepJialic  portion  of  the  sympathetic  consists  of  four  ganglia.  1.  The 
ophthalmic  ganglion.  2.  The  spheno-palatine,  or  Meckel's  ganglion.  3.  The 
otic,  or  Arnold's  ganglion.  4,  The  submaxillary  ganglion.  These  have  been 
already  described  in  connection  with  the  three  divisions  of  the  fifth  nerve. 

The  cervical  portion  of  the  sympathetic  consists  of  three  ganglia  on  each  side, 
which  are  distinguished  according  to  their  position,  as  the  superior,  middle, 
and  inferior  cervical. 

Cervical  Portion  of  the  Sympathetic. 

The  Superior  Cervical  Ganglion,  the  largest  of  the  three,  is  placed  opposite 
the  second  and  third  cervical  vertebrae,  and  sometimes  as  low  as  the  fourth  or 
fifth.  It  is  of  a  reddish-gray  color,  and  usually  fusiform  in  shape :  sometimes 
broad,  and  occasionally  constricted  at  intervals,  so  as  to  give  rise  to  the  opinion, 
that  it  consists  of  the  coalescence  of  several  smaller  ganglia.  It  is  in  relation, 
in  front,  with  the  sheath  of  the  internal  carotid  artery,  and  internal  jugular  vein ; 
behind,  it  lies  on  the  Eectus  Capitis  Anticus  Major  muscle. 

Its  branches  may  be  divided  into  superior,  inferior,  external,  internal,  and 
anterior. 

The  superior  branch  appears  to  be  a  direct  continuation  of  the  ganglion.  It 
is  soft  in  texture,  and  of  a  reddish  color.  It  ascends  by  the  side  of  the  internal 
carotid  artery,  and,  entering  the  carotid  canal  in  the  temporal  bone,  divides  into 
two  branches,  which  lie,  one  on  the  outer,  and  the  other  on  the  inner  side,  of 
that  vessel. 

The  outer  branch,  the  larger  of  the  two,  distributes  filaments  to  the  internal 
carotid  artery,  and  forms  the  carotid  plexus. 

The  ifiner  branch  also  distributes  filaments  to  the  internal  carotid,  and  con- 
tinuing onwards,  forms  the  cavernous  plexus. 

Carotid  Plexus. 

The  Carotid  Plexus  is  situated  on  the  outer  side  of  the  internal  carotid. 
Filaments  from  this  plexus  occasionally  form  a  small  gangliform  swelling  on 
the  under  surface  of  the  artery,  which  is  called  the  carotid  ganglion.  The 
carotid  plexus  communicates  with  the  Casserian  ganglion,  with  the  sixth  nerve, 
and  spheno-palatine  ganglion,  and  distributes  filaments  to  the  wall  of  the  carotid 
artery,  and  to  the  dura  mater  (Valentin). 

The  communicating  branches  with  the  sixth  nerve  consist  of  one  or  two  fila- 
ments, which  join  that  nerve  as  it  lies  upon  the  outer  side  of  the  internal  carotid. 
Other  filaments  are  also  connected  with  the  Casserian  ganglion.  The  communi- 
cation with  the  spheno-palatine  ganglion  is  effected  by  the  carotid  portion  of 
the  Vidian  nerve,  which  passes  forwards,  through  the  cartilaginous  substance 
filling  the  foramen  lacerum  medium,  along  the  pterygoid  or  Vidian  canal,  to 
the  spheno-palatine  ganglion.  In  this  canal  it  joins  the  petrosal  branch  of  the 
Vidian. 

Cavernous  Plexus. 

The  Cavernous  Plexus  is  situated  below,  and  internal  to  that  part  of  the 
internal  carotid,  which  is  placed  by  the  side  of  the  sella  Turcica,  in  the  cavern- 
ous sinus,  and  is  formed  chiefly  by  the  internal  division  of  the  ascending  branch 
from  the  superior  cervical  ganglion.  It  communicates  with  the  third,  fourth, 
fifth,  and  sixXth  nerves,  and  with  the  ophthalmic  ganglion,  and  distributes  fila- 
ments to  the  wall  of  the  internal  carotid.  The  branch  of  communication  with 
the  third  nerve  joins  it  at  its  point  of  division ;  the  branch  to  the  fourth  nerve 
joins  it  as  it  lies  on  the  outer  wall  of  the  cavernous  sinus ;  other  filaments  are 
connected  with  the  under  surface  of  the  trunk  of  the  ophthalmic  nerve;  and  a 
second  filament  of  communication  joins  the  sixth  nerve. 

The  filament  of  connection  with  the  ophthalmic  ganglion  arises  from  the 


666  SYMPATHETIC    NERVE. 

anterior  part  of  tlie  cavernous  plexus ;  it  accompanies  the  nasal  nerve,  or  con- 
tinues forwards  as  a  separate  branch. 

The  terminal  filaments  from  the  carotid  and  cavernous  plexuses  are  prolonged 
along  the  internal  carotid,  forming  plexuses  which  entwine  round  the  cerebral 
and  ophthalmic  arteries ;  along  the  former  vessel  they  may  be  traced  on  to  the 
pia  mater ;  along  the  latter,  into  the  orbit,  where  they  accompany  each  of  the 
subdivisions  of  the  vessel,  a  separate  plexus  passing  with  the  arteria  centralis 
retinae  into  the  interior  of  the  eyeball. 

The  inferior  or  descending  branch  of  the  superior  cervical  ganglion  communi- 
cates with  the  middle  cervical  ganglion. 

The  external  branches  are  numerous,  and  communicate  with  the  cranial  nerves, 
and  with  the  four  upper  spinal  nerves.  Sometimes,  the  branch  to  the  fourth 
spinal  nerve  may  come  from  the  cord  connecting  the  upper  and  middle  cervical 
ganglia.  The  branches  of  communication  with  the  cranial  nerves  consist  of 
delicate  filaments,  which  pass  from  the  superior  cervical  ganglion  to  the  gan- 
glion of  the  trunk  of  the  pneumogastric,  and  to  the  ninth  nerve.  A  separate 
filament  from  the  cervical  ganglion  subdivides  and  joins  the  petrosal  ganglion 
of  the  glosso-pharyngeal,  and  the  ganglion  of  the  root  of  the  pneumogastric  in 
the  jugular  foramen. 

The  internal  branches  are  three  in  number :  pharyngeal,  laryngeal,  and  the 
superior  cardiac  nerve.  The  pharyngeal  branches  pass  inwards  to  the  side  of 
the  pharynx,  where  they  join  with  branches  from  the  pneumogastric,  glosso- 
pharyngeal, and  external  laryngeal  nerves  to  form  i\\e  j)haryngeal  plexus.  The 
laryngeal  branches  unite  with  the  superior  laryngeal  nerve  and  its  branches. 

The  superior  cardiac  nerve  will  be  described  in  connection  with  the  other 
cardiac  nerves. 

The  anterior  branches  ramify  upon  the  external  carotid  artery  and  its  branches, 
forming  round  each  a  delicate  plexus,  on  the  nerves  composing  which  small 
ganglia  are  occasionally  found.  These  ganglia  have  been  named,  according  to 
their  position,  intercarotid  (one  placed  at  the  angle  of  bifurcation  of  the  common 
carotid),  lingual,  temporal,  and  pharyngeal.  The  plexuses  accompanying  some 
of  these  arteries  have  important  communications  with  other  nerves.  That  sur- 
rounding the  external  carotid,  is  connected  with  the  digastric  branch  of  the 
facial ;  that  surrounding  the  facial,  communicates  with  the  submaxillary  gan- 
glion by  one  or  two  filaments ;  and  that  accompanying  the  middle  meningeal 
artery,  sends  offsets  which  pass  to  the  otic  ganglion  and  to  the  intumescentia 
ganglioformis  of  the  facial  nerve. 

The  Middle  Cervical  Ganglion  (thyroid  ganglion)  is  the  smallest  of  the  three 
cervical  ganglia,  and  is  occasionally  altogether  wanting.  It  is  placed  opposite 
the  fifth  cervical  vertebra,  usually  upon,  or  close  to,  the  inferior  thyroid  artery; 
hence  the  name  "thyroid  ganglion,"  assigned  to  it  by  Haller. 

Its  sujyenor  branches  ascend  to  communicate  with  the  superior  cervical 
ganglion. 

Its  inferior  branches  descend  to  communicate  with  the  inferior  cervical 
ganglion. 

Its  external  branches  pass  outwards  to  join  the  fifth  and  sixth  spinal  nerves. 
Those  branches  are  not  constantly  found. 

Its  internal  branches  are,  the  tliyroid,  and  the  middle  cardiac  nerve. 

The  thyroid  branches  are  small  filaments,  which  accompany  the  inferior  thy- 
roid artery  to  tlie  thyroid  gland ;  they  communicate,  on  the  artery,  with  the 
superior  cardiac  nerve,  and,  in  the  gland,  with  branches  from  the  recurrent  and 
external  laryngeal  nerves. 

The  middle  cardiac  nerve  is  described  with  the  other  cardiac  nerves. 

The  Inferior  Cervical  Ganglion  is  situated  between  the  base  of  the  transverse 
process  of  the  last  cervical  vertebra  and  the  neck  of  the  first  rib,  on  the  inner 


CARDIAC.  667 

side  of  the  superior  intercostal  artery.  Its  form  is  irregular;  it  is  larger  in 
size  than  the  preceding,  and  frequently  joined  with  the  first  thoracic  ganglion. 

Its  superior  branches  communicate  with  the  middle  cervical  ganglion. 

Its  inferior  branches  descend,  some  in  front  of,  others  behind  the  subclavian 
artery,  to  join  the  first  thoracic  ganglion.  The  most  important  of  these  branches 
constitutes  the  inferior  cardiac  nerve,  to  be  presently  described. 

The  external  branches  consist  of  several  filaments,  some  of  which  communicate 
with  the  seventh  and  eighth  spinal  nerves ;  others  acco.mpany  the  vertebral 
artery  along  the  vertebral  canal,  forming  a  plexus  round  the  vessel,  supplying 
it  with  filaments,  and  communicating  with  the  cervical  spinal  nerves  as  high 
as  the  fourth. 

Cardiac  Nerves. 

The  Cardiac  Nerves  are  three  in  number  on  each  side ;  superior,  middle,  and 
inferior,  one  being  derived  from  each  of  the  cervical  ganglia. 

The  superior  cardiac  nerve  (nervus  superficialis  cordis)  arises  by  two  or  more 
branches  from  the  superior  cervical  ganglion,  and  occasionally  receives  a  fila- 
ment from  the  cord  of  communication  between  the  first  and  second  cervical 
ganglia.  It  runs  down  the  neck  behind  the  common  carotid  artery,  lying  upon 
the  Longus  Colli  muscle ;  and  crosses  in  front  of  the  inferior  thyroid  artery, 
and  the  recurrent  laryngeal  nerve. 

The  right  superior  cardiac  nerve,  at  the  root  of  the  neck,  passes  either  in  front 
of  or  behind  the  subclavian  artery,  and  along  the  arteria  innominata,  to  the 
back  part  of  the  arch  of  the  aorta,  where  it  joins  the  deep  cardiac  plexus.  This 
nerve,  in  its  co-urse,  is  connected  with  other  branches  of  the  sympathetic ;  about 
the  middle  of  the  neck  it  receives  filaments  from  the  external  laryngeal  nerve; 
lower  down,  one  or  two  twigs  from  the  pneumogastric ;  and  as  it  enters  the 
thorax,  it  joins  with  the  recurrent  laryngeal.  Filaments  from  this  nerve  accom- 
pany the  inferior  thyroid  artery  to  the  thyroid  gland. 

The  left  superior  cardiac  nerve  runs  by  the  side  of  the  left  carotid  artery,  and 
in  front  of  the  arch  of  the  aorta,  to  the  superficial  cardiac  plexus ;  but  occa- 
sionally it  passes  behind  the  aorta,  and  terminates  in  the  deep  cardiac  plexus. 

The  middle  cardiac  nerve  (nervus  cardiacus  magnus),  the  largest  of  the  three, 
arises  from  the  middle  cervical  ganglion,  or  from  the  cord  between  the  middle 
and  inferior  ganglia.  On  the  right  side,  it  descends  behind  the  common  carotid 
artery ;  and,  at  the  root  of  the  neck,  passes  either  in  front  of  or  behind  the  sub- 
clavian artery ;  it  then  descends  on  the  trachea,  receives  a  few  filaments  from 
the  recurrent  laryngeal  nerve,  and  joins  the  deep  cardiac  plexus.  In  the  neck, 
it  communicates  with  the  superior  cardiac  and  recurrent  laryngeal  nerves.  On 
the  left  side,  the  middle  cardiac  nerve  enters  the  chest  between  the  left  carotid 
and  subclavian  arteries,  and  joins  the  left  side  of  the  deep  cardiac  plexus. 

The  inferior  cardiac  nerve  (nervus  cardiacus  minor)  arises  from  the  inferior 
cervical  or  first  thoracic  ganglion.  It  passes  down  behind  the  subclavian  artery, 
and  along  the  front  of  the  trachea,  to  join  the  deep  cardiac  plexus.  It  commu- 
nicates freely  behind  the  subclavian  artery  with  the  recurrent  laryngeal  and 
middle  cardiac  nerves. 

The  great  or  deep  cardiac  plexus  {plexus  magnus  profundus — Scarpa)  is  situated 
in  front  of  the  trachea  at  its  bifurcation,  above  the  point  of  division  of  the  pul- 
monary artery,  and  behind  the  arch  of  the  aorta.  It  is  formed  by  the  cardiac 
nerves  derived  from  the  cervical  ganglia  of  the  sympathetic,  and  the  cardiac 
branches  of  the  recurrent  laryngeal  and  pneumogastric.  The  only  cardiac 
nerves  which  do  not  enter  into  the  formation  of  this  plexus,  are  the  left  supe- 
rior cardiac  nerve,  and  the  left  inferior  cardiac  branch  from  the  pneumogastric. 
The  branches  derived  from  the  great  cardiac  plexus  form  the  posterior  coronary 
plexus,  and  part  of  the  anterior  coronary  plexus ;  whilst  a  few  filaments  pro- 
ceed to  the  pulmonary  plexuses,  and  to  the  auricles  of  the  heart. 


668  SYMPATHETIC    NERVE. 

The  branches  from  the  right  side  of  this  plexus  pass,  some  in  front  of  and 
others  behind  the  right  pulmonary  artery ;  the  former,  the  more  numerous, 
transmit  a  few  filaments  to  the  anterior  pulmonary  plexus,  and  are  continued 
along  the  trunk  of  the  pulmonary  artery,  to  form  part  of  the  anterior  coronary 
plexus;  those  behind  the  pulmonary  artery  distribute  a  few  filaments  to  the 
right  auricle,  and  form  part  of  the  posterior  coronary  plexus. 

The  branches  from  the  kft  side  of  the  deep  cardiac  plexus  distribute  a  few 
filaments  to  the  left  auricle  of  the  heart  and  the  anterior  pulmonary  plexus, 
and  then  pass  on  to  form  the  greater  part  of  the  posterior  coronary  plexus,  a 
few  branches  passing  to  the  superficial  cardiac  plexus. 

The  superficial  {anterior)  cardiac  plexus  lies  beneath  the  arch  of  the  aorta,  in 
front  of  the  right  pulmonary  artery.  It  is  formed  by  the  left  superior  cardiac 
nerve,  the  left  (and  occasionally  the  right)  inferior  cardiac  branches  of  the 
pneumogastric,  and  filaments  from  the  deep  cardiac  plexus.  A  small  ganglion 
(cardiac  ganglion  of  Wrisberg)  is  occasionally  found  connected  with  these 
nerves  at  their  point  of  junction.  This  ganglion,  when  present,  is  situated 
immediately  beneath  the  arch  of  the  aorta,  on  the  right  side  of  the  ductus  arte- 
riosus. The  superficial  cardiac  plexus  forms  the  chief  part  of  the  anterior 
coronary  plexus,  and  several  filaments  pass  along  the  pulmonary  artery  to  the 
left  anterior  pulmonary  plexus. 

The  posterior  cororhary  plexus  is  chiefly  formed  by  filaments  prolonged  from 
the  left  side  of  the  deep  cardiac  plexus,  and  by  a  few  from  the  right  side.  It 
surrounds  the  branches  of  the  coronary  artery  at  the  back  of  the  heart,  and  its 
filaments  are  distributed  with  those  vessels  to  the  muscular  substance  of  the 
ventricles. 

The  anterior  coronary  plexus  is  formed  chiefly  from  the  superficial  cardiac 
plexus,  but  receives  filaments  from  the  deep  cardiac  plexus.  Passing  forwards 
between  the  aorta  and  pulmonary  artery,  it  accompanies  the  right  coronary j 
artery  on  the  anterior  surface  of  the  heart. 

Valentin  has  described  nervous  filaments  ramifying  under  the  endocardium; 
and  Remak  has  found,  in  several  mammalia,  numerous  small  ganglia  on  the 
cardiac  nerves,  both  on  the  surface  of  the  heart  and  in  its  muscular  substance. 
The  elaborate  dissections  lately  completed  by  Dr.  Robert  Lee  have  demon 
strated  without  any  doubt  the  existence  of  a  dense  mesh  of  nerves  distributed 
both  to  the  surface,  and  in  the  substance  of  the  heart,  having  numerous  ganglia- 
developed  upon  them. 

Thoracic  Part  of  the  Sympathetic. 

The  Thoracic  Portion  of  the  Sympathetic  consists  of  a  series  of  ganglia, 
which  usually  correspond  in  number  to  that  of  the  vertebrae;  but,  from  the 
occasional  coalescence  of  two,  their  number  is  uncertain.  These  ganglia  are 
placed  on  each  side  of  the  spine,  resting  against  the  heads  of  the  ribs,  and 
covered  by  the  pleura  costalis:  the  last  two  are,  however,  anterior  to  the  rest, 
being  placed  on  the  side  of  the  bodies  of  the  vertebrae.  The  ganglia  are  small 
in  size,  and  of  a  grayish  color.  Ths  first,  larger  than  the  rest,  is  of  an  elongated 
form,  and  usually  blended  with  the  last  cervical.  They  are  connected  together 
by  cord-like  prolongations  from  their  substance. 

The  external  branches  from  each  ganglion,  usually  two  in  number,  communi- 
cate with  each  of  the  dorsal  spinal  nerves. 

The  internal  branches  from  the  six  upper  ganglia  are  very  small:  they  supply 
filaments  to  the  thoracic  aorta  and  its  branches,  besides  small  branches  to  the 
bodies  of  the  vertebrae  and  their  ligaments.  Branches  from  the  third  and  fourth 
ganglia  form  part  of  the  posterior  pulmonary  plexus. 

The  internal  branches  from  the  six  lower  ganglia  are  large  and  white  in  color; 
they  distribute  filaments  to  the  aorta,  and  unite  to  form  the  three  splanchnic 
nerves.  These  are  named,  the  great,  the  lesser,  and  the  smallest  or  rerial 
splanchnic. 


i 


I 

I 


THORACIC    GANGLIA.  669 

The  great  splanclmic  nerve  is  of  a  white  color,  firm  in  texture,  and  bears  a 
marked  contrast  to  the  ganglionic  nerves.  It  is  formed  by  branches  from  the 
thoracic  ganglia  between  the  sixth  and  tenth,  receiving  filaments  (according  to 
Dr.  Beck)  from  all  the  thoracic  ganglia  above  the  sixth.  These  roots  unite  to 
form  a  large  round  cord  of  considerable  size.  It  descends  obliquely  inwards  in 
front  of  the  bodies  of  the  vertebrae  along  the  posterior  mediastinum,  perforates 
the  crus  of  the  Diaphragm,  and  terminates  in  the  semilunar  ganglion,  distri- 
buting filaments  to  the  renal  plexus  and  suprarenal  capsule. 

The  lesser  splanchnic  nerve  is  formed  by  filaments  from  the  tenth  and  eleventh 
ganglia,  and  from  the  cord  between  them.  It  pierces  the  Diaphragm  with  the 
preceding  nerve,  and  joins  the  coeliac  plexus.  It  communicates  in  the  chest 
with  the  great  splanchnic  nerve,  and  occasionally  sends  filaments  to  the  renal 
plexus. 

The  smallest  or  renal  S2:)lanchnic  nerve  arises  from  the  last  ganglion,  and 
piercing  the  Diaphragm,  terminates  in  the  renal  plexus  and  lower  part  of  the 
coeliac  plexus.     It  occasionally  communicates  with  the  preceding  nerve. 

A  striking  analogy  appears  to  exist  between  the  splanchnic  and  the  cardiac 
nerves.  The  cardiac  nerves  are  three  in  number;  they  arise  from  the  three 
cervical  ganglia,  and  are  distributed  to  a  large  and  important  organ  in  the 
thoracic  cavity.  The  splanchnic  nerves,  also  three  in  number,  are  connected 
probably  with  all  the  dorsal  ganglia,  and  are  distributed  to  important  organs  in 
the  abdominal  cavity. 

The  epigastric  or  solar  plexics  supplies  all  the  viscera  in  the  abdominal  cavity. 
It  consists  of  a  dense  network  of  nerves  and  ganglia,  situated  behind  the 
stomach  and  in  front  of  the  aorta  and  crura  of  the  Diaphragm.  It  surrounds 
the  coeliac  axis  and  root  of  the  superior  mesenteric  artery,  extending  down- 
wards as  low  as  the  pancreas,  and  outwards  to  the  suprarenal  capsules.  This 
plexus,  and  the  ganglia  connected  with  it,  receive  the  great  splanchnic  nerve 
of  both  sides,  part  of  the  lesser  splanchnic  nerves,  and  the  termination  of  the 
right  pneumogastric.  It  distributes  filaments,  which  accompany,  under  the  name 
of  plexuses,  all  the  branches  from  the  front  of  the  abdominal  aorta. 

The  semilunar  ganglia,  of  the  solar  plexus,  two  in  number,  one  on  each  side, 
are  the  largest  ganglia  in  the  body.  They  are  large  irregular  gangliform 
masses,  formed  by  the  aggregation  of  smaller  ganglia,  having  interspaces 
between  them.  They  are  situated  by  the  side  of  the  coeliac  axis  and  superior 
mesenteric  artery,  close  to  the  suprarenal  capsules:  the  one  on  the  right  side 
lies  beneath  the  vena  cava;  the  upper  part  of  each  ganglion  is  joined  by  the 
greater  and  lesser  splanchnic  nerves,  and  to  the  inner  side  of  each  the  branches 
of  the  solar  plexus  are  connected.  From  the  solar  plexus  are  derived  the 
following: — • 

Phrenic  or  Diaphragmatic  plexus.  Suprarenal  plexus. 

Coeliac  plexus.  Renal  plexus. 

Gastric  plexus.  Superior  mesenteric  plexus. 

Hepatic  plexus.  Spermatic  plexus. 

Splenic  plexus.  Inferior  mesenteric  plexus. 

The  phrenic  jjlexus  accompanies  the  phrenic  artery  to  the  Diaphragm,  which 
it  supplies,  some  filaments  passing  to  the  suprarenal  capsule.  It  arises  from 
the  upper  part  of  the  semilunar  ganglion,  and  is  larger  on  the  right  side  than 
on  the  left  side.  In  connection  with  this  plexus,  on  the  right  side,  at  its  point 
of  junction  with  the  phrenic  nerve,  is  a  small  ganglion  (ganglion  diaphragma- 
ticum).  This  ganglion  is  placed  on  the  under  surface  of  the  Diaphragm,  near 
the  suprarenal  capsule.  Its  branches  are  distributed  to  the  vena  -cava,  supra- 
renal capsule,  and  the  hepatic  plexus.     There  is  no  ganglion  on  the  left  side. 

The  suprarenal  plexus  is  formed  by  branches  from  the  solar  plexus,  from  the 
semilunar  ganglion,  and  from  the  splanchnic  and  phrenic  nerves,  a  ganglion 
being  formed  at  the  point  of  junction  of  the  latter  nerve.    It  supplies  the  supra- 


610  SYMPATHETIC    XERVE. 

renal  gland.     The  branches  of  this  plexus  are  remarkable  for  their  large  size 
in  comparison  with  the  size  of  the  organ  they  supply. 

The  renal  plexus  is  formed  by  filaments  from  the  solar  plexus,  the  outer  part 
of  the  semilunar  ganglion,  and  the  aortic  plexus.  It  is  also  joined  by  filaments 
from  the  lesser  and  smallest  splanchnic  nerves.  The  nerves  from  these  sources, 
fifteen  or  twenty  in  number,  have  numerous  ganglia  developed  upon  them. 
They  accompany  the  branches  of  the  renal  artery  into  the  kidney ;  some  fila- 
ments on  the  right  side  being  distributed  to  the  vena  cava,  and  others  to  the 
spermatic  plexus,  on  both  sides. 

The  spermatic  plexus  is  derived  from  the  renal  plexus,  receiving  branches 
from  the  aortic  plexus.     It  accompanies  the  spermatic  vessels  to  the  testes. 

In  the  female,  the  ovarian  plexus,  is  distributed  to  the  ovaries  and  fundus  of 
the  uterus. 

The  coeliac plexus,  of  large  size,  is  a  direct  continuation  from  the  solar  plexus: 
it  surrounds  the  coeliac  axis,  and  subdivides  into  the  gastric,  hepatic,  and 
splenic  plexuses.  It  receives  branches  from  one  or  more  of  the  splanchnic 
nerves,  and,  on  the  left  side,  a  filament  from  the  pneumogastric. 

The  gastric  plexus  accompanies  the  gastric  artery  along  the  lesser  curvature 
of  the  stomach,  and  joins  with  branches  from  the  left  pneumogastric  nerve. 
It  is  distributed  to  the  stomach. 

The  hepatic  plexus,  the  largest  offset  from  the  coeliac  plexus,  receives  fila- 
ments from  the  left  pneumogastric  and  right  phrenic  nerves.  It  accompanies 
the  hepatic  artery,  ramifying  in  the  substance  of  the  liver,  upon  its  branches, 
and  upon  those  of  the  vena  portae. 

Branches  from  this  plexus  accompany  all  the  divisions  of  the  hepatic  artery. 
Thus  there  is  a  pyloric  plexus  accompanying  the  pyloric  branch  of  the  hepatic, 
which  joins  with  the  gastric  plexus,  and  pneumogastric  nerves.  There  is  also 
a  gastro-duodenal  plexus,  which  subdivides  into  the  pancreatico-duodenal 
plexus,  which  accompanies  the  pancreatico-duodenal  artery,  to  supply  the 
pancreas  and  duodenum,  joining  with  branches  from  the  mesenteric  plexus; 
and  a  gastro-epiploic  plexus,  which  accompanies  the  right  gastro-epiploic  artery 
along  the  greater  curvature  of  the  stomach,  and  anastomoses  with  branches 
from  the  splenic  plexus.  A  cystic  plexus,  which  supplies  the  gall  bladder, 
also  arises  from  the  hepatic  plexus,  near  the  liver. 

The  sjilenic  plexus  is  formed  hj  hrRnohes  from  the  right  and  left  semilunar 
ganglia,  and  from  the  right  pneumogastric  nerve.  It  accompanies  the  splenic 
artery  and  its  branches  to  the  substance  of  the  spleen,  giving  off,  in  its  course, 
filaments  to  the  pancreas  (pancreatic  plexus),  and  the  left  gastro-epiploic  plexus, 
which  accompanies  the  gastro-epiploica  sinistra  artery  along  the  convex  border 
of  the  stomach. 

The  suj)erior  mesenteric  plexus  is  a  continuation  of  the  lower  part  of  the  great 
solar  plexus,  receiving  a  branch  from  the  junction  of  the  right  pneumogastric  -■! 
nerve  with  the  coeliac  plexus.  It  surrounds  the  superior  mesenteric  artery,  fll 
which  it  accompanies  into  the  mesentery,  and  divides  into  a  number  of  second- 
ary plexuses,  which  are  distributed  to  all  the  parts  supplied  by  the  artery,  viz., 
pancreatic  branches  to  the  pancreas;  intestinal  branches  which  supply  the 
whole  of  the  small  intestine;  and  ileo-colic,  right  colic,  and  middle  colic 
branches,  which  supply  the  corresponding  parts  of  the  great  intestine.  The 
nerves  composing  this  plexus  are  white  in  color,  and  firm  in  texure,  and  have 
numerous  ganglia  developed  upon  them  near  their  origin. 

The  aortic  plexus  is  formed  by  branches  derived,  on  each  side,  from  the  semi- 
lunar ganglia  and  renal  plexuses,  receiving  filaments  from  some  of  the  lumbar 
ganglia.  It  is  situated  upon  the  sides  and  front  of  the  aorta,  between  the 
origins  of  the  superior  and  inferior  mesenteric  arteries.  From  this  plexus  arise 
the  inferior  mesenteric,  part  of  the  spermatic,  and  the  hypogastric  plexuses; 
and  it  distributes  filaments  to  the  inferior  vena  cava. 

The  inferior  mesenteric  plexus  is  derived  chiefly  from  the  left  side  of  the  aortio 


PELVIC  PLEXUS.  en 

plexus.  It  surrounds  the  inferior  mesenteric  artery,  and  divides  into  a  number 
of  secondary  plexuses,  which  are  distributed  to  all  the  parts  supplied  by  the 
artery,  viz.,  the  left  colic  and  sigmoid  plexuses,  which  supply  the  descending 
and  sigmoid  flexure  of  the  colon;  and  the  superior  haemorrhoidal  plexus, 
which  supplies  the  upper  part  of  the  rectum,  and  joins  in  the  pelvis  with 
branches  from  the  left  hypogastric  plexus. 

The  Lumbar  Portion  of  the  Sympathetic. 

The  Lumbar  Portion  of  the  Sympathetic  is  situated  in  front  of  the  vertebral 
column,  along  the  inner  margin  of  the  Psoas  muscle.  It  consists  usually  of 
four  ganglia,  connected  together  by  interganglionic  cords.  The  ganglia  are  of 
small  size,  of  a  grayish  color,  shaped  like  a  barley-corn,  and  placed  much  nearer 
the  median  line  than  the  thoracic  ganglia. 

The  superior  and  inferior  branches  of  the  lumbar  ganglia  serve  as  communi- 
cating branches  between  the  chain  of  ganglia  in  this  region.  They  are  usually 
single,  and  of  a  white  color. 

The  external  branches  communicate  with  the  lumbar  spinal  nerves.  From  the 
situation  of  the  lumbar  ganglia,  these  branches  are  longer  than  in  the  other 
regions.  They  are  usually  two  in  number  for  each  ganglion,  and  accompany 
the  lumbar  arteries  around  the  sides  of  the  bodies  of  the  vertebrae,  passing 
beneath  the  fibrous  arches  from  which  some  of  the  fibres  of  the  Psoas  muscle 
arise. 

The  internal  branches  pass  inwards,  in  front  of  the  aorta,  and  form  the  lumbar 
aortic  plexus,  already  described.  Other  branches  descend  in  front  of  the  com- 
mon iliac  arteries,  and  join,  over  the  promontory  of  the  sacrum,  to  form  the 
hypogastric  plexus.  Numerous  delicate  filaments  are  also  distributed  to  the 
bodies  of  the  vertebrae,  and  the  ligaments  connecting  them. 

Pelvic  Portion  of  the  Sympathetic. 

The  Pelvic  Portion  of  the  Sympathetic  is  situated  in  front  of  the  sacrum, 
along  the  inner  side  of  the  anterior  sacral  foramina.  It  consists  of  four  or  five 
small  ganglia  on  each  side,  connected  together  by  interganglionic  cords. 
Below,  these  cords  converge  and  unite  on  the  front  of  the  coccyx,  by  means  of 
a  small  ganglion  (ganglion  impar). 

The  superior  and  inferior  branches  are  the  cords  of  communication  between 
the  ganglia  above  and  below. 

The  external  branches^  exceedingly  short,  communicate  with  the  sacral  nerves. 
They  are  two  in  number  to  each  ganglion.  The  coccygeal  nerve  comniunicates 
either  with  the  last  sacral,  or  coccygeal  ganglion. 

The  internal  branches  communicate,  on  the  front  of  the  sacrum,  with  the 
corresponding  branches  from  the  opposite  side;  some,  from  the  first  two  gan- 
glia, pass  to  join  the  pelvic  plexus,  and  others  form  a  plexus,  which  accompa- 
nies the  middle  sacral  artery. 

The  hypogastric  plexus  supplies  the  viscera  of  the  pelvic  cavity.  It  is  situ- 
ated in  front  of  the  promontory  of  the  sacrum,  between  the  two  common  iliao 
arteries,  and  is  formed  by  the  union  of  numerous  filaments,  which  descend  on 
each  side  from  the  aortic  plexus,  from  the  lumbar  ganglia,  and  from  the  first 
two  sacral  ganglia.  This  plexus  contains  no  ganglia,  and  bifurcates,  below,  into 
two  lateral  portions,  which  form  the  inferior  hypogastric,  or  pelvic  plexuses. 

Inferior  Hypogastric,  or  Pelvic  Plexus. 

The  Inferior  Hypogastric,  or  Pelvic  Plexus,  is  situated  at  the  side  of  the 
rectum  and  bladder  in  the  male,  and  at  the  side  of  the  rectum,  vagina,  and 
bladder,  in  the  female.  It  is  formed  by  a  continuation  of  the  hypogastric 
plexus,  by  bran'ches  from  the  second,  third,  and  fourth  sacral  nerves,  and  by  a 


672 


SYMPATHETIC    NERYE. 


Fig.  361. — Ganglia  aad  Nerves  of  the  Gravid  Uterus  at  the  end  of  the  Ninth  Month. 

After  Dr.  K.  Lee. 


A.  The  funda!)  and  body  of  the  ateruM,  having  the  peritonpnra  dissficted  off  from  the  l*ft  side.  B.  The  vagina  covered 
Willi  tuTveit  proceeding  from  the  inferior  border  of  the  left  byixi^'tttitric  f,'»'itflion.  C.  The  rectum.  D.  The  loft  ovariom 
and  Fallopian  tube.  E.  The  tranlc  of  the  lefl  spermatic  vein  and  artery  surrounded  by  the  loft  spermatic  gauj^lion.  F. 
The  uorta  divided  a  little  above  the  origin  of-the  ri^ht  spermatic  artery,  and  about  three  inches  above  it.s  division  into  the 
two  common  iliac  arteries.  0.  The  vena  cava.  H.  Traiik  of  the  ri^rht  spermatic  vein  entering  the  vena  cava.  I.  Kight 
ureter.  K.  The  two  cords  of  the  great  sympathetic  nerve  pussiug  down  along  the  front  of  the  aorta.  L.  Trunk  of  the 
inferior  mesenteric  artery,  passing  off  from  the  aorta,  aud  covered  with  a  great  plexus  of  nerves  sent  off  from  the  left  and 
riirht  cords  oftha  great  sympathetic.  M  M.  The  two  cords  of  the  great  sympathetic  pavsing  dovrn  below  the  bii'nrcation 
of  the  aorta  to  tho  point  where  they  separate  Into  the  right  aud  loft  hypogastric  nerves.  N  The  right  hypogastric  nerve 
with  it!  artery  injected  proceeding  to  tho  neck  of  the  uterus,  t-)  terminate  iu  the  right  hypogastric  ganglion.  O.  The  lefl 
hypogastic  nerve  where  it  Is  entering  the  left  hypogastric  ganglion,  and  giving  off  brandies  to  the  left  snbperitoneni  gan- 
glion. P.  Ilnmorrhoidal  nerves  accompanying  the  liwmorrhoidal  artery  and  proceeding  from  the  greiit  plexns  which  sur- 
rounded tho  inferior  mesenteric  artery.  Q.  The  sacral  nerves  entering  the  whole  outer  surface  of  the  hypogastric  gan- 
glion. K.  The  left  hypogastric  ganglion  with  its  arteries  injected.  S.  The  nerves  of  the  vagina.  T.  Kerveswithsn 
injected  art.-ry  proceeding  from  the  upper  part  of  the  left  hypogastric  ganglion  along  the  l)ody  of  the  titerus,  and  ternii- 
DHtlng  in  the  left  spermatic  ganglion.  V.  Continuation  of  these  nerves  and  the  branches  which  they  give  off  to  the  sub- 
peritoneal plexuses.  V.  The  same  nerves  passing  upward  beneath  the  subperitoneal  plexuses,  and  anastomosing  freely 
with  them  W.  The  left  spermatic  ganglion,  in  which  the  nerves  and  artery  from  the  hypogastric  ganglion,  and  the 
branches  of  tho  left  subperitoneal  plexuses  terminate,  and  from  which  the  nerves  of  the  fundus  nteri  are  supplied.  X.  The 
left  subperitoneal  plexuses  covering  the  body  of  the  uterus.  Y.  The  left  subperitoneal  ganglion,  with  numerons  b'anrheu 
ot  nerves  exteudinif  between  it  and  tho  left  hypogastric  nerve  and  irank'lion.  Z.  The  left  common  iliac  artery  cut  across 
aud  turned  aside,  that  the  left  hypogastric  uerve  and  ganglion  mi^ht  be  traced  auJ  exposed. 


I 


PELVIC    PLEXUS.  673 

few  filaments  from  the  sacral  ganglia.  At  the  point  of  junction  of  these  nerves, 
small  ganglia  are  found.  From  this  plexus  numerous  branches  are  distributed 
to  all  the  viscera  of  the  pelvis.  Thej  accompany  the  branches  of  the  internal 
iliac  artery. 

The  inferior  hsemorrhoidal  plexus  arises  from  the  back  part  of  the  pelvic 
plexus.  It  supplies  the  rectum,  joining  with  branches  of  the  superior  ha^mor- 
rhoidal  plexus. 

The  vesical  ijlexus  arises  from  the  fore  part  of  the  pelvic  plexus.  The  nerves 
composing  it  are  numerous,  and  contain  a  large  proportion  of  spinal  nerve- 
iibres.  They  accompany  the  vesical  arteries,  and  are  distributed  to  the  side 
and  base  of  the  bladder.  Numerous  filaments  also  pass  to  the  vesiculae  semi- 
nales,  and  vas  deferens:  those  accompanying  the  vas  deferens  join,  on  the 
spermatic  cord,  with  branches  from  the  spermatic  plexus. 

1^\\Q  prostatic  plexus  is  continued  from  the  lower  part  of  the  pelvic  plexus. 
The  nerves  composing  it  are  of  large  size.  They  are  distributed  to  the  prostate 
gland,  vesiculse  seminales,  and  erectile  structure  of  the  penis.  The  nerves 
supplying  the  erectile  structure  of  the  penis  consist  of  two  sets,  the  small  and 
large  cavernous  nerves.  They  are  slender  filaments,  which  arise  from  the  fore 
part  of  the  prostatic  plexus;  and  after  joining  with  branches  from  the  internal 
pudic  nerve,  pass  forwards  beneath  the  pubic  arch. 

The  small  cavernous  nerves  perforate  the  fibrous  covering  of  the  penis,  near  its 
roots. 

Tne  large  cavernous  nerve  passes  forwards  along  the  dorsum  of  the  penis,  joins 
with  the  dorsal  branch  of  the  pudic  nerve,  and  is  distributed  to  the  corpus 
cavernosum  and  spongiosum. 

The  vaginal  plexus  arises  from  the  lower  part  of  the  pelvic  plexus.  It  is  lost 
on  the  walls  of  the  vagina,  being  distributed  to  the  erectile  tissue  at  its  anterior 
part,  and  to  the  mucous  membrane.  The  nerves  composing  this  plexus  contain, 
like  the  vesical,  a  large  proportion  of  spinal  nerve-fibres. 

The  uterine  nerves  arise  from  the  lower  part  of  the  hypogastric  plexus,  above 
the  point  where  the  branches  from  the  sacral  nerves  join  the  pelvic  plexus. 
They  accompany  the  uterine  arteries  to  the  side  of  the  organ  between  the  layers 
of  the  broad  ligament,  and  are  distributed  to  the  cervix  and  lower  part  of  the 
body  of  the  uterus,  penetrating  its  substance. 

Other  filaments  pass  separately  to  the  body  of  the  uterus  and  Fallopian  tube. 

Branches  from  the  hypogastric  plexus  accompany  the  uterine  arteries  into  the 
substance  of  the  uterus.  Upon  these  filaments  ganglionic  enlargements  are 
found.' 


For  a  detailed  account  of  the  supply  of  nerves  to  the  uterus,  and  for  a  description  of  the 
(•hanges  which  these  nerves  and  their  ganglia  undergo  during  pregnancy,  the  reader  is  referred 
to  the  papers  on  "  The  Anatomy  of  the  Nerves  of  the  Uterus,"  published  by  Dr.  Robert  Lee. 


'  This  description  of  the  sympathetic  nerve  accords  with  the  works  which  are  received  as 
standard  authorities  in  anatomy ;  but  when  the  result  of  Dr.  Robert  Lee's  dissections  shall  have 
been  published,  our  knowledge  of  the  distribution  of  the  sympathetic  system  of  nerves  will  be 
placed  upon  a  different  footing.  Dr.  Lee's  beautiful  dissections  of  the  nerves  of  the  heart,  and 
those  of  the  uterus,  have  been  long  known  to  anatomists.  Other  preparations,  as  accurate  and 
beautiful  as  these,  showing  the  communication  between  the  pneumogastric  and  sympathetic,  and 
the  supply  of  nerves  to  the  oesophagus,  stomach,  and  some  other  viscera,  were  recently  exhibited 
by  Dr.  Lee  to  the  College  of  Physicians ;  and  it  may  be  anticipated  that  Dr.  Lee  will  soon  be 
able  to  complete  and  publish  the  account  of  the  whole  sympathetic  system. 


43 


Organs  of  Sense. 


The  Organs  of  the  Senses  are  five  in  number,  viz.,  those  of  touch,  of  taste, 
of  smell,  of  hearing,  and  of  sight.  The  skin,  which  is  the  principal  seat  of  the 
sense  of  touch,  has  been  described  in  the  Introduction. 

The  Tongue. 

The  Tongue  is  the  organ  of  the  special  sense  of  taste.  It  is  situated  in  the 
floor  of  the  mouth,  in  the  interval  between  the  two  lateral  portions  of  the  body 

Fig.  362. — Upper  Surface  of  the  Tongue, 


^iTifor-m 


Fig.  363.  Theakindt    eT    ?h9\\.\.li.  ma(;nified 


of  the  lower  jaw.     Its  base,  or  root,  is  directed  backwards,  and  connected  with 
the  OS  hyoides  by  numerous  muscles,  with  the  epiglottis  by  three  folds  of 
674 


I 


THE    TONGUE.  675 

mucous  membrane,  wTiich  form  the  glosso-epiglottic  ligaments,  and  with  the 
soft  palate  and  pharynx  by  means  of  the  anterior  and  posterior  pillars  of  the 
fauces.  Its  apex  or  tip,  thin  and  narrow,  is  directed  forwards  against  the  inner 
surface  of  the  lower  incisor  teeth.  The  under  surface  of  the  tongue  is  connected 
with  the  lower  jaw  by  the  Genio-hyo-glossi  muscles;  from  its  sides,  the  mucous 
membrane  is  reflected  to  the  inner  surface  of  the  gums ;  and,  in  front,  a  distinct 
fold  of  that  membrane,  the  frsemim  Unguse,  is  formed  beneath  its  under  surface. 

The  ii2)  of  the  tongue,  part  of  its  under  surface,  its  sides,  and  dorsum,  jire  free. 

The  dorsum  of  the  tongue  is  convex,  marked  along  the  middle  line  by  a 
raphe,  which  divides  it  into  two  symmetrical  halves;  and  this  raphe  terminates 
behind,  about  half  an  inch  from  the  base  of  the  organ,  a  little  in  front  of  a  deep 
mucous  follicle,  the  foramen  csecum.  The  anterior  two-thirds  of  this  surface 
are  rough,  and  covered  with  papillao;  the  posterior  third  is  more  smooth,  and 
covered  by  the  projecting  orifices  of  numerous  muciparous  glands. 

The  mucous  membrane  invests  the  entire  extent  of  the  free  surface  of  the 
tongue.  On  the  under  surface  of  the  organ  it  is  thin  and  smooth,  and  may  be 
traced  on  either  side  of  the  frasnum,  through  the  ducts  of  the  submaxillary 
glands;  and  between  the  sides  of  the  tongue  and  the  lower  jaw,  through  the 
ducts  of  the  sublingual  glands.  As  it  passes  over  the  borders  of  the  organ,  it 
gradually  assumes  its  papillary  character. 

The  mucous  membrane  of  the  tongue  consists  of  structures  analogous  to 
those  of  the  skin,  namely,  a  cutis  or  corium,  supporting  numerous  jsopiY^a?,  and 
covered,  as  well  as  the  papillae,  with  epithelium. 

The  cutis  is  tough,  but  thinner  and  less  dense  than  in  most  parts  of  the  skin, 
and  is  composed  of  similar  tissue.  It  contains  the  ramifications  of  the  nume- 
rous vessels  and  nerves  from  which  the  papillas  are  supplied,  and  affords  inser- 
tion to  all  the  intrinsic  muscular  fibres  of  the  organ. 

The  papillae  of  the  tongue  are  thickly  distributed  over  the  whole  of  its  upper 
surface,  giving  to  it  its  characteristic  roughness.  They  are  more  prominent 
than  those  of  the  skin,  standing  out  from  the  surface  like  the  villi  of  the  intes- 
tine. The  principal  varieties  are  the  papillae  minimae  (circumvallatee),  papillae 
mediae  (fungiformes),  and  papillae  minimae  (conic£e  or  filiformes). 

The  7)a/>«7/a?  maximse  (circumvallatae)  are  of  large  size,  and  vary  from  eight 
to  ten  in  number.  They  are  situated  at  the  back  part  of  the  dorsum  of  the 
tongue,  near  its  base,  forming  a  row  on  each  side,  Avhich,  running  backwards 
and  inwards,  meet  in  the  middle  line,  like  the  two  lines  of  the  letter  V  inverted. 
Each  papilla  consists  of  a  central  flattened  projection  of  mucous  membrane,  cir- 
cular in  form,  from  ^'^  to  ^'.3  of  an  inch  wide,  attached  to  the  bottom  of  a  cup- 
shaped  depression  of  the  mucous  membrane ;  the  exposed  part  being  covered 
with  numerous  small  papillae.  The  cup-shaped  depression  forms  a  kind  of  fossa 
round  the  papilla,  having  a  circular  margin  of  about  the  same  elevation,  covered 
with  smaller  papillae.  The  fissure  corresponding  to  the  papilla,  which  is  situ- 
ated at  the  junction  of  the  two  lines  of  the  circumvallate  papilla,  is  so  large 
and  deep,  that  the  name /ommew  csecum  has  been  applied  to  it.  In  the  smaller 
papillee,  the  fissure  exists  only  on  one  side. 

The  papillse  medise  (fungiformes),  more  numerous  than  the  preceding,  are 
scattered  irregularly  and  sparingly  over  -the  dorsum  of  the  tongue ;  but  are 
found  chiefly  at  its  sides  and  apex.  They  are  easily  recognized,  among  the 
other  papilla9,  by  their  large  size,  rounded  eminences,.and  deep  red  color.  They 
are  narrow  at  their  attachment  to  the  tongue,  but  broad  and  rounded  at  their 
free  extremities,  and  covered  with  secondary  papillae.  Their  epithelial  invest- 
ment is  very  thin. 

The  papillae  minimse  (conicae,  filiformes)  cover  the  anterior  two-thirds  of  the 
dorsum  of  the  tongue.  They  are  very  minute,  more  or  less  conical  or  filiform 
in  shape,  and  arranged  in  lines  corresponding  in  direction  with  the  two  rows 
of  the  papillae  circumvallatae ;  excepting  at  the  apex  of  the  organ,  where  their 
direction  is  transverse.     The  filiform  papillse  are  of  a  whitish  tint,  owing  to  the 


C76  ORGANS    OF    SENSE. 

thickness  and  density  of  their  epithelium ;  they  are  covered  with  numerous 
secondary  papillas,  are  firmer  and  more  elastic  than  the  papilloe  of  mucous  mem- 
brane generally,  and  often  inclose  minute  hairs. 

Simple  j^apillse,  similar  to  those  of  the  skin,  are  dispersed  very  unequally 
among  the  compound  forms,  and  exist  sparingly  on  the  surface  of  the  tongue 
behind  the  circumvallate  variety,  buried  under  a  layer  of  epithelium. 

Structure  of  the  papillse.  The  papillae  apparently  resemble  in  structure  those 
of  the  cutis,  consisting  of  a  cone-shaped  projection  of  homogeneous  tissue, 
covered  with  a  thick  layer  of  squamous  epithelium,  and  contain  one  or  more 
capillary  loops,  amongst  which  nerves  are  distributed  in  great  abundance.  If 
the  epithelium  is  removed,  it  will  be  found  that  they  are  not  simple  processes 
like  the  papillae  of  the  skin,  for  the  surface  of  each  is  studded  with  minute 
conical  processes  of  the  mucous  membrane,  which  form  secondary  papilla3  (Todd 
and  Bowman).  In  the  papillae  circumvallatae,  the  nerves  are  numerous  and  of 
large  size;  in  the  papillae  fungiformes  they  are  also  numerous,  and  terminate  in 
a  plexiform  network,  from  which  brush-like  branches  proceed ;  in  the  papillae 
filiforraes,  their  mode  of  termination  is  uncertain. 

Besides  the  papillae,  the  mucous  membrane  of  the  tongue  is  provided  with 
numerous  foll'cles  and  glands. 

The  follicles  are  found  scattered  over  its  entire  surface,  but  are  especially 
numerous  between  the  papillae  circumvallatae  and  the  epiglottis. 

The  mucous  glands  (lingual),  similar  in  structure  to  the  labial  and  buccal,  are 
found  chiefly  beneath  the  mucous  membrane  of  the  posterior  third  of  the 
dorsum  of  the  tongue.  There  is  a  small  group  of  these  glands  beneath  the  tip 
of  the  tongue,  a  few  along  the  borders  of  the  organ,  and  some  in  front  of  the 
circumvallate  papillae  projecting  into  the  muscular  substance.  Their  ducts  open 
either  upon  the  surface,  or  into  the  depressions  round  the  large  papillae. 

The  epithelium  is  of  the  scaly  variety  like  that  of  the  epidermis.  It  covers  the 
free  surface  of  the  tongue,  as  may  be  easily  demonstrated  by  maceration,  or 
boiling,  when  it  can  be  detached  entire.  It  is  much  thinner  than  in  the  skin ; 
the  intervals  between  the  large  papillae  are  not  filled  up  by  it,  but  each  papillae 
has  a  separate  investment  from  root  to  summit.  The  deepest  cells  may  some- 
times be  detached  as  a  separate  layer,  corresponding  to  the  rete  mucosum,  but 
they  never  contain  coloring  matter. 

The  tongue  consists  of  two  symmetrical  halves,  separated  from  each  other, 
in  the  middle  line,  by  a  fibrous  septum.  Each  half  is  composed  of  muscular  fibres 
arranged  in  various  directions,  containing  much  interposed  fat,  and  supplied  by 
vessels  and  nerves;  the  entire  organ  is  invested  by  mucous  membrane,  and  a 
submucous  fibrous  stratum.  The  latter  membrane  invests  the  greater  part  of 
the  surface  of  the  tongue,  and  into  it  the  muscular  fibres  are  inserted  that  pass 
to  the  surface.  It  is  thicker  behind  than  in  front,  and  is  continuous  with  the 
sheaths  of  the  muscles  attached  to  it. 

The  fibrous  sej>tum  consists  of  a  vertical  layer  of  fibrous  tissue,  extending 
throughout  the  entire  length  of  the  middle  line  of  the  tongue,  from  the  base  to 
the  apex.  It  is  thicker  behind  than  in  front,  and  occasionally  contains  a  small 
fibro-cartilage,  about  a  quarter  of  an  inch  in  length.  It  is  well  displayed  by 
making  a  vertical  section  across  the  organ.  Another  strong  fibrous  lamina, 
termed  the  liyo-glossal  membrane^  connects  the  under  surface  of  the  base  of  the 
tongue  to  the  body  of  the  hyoid  bone.  This  membrane  receives,  in  front,  some 
of  the  fibres  of  the  Genio-hyo-glossi. 

Each  half  of  the  tongue  consists  of  extrinsic  and  intrinsic  muscles.  The 
former  have  been  already  described ;  they  are  the  Ily  o-glossus,  Genio-hyo-glossus, 
Sty  lo-glossus,  Palato-glossus,  and  part  of  the  Superior  Constrictor.  The  intrinsic 
muscles  are  the  Superior  Longitudinal,  Inferior  Longitudinal,  and  Transverse. 

The  superior  longitudinal  fibres  {lingnalis  stiperficialin)  form  a  superficial 
stratum  of  oblique  and  longitudinal  fibres  on  the  upper  surface  of  the  organ, 
beneath  the  mucous  membrane,  and  extend  from  the  apex  backwards  to  the 


THE    NOSE. 


cn 


hyoid  bone,  the  individual  fibres  being  attacbed  in  tbeir  course  to  the  sub- 
mucous and  glandular  structures. 

The  inferior  longitudinal  fibres  are  formed  by  the  Lingualis  muscle,  already 
described  (p.  339). 

The  transverse  fibres  are  placed  between  the  two  preceding  layers ;  they  are 
intermixed  with  a  considerable  quantity  of  adipose  substance,  and  form  the 
chief  part  of  the  substance  of  the  organ.  They  are  attached  internally  to  the 
median  fibrous  septum;  and,  passing  outwards,  the  posterior  ones  taking  an 
arched  course,  are  inserted  into  tTie  dorsum  and  margins  of  the  organ,  inter- 
secting the  other  muscular  fibres. 

The  arteries  of  the  tongue  are  derived  from  the  lingual,  the  facial,  and  ascend- 
ing pharyngeal.  ^ 

The  nerves  of  the  tongue  are  three  in  number  in  each  half:  the  gustatory 
branch  of  the  fifth,  which  is  distributed  to  the  papillae  at  the  fore  part  and 
sides  of  the  tongue;  the  lingual  branch  of  the  glosso-pharyngeal,  which  is 
distributed  to  the  mucous  membrane  at  the  base  and  side  of  the  tongue,  and  to 
the  papillae  circumvallata? ;  and  the  hypoglossal  nerve,  which  is  distributed  to 
the  muscular  substance  of  the  tongue.  The  two  former  are  nerves  of  common 
sensation  and  of  taste ;  the  latter  is  the  motor  nerve  cf  the  tongue. 

The  Nose. 

The  Nose  is  the  special  organ  of  the  sense  of  smell :  by  means  of  the  peculiar 
properties  of  its  nerves,  it  protects  the  lungs  from  the  inhalation  of  deleterious 
gases,  and  assists  the  organ  of  taste  in  discriminating  the  properties  of  food. 

The  organ  of  smell  consists  of  two  parts,  one  external,  the  nose ;  the  other 
internal,  the  nasal  fosste. 

The  nose  is  the  more  anterior  and  prominent  part  of  the  organ  of  smell.  It 
is  of  a  triangular  form,  directed  vertically  downwards,  and  projects  from  the 
centre  of  the  face,  immediately  above  the  upper  lip.  Its  summit,  or  root,  is 
connected  directly  with  the  forehead.     Its  inferior  part,  the  base  of  the  nose, 

Figs.  364,  365.— Cartilages  of  the  Nose. 


Seen   from    Iclov 


Lou-erLateirat  Ct 


Suamcld  Ct 


presents  two  elliptical  orifices,  the  nostrils,  separated  from  each  other  by  an 
antero-posterior  septum,  the  columna.  The  margins  of  these  orifices  are  pro- 
vided with  a  number  of  stiff  hairs,  or  vibrissa;,  which  arrest  the  passage  of 
foreign  substances  carried  with  the  current  of  air  intended  for  respiration.  The 
lateral  surfaces  of  the  nose  form,  by  their  union,  the  dorsum,  the  direction  of 


678 


ORGANS    OF    SENSE. 


which  varies  considerably  in  different  individuals.  The  dorsum  terminates 
below  in  a  rounded  eminence,  the  lobe  of  the  nose. 

The  nose  is  composed  of  a  framework  of  bones  and  cartilages,  the  latter 
being  slightly  acted  upon  by  certain  muscles.  It  is  covered  externally  by  the 
integument,  internally  by  mucous  membrane,  and  supplied  with  vessels  and 
nerves. 

The  hony  framework  occupies  the  upper  part  of  the  organ;  it  consists  of  the 
nasal  bones,  and  the  nasal  processes  of  the  superior  maxillary. 

The  cartilaginous  framework  consists  of  five  pieces,  the  two  upper,  and  the  two 
lower  lateral  cartilages,  and  the  cartilage  of  the  septum. 

The  upper  lateral  cartilages  are  situated  below  the  free  margin  of  the  nasal 
bones  ;  each  cartilage  is  flattened,  and  triangular  in  shape.  Its  anterior  margin 
is  thicker  than  the  posterior,  and  connected  with  the  fibro-cartilage  of  the  sep- 
tum. Its  posterior  margin  is  attached  to  the  nasal  process  of  the  superior  max- 
illary and  nasal  bones.  Its  inferior  margin  is  connected  by  fibrous  tissue  with 
the  lower  lateral  cartilage ;  one  surface  is  turned  outwards,  the  other  inwards 
towards  the  nasal  cavity. 

The  hiver  lateral  cartilages  are  two  thin,  flexible  plates,  situated  immediately 
below  the  preceding,  and  curved  in  such  a  manner  as  to  form  the  inner  and  outer 

walls  of  each  orifice  of  the  nostril. 


Fig.  366. — Bones  and  Cartilages  of  Septum 
of  Nose.    Right  Side. 


The  portion  which  forms  the  inner 
wall,  thicker  than  the  rest,  is  loosely 
connected  with  the  same  part  of  the 
opposite  cartilage,  and  forms  a  small 
part  of  the  columna.  Its  outer  ex- 
tremity, free,  rounded,  and  projecting, 
forms,  with  the  thickened  integument 
and  subjacent  tissue,  the  lobe  of  the 
nose.  The  part  which  forms  the 
outer  wall  is  curved  to  correspond 
with  the  ala  of  the  nose ;  it  is  oval 
and  flattened,  narrow  behind,  where 
it  is  connected  with  the  nasal  process 
of  the  superior  maxilla  by  a  tough 
fibrous  membrane,  in  which  are  found 
three  or  four  small  cartilaginous 
plates  (sesamoid  cartilages),  cartila- 
gines  minores.  Above,  it  is  connected 
to  the  upper  lateral  cartilage  and 
front  part  of  the  cartilage  of  the  septum  ;  below,  it  is  separated  from  the  mar- 
gin of  the  nostril  by  dense  cellular  tissue ;  and  in  front,  it  forms,  with  its  fellow, 
the  prominence  of  the  tip  of  the  nose. 

The  cartilage  of  the  septum  is  somewhat  triangular  in  form,  thicker  at  its 
margins  than  at  its  centre,  and  completes  the  separation  between  the  nasal  fossa 
in  front.  Its  anterior  margin,  thickest  above,  is  connected  from  above  down- 
wards with  the  nasal  bones,  the  front  part  of  the  two  upper  lateral  cartilages, 
and  the  inner  portion  of  the  two  lower  lateral  cartilages.  Its  posterior  margin 
is  connected  with  the  perpendicular  lamella  of  the  ethmoid;  its  inferior  margin 
with  the  vomer  and  the  palate  processes  of  the  superior  maxillary  bones. 

These  various  cartilages  are  connected  to  each  other,  and  to  the  bones,  by  a 
tough  fibrous  membrane,  the  perichondrium,  which  allows  the  utmost  facility 
of  movement  between  them. 

The  muscles  of  the  nose  are  situated  immediately  beneath  the  integument; 
they  are  (on  each  side)  the  Pyramidalis  Nasi,  the  Levator  Labii  Superioris  Ala?- 
que  Nasi,  the  Dilatator  Naris  (anterior  and  posterior,)  the  Compressor  Nasi,  the 
Com)n'esHor  Narium  Minor,  and  the  Depressor  Alie  Nasi.  They  have  been 
already  described  under  the  muscles  of  the  nasal  region. 


NASAL    FOSS^.  679 

The  integument  covering  the  dorsum  and  sides  of  the  nose  is  thin,  and  loosely 
connected  with  the  subjacent  parts;  but  where  it  forms  the  tip  or  lobe,  and  the 
alas  of  the  nose,  it  is  thicker  and  more  firmly  adherent.  It  is  furnished  with  a 
large  number  of  sebaceous  follicles,  the  orifices  of  which  are  usually  very  dis- 
tinct. 

The  mucous  memh-ane,  lining  the  interior  of  the  nose,  is  continuous  with  the 
skin  externally,  and  with  that  which  lines  the  nasal  fossae  within. 

The  arteries  of  the  nose  are  the  lateralis  nasi,  from  the  facial,  and  the  nasal 
artery  of  the  septum,  from  the  superior  coronary,  which  supplies  the  alae  and 
septum;  the  sides  and  dorsum  being  supplied  from  the  nasal  branch  of  the  oph- 
thalmic and  the  infraorbital. 

The  veins  of  the  nose  terminate  in  the  facial  and  ophthalmic. 

The  nerves  of  the  nose  are  branches  from  the  facial,  infraorbital,  and  infra- 
trochlear,  and  a  filament  from  the  nasal  branch  of  the  ophthalmic. 

Nasal  Fossje. 

The  Nasal  Fossae  are  two  irregular  cavities,  situated  in  the  middle  of  the  face 
and  extending  from  before  backwards.  They  open  in  front  by  the  two  anterior 
nares,  and  terminate  in  the  pharynx,  behind  by  the  posterior  nares.  The  boun- 
daries of  these  cavities,  and  the  openings  which  are  connected  with  them,  as  they 
exist  in  the  skeleton,  have  been  already  described  (pp.  187-189). 

The  mucous  membrane  lining  the  nasal  fossas  is  called  pituitary,  from  the 
nature  of  its  secretion  ;  or  Schneiderian,  from  Schneider,  the  first  anatomist  who 
showed  that  the  secretion  proceeded  from  the  mucous  membrane,  and  not,  as  was 
formerly  imagined,  from  the  brain.  It  is  intimately  adherent  to  the  periosteum, 
or  perichondrium,  over  which  it  lies.  It  is  continuous  externally  with  the  skin, 
through  the  anterior  nares,  and  with  the  mucous  membrane  of  the  pharynx, 
through  the  posterior  nares.  From  the  nasal  fossae  its  continuity  may  be  traced 
with  the  conjunctiva,  through  the  nasal  duct  and  lachrymal  canals;  with  the 
lining  membrane  of  the  tympanum  and  mastoid  cells,  through  the  Eustachian 
tube ;  and  with  the  frontal,  ethmoidal,  and  sphenoidal  sinuses,  and  the  antrum 
maxillare,  through  the  several  openings  in  the  meatuses.  The  mucous  mem- 
brane is  thickest,  and  most  vascular,  over  the  turbinated  bones.  It  is  also  thick 
over  the  septum  ;  but,  in  the  intervals  between  the  spongy  bones,  and  on  the 
floor  of  the  nasal  fossa,  it  is  very  thin.  Where  it  lines  the  various  sinuses  and 
the  antrum  maxillare,  it  is  thin  and  pale. 

The  surface  of  the  membrane  is  covered  with  a  layer  of  tessellated  epithelium, 
at  the  upper  part  of  the  nasal  fossae,  corresponding  with  the  distribution  of  the 
olfactory  nerve,  but  is  ciliated  throughout  the  rest  of  its  extent,  excepting  near 
the  aperture  of  the  nares. 

This  membrane  is  also  provided  with  a  nearly  continuous  layer  of  branched 
mucous  glands,  the  ducts  of  which  open  upon  its  surface.  They  are  most  nume- 
rous at  the  middle  and  back  parts  of  the  nasal  fossae,  and  largest  at  the  lower 
and  back  part  of  the  septum. 

Owing  to  the  great  thickness  of  this  membrane,  the  nasal  fossae  are  much  nar- 
rower, and  the  turbinated  bones,  especially  the  lower  ones,  appear  larger,  and 
more  prominent,  than  in  the  skeleton.  From  the  same  circumstance,  also,  the 
various  apertures  communicating  with  the  meatuses  are  either  narrowed  or 
completely  closed. 

In  the  superior  meatus,  the  aperture  of  communication  with  the  posterior 
ethmoidal  cells  is  considerably  diminished  in  size,  and  the  spheno-palatine  fora- 
men completely  covered  in. 

In  the  middle  meatus,  the  opening  of  the  infundibulum  is  partially  hidden  by 
a  projecting  fold  of  mucous  membrane,  and  the  orifice  of  the  antrum  is  con- 
tracted to  a  small  circular  aperture,  much  narrower  than  in  the  skeleton. 

In  the  inferior  meatus,  the  orifice  of  the  nasal  duct  is  partially  hidden  by  either 


Side. 


680  ORGANS    OF    SENSE. 

a  single  or  double  valvular  mucous  fold,  and  the  anterior  palatine  canal  either 
completely  closed  in,  or  a  tubular  cul-de-sac  of  mucous  membrane  is  continued 
a  short  distance  into  it. 

In  the  roof^  the  opening  leading  to  the  sphenoidal  sinus  is  narrowed,  and  the 
apertures  in  the  cribriform  plate'of  the  ethmoid  completely  closed  in. 

The  arteries  of  the  nasal  fossse  are  the  anterior  and  posterior  ethmoidal,  from 
the  ophthalmic,  which  supply  the  ethmoidal  cells,  frontal  sinuses,  and  roof  of 
the  nose ;  the  spheno-palatine,  from  the  internal  maxillary,  which  supplies  the 
mucous  membrane  covering  the  spongy  bones,  the  meatuses,  and  septum ;  and 
the  alveolar  branch  of  the  internal  maxillary,  which  supplies  the  lining  mem- 
brane of  the  antrum.  The  ramifications  of  these  vessels  form  a  close,  plexiform 
network,  beneath  and  in  the  substance  of  the  mucous  membrane. 

The  veins  of  the  nasal  fossse  form  a  close  network  beneath  the  mucous  mem- 
brane.    They  pass,  some  with  the  veins  accompanying  the  spheno-palatine 

artery,  through  the  spheno-palatine 
Fig.  367.— Nerves  of  Septum  of  Nose.  Right  foramen ;  and  others,  through  the  al- 
veolar branch,  join  the  facial  vein ; 
some  accompany  the  ethmoidal  arte- 
ries, and  terminate  in  the  ophthalmia 
vein ;  and,  lastly,  a  few  communicate 
with  the  veins  in  the  interior  of  the 
skull,  through  the  foramina  in  the 
cribriform  plate  of  the  ethmoid  bone, 
and  the  foramen  caecum. 

The  nerves  are,  the  olfactory,  the 
nasal  branch  of  the  ophthalmic,  fila- 
ments from  the  anterior  dental  branch 
of  the  superior  maxillary,  the  Vidian, 
naso-palatine,  descending  anterior  pala- 
tine, and  spheno-palatine  branches  of 
Meckel's  ganglion. 

The  olfactory,  the  special  nerve  of  tho 
sense  of  smell,  is  distributed  over  the 
upper  third  of  the  septum,  and  over  the  surface  of  the  superior  and  middle 
spongy  bones. 

The  nasal  branch  of  the  ophthalmic  distributes  filaments  to  the  upper  and 
anterior  part  of  the  septum,  and  outer  wall  of  the  nasal  fossa). 

Filaments  froin  the  anterior  dental  branch  of  the  superior  maxillary  supply  the 
inferior  meatus  and  inferior  turbinated  bone. 

The  Vidian  nerve  supplies  the  upper  and  back  part  of  the  septum,  and  supe- 
rior spongy  bone;  and  the  upper  anterior  nasal  branches  from  the  spheno- 
palatine ganglion,  have  a  similar  distribution. 

The  naso-palatine  nerve  supplies  the  middle  of  the  septum. 
The  larger^  or  anterior  palatine  nerve,  supplies  the  middle  and  lower  spongy 
bones. 

The  Eye. 

The  Eyeball  is  contained  in  the  cavity  of  the  orbit.  In  this  situation  it  is 
securely  protected  from  injury,  whilst  its  position  is  such  as  to  insure  the  most 
extensive  range  of  sight.  It  is  acted  upon  by  numerous  muscles,  by  which  it 
is  capable  of  being  directed  to  any  part,  supplied  by  vessels  and  nerves,  and  is 
additionally  protected  in  front  by  several  appendages,  such  as  the  eyebrow, 
eyelids,  &c. 

The  eyeball  is  spherical  in  form,  having  the  segments  of  a  smaller  and  mrro 
prominent  sphere  engrafted  upon  its  anterior  part.  It  is  from  this  circumstance 
that  the  antero-posterior  diameter  of  the  eyeball,  which  measures  about  an  inch, 
exceeds  the  transverse  diameter  by  about  a  line.     The  segment  of  the  larger 


THE    EYE. 


681 


sphere,  whicli  forms  about  five-sixths  of  the  globe,  is  opaque,  and  formed  by 
the  sclerotic,  the  tunic  of  protection  to  the  eyeball;  the  smaller  sphere,  which 
forms  the  remaining  sixth,  is  transparent,  and  formed  by  the  cornea.  The  axes 
of  the  ej^eballs  are  nearly  parallel,  and  do  not  correspond  to  the  axes  of  the 
orbits,  which  are  directed  outwards.  The  optic  nerves  follow  the  direction  of 
the  axes  of  the  orbits,  and  enter  the  eyeball  a  little  to  their  inner  or  nasal  side. 
The  eyeball  is  composed  of  several  investing  tunics,  and  of  fluid  and  solid 
refracting  media,  called  humors. 

The  tunics  are  three  in  number: — • 

1.  Sclerotic  and  Cornea. 

2.  Choroid,  Iris,  and  Ciliary  Processes. 

3.  Retina. 

The  refracting  media,  or  humors,  are  also  three : — 

Aqueous.  Crystalline  (lens)  and  Capsule.  Vitreous. 

The  sclerotic  and  cornea  form  the  external  tunic  of  the  eyeball ;  they  are 
essentially  fibrous  in  structure,  the  sclerotic  being  opaque,  and  forming  the 
posterior  five-sixths  of  the  globe;  the  cornea,  which  forms  the  remaining  sixth, 
being  transparent. 

The  Sclerotic  ((rxxi^pdj,  hard)  (Fig.  868)  has  received  its  name  from  its  extreme 
density  and  hardness ;  it  is  a  firm,  unyielding,  fibrous  membrane,  serving  to 

Fig.  368.— A  Yertical  Section  of  the  Eyeball.     (Enlarged.) 


Tendon  of  RECTO* 


Uyalold  Me  mi  rant 


Ciliary  Mimele 
It  Lignme-nt 


'irciiTar  Stnu» 
■anal   rf  JPetit 


maintain  the  form  of  the  globe.  It  is  much  thicker  behind  than  in  front.  Its 
external  surface  is  of  a  white  color,  quite  smooth,  except  at  the  points  where 
the  Recti  and  Obliqui  muscles  are  inserted  into  it,  and  covered,  for  part  6f  its 
extent,  by  the  conjunctival  membrane;  hence  the  whiteness  and  brilliancy  of 
the  front  of  the  eyeball.  Its  inner  surface  is  stained  of  a  brown  color,  marked 
by  grooves,  in  which  are  lodged  the  ciliary  nerves,  and  connected  by  an  exceed- 
ingly fine  cellular  tissue  {lamina  fusca  with  the  outer  surface  of  the  choroid. 
Behind,  it  is  pierced  by  the  optic  nerve  a  little  to  its  inner  or  nasal  side,  and  is 
continuous  with  the  fibrous  sheath  of  the  nerve,  which  is  derived  from  the  dura 
mater.  At  the  point  where  the  optic  nerve  passes  through  the  sclerotic,  this 
membrane  forms  a  thin  cribriform  lamina  (the  lainina  criorosa);  the  minute 


682  ORGANS    OF    SENSE. 

orifices  in  this  layer  serve  for  tlie  transmission  of  the  nervous  filaments,  and 
the  fibrous  septa  dividing  them  from  one  another  are  continuous  with  the  mem- 
branous processes  which  separate  the  bundles  of  nerve-fibres.  One  of  these 
openings,  larger  than  the  rest,  occupies  the  centre  of  the  lamella ;  it  is  called 
the  porus  opticus,  and  transmits  the  arteria  centralis  retinas  to  the  interior  of  the 
eyeball.  Around  the  cribriform  lamella  are  numerous  smaller  apertures  for  the 
transmission  of  the  ciliary  vessels  and  nerves.  In  front,  the  sclerotic  is  con- 
tinuous with  the  cornea  by  direct  continuity  of  tissue ;  but  the  opaque  sclerotic 
overlaps  the  cornea  rather  more  on  its  outer  than  upon  its  inner  surface. 

Structure.  The  sclerotic  is  formed  of  white  fibrous  tissue  intermixed  with 
fine  elastic  fibres,  and  fusiform  nucleated  cells.  These  are  aggregated  into 
bundles,  which  are  arranged  chiefly  in  a  longitudinal  direction.  It  yields 
gelatin  on  boiling.  Its  vessels  are  not  numerous,  the  capillaries  being  of  small 
size,  uniting  at  long  and  wide  intervals.  The  existence  of  nerves  in  it  is 
doubtful. 

The  Cornea  is  the  projecting  transparent  part  of  the  external  tunic  of  the 
eyeball,  and  forms  the  anterior  sixth  of  the  globe.  It  is  not  quite  circular, 
being  a  little  broader  in  the  transverse  than  in  the  vertical  direction,  in  conse- 
quence of  the  sclerotic  overlapping  the  margin  above  and  below.  It  is  convex 
anteriorly,  and  projects  forwards  from  the  sclerotic  in  the  same  manner  that  a 
watch-glass  does  from  its  case.  Its  degree  of  curvature  varies  in  different  indi- 
viduals, and  in  the  same  individual  at  different  periods  of  life,  it  being  more 
prominent  in  youth  than  in  advanced  life,  when  it  becomes  flattened.  The 
cornea  is  dense  and  of  uniform  thickness  throughout;  its  posterior  surface  is 
perfectly  circular  in  outline,  and  exceeds  the  anterior  surface  slightly  in  extent, 
from  the  latter  being  overlapped  by  the  sclerotic. 

Structure.  The  cornea  consists  of  five  layers:  namely,  of  a  thick  central 
fibrous  structure,  the  cornea  proper;  in  front  of  this  is  the  anterior  elastic 
lamina,  covered  by  the  conjunctiva;  behind,  the  posterior  elastic  lamina, 
covered  by  the  lining  membrane  of  the  anterior  chamber  of  the  eyeball. 

The  proper  substance  of  the  cornea  is  fibrous,  tough,  unyielding,  perfectly 
transparent,  and  continuous  with  the  sclerotic,  with  which  it  is  in  structure 
identical.  The  anastomosing  fusiform  cells  of  which  it  is  composed  are  arranged 
in  superimposed  flattened  laminae,  at  least  sixty  in  number,  all  of  which  have 
the  same  direction,  the  contiguous  laminae  becoming  united  at  frequent  inter- 
vals. If  the  relative  position  of  the  component  parts  of  this  tissue  is  in  any 
way  altered,  either  by  pressure  or  by  an  increase  of  its  natural  tension,  it  im- 
mediately presents  an  opaque  milky  appearance.  The  interstices  between  the 
laminae  are  tubular,  and  usually  contain  a  small  amount  of  transparent  fluid. 

The  anterior  and  posterior  elastic  laminse,  which  cover  the  proper  structure  of 
the  cornea  behind  and  in  front,  present  an  analogous  structure.  They  consist 
of  a  hard,  elastic,  and  perfectly  transparent  homogeneous  membrane,  of  extreme 
thinness,  which  is  not  rendered  opaque  by  either  water,  alcohol,  or  acids.  This 
membrane  is  intimately  connected  by  means  of  a  fine  cellular  web  to  the  proper 
substance  of  the  cornea  both  in  front  and  behind.  Its  most  remarkable  pro- 
perty is  its  extreme  elasticity,  and  the  tendency  which  it  presents  to  curl  up, 
or  roll  upon  itself,  with  the  attached  surface  innermost,  when  separated  from 
the  proper  substance  of  the  cornea.  Its  use  appears  to  be  (as  suggested  by  Dr. 
Jacob),  "  to  preserve  the  requisite  permanent  correct  curvature  of  the  flaccid 
cornea  proper." 

The  conjunctival  epithelium,  which  covers  the  front  of  the  anterior  elastic 
lamina,  consists  of  two  or  three  layers  of  transparent  nucleated  cells,  the  deepest 
being  of  an  oblong  form  and  placed  perpendicular  to  the  surface,  the  sui)erficial 
ones  more  flattened. 

The  epithelial  lining  of  the  aqueous  chamber  covers  the  posterior  surface  of 
the  posterior  elastic  lamina.  It  consists  of  a  single  layer  of  polygonal  transpa- 
rent nucleated  cells,  similar  to  those  found  lining  other  serous  cavities. 


THE  SCLEROTIC  AND  CORNEA. 


683 


Arteries  and  Nerves.  The  cornea  is  a  non-vascular  structure,  the  capillary 
vessels?  terminating  in  loops  at  its  circumference.  Lymphatic  vessels  have  not 
as  yet  been  demonstrated  in  it.  The  nerves  are  numerous,  twenty  or  thirty  in 
number:  they  are  derived  from  the  ciliary  nerves,  and  enter  the  laminated 
substance  of  the  cornea.  They  ramify  throughout  its  substance  in  a  delicate 
network. 

Dissection.  In  order  to  separate  the  sclerotic  and  cornea,  so  as  to  expose  the  second  tunic, 
the  ej'eball  should  be  immersed  in  a  small  vessel  of  water.  A  fold  of  the  sclerotic  near  its  ante- 
rior part  having  been  pinched  up,  an  operation  not  easily  performed,  from  the  extreme  tension 
of  the  membrane,  it  should  be  divided  with  a  pair  of  blunt-pointed  scissors.  As  soon  as  the 
choroid  is  exposed,  the  end  of  a  blowpipe  should  be  introduced  into  the  orifice,  and  a  stream 
of  air  forced  into  it,  so  as  to  separate  the  slight  cellular  connection  between  the  sclerotic  and 
choroid.  The  sclerotic  should  now  be  divided  around  its  entire  circumference,  and  may  be 
removed  in  separate  portions.  The  front  segment  being  then  drawn  forwards,  the  handle  of  the 
scalpel  should  be  pressed  gently  against  it  at  its  connection  with  the  iris,  and  these  being  sepa- 
rated, a  quantity  of  perfectly  transparent  fluid  will  escape ;  this  is  the  aqueous  humor.  In  the 
course  of  the  dissection,  the  ciliary  nerves  may  be  seen  lying  in  the  loose  cellular  tissue  between 
the  choroid  and  sclerotic,  or  contained  in  delicate  grooves  on  the  inner  surface  of  the  latter 
membrane. 

Fig.  369. — The  Choroid  and  Iris.     (Enlarged.) 


Second  Tunic.  This  is  formed  by  the  choroid  behind;  the  iris  and  ciliary 
processes  in  front;  and  by  the  ciliary  ligament,  and  Ciliary  muscle,  at  the  point 
of  junction  of  the  .sclerotic  and  cornea. 

The  choroid  is  the  vascular  and  pigmentary  tunic  of  the  eyeball,  investing 
the  posterior  five-sixths  of  the  globe,  and  extending  as  far  forwards  as  the 
cornea;  the  ciliary  processes  being  appendages  of  the  choroid  developed  from 
its  inner  surface  in  front.  The  iris  is  the  circular  muscular  septum,  which 
hangs  vertically  behind  the  cornea,  presenting  in  its  centre  a  large  circular 
aperture,  the  pupil.  The  ciliary  ligament  and  Ciliary  muscle  form  the  white 
ring  observed  at  the  point  where  the  choroid  and  iris  join  with  each  other,  and 
with  the  sclerotic  and  cornea. 

The  Choroid  is  a  thin,  highly  vascular  membrane,  of  a  dark  brown  or  choco- 
late color,  which  invests  the  posterior  five-sixths  of  the  central  part  of  the 
globe.  It  is  pierced  behind  by  the  optic  nerve,  and  terminates  in  front  at  the 
ciliary  ligament,  where  it  bends  inwards,  and  forms  on  its  inner  surface  a  series 
of  folds  or  plaitings,  the  ciliary  processes.     It  is  thicker  behind  than  in  front. 


684  ORGANS    OF    SENSE. 

Externally,  it  is  connected  by  a  fine  cellular  web  {membrana  fusca)  with  the 
inner  surface  of  the  sclerotic.  Its  inner  surface  is  smooth,  and  lies  in  contact 
with  the  retina.  The  choroid  is  composed  of  three  layers,  external,  middle, 
and  internal. 


The  Veins  of  the  Choroid.    (Enlarged.) 


The  external  layer  consists,  in  part,  of  the  larger  branches  of  the  short  ciliary 
arteries,  which  run  forwards  between  the  veins  before  they  bend  downwards  to 
terminate  on  the  inner  surface.  This  coat  is  formed,  however,  principally  of 
veins,  which  are  named,  from  their  distribution,  venw  vorticosse.  They  converge 
to  four  or  five  equidistant  trunks,  which  pierce  the  sclerotic  midway  between 
the  margin  of  the  cornea  and  the  entrance  of  the  optic  nerve.  Interspersed 
between  the  vessels  are  lodged  dark  star-shaped  pigment-cells,  the  fibrous  offsets 
from  which,  communicating  with  similar  branchings  from  neighboring  cells, 
form  a  delicate  network,  which,  towards  the  inner  surface  of  the  choroid,  loses 
its  pigmentary  character. 

The  middle  layer  consists  of  an  exceedingly  fine  capillary  plexus,  formed  by 
the  short  ciliary  vessels,  and  is  known  as  the  tunica  Ruyschiana.  The  network 
is  close,  and  finer  at  the  hinder  part  of  the  choroid  than  in  front.  About  half 
an  inch  behind  the  cornea,  its  meshes  become  larger,  and  are  continuous  with 
those  of  the  ciliary  process. 

The  internal^  or  pigmentary  layer,  is  a  delicate  membrane,  consisting  of  a 
single  layer  of  hexagonal  nucleated  cells,  loaded  with  pigment-granules,  and 
applied  to  each  other,  so  as  to  resemble  a  tessellated  pavement.  Each  cell  con- 
tains a  nucleus,  and  is  filled  with  grains  of  pigment,  which  are  in  greater 
abundance  at  the  circumference  of  the  cell.  In  perfect  albinos  this  epitheliunl 
contains  no  pigment,  and  none  is  present  in  the  star-shaped  cells  found  in  the 
other  layers  of  the  choroid. 

The  ciliary  processes  should  be  next  examined  :  they  may  be  exposed,  either  by  detachin;^  the 
iris  from  its  connection  with  the  ciliary  ligament,  or  by  making  a  transverse  section  of  the 
globe,  and  examining  them  from  behind. 

The  Ciliary  2'>rocesscs  are  formed  by  the  plaiting  or  folding  inwards  of  the 
middle  and  internal  layers  of  the  choroid,  at  its  anterior  margin,  and  are  received 
between  corresponding  foldings  of  the  suspensory  ligament  of  the  lens,  thus 
establishing  a  communication  between  the  choroid  and  inner  tunic  of  the  eye. 
They  are  arranged  in  a  circle,  behind  the  iris,  round  the  margin  of  the  lens. 
They  vary  between  sixty  and  eighty  in  number,  lie  side  by  side,  and  may  be 
divided  into  large  and  small;  the  latter,  consisting  of  about  one-third  of  the 
entire  number,  are  situated  in  the  spaces  between  the  former,  but  without  regu- 


CILIARY    PROCESSES. 


685 


lar  alternation.  The  larger  processes  are  each  about  one-tenth  of  an  inch  in 
length,  and  hemispherical  in  shape,  their  periphery  being  attached  to  the  ciliary 
ligament,  and  continuous  with  the  middle  and  inner  layers  of  the  choroid:  the 
opposite  margin  is  free,  and  rests  upon  the  circumstance  of  the  lens.     Their 

Fig.  371. — The  Arteries  of  the  Choroid  and  Iris.    The  Sclerotic  has  been  mostly  removed. 

(Enlarged.) 

Jtntrrror 
Ciliary  Af 


Short 
Ciliary  4/ 


Anterior 
Ciliary  JX 


anterior  surface  is  turned  towards  the  back  of  the  iris,  with  the  circumference 
of  which  it  is  continuous.  The  posterior  surface  is  closely  connected  with  the 
suspensory  ligament  of  the  lens. 

Structure.  The  ciliary  processes  are  similar  in  structure  to  the  choroid  ;  the 
vessels  are  larger,  having  chiefly  a  longitudinal  direction.  Externally  they  are 
covered  with  several  layers  of  pigment-cells;  the  component  cells  are  small, 
rounded,  and  full  of  pigment-granules. 

The  Iris  {iris,  a  rainbow)  has  received  its  name  from  its  various  color  in 
different  individuals.  It  is  a  thin,  circular-shaped,  contractile  curtain,  suspended 
in  the  aqueous  humor  behind  the  cornea,  and  in  front  of  the  lens,  being  perfo- 
rated at  the  nasal  side  of  its  centre  by  a  oiVcular  aperture,  the  pupil,  for  the 
transmission  of  light.  By  its  circumference  it  is  intimately  connected  with  the 
choroid ;  externally  to  this  is  the  ciliary  ligament,  by  which  it  is  connected  to 
the  sclerotic  and  cornea ;  its  inner  edge  forms  the  margin  of  the  pupil ;  its 
surfaces  are  flattened,  and  look  forwards  and  backwards,  the  anterior  surface 
towards  the  cornea,  the  posterior  towards  the  ciliary  processes  and  lens.  The 
anterior  surface  is  variously  colored  in  different  individuals,  and  marked  by 
lines  which  converge  towards  the  pupil.  The  posterior  surface  is  of  a  deep 
purple  tint,  from  being  covered  by  dark  pigment ;  it  is  hence  named  uvea,  from 
its  resemblance  in  color  to  a  ripe  grape. 

Structure.  The  iris  is  composed  of  a  fibrous  stroma,  muscular  fibres,  and 
pigment-cells. 

The  fibrous  stroma  consists  of  fine,  delicate  bundles  of  fibrous  tissue,  which 
have  a  circular  direction  at  the  circumference ;  but  the  chief  mass  radiate 
towards  the  pupil.  They  form,  by  their  interlacement,  a  delicate  mesh,  in 
which  the  pigment-cells,  vessels,  and  nerves  are  contained. 

The  muscular  fibre  is  involuntary,  and  consists  of  circular  and  radiating  fibres. 
The  circular  fibres  (sphincter  of  the  pupil)  surround  the  margin  of  the  pupil  on 
the  posterior  surface  of  the  iris,  like  a  sphincter,  forming  a  narrow  band,  about 
one-thirtieth  of  an  inch  in  width;  those  near  the  free  margin  being  closely 
aggregated;  those  more  external  somewhat  separated,  and  forming  less  com- 
plete circles.     The  radiating  fibres  (dilator  of  the  pupil)  converge  from  the 


086  ORGANS    OF    SENSE. 

circumference  towards  the  centre,  and  blend  with  the  circular  fibres  near  the 
margin  of  the  pupil. 

The  pigment-cells  are  found  in  the  stroma  of  the  iris,  and  also  as  a  distinct 
layer  on  its  anterior  and  posterior  surfaces.  In  the  stroma,  the  cells  are  rami- 
fied, and  contain  yellow  or  brown  pigment,  according  to  the  color  of  the  eye. 
On  the  front  of  the  iris,  there  is  a  single  layer  of  oval  or  rounded  cells,  with 
branching  offsets.  On  the  back  of  the  iris,  there  are  several  layers  of  small 
round  cells,  filled  with  dark  pigment.  This  layer  is  continuous  with  the 
pigmentary  covering  of  the  ciliary  processes. 

The  arteries  of  the  iris  are  derived  from  the  long  and  anterior  ciliary,  and 
from  the  vessels  of  the  ciliary  processes. 

Memhrana  pupillaris.  In  the  foetus,  the  pupil  is  closed  by  a  delicate,  transpa- 
rent, vascular  membrane,  the  membrana  pupillaris,  which  divides  the  space  in 
which  the  iris  is  suspended  into  two  distinct  chambers.  This  membrane  con- 
tains numerous  minute  vessels  continued  from  the  margin  of  the  iris  to  those 
on  the  front  part  of  the  capsule  of  the  lens.  These  vessels  have  a  looped 
arrangement,  converging  towards  each  other  without  anastomosing.  Between 
the  seventh  and  eighth  month,  the  membrane  begins  to  disappear,  by  its  gradual 
absorption  from  the  centre  towards  the  circumference,  and  at  birth  only  a  few 
fragments  remain.  It  is  said  sometimes  to  remain  permanent,  and  produce 
blindness. 

The  ciliary  ligament  is  a  narrow  ring  of  circular  fibres,  about  one-fortieth  of 
an  inch  thick,  and  of  a  whitish  color,  which  serves  to  connect  the  external  and 
middle  tunics  of  the  eye.  It  is  placed  around  the  circumference  of  the  iris,  at 
its  point  of  connection  with  the  external  layer  of  the  choroid,  the  cornea,  and 
sclerotic.  Its  component  fibres  are  delicate,  and  resemble  those  of  elastic  tissue. 
At  this  point  of  connection  with  the  sclerotic  a  minute  canal  is  situated  between 
the  two,  called  the  sinus  circularis  iridis. 

The  ciliary  muscle  (Bowman)  consists  of  unstriped  fibres:  it  forms  a  grayish, 
semitransparent,  circular  band,  about  one-eighth  of  an  inch  broad,  on  the  outer 
surface  of  the  fore  part  of  the  choroid.  It  is  thickest  in  front,  and  gradually 
becomes  thinner  behind.  Its  fibres  are  soft,  of  a  yellowish-white  color,  longi- 
tudinal in  direction,  and  arise  at  the  point  of  junction  of  the  cornea  and  scle- 
rotic. Passing  backwards,  they  are  attached  to  the  choroid,  in  front  of  the 
retina,  and  correspond  by  their  inner  surface  to  the  plicated  part  of  the  former 
membrane.  Mr.  Bowman  supposes  that  this  muscle  is  so  placed  as  to  advance 
the  lens,  by  exercising  compression  on  the  vitreous  body,  and  by  drawing  the 
ciliary  processes  towards  the  line  of  junction  of  the  sclerotic  and  cornea,  and 
by  this  means  to  adjust  the  eye  to  the  vision  of  near  objects. 

The  Retina  may  be  exposed  by  carefully  removing  the  choroid  from  its 
external  surface.  It  is  a  delicate  nervous  membrane,  upon  the  surface  of  which 
the  images  of  external  objects  are  received.  Its  outer  surface  is  in  contact 
with  the  pigmentary  layer  of  the  choroid;  its  inner  surface,  with  the  vitreous 
body.  Behind,  it  is  continuous  with  the  optic  nerve ;  it  gradually  diminishes 
in  thickness  from  behind  forwards;  and,  in  front,  extends  nearly  as  fiir  forwards 
as  the  ciliary  ligament,  where  it  terminates  by  a  jagged  margin,  the  ora  scrm/a. 
It  is  soft,  and  semitransparent,  in  the  fresh  state ;  but  soon  becomes  clouded, 
opaque,  and  of  a  pinkish  tint.  Exactly  in  the  centre  of  the  posterior  part  of 
#  the  retina,  and  at  a  point  corresponding  to  the  axis  of  the  eye,  in  which  the 
sen.se  of  vision  is  most  perfect,  is  a  round,  elevated,  yellowish  spot,  called,  after 
its  discoverer,  the  yellow  spot  or  limhus  Inteiis,  of  Stimmerring;  having  a  central 
depression  at  its  summit,  the  fovea  centralis.  The  retina  in  the  situation  of  the 
fovea  centralis  is  exceedingly  thin;  so  much  so,  that  the  dark  color  of  the 
choroid  is  distinctly  seen  through  it;  so  that  it  presents  more  the  appearance 
of  a  foramen,  and  hence  the  name  'foramen  of  Scimmerring'  at  first  given  to  it. 
It  exists  only  in  man,  the  quadrumana,  and  some  saurian  reptiles.  Its  use  is 
unknown.      About  y^  of  an  inch  to  the  inner  side  of  the  yellow  spot,  is  the 


THE    IRIS.  — THE    RETINA. 


687 


point  of  entrance  of  the  optic  nerve;  the  arteria  centralis  retinae  piercing  its 
centre.  This  is  the  only  part  of  the  surface  of  the  retina  from  which  the 
power  of  vision  is  absent. 

Fig.  372.— The  Arteria  Centralis  Retinae,  Yellow  Spot,  etc.,  the  Anterior  Half  of  the  Eyeball 

being  removed.     (Enlarged.) 


Structure.  The  retina  is  composed  of  three  layers,  together  with  blood- 
vessels:— 

External  or  columnar  layer  (Jacob's  membrane). 
Middle  or  granular  layer. 
Internal  or  nervous  layer. 

The  bloodvessels  do  not  form  a  distinct  layer;  they  ramify  in  the  substance 
of  the  internal  layer. 

The  external^  or  JacoVs  membrane^  is  exceedingly  thin,  and  can  be  detached 
from  the  external  surface  of  the  retina  by  the  handle  of  the  scalpel,  in  tlie 
form  of  a  flocculent  film.  It  is  thicker  behind  than  in  front,  and  consists  of 
rod-like  bodies  of  two  kinds:  1.  Columnar  rods^  solid,  nearly  of  uniform  size, 
and  arranged  perpendicularly  to  the  surface.  2.  Bulbous  particles,  or  co7ies^ 
which  are  interspersed  at  regular  intervals  among  the  former;  these  are  conical 
or  flask-shaped,  their  broad  ends  resting  upon  the  granular  layer,  the  narrow 
pointed  extremity  being  turned  towards  the  choroid;  they  are  not  sol'd,  like 
the  columnar  rods,  but  consist  of  an  external  membrane  with  fluid  contents. 
Bv  their  deep  ends,  both  kinds  are  joined  to  the  fibres  of  Muller. 

The  middle  or  gramilar  layer  forms  about  one-third  of  the  entire  thickness  of 
the  retina.  It  consists  of  two  laminae  of  rouiided  or  oval  nuclear  particles, 
separated  from  each  other  by  an  intermediate  layer,  which  is  transparent,  finely 
fibrillated,  and  contains  no  bloodvessels.  The  outermost  layer  is  the  thicker, 
and  its  constituent  particles  are  globular.  The  innermost  layer  is  the  thinner; 
its  component  particles  are  flattened,  looking  like  pieces  of  money  seen  edge- 
ways; hence  it  has  been  called,  by  Bowman,  ihe  nummular  layer. 

The  internal  or  nervous  layer  is  a  thin  semitransparent  membrane,  consisting 
of  an  expansion  of  the  terminal  fibres  of  the  optic  nerve  and  nerve-cells. 
The  nerve-fibres  are  collected  into  bundles,  which  radiate  from  the  point  at 
which  the  trunk  of  the  optic  nerve  terminates.  As  they  proceed  in  a  tolerably 
straight  course  towards  the  anterior  margin  of  the  retina,  the  bundles  interlace, 
forming  a  delicate  net,  with  flattened  elongated  meshes.  The  nerve-fibres  which 
form  this  layer  differ  from  the  fibres  of  the  optic  nerve  in  this  respect ;  they 
lose  their  dark  outline,  and  their  tendency  to  become  varicose ;  and  consist 


688  ORGANS    OF    SENSE. 

only  of  the  central  part,  or  axis,  of  the  nerve-tubes.  The  mode  of  termination 
of  the  nerve-fibres  is  unknown.  According  to  some  observers,  they  terminate 
in  loops ;  according  to  others,  in  free  extremities.  Recent  observers  have  stated 
that  some  of  the  nerve-fibres  are  continuous  with  the  caudate  prolongations  of 
the  nerve-cells  external  to  the  fibrous  layer.  The  nerve-cells  are  placed  on 
both  sides  of  the  fibrous  layer,  but  chiefly  upon  its  inner  surface,  and  imbedded 
within  the  meshes  formed  by  the  interlacing  nerve-fibres;  they  are  round  or 
pear-shaped  transparent  cells,  nucleated,  with  granular  contents,  furnished  with 
caudate  prolongations,  some  of  which  join  the  fibres  of  the  optic  nerve,  whilst 
others  are  directed  externally  towards  the  granular  layer.  It  is  probable  that 
these  cells  are  identical  with  the  ganglion-corpuscles  of  vesicular  nervous 
substance. 

An  extremely  thin  and  delicate  structureless  membrane  lines  the  inner  surface 
of  the  retina,  and  separates  it  from  the  vitreous  body ;  it  is  called  the  membrana 
limitans. 

The  radiating  fibres  of  the  retina,  described  by  Heinrich  Miiller,  consist  of 
extremely  fine  fibrillated  threads,  which  are  connected  externally  with  each  of 
the  rods  of  the  columnar  layer,  of  which  they  appear  to  be  direct  continuations, 
and,  passing  through  the  entire  substance  of  the  retina,  are  united  to  the  outer 
surface  of  the  membrana  limitans.  In  their  course  through  the  retina,  they 
become  connected  with  the  nuclear  particles  of  the  granular  layer,  and  give  off 
branching  processes  opposite  its  innermost  lamina;  as  they  approach  the  fibrous 
expansion  of  the  optic  nerve,  they  are  collected  into  bundles,  Aviiich  pass  through 
the  areolae  between  its  fibres,  and  are  finally  attached  to  the  inner  surface  of  the 
membrana  limitans,  where  each  fibre  terminates  in  a  triangular  enlargement. 

The  arteria  centralis  reiinve  and  its  accompanying  vein  pierce  the  optic  nerve, 
and  enter  the  globe  of  the  eye  through  the  porus  opticus.  It  immediately 
divides  into  four  or  five  branches,  which  at  first  run  between  the  hyaloid  mem- 
brane and  the  nervous  layer;  but  they  soon  enter  the  latter  membrane,  and 
form  a  close  capillary  network  in  its  substance.  At  the  ora  serrata,  they  ter- 
minate in  a  single  vessel  which  bounds  the  terminal  margin  of  the  retina. 

The  structure  of  the  retina  at  the  yellow  spot,  presents  some  modifications. 
Jacob's  membrane  is  thinner,  and  of  its  constituents  only  the  cones  .are  present; 
but  they  are  small,  and  more  closely  aggregated  than  in  any  other  part.  The 
granular  layer  is  absent  over  the  fovea  centralis.  Of  the  two  elements  of  the 
nervous  layer,  the  nerve-fibres  extend  only  to  the  circumference  of  the  spot; 
but  the  nerve-cells  cover  its  entire  surface.  The  radiating  fibres  are  found  at 
the  circumference,  and  here  only  extend  to  the  inner  strata  of  the  granular 
layer.  Of  the  capillary  vessels,  the  larger  branches  pass  round  the  spot ;  but 
the  smaller  capillaries  meander  through  it.  The  color  of  the  spot  appears  to 
imbue  all  the  layers  except  Jacob's  membrane;  it  is  of  a  rich  yellow,  deepest 
towards  the  centre,  and  does  not  appear  to  consist  of  pigment-cells,  but  resem- 
bles more  a  staining  of  the  constituent  parts. 

Aqueous  Humor. 

The  Aqueous  Humor  completely  fills  the  anterior  and  posterior  chambers  of 
the  eyeball.  It  is  small  in  quantit}'  (scarcely  exceeding,  according  to  Petit, 
four  or  five  grains  in  weight),  has  an  alkaline  reaction,  in  composition  is  little 
more  than  water,  less  than  one-fiftieth  of  its  weight  being  solid  matter,  chiefly 
chloride  of  sodium. 

The  anterior  chamber  is  the  space  bounded  in  front  by  the  cornea;  behind, 
by  the  front  of  the  iris  and  ciliary  ligament. 

The  jtosterior  chamber^  smaller  than  the  anterior,  is  bounded  in  front  by  the 
iris ;  behind,  by  the  capsule  of  the  lens  and  its  suspensory  ligament,  and  the 
ciliary  processes. 

In  the  adult,  these  two  chambers  communicate  through  the  pupil;  but  in  the 


AQUEOUS    HUMOR.— VITREOUS    BODY,  ETC.  689 

foetus  before  the  seventli  month,  when  the  pupil  is  closed  by  the  membrana 
pupillaris,  the  two  chambers  are  quite  separate. 

It  has  been  generally  supposed  that  the  two  chambers  are  lined  by  a  distinct 
membrane,  the  secreting  membrane  of  the  aqueous  humor,  analogous  in  struc- 
ture to  that  of  a  serous  sac.  An  epithelial  covering  can,  however,  only  be  found 
on  the  posterior  surface  of  the  cornea.  That  the  two  chambers  do,  however, 
secrete  this  fluid  separately,  is  shown  from  its  being  found  in  both  spaces  before 
the  removal  of  the  membrana  pupillaris.  It  is  probable  that  the  parts  concerned 
in  the  secretion  of  the  fluid,  are  the  posteripr  surface  of  the  cornea,  both  surfaces 
of  the  iris,  and  the  ciliary  processes. 

"Vitreous  Body. 

The  Vitreous  Body  forms  about  four-fifths  of  the  entire  globe.  It  fills  the 
concavity  of  the  retina,  and  is  hollowed  in  front  for  the  reception  of  the  lens 
and  its  capsule.  It  is  perfectly  transparent,  of  the  consistence  of  thin  jelly,  and 
consists  of  an  albuminous  fluid  inclosed  in  a  delicate  transparent  membrane, 
the  hyaloid.  This  membrane  invests  the  outer  surface  of  the  vitreous  body  ;  it 
is  intimately  connected  in  front  with  the  suspensory  ligament  of  the  lens ;  and 
is  continued  into  the  back  part  of  the  capsule  of  the  lens.  It  has  been  sup- 
posed, by  Hannover,  that  from  its  inner  surface  numerous  thin  lamellae  are 
prolonged  inwards,  in  a  radiating  manner,  forming  spaces  in  which  the  fluid  is 
contained.  In  the  adult,  these  lamellae  cannot  be  detected  even  after  careful 
microscopic  examination  ;  but  in  the  foetus  a  peculiar  fibrous  texture  pervades 
the  mass,  the  fibres  joining  at  numerous  points,  and  presenting  minute  nuclear 
granules  at  their  point  of  junction.  The  fluid  from  the  vitreous  body  resembles 
nearly  pure  water;  it  contains,  however,  some  salts,  and  a  little  albumen. 

In  the/ce^t<s,  the  centre  of  the  vitreous  humor  presents  a  tubular  canal,  through 
which  a  minute  artery  passes  along  the  vitreous  body  to  the  capsule  of  the  lens. 
In  the  adult,  no  vessels  penetrate  its  substance ;  so  that  its  nutrition  must  be 
carried  on  by  the  vessels  of  the  retina  and  ciliary  processes,  situated  upon  its 
exterior. 

Crystalline  Lens  and  its  Capsule. 

The  Crystalline  Lens,  inclosed  in  its  capsule,  is  situated  immediately  behind 
the  pupil,  in  front  of  the  vitreous  body,  and  surrounded  by  the  ciliary  processes, 
which  slightly  overlap  its  margin. 

The  capsule  of  the  lens  is  a  transparent,  highly  elastic,  and  brittle  membrane, 
which  closely  surrounds  the  lens.  It  rests,  behind,  in  a  depression  in  the  fore 
part  of  the  vitreous  body :  in  front,  it  forms  part  of  the  posterior  chamber  of 
the  eye ;  and  it  is  retained  in  its  position  chiefly  by  the  suspensory  ligament  of 
the  lens.  The  capsule  is  much  thicker  in  front  than  behind,  structureless  in 
texture ;  and  when  ruptured,  the  edges  roll  up  with  the  outer  surface  inner- 
most, like  the  elastic  laminae  of  the  cornea.  The  lens  is  connected  to  the  inner 
surface  of  the  capsule  by  a  single  layer  of  transparent,  polygonal,  nucleated 
cells.  These,  after  death,  absorb  moisture  from  the  fluids  of  the  eye;  and, 
breaking  down,  form  the  liquor  Morgagni, 

In  the  foetus,  a  small  branch  from  the  arteria  centralis  retinae  runs  forwards, 
as  already  mentioned,  through  the  vitreous  humor  to  the  posterior  part  of  the 
capsule  of  the  lens,  where  its  branches  radiate  and  form  a  plexiform  network, 
which  covers  its  surface,  and  are  continuous  round  the  margin  of  the  capsule 
with  the  vessels  of  the  pupillary  membrane,  and  with  those  of  the  iris.  In  the 
adult  no  vessels  enter  its  substance. 

The  lens  is  a  transparent,  double-convex  body,  the  convexity  being  greater 
on  the  posterior  than  on  the  anterior  surface.  It  measures  about  a  third  of  an 
44 


690  ORGANS    OF    SENSE. 

Fig.  373.— the  Crystal-    inch  in  the  transverse  diameter,  and  about  one-fourth  in 
hne  Lens,  hardened  and     ^|,q  antero-posterior.    It  consists  of  concentric  layers,  of 
[  u\  arge  .)  which  the  external,  in  tliefre.sh  state,  are  soft  and  easily- 

detached;   those   beneath  are  firmer,  the  central  ones 
forming  a  hardened  nucleus.     These  laminse  are  best 
demonstrated  by  boiling,  or  immersion  in  alcohol.    The 
same  reagents  demonstrate  that  the  lens  consists  of  three 
triangular   segments,    the   sharp   edges   of    which   are 
directed  towards  the  centre,  the  bases  towards  the  cir- 
cumference.    The  laminae   consist   of  minute  parallel 
fibres,  which  are  united  to  each  other  by  means  of  wavy 
margins,  the  convexities  upon  one  fibre  fitting  accu- 
rately into  the  concavities  of  the  adjoining  fibre. 
The  changes  produced  in  the  lens  hy  age  are  the  following : — 
In  the  foetus^  its  form  is  nearly  spherical,  its  color  of  a  slightly  reddish  tint, 
it  is  not  perfectly  transparent,  and  is  so  soft  as  to  break  down  readily  on  the 
slightest  pressure. 

In  the  aduU^  the  posterior  surface  is  more  convex  than  the  anterior ;  it  is 
colorless,  transparent,  and  firm  in  texture. 

In  old  age,  it  becomes  flattened  on  both  surfaces,  slightly  opaque,  of  an  amber 
tint,  and  increases  in  density. 

The  suspensonj  ligament  of  the  lens  is  a  thin,  transparent  membranous  struc- 
ture, placed  between  the  vitreous  body  and  the  ciliary  processes  of  the  choroid; 
it  connects  the  anterior  margin  of  the  retina  with  the  anterior  surface  of  the 
lens  near  its  circumference.  It  assists  in  retaining  the  lens  in  its  position.  Its 
outer  surface  presents  a  number  of  folds  or  plaitings,  in  which  the  correspond- 
ing folds  of  the  ciliary  processes  are  received.  These  plaitings  are  arranged 
round  the  lens  in  a  radiating  form,  and  are  stained  by  the  pigment  of  the  ciliary 
processes.  The  suspensory  ligament  consists  of  two  layers,  which  commence 
behind,  at  the  ora  serrata.  The  external,  a  tough,  milky,  granular  membrane, 
covers  the  inner  surface  of  the  ciliary  processes,  and  extends  as  far  forwards  as 
their  anterior  free  extremities.  The  inner  layer,  an  elastic,  transparent,  fibro- 
membranous  structure,  extends  as  far  forwards  as  the  anterior  surface  of  the 
capsule  of  the  lens,  near  its  circumference.  That  portion  of  this  membrane 
whicn  intervenes  between  the  ciliary  processes  and  the  capsule  of  the  lens,  forms 
part  of  the  boundary  of  the  posterior  chamber  of  the  eye.  The  posterior  sur- 
face of  this  layer  is  turned  towards  the  hyaloid  membrane,  being  separated  from 
it  at  the  circumference  of  the  lens  by  a  space  called  the  canal  of  Petit. 

The  canal  of  Petit  is  about  one-tenth  of  an  inch  wide.  It  is  bounded  in  front 
by  the  suspensory  ligament;  behind,  by  the  hyaloid  membrane,  its  base  being 
formed  by  the  capsule  of  the  lens.  When  inflated  with  air,  it  is  sacculated  at 
intervals,  owing  to  the  foldings  on  its  anterior  surface. 

The  Vessels  of  the  globe  of  the  eye  are  the  short,  long,  and  anterior  ciliary 
arteries,  and  the  arteria  centralis  retinai. 

The  short  ciliary  arteries  pierce  the  back  part  of  the  sclerotic,  round  the 
entrance  of  the  optic  nerve,  and  divide  into  branches  which  run  parallel  with 
the  axis  of  the  eyeball :  they  are  distributed  to  the  middle  layer  of  the  choroid, 
and  to  the  ciliary  processes. 

The  long  ciliary  arteries,  two  in  number,  pierce  the  back  part  of  the  sclerotic 
and  run  forward,  between  that  membrane  and  the  choroid,  to  the  Ciliary  muscle, 
where  they  each  divide  into  an  upper  and  lower  branch ;  these  anastomose,  and 
form  avascular  circle  round  the  outer  circumference  of  the  iris;  from  this 
circle  branches  are  given  off,  which  unite,  near  the  margin  of  the  pupil,  in  a 
smaller  vascular  circle.  These  branches,  in  their  course,  supply  the  muscular 
structure. 

The  anterior  ciliary  arteries,  five  or  six  in  number,  are  branches  of  the  mus- 


APPENDAGES    OF    THE    EYE.  691 

cular  and  lachrymal  branches  of  the  ophthalmic.  They  pierce  the  eyeball,  at 
the  anterior  part  of  the  sclerotic,  immediately  behind  the  margin  of  the  cornea, 
and  are  distributed  to  the  ciliary  processes,  some  branches  joining  the  greater 
vascular  circle  of  the  iris. 

The  arieria  centralis  retinse  has  been  already  described. 

The  veins,  usually  four  in  number,  are  formed  mainly  by  branches  from  the 
surface  of  the  choroid.  They  perforate  the  sclerotic,  midway  between  the  cornea 
and  the  optic  nerve,  and  end  in  the  ophthalmic  vein. 

The  nerves  of  the  eyeball  are  the  optic,  the  long  ciliary  nerves  from  the  nasal 
branch  of  the  ophthalmic,  and  the  short  ciliary  nerves  from  the  ciliary  ganglion. 

Appendages  of  the  Eye. 

The  Appendages  of  the  Eye  [tutamina  ociili)  include  the  eyebrows,  the  eye- 
lids, the  conjunctiva,  and  the  lachrymal  apparatus,  viz.,  the  lachrymal  gland, 
the  lachrymal  sac,  and  the  nasal  duct. 

The  eyebrows  (supercilia)  are  two  arched  eminences  of  integument,  which  sur- 
mount the  upper  circumference  of  the  orbit  on  each  side,  and  support  numerous 
short,  thick  hairs,  directed  obliquelyon  the  surface.  In  structure,  the  eyebrows 
consist  or  thickened  integument,  connected  beneath  with  the  Orbicularis  Palpe- 
brarum, Corrugator  Supercilii,  and  Occipito-frontalis  muscles.  These  muscles 
serve,  by  their  action  on  this  part,  to  control  to  a  certain  extent  the  amount  of 
light  admitted  into  the  eye. 

The  eyelids  {palpebrse)  are  two  thin,  movable  folds,  placed  in  front  of  the  eye, 
protecting  it  from  injury  by  their  closure.  The  upper  lid  is  the  larger,  and  the 
more  movable  of  the  two,  and  is  furnished  with  a  separate  elevator  muscle,  the 
Levator  Palpebrse  Superioris.  When  the  eyelids  are  opened,  an  elliptical  space 
{fissura  palpebrarura)  is  left  between  their  margins,  the  angles  of  which  corre- 
spond to  the  junction  of  the  upper  and  lower  lids,  and  are  called  canthi. 

The  outer  canthus  is  more  acute  than  the  inner,  and  the  lids  here  lie  in  close 
contact  with  the  globe :  but  the  inner  canthus  is  prolonged  for  a  short  distance 
inwards,  towards  the  nose,  and  the  two  lids  are  separated  by  a  triangular  space, 
the  lacus  iachrymalis.  At  the  commencement  of  the  lacus  Jachrymalis,  on  the 
margin  of  each  eyelid,  is  a  small  conical  elevation,  the  lachrymal  papilla,  or 
tubercle,  the  apex  of  which  is  pierced  by  a  small  orifice,  the punctum  lachrymale, 
the  commencement  of  the  lachrymal  canal. 

Structure  of  the  eyelids.  The  eyelids  are  composed  of  the  following  structures, 
taken  in  their  order  from  without  inwards : — 

Integument,  areolar  tissue,  fibres  of  the  Orbicularis  muscle,  tarsal  cartilage, 
fibrous  membrane,  Meibomian  glands,  and  conjunctiva.  The  upper  lid  has,  in 
addition,  the  aponeurosis  of  the  Levator  Palpebraa. 

The  integument  is  extremely  thin,  and  continuous  at  the  margin  of  the  lids 
with  the  conjunctiva. 

The  subcutaneous  areolar  tissue  is  very  lax  and  delicate,  seldom  contains  any 
fat,  and  is  extremely  liable  to  serous  infiltration. 

The  fibres  of  the  Orbicularis  muscle,  where  they  cover  the  palpebrse,  are  thin, 
pale  in  color,  and  possess  an  involnntary  action. 

The  tarsal  cartilages  are  two  thin,  elongated  plates  of  fibro-cartilage,  about  an 
inch  in  length.  They  are  placed  one  in  each  lid,  contributing  to  their  form  and 
support. 

The  superior,  the  larger,  is  of  a  semilunar  form,  about  one-third  of  an  inch 
in  breadth  at  the  centre,  and  becoming  gradually  narrowed  at  each  extremity. 
Into  the  fore  part  of  this  cartilage  the  aponeurosis  of  the  Levator  Palpebrae  is 
attached. 

The  inferior  tarsal  cartilage,  the  smaller,  is  thinner,  and  of  an  elliptical  form. 

The  free  or  ciliary  m.argin  of  the  cartilage  is  thick,  and  presents  a  perfectly 
straight  edge.     The  attached,  or  orbital  margin,  is  connected  to  the  circumference 


692 


ORGANS    OF    SENSE. 


of  the  orbit  by  the  fibrous  membrane  of  the  lids.  The  outer  angle  of  each 
cartilage  is  attached  to  the  malar  bone  by  the  external  palpebral  or  tarsal  liga- 
ment. The  inner  angles  of  the  two  cartilages  terminate  at  the  commencement 
of  the  lacus  lachrymalis,  being  fixed  to  the  margins  of  the  orbit  by  the  tendo 
oculi. 

The  Jihrous  membrane  of  the  lids,  or  tarsal  ligament,  is  a  layer  of  fibrous  mem- 
brane, beneath  the  Orbicularis,  attached  externally,  to  the  margin  of  the  orbit, 
and  internally  to  the  orbital  margin  of  the  lids.  It  is  thick  and  dense  at  the 
outer  part  -of  the  orbit,  but  becomes  thinner  as  it  approaches  the  cartilages. 
This  membrane  serves  to  support  the  eyelids,  and  retains  the  tarsal  cartilages 
in  their  position. 

The  Meibomian  glands  (Fig.  374)  are  situated  upon  the  inner  surface  of  the 
eyelids,  between  the  tarsal  cartilages  and  conjunctiva,  and  may  be  distinctly 

Fig.  374. — The  Meibomiaa  Glands,  etc.,  seen  from  the  Inner  Surface  of  the  Eyelids. 


seen  through  the  mucous  membrane  on  everting  the  eyelids,  presenting  the  ap- 
pearance of  parallel  strings  of  pearls.  They  are  about  thirty  in  number  in  the 
upper  cartilage,  and  somewhat  fewer  in  the  lower.  They  are  imbedded  in 
grooves  in  the  inner  surface  of  the  cartilages,  and  correspond  in  length  Avith 
the  breadth  of  each  cartilage;  they  are,  consequently,  longer  in  the  upper  than 
in  the  lower  eyelid.  Their  ducts  open  on  the  free  margin  of  the  lids  by  minute 
foramina,  which  correspond  in  number  to  the  follicles.  These  glands  are  a 
variety  of  the  cutaneous  sebaceous  glands,  each  consisting  of  a  single  straight 
tube  or  follicle,  having  a  ca^cal  termination,  into  which  open  a  number  of  small 
secondary  follicles.  The  tubes  consist  of  basement  membrane,  covered  by  a 
layer  of  scaly  epithelium  ;  the  cells  are  charged  with  sebaceous  matter,  which 
constitutes  the  secretion.  The  peculiar  parallel  arrangement  of  these  glands 
side  by  side,  forms  a  smooth  layer,  adapted  to  the  surface  of  the  globe,  over 
which  they  constantly  glide.  The  use  of  their  secretion  is  to  prevent  adhesion 
of  the  lids. 

The  eyelashes  (cilia)  are  attached  to  the  free  edges  of  the  eyelids ;  they  are 
short,  thick,  curved  hairs,  arranged  in  a  double  or  triple  row  at  the  margin  of 
the  lids;  those  of  the  upper  lid,  more  numerous  and  longer  than  the  lower, 
carve  upwards  ;  those  of  the  lower  lid  curve  down.wards,  so  that  they  do  not 
interlace  in  closing  the  lids. 

The  conjunctiva  is  the  mucous  membrane  of  the  eye.  It  lines  the  inner  sur- 
face of  the  eyelids,  and  is  reflected  over  the  forepart  of  the  sclerotic  and  cornea. 
In  each  of  these  situations,  its  structure  presents  some  peculiarities. 

'Y\i^  palpebral  portion  of  the  conjunctiva  is  thick,  opaque,  highly  vascular,  and 


n 


LACHRYMAL    APPARATUS.  693 

covered  witli  numerous  papillaB,  which  in  the  disease  called  granular  lids,  be- 
come greatly  hjpertrophied.  At  the  margin  of  the  lids,  it  becomes  continuous 
with  the  lining  membrane  of  the  ducts  of  the  Meibomian  glands,  and,  through 
the  lachrymal  canals,  with  the  lining  membrane  of  the  lachrymal  sac  and  nasal 
duct.  At  the  outer  angle  of  the  upper  lid,  it  may  be  traced  along  the  lachrymal 
ducts  into  the  lachrymal  gland ;  and  at  the  inner  angle  of  the  eye,  it  forms  a 
semilunar  fold,  the  plica  semilunaris.  The  folds  formed  by  the  reflection  of  the 
conjunctiva  from  the  lids  on  to  the  eye  are  called  the  superior  and  inferior  pal- 
jjebral  folds,  the  former  being  the  deeper  of  the  two.  Upon  the  sclerotic,  the 
conjunctiva  is  loosely  connected  to  the  globe;  it  becomes  thinner,  loses  its 
papillary  structure,  is  transparent,  and  only  slightly  vascular  in  health.  Upon 
the  cornea,  the  conjunctiva  is  extremely  thin  and  closely  adherent,  and  no  ves- 
sels can  be  traced  into  it  in  the  adult  in  a  healthy  state.  In  the  fcettis,  fine 
capillary  loops  extend,  for  some  little  distance  forwards,  into  this  membrane; 
but  in  the  %duli,  they  pass  only  to  the  circumference  of  the  cornea 

The  carwmula  lachrymalis  is  a  small,  reddish,  conical-shaped  Oody,  situated 
at  the  inner  canthus  of  the  eye,  and  filling  up  the  small  triangular  cpace  in  this 
situation,  the  lacus  lachrymalis.  It  consists  of  a  cluster  of  follicles  similar  in 
structure  to  the  Meibomian,  covered  with  mucous  membrane,  and  is  the  source 
of  the  whitish  secretion  which  constantly  collects  at  the  inner  angle  of  the  eye. 
A  few  slender  hairs  are  attached  to  its  surface.  On  the  outer  side  of  the  carun- 
cula  is  a  light  semilunar  fold  of  mucous  membrane,  the  concavity  of  which  is 
directed  towards  the  cornea  ;  it  is  called  the  plica  semilunaris.  Between  its  two 
layers  is  found  a  thin  plate  of  cartilage.  This  structure  is  considered  to  be  the 
rudiment  of  the  third  eyelid  in  birds,  the  memhrana  nictitans. 

Lachrymal  Apparatus.    (Fig.  375.) 
The  Lachrymal  Apparatus  consists  of  the  lachrymal  gland,  which  secretes 

Fig.  375. — The  Lachrymal  Apparatus.     Eight  Side. 


the  tears,  and  its  excretory  ducts,  which  convey  the  fluid  to  the  surface  of  the 
eye.  This  fluid  is  carried  away  by  the  lachrymal  canals  into  the  lachrymal 
sac,  and  along  the  nasal  duct  into  the  cavity  of  the  nose. 

The  lachrymal  gland  is  lodged  in  a  depression  at  the  outer  angle  of  the  orbit, 
on  the  inner  side  of  the  external  angular  process  of  the  frontal  bone.  It  is  of 
an  oval  form,  about  the  size  and  shape  of  an  almond.  Its  upper  convex  sur- 
face is  in  contact  with  the  periosteum  of  the  orbit,  to  which  it  is  connected  by 
a  few  fibrous  bands.  Its  under  concave  surface  rests  upon  the  convexity  of  the 
eyeball,  and  upon  the  Superior  and  External  Recti  muscles.     Its  vessels  and 


694  ORGANS    OF    SENSE. 

nerves  enter  its  posterior  border,  whilst  its  anterior  margin  is  closely  adherent 
to  the  back  part  of  the  upper  eyelid,  and  is  covered,  on  its  inner  surface,  by  a 
reflection  of  the  conjunctiva.  This  margin  is  separated  from  the  rest  of  the 
gland  by  a  slight  depression,  hence  it  is  sometimes  described  as  a  separate  lobe, 
called  the  palpebral  poiHion  of  the  gland.  In  structure  and  general  appearance 
the  lachrymal  resembles  the  salivary  glands.  Its  ducts,  about  seven  in  num- 
ber, run  obliquely  beneath  the  mucous  membrane  for  a  short  distance,  and 
separating  from  each  other,  open  by  a  series  of  minute  orifices  on  the  upper 
and  outer  half  of  the  conjunctiva,  near  its  reflection  on  to  the  globe.  These 
orifices  are  arranged  in  a  row,  so  as  to  disperse  the  secretion  over  the  surface 
of  the  membrane. 

The  lachrymal  canals  commence  a"t  the  minute  orifices,  puncta  lachrymalia, 
seen  on  the  margin  of  the  lids,  at  the  outer  extremity  of  the  lacus  lachrymalis. 
They  commence  on  the  summit  of  a  slightly  elevated  papilla,  the  papilla  lach- 
rymalis, and  lead  into  minute  canals,  the  canaliculi,  which  proceed  inwards  to 
terminate  in  the  lachrymal  sac.  The  superior  canal,  the  smaller  and  longer  of 
the  two,  at  first  ascends,  and  then  bends  at  an  acute  angle,  and  passes  inwards 
and  downwards  to  the  lachrymal  sac.  The  inferior  canal  at  first  descends,  and 
then  abruptly  changing  its  course,  passes  almost  horizontally  inwards.  They 
are  dense  and  elastic  in  structure,  and  somewhat  dilated  at  their  angle. 

The  lachrymal  sac  is  the  upper  dilated  extremity  of  the  nasal  duct,  and  is 
lodged  in  a  deep  groove  formed  by  the  lachrymal  bone  and  nasal  process  of 
the  superior  maxillary.  It  is  oval  in  form,  its  upper  extremity  being  closed  in 
and  rounded,  whilst  below  it  is  continued  into  the  nasal  duct.  It  is  covered  by 
the  Tensor  Tarsi  muscle  and  by  a  fibrous  expansion  derived  from  the  tendo 
oculi,  which  is  attached  to  the  ridge  on  the  lachrymal  bone.  In  structure,  it 
consists  of  a  fibrous  elastic  coat,  lined  internally  by  mucous  membrane;  the 
latter  being  continuous,  through  the  canaliculi,  with  the  mucous  lining  of  the 
conjunctiva,  and  through  the  nasal  duct  with  the  pituitary  membrane  of  the 
nose. 

The  nasal  duct  is  a  membranous  canal,  about  three-quarters  of  an  inch  in 
length,  which  extends  from  the  lower  part  of  the  lachrymal  sac  to  the  inferior 
meatus  of  the  nose,  where  it  terminates  by  a  somewhat  expanded  orifice,  pro- 
vided with  an  imperfect  valve  formed  by  the  mucous  membrane.  It  is  con- 
tained in  an  osseous  canal,  formed  by  the  superior  maxillary,  the  lachrymal, 
and  the  inferior  turbinated  bones,  is  narrower  in  the  middle  than  at  each 
extremity,  and  takes  a  direction  downwards,  backwards,  and  a  little  outwards. 
It  is  lined  by  mucous  membrane,  which  is  continuous  below  with  the  pituitary 
lining  of  the  nose.  In  the  canaliculi,  this^  membrane  is  provided  with  scaly 
epithelium ;  but  in  the  lachrymal  sac  and  nasal  duct,  the  epithelium  is  ciliated 
as  in  the  nose. 

The  Ear. 

The  Organ  of  Hearing  has  three  parts;  the  external  ear,  the  middle  ear  or 
tympanum,  and  the  internal  ear  or  labyrinth. 

The  External  Ear. 

The  External  Ear  consists  of  an  expanded  portion  named  pinna,  or  auricle, 
and  the  auditory  canal,  or  meatus.  The  former  serves  to  collect  the  vibrations 
of  the  air  by  which  sound  is  produced,  and  the  latter  conducts  those  vibrations 
to  the  tympanum. 

The  pi7ma,  or  auricle  (Fig.  376),  is  formed  by  a  layer  of  cartilage,  covered 
with  integument,  and  connected  to  the  commencement  of  the  auditory  canal; 
it  is  of  an  ovoid  form,  its  surface  uneven,  with  its  larger  end  directed  upwards. 
Its  outer  surface  is  irregularly  concave,  directed  slightly  forwards,  and  presents 


THE    EXTERNAL    EAR. 


695 


numerous  eminences  and  depressions  which  result    Fig.  376.— The  Pinna,  or  Au- 
from  the  foldings  of  its  fibro-cartilaginous  element.  "^^^-    ^«ter  Surface. 

To  each  of  these  names  have  been  assigned.  Thus, 
the  external  prominent  rim  of  the  auricle  is  called 
the  helix.  Another  curved  prominence  parallel 
with,  and  in  front  of  the  helix,  is  called  the  anti- 
helix;  this  bifurcates  above,  so  as  to  inclose  a 
triangular  depression,  the  fossa  of  the  antihelix. 
The  narrow  curved  depression  between  the  helix 
and  antihelix  is  called  the  fossa  of  the  helix  [fossa 
innominata^  f.  scaphoidea).  The  antihelix  describes 
a  curve  round  a  deep,  capacious  cavity,  the  concha, 
which  is  partially  divided  into  two  parts  by  the 
commencement  of  the  helix.  In  front  of  the  con- 
cha, and  projecting  backwards  over  the  meatus, 
is  a  small  pointed  eminence,  the  tragus ;  so  called 
from  its  being  generally  covered,  on  its  under  sur- 
face, with  a  tuft  of  hair,  resembling  a  goat's  beard. 
Opposite  the  tragus,  and  separated  from  it  by  a  deep 
notch  {incisura  intertragica),  is  a  small  tubercle,  the 
antitragus.  Below  this  is  the  lohule,  composed  of 
tough  areolar  and  adipose  tissues,  wanting  the  firmness  and  elasticity  of  the 
rest  of  the  pinna. 

Structure  of  the  pinna.  The  pinna  is  composed  of  a  thin  plate  of  yellow 
cartilage,  covered  with  integument,  and  connected  to  the  surrounding  parts  by 
ligaments,  and  a  few  muscular  fibres. 

The  integument  is  thin,  closely  adherent  to  the  cartilage,  and  furnished  with 
sebaceous  glands,  which  are  most  numerous  in  the  concha  and  scaphoid  fossa. 

The  cartilage  of  the  pinna  consists  of  one  single  piece;  it  gives  form  to  this 
part  of  the  ear,  and  upon  its  surface  are  found  all  the  eminences  and  depres- 
sions above  described.  It  does  not  enter  into  the  construction  of  all  parts  of 
the  auricle;  thus  it  does  not  form  a  constituent  part  of  the  lobule;  it  is  defi- 
cient, also,  between  the  tragus  and  beginning  of  the  helix,  the  notch  between 
them  being  filled  up  by  dense  fibrous  tissue.  It  presents  several  intervals  of 
fissures  in  its  substance,  which  partially  separate  the  different  parts.  The 
fissure  of  the  helix  is  a  short,  vertical  slit,  situated  at  the  fore  part  of  the  pinna, 
immediately  behind  a  small  conical  projection  of  cartilage,  opposite  the  first 
curve  of  the  helix  (process  of  the  helix).  Another  fissure,  the  fissure  of  the 
tragus,  is  seen  upon  the  anterior  surface  of  the  tragus.  The  antihelix  is 
divided  below,  by  a  deep  fissure,  into  two  parts;  one  part  terminates  by  a 
pointed,  tail-like  extremity  {processus  caudatus);  the  other  is  continuous  with 
the  antitragus.  The  cartilage  of  the  pinna  is  very  pliable,  elastic,  of  a  yellow- 
ish color,  and  similar  in  structure  to  the  cartilages  of  the  nose. 

The  ligaments  of  the  pinna  consist  of  two  sets.  1.  Those  connecting  it  to 
the  side  of  the  head.  2.  Those  connecting  the  various  parts  of  its  cartilage 
together. 

The  former,  the  most  important,  are  two  in  number,  anterior  and  posterior. 
The  anterior  ligament  extends  from  the  process  of  the  helix  to  the  root  of  the 
zygoma.  The  posterior  ligament  passes  from  the  posterior  surface  of  the  concha 
to  the  outer  surface  of  the  mastoid  process  of  the  temporal  bone.  A  few  fibres 
connect  the  tragus  to  the  root  of  the  zygoma. 

The  ligaments  connecting  the  various  parts  of  the  cartilage  together  are 
also  two  in  number.  Of  these,  one  is  a  strong  fibrous  band,  stretching  across 
from  the  tragus  to  the  commencement  of  the  helix,  completing  the  meatus  in 
front,  and  partly  encircling  the  boundary  of  the  concha;  the  other  extends 
between  the  concha  and  the  processus  caudatus. 

The  muscles  of  the  pin7ia  (Fig.  377),  like  the  ligaments,  consist  of  two  sets; 


696 


ORGANS    OF    SENSE. 


1.  Those  whicli  connect  it  with  the  side  of  the  head,  moving  the  pinna  as  a 
whole,  viz.,  the  Attollens  Aurem,  Attrahens  Aurem,  and  Retrahens  Aurera 
(p.  319);  and  the  proper  muscles  of  the  pinna,  which  extend  from  one  part  of 
the  auricle  to  another.     These  are,  the 


Helicis  Major. 
Helicis  Minor. 
Tragicus. 


Antitragicus. 
Transversus  Auriculae. 
Obliquus  Auris. 


The  Helicis  Major  is  a  narrow,  vertical  band  of  muscular  fibres,  situated 
upon  the  anterior  margin  of  the  helix.  It  arises,  below,  from  the  tubercle  of 
the  helix,  and  is  inserted  into  the  anterior  border  of  the  helix,  just  where  it  is 
about  to  curve  backwards.     It  is  pretty  constant  in  its  existence. 

Fig.  377.— The  Muscles  of  the  Pinna. 


The  Helicis  Minor  is  an  oblique  fasciculus,  attached  to  that  part  of  the  helix 
which  commences  from  the  bottom  of  the  concha. 

The  Trcifjficus  is  a  short,  flattened  band  of  muscular  fibres  situated  upon  the 
outer  surface  of  the  tragus,  the  direction  of  its  fibres  being  vertical. 

The  Antitragicus  arises  from  the  outer  part  of  the  antitragus ;  its  fibres  are 
inserted  into  the  processus  caudatus  of  the  helix.  This  muscle  is  usually  very 
distinct. 

The  Transversus  Auriculae  is  placed  on  the  cranial  surface  of  the  pinna.  It 
consists  of  radiating  fibres,  partly  tendinous  and  partly  muscular,  extending 
from  the  convexity  of  the  concha  to  the  prominence  corresponding  with  the 
groove  of  the  helix. 

The  Obliquus  Ann's  (Todd)  consists  of  a  few  fibres  extending  from  the  upper 
and  back  part  of  the  concha  to  the  convexity  immediately  above  it. 

The  arteries  of  the  pinna  are,  the  posterior  auricular,  from  the  external  carotid ; 
the  anterior  auricular,  from  the  temporal ;  and  an  auricular  branch  from  the 
occipital  artery. 

The  veins  accompany  the  corresponding  arteries. 

The  nerves  are,  the  auricularis  magnus,  from  the  cervical  plexus;  the  posterior 


THE    EXTERNAL    EAR. 


61)7 


auricular,  from  the  facial';  the  auricular  branch  of  the  pneumogastric;  and  the 
auriculo-temporal  branch  of  the  inferior  maxillary  nerve. 

The  Auditory  Canal  (Fig.  878),  {meatus  auditorius  exiernvs),  extends  from  the 
bottom  of  the  concha  to  the  membrana  tympani.  It  is  about  an  inch  and  a 
quarter  in  length,  its  direction  is  obliquely  forwards  and  inwards,  and  it  is 

Fig.  378.— A  Front  View  of  the  Organ  of  Hearing.    Right  Side. 


slightly  curved  upon  itself,  so  as  to  be  higher  in  the  middle  than  at  either 
extremity.  It  forms  an  oval  cylindrical  canal,  narrowest  at  the  middle,  some- 
what flattened  from  before  backwards,  the  greatest  diameter  being  in  the  verti- 
cal direction  at  the  external  orifice ;  but,  in  the  transverse  direction,  at  the 
tympanic  end.  The  membrana  tympani,  which  occupies  the  termination  of  the 
meatus,  is  obliquely  directed,  in  consequence  of  the  floor  of  the  canal  being 
longer  than  the  roof,  and  the  anterior  wall  longer  than  the  posterior.  The 
auditory  canal  is  formed  partly  by  cartilage  and  membrane,  and  partly  by 
bone. 

The  cartilaginous  portion  is  about  half  an  inch  in  length,  being  rather  less 
than  half  the  canal;  it  is  formed  by  the  cartilage  of  the  concha  and  tragus, 
prolonged  inwards,  and  firmly  attached  to  the  circumference  of  the  auditory 
process.  The  cartilage  is  deficient  at  its  upper  and  back  part,  its  place  being 
supplied  by  fibrous  membrane.  This  part  of  the  canal  is  rendered  extremely 
movable  by  two  or  three  deep  fissures  {incisurse  Santorini),  which  extend 
through  the  cartilage  in  a  vertical  direction. 

The  osseous  portion  is  about  three-quarters  of  an  inch  in  length,  and  narrower 
than  the  cartilaginous  portion.  It  is  directed  inwards  and  a  little  forwards, 
forming  a  slight  curve  in  its  course,  the  convexity  of  which  is  upwards  and 
backwards.  Its  inner  end,  which  communicates  with  the  cavity  of  the  tympa- 
num, is  smaller  than  the  outer,  and  sloped,  the  anterior  wall  projecting  beyond 
the  posterior  about  two  lines;  it  is  marked,  except  at  its  upper  part, 'by  a  nar- 
row groove  for  the  insertion  of  the  membrana  tympani.  Its  outer  end  is  dilated, 
and  rough,  in  the  greater  part  of  its  circumference,  for  the  attachment  of  the 
cartilage  of  the  pinna.  Its  vertical  transverse  section  is  oval,  the  greatest 
diameter  being  from  above  downwards.  The  front  and  lower  parts  of  this 
canal  are  formed  by  a  curved  plate  of  bone,  which,  in  the  foetus,  exists  as  a 
separate  ring  (tympanic  bone),  incomplete  in  its  upper  part. 

The  skin  lining  the  meatus  is  very  thin,  adheres  closely  to  the  cartilaginous 
and  osseous  portions  of  the  tube,  and  covers  the  surface  of  the  membrana  tym- 
pani, forming  its  outer  layer.  After  maceration,  the  thin  pouch  of  epidermis, 
when  withdrawn,  preserves  the  form  of  the  meatus.     The  skin  near  the  orifice 


698  ORGANS    OF    SENSE. 

is  furnished  witli  hairs  and  sebaceous  glands.  In  the  thick  subcutaneous  tissue 
of  the  cartilaginous  part  of  the  meatus  are  numerous  ceruminous  glands,  which 
secrete  the  ear-wax:  their  ducts  open  on  the  surface  of  the  skin. 

The  arteries  supplying  the  meatus  are  branches  from  the  posterior  auricular, 
internal  maxillary,  and  temporal. 

The  nerves  are  chiefly  derived  from  the  auriculo-temporal  branch  of  the  infe- 
rior maxillary  nerve. 

Middle  Ear,  or  Tympanum. 

The  Middle  Ear,  or  Tympanum,  is  an  irregular  cavity,  compressed  from 
•without  inwards,  and  situated  within  the  petrous  bone.  It  is  placed  above  the 
jugular  fossa,  the  carotid  canal  lying  in  front,  the  mastoid  cells  behind,  the 
meatus  auditorius  externally,  and  the  labyrinth  internally.  It  is  filled  with  air, 
and  communicates  with  the  pharynx  by  the  Eustachian  tube.  The  tympanum 
is  traversed  by  a  chain  of  movable  bones,  which  connect  the  membraua  tym- 
pani  with  the  labyrinth,  and  serve  to  convey  the  vibrations  communicated  to 
the  membrana  tympani  across  the  cavity  of  the  tympanum  to  the  internal  ear. 

The  cavity  of  the  tympanum  measures  about  five  lines  from  before  backwards, 
three  lines  in  the  vertical  direction,  and  between  two  and  three  in  the  trans- 
verse, being  a  little  broader  behind  and  above  than  it  is  below  and  in  front. 
It  is  bounded  excernally  by  the  membrani  tympani  and  meatus;  internally,  by 
the  outer  surface  of  the  internal  ear;  and  communicates,  behind,  with  the 
mastoid  cells;  and,  in  front,  with  the  Eustachian  tube  and  canal  for  the  Tensor 
Tympani.  Its  roof  and  floor  are  formed  by  thin  osseous  laminae,  which  connect 
the  squamous  and  petrous  portions  of  the  temporal  bone. 

The  roof  is  broad,  flattened,  and  formed  of  a  thin  plate  of  bone,  which  sepa- 
rates the  cranial  and  tympanic  cavities. 

The ^oor  is  narrow,  and  corresponds  to  the  jugular  fossa,  which  lies  beneath. 

The  outer  wall  is  formed  by  the  membrana  tympani,  a  small  portion  of  bone 
being  seen  above  and  below  this  membrane.  It  presents  three  small  apertures, 
the  iter  chordae  posterius,  the  Glaserian  fissure,  and  the  iter  chord®  anterius. 

The  ajjerture  of  the  iter  chordse  posterius  is  behind  the  aperture  for  the  mem- 
brana tympani,  close  to  its  margin,  on  a  level  with  its  centre;  it  leads  into  a 
minute  canal,  which  descends  in  front  of  the  aquaeductus  Fallopii,  and  termi- 
nates in  that  canal  near  the  stylo-mastoid  foramen.  Through  it  the  chorda 
tympani  nerve  enters  the  tympanum. 

The  Olaserian  fissure  opens  just  above  and  in  front  of  the  orifice  of  the  mem- 
brana tympani ;  in  this  situation  it  is  a  mere  slit,  about  a  line  in  length.  It 
gives  passage  to  the  long  process  of  the  malleus,  the  Laxator  Tympani  muscle, 
and  some  tympanic  vessels. 

The  aperture  of  the  iter  chordse  anterius  is  seen  just  above  the  preceding  fissure ; 
it  leads  into  a  canal  (canal  of  Huguier),  which  runs  parallel  with  the  Glaserian 
fissure.     Through  it  the  chorda  tympani  nerve  leaves  the  tympanum. 

The  internal  wall  of  the  tympamim  (Fig.  379)  is  vertical  in  direction,  and  looks 
directly  outwards.     It  presents  for  examination  the  following  parts: — 

Fenestra  ovalis.  Ridge  of  the  Aquaeductus  Fallopii. 

Fenestra  rotunda.  Pyramid. 

Promontory.  Opening  for  the  Stapedius. 

The  fenestra  ovalis  is  a  reniform  opening,  leading  from  the  tympanum  into" 
the  vestibule;  its  long  diameter  is  directed  horizontally,  and  its  convex  border 
is  upwards.  The  opening  in  the  recent  state  is  closed  by  the  lining  membrane 
common  to  both  cavities,  and  is  occupied  by  the  base  of  the  stapes.  This 
membrane  is  placed  opposite  the  membrana  tympani,  and  is  connected  with  it 
by  the  ossicula  auditus. 

The  fenestra  rotunda  is  an  oval  aperture,  placed  at  the  bottom  of  a  funnel- 
shaped  depression,  leading  into  the  cochlea.     It  is  situated  below  and  rather 


THE    MIDDLE    EAR. 


699 


behind  the  fenestra  ovalis,  from  which  it  is  separated  by  a  rounded  elevation, 
the  promontory;  it  is  closed  in  the  recent  state  by  a  membrane  {memhrana  tym- 
pani  secundaria,  Scarpa).  This  membrane  is  concave  towards  the  tympanum, 
convex  towards  the  cochlea.  It  consists  of  three  layers:  the  external,  or 
mucous,  derived  from  the  mucous  lining  of  the  tympanum;  the  internal,  or 
serous,  from  the  lining  membrane  of  the  cochlea;  and  an  intermediate,  or 
fibrous  layer. 

The  promontory  is  a  roiinded  hollow  prominence,  formed  by  the  projection 

Fig.  379. — View  of  Inner  Wall  of  Tympanum.    (Enlarged.) 


Chorda  Tymgt 


outwards  of  the  first  turn  of  the  cochlea;  it  is  placed  between  the  fenestras,  and 
is  furrowed  on  its  surface  by  three  small  grooves,  which  lodge  branches  of  the 
tympanic  plexus. 

The  rounded  eminence  of  the  aquseductus  Fallopii  is  placed  beneath  the  fenestra 
ovalis  and  roof  of  the  tympanum;  it  is  the  prominence  of  the  bony  canal  in 
which  the  portio  dura  is  contained.  It  traverses  the  inner  wall  of  the  tym- 
panum above  the  fenestra  ovalis,  and  behind  that  opening  curves  nearly  verti- 
cally downwards  along  the  posterior  wall. 

The  pyramid  is  a  conical  eminence,  situated  immediately  behind  the  fenestra 
ovalis,  and  in  front  of  the  vertical  portion  of  the  eminence  above  described;  it 
is  hollow  in  the  interior,  and  contains  the  Stapedius  muscle;  its  summit  projects 
forwards  towards  the  fenestra  ovalis,  and  presents  a  small  aperture,  which 
transmits  the  tendon  of  the  muscle.  The  cavity  in  the  pyramid  is  prolonged 
into  a  minute  canal,  which  communicates  with  the  aqua^ductus  Fallopii,  and 
transmits  the  nerve  which  supplies  the  Stapedius. 

^\\Q  2')Qsterior  wall  of  the  tymjpanum  is  wider  above  than  below,  and  presents 
for  examination  the 

Openings  of  the  Mastoid  Cells. 

These  consist  of  one  large  irregular  aperture,  and  several  smaller  openings, 
situated  at  the  upper  part  of  the  posterior  wall ;  they  lead  into  canals,  which 
communicate  with  large  irregular  cavities  contained  in  the  interior  of  the  mas- 
toid process.  These  cavities  vary  considerably  in  number,  size,  and  form; 
they  are  lined  by  mucous  membrane,  continuous  with  that  covering  the  cavity 
of  the  tympanum. 

The  anterior  wall  of  the  tympanum  is  wider  above  than  below;  it  corresponds 
with  the  carotid  canal,  from  which  it  is  separated  by  a  thin  plate  of  bone;  it 
presents  for  examination  the 

Canal  for  the  Tensor  Tympani.  Orifice  of  the  Eustachian  Tube. 

The  Processus  Cochleariformis. 


700  ORGANS    OF    SENSE. 

The  orifice  of  the  canal  for  the  Tensor  Tympani,  and  the  orifice  of  the  Eusta- 
chian tube,  are  situated  at  the  upper  part  of  the  anterior  wall,  being  separated 
from  each  other  by  a  thin,  delicate  horizontal  plate  of  bone,  the  processus 
cochleariforinis.  These  canals  run  from  the  tympanum  forward^  inward,  and  a 
little  downward,  to  the  retiring  angle  between  the  squamous  and  petrous  por- 
tions of  the  temporal  bone. 

The  canal  for  the  Tensor  Tympani  is  the  superior  and  the  smaller  of  the  two ; 
it  is  rounded,  and  lies  beneath  the  upper  surface  of  the  petrous  bone,  close  to 
the  hiatus  Fallopii.  The  tympanic  end  of  this  canal  forms  a  conical  eminence, 
which  is  prolonged  backwards  into  the  cavity  of  the  tympanum,  and  is  per- 
forated at  its  summit  by  an  aperture,  which  transmits  the  tendon  of  the  muscle 
contained  in  it.  This  eminence  is  sometimes  called  the  anterior  i^yramid.  The 
canal  contains  the  Tensor  Tympani  muscle. 

The  Eustachian  tuhe  is  the  channel  through  which  the  tympanum  commu- 
nicates with  the  pharynx.  Its  length  is  from  an  inch  and  a  half  to  two  inches, 
and  its  direction  downwards,  forwards,  and  inwards.  It  is  formed  partly  of 
bone,  partly  of  cartilage  and  fibrous  tissue. 

The  osseoiis  portion  is  about  half  an  inch  in  length.  It  commences  in  the  lower 
part  of  the  anterior  wall  of  the  tympanum,  below  the  processus  cochleariformis, 
and  gradually  narrowing,  terminates  in  an  oval  dilated  opening,  at  the  angle  of 
junction  of  the  petrous  and  squamous  portions,  its  extremity  presenting  a 
jagged  margin,  which  serves  for  the  attachment  of  the  cartilaginous  portion. 

The  cartilaginous  portion,  about  an  inch  in  length,  is  formed  of  a  triangular 
plate  of  cartilage,  curled  upon  itself,  an  interval  being  left  below,  between  the 
margins  of  the  cartilage,  which  is  completed  by  fibrous  tissue.  Its  canal  is 
narrow  behind,  wide,  expanded,  and  somewhat  trumpet-shaped  in  front,  termi- 
nating by  an  oval  orifice,  at  the  upper  part  and  side  of  the  pharynx,  behind 
the  back  part  of  the  inferior  meatus.  Through  this  canal  the  mucous  mem- 
brane of  the  pharynx  is  continuous  with  that  which  lines  the  tympanum. 

The  memhrana  tymjyani  separates  the  cavity  of  the  tympanum  from  the  bottom 
of  the  external  meatus.  It  is  a  thin  semi-transparent  membrane,  nearly  oval  in 
form,  somewhat  broader  above  than  below,  and  directed  very  obliquely  down- 
wards and  inwards.  Its  circumference  is  contained  in  a  groove  at  the  inner  end 
of  the  meatus,  which  skirts  the  circumference  of  this  part  excepting  above. 
The  handle  of  the  malleus  descends  vertically  betAveen  the  inner  and  middle 
layers  of  this  membrane,  as  far  down  as  its  centre,  where  it  is  firmly  attached, 
drawing  the  membrane  inwards,  so  that  its  outer  surface  is  concave,  its  inner 
convex. 

Structure.  This  membrane  is  composed  of  three  layers,  an  external  (cuti- 
cular),  a  middle  (fibrous),  and  an  internal  (mucous).  The  cuticular  lining  is  de- 
rived from  the  integument  lining  the  meatus.  The  Jibrous  layer  consists  of 
fibrous  and  elastic  tissues;  some  of  the  fibres  radiate  from  near  the  centre  to 
the  circumference ;  others  are  arranged,  in  the  form  of  a  dense  circular  ring, 
round  the  attached  margin  of  the  membrane.  The  mucous  lining  is  derived 
from  the  mucous  lining  of  the  tympanum.  The  vessels  pass  to  the  niembrana 
tympani  along  the  handle  of  the  malleus,  and  are  distributed  between  its  layers. 

Ossicles  of  the  Tympanum.    (Fig.  380.) 

The  tympanum  is  traversed  by  a  chain  of  movable  bones,  three  in  number, 
the  malleus,  incus,  and  stapes.  The  former  is  attached  to  the  membrana  tym- 
pani, the  latter  to  ther  fenestra  ovalis,  the  incus  being  placed  between  the  two, 
to  both  of  which  it  is  connected  by  delicate  articulations. 

The  Malleus,  so  named  from  its  fancied  resemblance  to  a  hammer,  consists  of 
a  head,  neck,  and  three  processes :  the  handle,  or  manubrium,  the  processus 
gracilis,  and  the  ])rocessus  brevis. 

The  head  is  the  large  upper  extremity  of  the  bone  ;  it  is  oval  in  shape,  and 
articulates  posteriorly  with  the  incus,  being  free  in  the  rest  of  its  extent. 


OSSICLES    OF    THE    TYMPANUM.  7C1 

The  neck  is  the  narrow  contracted  part  just  beneath  the  head ;  and  below  this 
is  a  prominence,  to  which  the  various  processes  are  attached. 

The  manubrium  is  a  vertical  process  of  bone,  which  is  connected  by  its  outer 
margin  with  the  membrana  tympani.  It  decreases  in  size  towards  its  extremity, 
where  it  is  curved  slightly  forwards,  and  flattened  from  within  outwards. 

The  processus  gracilis  is  a  long  and  very  delicate  process,  which  passes  from 
the  eminence  below  the  neck  forwards  and  outwards  to  the  Glaserian  fissure,  to 
which  it  is  connected  by  bone  and  ligamentous  fibres.  It  gives  attachment  to 
the  Laxator  Tympani. 

The  'processus  brevis  is  a  slight  conical  projection,  which  springs  from  the  root 
of  the  manubrium,  and  lies  in  contact  with  the  membrana  tympani.  Its  summit 
gives  attachment  to  the  Tensor  Tympani. 

The  Incus  has  received  its  name  from  its  supposed  resemblance  to  an  anvil, 
but  it  is  more  like  a  bicuspid  tooth,  with  two  roots,  which  differ  in  length,  and 
are   widely  separated   from  each   other.     It 
consists  of  a  body  and  two  processes.  Fig.  380.— The  Small  Bones  of  the  Ear» 

The   body  is    somewhat  quadrilateral,  but        seen  from  the  Outside.  (Enlarged.) 
compressed  laterally.     Its  summit  is  deeply 
concave,  and  articulated  with  the  malleus  ;  in 
the  fresh  state,  it  is  covered  with  cartilage 
and  lined  with  synovial  membrane. 

The  two  processes  diverge  from  one  another 
nearly  at  right  angles. 

The  sliort process,  somewhat  conical  in  shape, 
projects  nearly  horizontally  backwards,  and 
is  attached  to  the  margin  of  the  opening  lead- 
ing into  the  mastoid  cells,  by  ligamentous 
fibres. 

The  long  ^Jrocess^  longer  and  more  slender 
than  the  preceding,  descends  nearly  vertically  behind  the  handle  of  the  malleus, 
and,  bending  inwards,  terminates  in  a  rounded  globular  projection,  the  os  orbi- 
culare,  or  lenticular  process,  which  is  tipped  with  cartilage,  and  articulates  with 
the  head  of  the  stapes.  In  the  foetus  the  os  orbiculare  exists  as  a  separate  bone, 
but  becomes  united  to  the  long  process  of  the  incus  in  the  adult. 

The  /Stapes,  so  called  from  its  close  resemblance  to  a  stirrup,  consists  of  a  head, 
neck,  two  branches,  and  a  base. 

The  head  presents  a  depression,  tipped  with  cartilage,  which  articulates  with 
the  OS  orbiculare. 

The  neck,  the  constricted  part  of  the  bone  below  the  head,  receives  the  inser- 
tion of  the  Stapedius  muscle. 

The  two  branches  {crura)  diverge  from  the  neck,  and  are  connected  at  their 
extremities  by  a  flattened,  oval-shaped  plate  (the  base),  which  forms  the  foot  of 
the  stirrup,  and  is  fixed  to  the  margin  of  the  fenestra  ovalis  by  ligamentous 
fibres. 

Ligaments  of  the  Ossicula.  These  small  bones  are  connected  with  each  other 
and  with  the  walls  of  the  tympanum,  by  ligaments,  and  moved  by  small  mus- 
cles. The  articular  surfaces  of  the  malleus  and  incus,  the  orbicular  process  of 
the  incus  and  head  of  the  stapes,  are  covered  with  cartilage,  connected  together 
by  delicate  capsular  ligaments,  and  lined  by  synovial  membrane.  The  liga- 
ments connecting  the  ossicula  with  the  walls  of  the  tympanum  are  three  in 
number,  one  for  each  bone. 

The  suspensory  ligament  of  the  malleus  is  a  delicate,  round  bundle  of  fibres, 
which  descends  perpendicularly  from  the  roof  of  the  tympanum  to  the  head  of 
the  malleus. 

The  posterior  ligament  of  the  incus  is  a  short,  thick,  ligamentous  band,  which 
connects  the  extremity  of  the  short  process  of  the  incus  to  the  posterior  wall 
of  the  tympanum,  near  the  margin  of  the  opening  of  the  mastoid  cells. 


702  ORGANS    OF    SENSE. 

The  annular  ligament  of  the  stapes  connects  the  circumference  of  tlie  base  of 
this  bone  to  the  margin  of  the  fenestra  ovalis. 

A  suspensory  ligament  of  the  incus  has  been  described  bj  Arnold,  descending 
from  the  roof  of  the  tympanum  to  the  upper  part  of  the  incus,  near  its  articu- 
lation with  the  malleus. 

The  muscles  of  the  tympanum  are  three: — 

Tensor  Tympani.  Laxator  Tympani.  Stapedius. 

The  Tensor  Tympani,  the  largest,  is  contained  in  a  bony  canal,  above  the 
osseus  portion  of  the  Eustachian  tube,  from  which  it  is  separated  by  the  pro- 
cessus cochleariformis.  It  arises  from  the  under  surface  of  the  petrous  bone, 
from  the  cartilaginous  portion  of  the  Eustachian  tube,  and  from  the  osseous 
canal  in  which  it  is  contained.  Passing  backwards,  it  terminates  in  a  slender 
tendon,  which  is  reflected  outwards  over  the  processus  cochleariformis,  and  is 
inserted  into  the  handle  of  the  malleus,  near  its  root.  It  is  supplied  by  a 
branch  from  the  otic  ganglion. 

The  Laxator  Tympani  Major  (Sommerring)  arises  from  the  spinous  process 
of  the  sphenoid  bone,  and  from  the  cartilaginous  portion  of  the  Eustachian 
tube,  and  passing  backwards  through  the  Grlaserian  fissure,  is  inserted  into  the 
neck  of  the  malleus,  just  above  the  processus  gracilis.  It  is  supplied  by  the 
tympanic  branch  of  the  facial. 

The  Laxator  Tympani  Minor  (Sommerring)  arises  from  the  upper  and  back 
part  of  the  external  meatus,  passes  forwards  and  inwards  between  the  middle 
and  inner  layers  of  the  membrana  tympani,  and  is  inserted  into  the  handle  of 
the  malleus,  and  processus  brevis.  This  is  regarded  as  a  ligament  by  some 
anatomists. 

The  Stapedius  arises  from  the  sides  of  a  conical  cavity  hollowed  out  of  the 
interior  of  the  pyramid:  its  tendon  emerges  from  the  orifice  at  the  apex  of  the 
pyramid,  and  passing  forwards,  is  inserted  into  the  neck  of  the  stapes.  Its  sur- 
face is  aponeurotic,  its  interior  fleshy;  and  its  tendon  occasionally  contains  a 
slender  bony  spine,  which  is  constant  in  some  mammalia.  It  is  supplied  by  a 
filament  from  the  facial  nerve. 

Actions.  The  Tensor  Tympani  draws  the  membrana  tympani  inwards,  and 
thus  heightens  its  tenison.  The  Laxator  Tympani  draws  the  malleus  outwards, 
and  thus  the  tympanic  membrane,  especially  at  its  fore  part,  is  relaxed.  The 
Stapedius  depresses  the  back  part  of  the  base  of  the  stapes,  and  raises  its  fore 
part.     It  probably  compresses  the  contents  of  the  vestibule. 

The  mucous  membrane  of  the  tympanum  is  thin,  vascular,  and  continuous  with 
the  mucous  membrane  of  the  pharynx,  through  the  Eustachian  tube.  It  invests 
the  ossicula,  and  the  muscles  and  nerves  contained  in  the  tympanic  cavity; 
forms  the  internal  layer  of  the  membrana  tympani ;  covers  the  foramen  rotun- 
dum ;  and  is  reflected  into  the  mastoid  cells,  which  it  lines  throughout.  In 
the  tympanum  and  mastoid  cells,  this  membrane  is  pale,  thin,  slightly  vascular, 
and  covered  with  ciliated  epithelium.  In  the  osseous  portion  of  the  Eustachian 
tube,  the  membrane  is  thin;  but  in  the  cartilaginous  portion  it  is  very  thick, 
highly  vascular,  covered  with  laminar  ciliated  epithelium,  and  provided  with 
numerous  mucous  glands. 

The  arteries  suj'^jilying  the  tympanum  are  five  in  number.  Two  of  them  are 
larger  than  the  rest,  viz.,  the  tympanic  branch  of  the  internal  maxillary,  which 
supplies  the  membrana  tympani;  and  the  stylo-mastoid  branch  of  the  posterior 
auricular,  which  supplies  the  back  part  of  the  tympanum  and  mastoid  cells. 
The  smaller  branches  are,  the  petrosal  branch  of  the  middle  meningeal,  and 
branches  from  the  ascending  pharyngeal  and  internal  carotid. 

The  veins  of  the  tympanum  terminate  in  the  middle  meningeal  and  pharyngeal 
veins,  and,  through  these,  in  the  internal  jugular. 

1l\\q  nerves  of  tJie  tympanum  may  be  divided  into:  1.  Those  supplying  the 
muscles;  2.  Those  distributed  to  the  lining  membrane;  3.  Branches  communi- 
cating with  other  nerves. 


INTERNAL    EAR.  703 

Nerves  to  muscles.  The  Tensor  Tympani  is  supplied  by  a  brancli  from  the 
otic  ganglion;  the  Laxator  Tyrapani,  and  the  Stapedius,  by  a  filament  from 
the  facial  (Somm erring). 

The  nerves  distributed  to  the  lining  membrane  are  derived  from  the  tympanic 
plexus. 

Communications  between  the  following  nerves  take  place  in  the  tympanum : 
the  tympanic  branch  from  the  petrous  ganglion  of  the  glosso-pharyngeal;  a 
filament  from  the  carotid  plexus;  a  branch  which  joins  the  great  superficial 
petrosal  nerve  from  the  Vidian;  and  a  branch  to  the  otic  ganglion  (small  super- 
ficial petrosal  nerve). 

The  tym-panic  branch  of  the  glosso-pharyngeal  (Jacobson's  nerve)  enters  the 
tympanum  by  an  aperture  in  its  floor,  close  to  the  inner  wall,  and  ascends  on 
to  the  promontory.  It  distributes  filaments  to  the  lining  membrane  of  the 
tympanum,  and  divides  into  three  branches,  which  are  contained  in  grooves  on 
the  promontory,  and  serve  to  connect  this  with  other  nerves.  One  branch  runs 
in  a  groove,  forwards  and  downwards,  to  an  aperture  situated  at  the  junction 
of  the  anterior  and  inner  walls,  just  above  the  floor,  and  enters  the  carotid 
canal,  to  communicate  with  the  carotid  plexus  of  the  sympathetic.  The  second 
branch  is  contained  in  a  groove  which  runs  vertically  upwards  to  an  aperture 
on  the  inner  wall  of  the  tympanum,  just  beneath  the  anterioi  pyramid,  and  in 
front  of  the  fenestra  ovalis.  The  canal  leading  from  this  opens  into  the  hiatus 
Fallopii,  where  the  nerve  contained  in  it  joins  the  great  petrosal  nerve.  The 
third  branch  ascends  towards  the  anterior  surface  of  the  petrous  bone;  it  then 
passes  through  a  small  aperture  in  the  sphenoid  and  temporal  bones  to  the 
exterior  of  the  skull,  and  joins  the  otic  ganglion.  As  this  nerve  passes  by  the 
gangliform  enlargement  of  the  facial,  it  has  a  connecting  filament  with  it. 

The  chorda  tympani  quits  the  facial  near  the  stylo-mastoid  foramen,  enters 
the  tympanum  at  the  base  of  the  pyramid,  and  arches  forwards  across  its  cavity 
between  the  handle  of  the  malleus  and  long  process  of  the  incus,  to  an  opening 
internal  to  the  fissura  Glaseri.  It  is  invested  by  a  reflection  cf  the  lining  mem- 
brane of  ths  tympanum. 

Internal  Ear,  or  Labyrinth. 

The  Internal  Ear  is  the  essential  part  of  the  organ,  receiving  the  ultimate 
distribution  of  the  auditory  nerve.  It  is  called  the  labyrinth,  from  the  complexity 
of  its  shape,  and  consists  of  three  parts,  the  vestibule,  semicircular  canals,  and 
cochlea.  It  is  formed  by  a  series  of  cavities,  channelled  out  of  the  substance 
of  the  petrous  bone,  communicating  externally  with  the  cavity  of  the  tympa- 
num, through  the  fenestra  ovalis  and  rotunda;  and  internally,  with  the  meatus 
auditorius  internus,  which  contains  the  auditory  nerve.  Within  the  osseous 
labyrinth  is  contained  the  membranous  labyrinth,  upon  which  the  ramifications 
of  the  auditory  nerve  are  distributed. 

The  Vestibule  (Fig.  881)  is  the  common  central  cavity  of  communication 
between  the  parts  of  the  internal  ear.  It  is  situated  on  the  inner  side  of  the 
tympanum,  behind  the  cochlea,  and  in  front  of  the  semicircular  canals.  It  is 
somewhat  ovoidal  in  shape  from  before  backwards,  flattened  from  side  to  side, 
and  measures  about  one-fifth  of  an  inch  from  before  backwards,  as  well  as  from 
above  downwards,  being  narrower  from  without  inwards.  On  its  outer,  or  /?/?n- 
pjanic  luall,  is  the  fenestra  ovalis,  closed,  in  the  recent  state,  by  the  base  of  the 
stapes,  and  its  annular  ligament.  On  its  inner  wall,  at  the  fore  part,  is  a  small 
circular  Aq^xq^biow,  fovea  hemispherica,  which  is  perforated,  at  its  anterior  and 
inferior  part,  by  several  minute  holes  {macula  cribosa),  for  the  passage  of  the 
filaments  of  the  auditory  nerve;  and  behind  this  depression  is  a  vertical  ridge, 
the  pyramidal  eminence.  At  the  hinder  part  of  the  inner  wall  is  the  orifice  of 
the  aijuseductus  vestibuli,  which  extends  to  the  posterior  surface  of  the  petrous 
portion  of  the  temporal  bone.     It  transmits  a  small  vein,  and,  according  to 


704 


ORGANS    OF    SENSE. 


some,  contains  a  tubular  prolongation  of  the  lining  membrane  of  the  vestibule, 
which  ends  in  a  cul-de-sac,  between  the  layers  of  the  dura  mater  within  the 
cranial  cavity.  On  the  upper  wall  or  roof  is  a  transversely-oval  depression, 
fovea  semi-elliptica,  separated  from  the  fovea  hemispherica  by  the  pyramidal 
eminence,  already  mentioned.  Behind,  the  semicircular  canals  open  into  the 
vestibule  by  five  orifices.  In  front  is  a  large  oval  opening  which  communi- 
cates with  the  scala  vestibuli  of  the  cochlea  by  a  single  orifice,  apertura  scalar 
vestihuli  cochlese. 

The  Semilunar  Canals  are  three  bony  canals,  situated  above  and  behind  the 
vestibule.  They  are  of  unequal  length,  compressed  from  side  to  side,  and 
describe  the  greater  part  of  a  circle.  They  measure  about  one  one-twentieth 
of  an  inch  in  diameter,  and  each  presents  a  dilatation  at  one  end,  called  the 

Fig.  381. — The  Osseous  Labyrinth  laid  open.     (Enlarged.) 

„t» 


Tot  An  1^  -rt^u^td^ 


Op^^rtuna  of 


ampulla^  which  measures  more  than  twice  the  diameter  of  the  tube.  These 
canals  open  into  the  vestibule  by  five  orifices,  one  of  the  apertures  being  com- 
mon to  two  of  the  canals. 

The  superior  semicircular  canal  is  vertical  in  direction,  and  stretches  across 
the  petrous  portion  of  the  temporal  bone,  at  right  angles  to  its  posterior  sur- 
face ;  its  arch  forms  a  round  projection  on  the  anterior  surface  of  the  petrous 
bone.  It  describes  about  two-thirds  of  a  circle.  Its  outer  extremity,  which  is 
ampullated,  commences  by  a  distinct  orifice  in  the  upper  part  of  the  vestibule; 
the  opposite  end  of  the  canal,  which  is  not  dilated,  joins  with  the  correspond- 
ing part  of  the  posterior  canal,  and  opens  by  a  common  orifice  with  it  in  the 
back  part  of  the  vestibule. 

The  posterior  semicirctdar  canal,  also  vertical  in  direction,  is  directed  back- 
wards, nearly  parallel  to  the  posterior  surface  of  the  petrous  bone ;  it  is  the 
longest  of  the  three,  its  ampullated  end  commencing  at  the  lower  and  back 
part  of  the  vestibule,  its  opposite  end  joining  to  form  the  common  canal  already 
mentioned. 

The  external,  or  horizontal  canal,  is  the  shortest  of  the  three,  its  arch  being 
directed  outwards  and  backwards ;  thus  each  semicircular  canal  stands  at  right 
angles  to  the  other  two.  Its  ampullated  end  corresponds  to  the  upper  and 
outer  angle  of  the  vestibule,  just  above  the  fenestra  ovalis;  its  opposite  end 
opens  by  a  distinct  orifice  at  the  upper  and  back  part  of  the  vestibule. 


INTERNAL    EAR. 


t05 


The  Cochlea  bears  some  resemblance  to  a  common  snail-shell :  it  forms  the 
anterior  part  of  the  labyrinth,  is  conical  in  form,  and  placed  almost  horizontally 
in  front  of  the  vestibule ;  its  apex  is  directed  forwards  and  outwards  towards 
the  upper  and  front  part  of  the  inner  wall  of  the  tympanum ;  its  base  corre- 
sponds with  the  anterior  depression  at  the  bottom  of  the  internal  auditory 
meatus ;  and  is  perforated  by  numerous  apertures,  for  the  passage  of  the  cochlear 
branch  of  the  auditory  nerve.  It  measures  about  a  quarter  of  an  inch  in  length, 
and  its  breadth  towards  the  base  is  about  the  same.  It  consists  of  a  conical - 
shaped  central  axis,  the  modiolus  or  columella;  of  a  canal  wound  spirallv 
round  the  axis  for  two  turns  and  a  half,  from  the  base  to  the  apex ;  and  of  a 
delicate  lamina  (the  lamina  spiralis)  contained  within  the  canal,  which  follows 
its  windings,  and  subdivides  it  into  two. 

The  central  axis,  or  modiolus,  is  conical  in  form,  and  extends  from  the  base  to 
the  apex  of  the  cochlea.  Its  base  is  broad,  corresponds  with  the  first  turn  of 
the  cochlea,  and  is  perforated  with  numerous  orifices,  which  transmit  filaments 
of  the  cochlear  branch  of  the  auditory  nerve ;  the  axis  diminishes  rapidly  in 
size  in  the  second  coil,  and  terminates  within  the  last  half  coil,  or  cupola,  in  an 
expanded,  delicate,  bony  lamella,  which  resembles  the  half  of  a  funnel,  divided 
longitudinally,  and  called  the  infundihulum ;  the  broad  part  of  this  funnel  is 
directed  towards  the  summit  of  the  cochlea,  and  blends  with  the  last  half-turn 
of  the  spiral  canal  of  the  cochlea,  the  cupola.  The  outer  surface  of  the  modiolus 
is  formed  of  the  wall  of  the  spiral  canal,  and  is  dense  in  structure;  but  its 
centre  is  channelled,  as  far  as  the  last  half-coil,  by  numerous  branching  canals, 
which  transmit  nervous  filaments  in  regular  succession  into  the  canal  of  the 
cochlea,  or  on  to  the  surface  of  the  lamina  spiralis.  One  of  these,  larger  than 
the  rest,  occupies  the  centre  of  the  modiolus,  and  is  named  the  tuhnlus  centralis 
modioli ;  it  extends  from  the  base  to  the  extremity  of  the  modiolus,  and  trans- 
mits a  small  nerve  and  artery  {arteria  centralis  modioli). 

The  spiral  canal  (Fig.  382)  takes  two  turns  and  a  half  round  the  modiolus. 
It  is  about  an  incli  and  a  half  in  length,  measured  along  its  outer  wall ;  and 

Fig.  382.— The  Cochlea  laid  open.    (Enlarged.) 


diminishes  gradually  in  size  from  the  base  to  the  summit,  where  it  terminates 
in  a  cul-de-sac,  the  cupola,  which  forms  the  apex  of  the  cochlea.  The  com- 
mencement of  this  canal  is  about  the  tenth  of  an  inch  in  diameter  ;  it  diverges 
from  the  modiolus  towards  the  tympanum  and  vestibule,  and  presents  three 
openings.  One,  the  fenestra  rotunda,  communicates  with  the  tympanum :  in 
the  recent  state,  this  aperture  is  closed  by  a  membrane,  the  membrana  tympani 
secundaria.  Another  aperture,  of  an  oval  form,  enters  the  vestibule.  The 
third  is  the  aperture  of  the  aquseductus  cochlex  leading  to  a  minute  funnel-shaped 
canal,  which  opens  on  the  basilar  surface  of  the  petrous  bone,  and  transmits  a 
small  vein. 

The  interior  of  the  spiral  canal  is  divided  into  two  passages  (scalse)  by  a  thin, 
osseous,  and   membranous  lamina,  which  winds  spirally  round  the  modiolus. 
This  is  the  lamina  spiralis,  the  essential  part  of  the  cochlea  upon  which  the 
45 


706  ORGANS    OF    SENSE. 

nerve-tubules  are  distributed.  The  osseous  part  of  the  spiral  lamina  extends 
about  half  way  across  the  diameter  of  the  spiral  canal ;  it  is  called  the  osseous 
zone.  It  commences  in  the  vestibule  between  the  tympanic  and  vestibular 
opening  of  the  cochlea,  and,  gradually  becoming  narrower  in  its  course,  termi- 
nates in  a  projecting  hook,  the  hamular  process,  just  where  the  expansion  of 
the  infundibulum  commences.  The  lamina  spiralis  consists  of  two  thin  lamellae 
of  bone,  between  which  are  numerous  canals  for  the  passage  of  nervous  fila- 
ments, which  open  chiefly  on  the  lower  or  tympanic  surface.  At  the  point 
where  the  osseous  lamina  is  attached  to  the  modiolus,  and  following  its  wind- 
ings, is  a  small  canal,  called  by  Rosenthal  the  canalis  spiralis  modioli.  In  the 
recent  state,  the  osseous  zone  is  continued  to  the  opposite  wall  of  the  canal  by 
a  membranous  and  muscular  layer  (membranous  zone),  so  as  to  form  a  complete 
partition  in  the  tube  of  the  cochlea.  Two  passages,  or  scalae,  are  thus  formed, 
hj  the  division  of  the  canal  of  the  cochlea  into  two.  One,  the  scala  tyynpam, 
is  closed  below  by  the  membrane  of  the  fenestra  rotunda;  the  other,  the  scala 
vestihuli,  communicates,  by  an  oval  aperture,  with  the  vestibule.  Near  the  ter- 
mination of  the  scala  vestibuli,  close  by  the  fenestra  rotunda,  is  the  orifice  of 
the  aquseductus  cochleae.  The  scalae  communicate,  at  the  opening  of  the  cochlea, 
by  an  opening  common  to  both,  the  helicotrema,  which  exists  in  consequence  of 
the  deficiency  of  the  lamina  spiralis  in  the  last  half  coil  of  the  canal. 

In  structure,  the  membranous  zone  is  a  transparent  glassy  lamina,  presenting 
near  its  centre  a  number  of  minute  transverse  lines,  which  radiate  outwards, 
and  give  it  a  fibrous  appearance ;  and  at  its  circumference,  where  connected 
with  the  outer  wall  of  the  spiral  canal,  it  is  composed  of  a  semi-transparent 
structure,  which  is  described  by  Todd  and  Bowman  as  a  muscle  (the  Cochlearis), 
and  by  Kolliker  as  connective  tissue. 

The  vestibular  surface  of  the  osseous  portion  of  the  lamina  spiralis  is  covered 
for  about  the  outer  fifth  of  its  surface  with  a  thin  layer,  resembling  cartilage  in 
texture.  It  is  described  as  the  denticulate  lamina  (Todd  and  Bowman),  from  it.-i 
presenting  a  series  of  wedge-shaped  teeth  which  form  its  free  margin,  and  which 
project  into  the  vestibular  scala. 

The  inner  surface  of  the  osseous  labyrinth  is  lined  by  an  exceedingly  thin 
fibro-serous  membrane,  analogous  to  a  periosteum,  from  its  close  adhesion  to 
the  inner  surface  of  these  cavities,  and  performing  the  office  of  a  serous  mem- 
brane by  its  free  surface.  It  lines  the  vestibule,  and  from  this  cavity  is  con- 
tinued into  the  semicircular  canals  and  the  scala  vestibuli  of  the  cochlea,  and 
through  the  helicotrema  into  the  scala  tympani.  Two  delicate  tubular  pro- 
cesses are  prolonged  along  the  aquasducts  of  the  vestibule  and  cochlea,  to  the 
inner  surface  of  the  dura  mater.  This  membrane  is  continued  across  the  fenestra 
ovalis  and  rotunda,  and  consequently  has  no  communication  with  the  lining 
membrane  of  the  tympanum.  Its  attached  surface  is  rough  and  fibrous,  and 
closely  adherent  to  the  bone ;  its  free  surface  is  smooth  and  pale,  covered  with 
a  layer  of  epithelium,  and  secretes  a  thin,  limpid  fluid,  the  aqtia  lahyrinthi  {peri- 
lymph of  Blainville,  liquor  Cotunnii.)  In  the  vestibule  and  semicircular  canals, 
it  separates  the  osseous  from  the  membranous  labyrinth;  but  in  the  cochlea  it 
lines  the  two  surfaces  of  the  bony  lamina  spiralis;  and  being  continued  from 
its  free  margin  across  the  canal  to  its  outer  wall,  forms  the  lamina  spiralis 
ineraljj'anacea,  serving  to  complete  the  separation  between  the  two  scalae. 

The  Memhranous  Labyrinth  (Fig.  883)  is  a  closed  membranous  sac,  containing 
fluid.  The  ramifications  of  the  auditory  nerve  are  distributed  upon  the  wall  of 
the  sac.  It  has  the  same  general  form  as  the  vestibule  and  semicircular  canals, 
in  which  it  is  inclosed ;  but  is  considerably  smaller,  and  separated  from  their 
lining  membrane  by  the  perilymph. 

The  vestibular  jwrlion  consists  of  two  sacs,  the  utricle  and  the  saccule. 

The  utricle  is  the  larger  of  the  two,  of  an  oblong  form,  compressed  laterally, 
and  occupies  the  upper  and  back  part  of  the  vestibule,  lying  in  contact  with  the 


MEMBRANOUS    LABYRINTH. 


707 


fovea  semi-elHptica.  Numerous  filaments  of  the  auditory  nerve  are  distributed 
on  the  wall  of  this  sac ;  and  its  cavity  communicates  behind  with  the  mem- 
branous semicircular  canals  by  five  orifices. 

The  saccule  is  the  smaller  of  the  two  vestibular  sacs :  it  is  globular  in  form, 
lies  in  the  fovea  hemisph erica,  near  the  opening  of  the  vestibular  scala  of  the 
cochlea,  and  receives  numerous  nervous  filaments,  which  enter  from  the  bottom 
of  the  depression  in  which  it  is  contained.  Its  cavity  is  apparently  distinct 
from  that  of  the  utricle. 

The  memhranous  semicircular  canals  are  about  one-third  the  diameter  of  the 
osseous  canals,  but  in  number,  shape,  and  general  form  they  are  precisely  simi- 
lar; they  are  hollow,  and  open  by  five  orifices  into  the  utricle,  one  opening 
being  common  to  two  canals.  Their  ampullae  are  thicker  than  the  rest  of  the 
tubes,  and  nearly  fill  the  cavities  in  which  they  are  contained. 

Fig.  383.— The  Membranous  Labyrinth  detached.     (Enlarged.) 


otoliths 
tern  ttmugh  ihnw 


^'.  to  Cochlea 


The  membranous  labyrinth  is  held  in  its  position  by  the  numerous  nervous 
filaments  distributed  to  the  utricle,  to  the  saccule,  and  to  the  ampulla  of  each 
canal.  These  nerves  enter  the  vestibule  through  the  minute  apertures  on  its 
inner  wall. 

Structure.  The  wall  of  the  membranous  labyrinth  is  semi-transparent,  and 
consists  of  three  layers.  The  outer  layer  is  a  loose  and  flocculent  tissue,  con- 
taining bloodvessels  and  numerous  pigment-cells,  analogous  to  those  in  the 
choroid.  The  middle  layer,  thicker  and  more  transparent,  bears  some  resem- 
blance to  the  hyaloid  membrane,  but  it  presents  in  parts  marks  of  longitudinal 
fibrillation  and  elongated  nuclei  on  the  addition  of  acetic  acid.  The  inner  layer 
is  formed  of  polygonal  nucleated  epithelial  cells,  which  secrete  the  endolymph. 

The  endolymph  [liquor  Scarpas)  is  a  limpid  serous  fluid,  which  fills  the  mem- 
branous labyrinth;  in  composition,  it  closely  resem"bles  the  perilymph. 

The  otoliths  are  two  small  rounded  bodies,  consisting  of  a  mass  of  minute 
crystalline  grains  of  carbonate  of  lime,  held  together  in  a  mesh  of  delicate 
fibrous  tissue,  and  contained  in  the  wall  of  the  utricle  and  saccule,  opposite  the 
distribution  of  the  nerves.     A  calcareous  material  is  also,  according  to  Bow- 


708  ORGANS    OF    SENSE. 

man,  sparingly  scattered  in  the  cells  lining  the  ampulla  of  each  semicircular 
canal. 

The  Arteries  of  the  labyrinth  are  the  internal  auditory,  from  the  basilar  or 
superior  cerebellar,  the  stylo-mastoid,  from  the  posterior  auricular,  and  occasion- 
ally, branches  from  the  occipital.  The  internal  auditory  divides  at  the  bottom 
of  the  internal  meatus  into  two  branches,  cochlear  and  vestibular. 

The  cochlear  branch  subdivides  into  from  twelve  to  fourteen  twigs,  which 
traverse  the  canals  in  the  modiolus,  and  are  distributed,  in  the  form  of  a  capillary 
network,  in  the  substance  of  the  lamina  spiralis. 

The  vestibular  branches  accompany  the  nerves,  and  are  distributed,  in  the 
form  of  a  minute  capillary  network,  in  the  substance  of  the  membranous 
labyrinth. 

The  Veins  of  the  vestibule  and  semicircular  canals  accompany  the  arteries, 
and  receiving  those  of  the  cochlea  at  the  base  of  the  modiolus  terminate  in  the 
superior  petrosal  sinus. 

The  Auditory  Nerve,  the  special  nerve  of  the  sense  of  hearing,  divides,  at  the 
bottom  of  the  internal  auditory  meatus,  into  two  branches,  the  cochlear  and 
vestibular.  The  trunk  of  the  nerve,  as  well  as  the  branches,  contains  numerous 
ganglion-cells  with  caudate  prolongations. 

The  vestibular  nerve,  the  posterior  of  the  two,  divides  into  three  branches, 
superior,  middle,  and  inferior. 

The  superior  vestibular  branch,  the  largest,  divides  into  numerous  filaments, 
which  pass  through  minute  openings  at  the  upper  and  back  part  of  the  cul-de-sac 
at  the  bottom  of  the  meatus,  and  entering  the  vestibule,  are  distributed  to  the 
utricle,  and  to  the  ampulla  of  the  external  and  superior  semicircular  canals. 

The  middle  vestibular  branch  consists  of  numerous  filaments,  which  enter  the 
vestibule  by  a  smaller  cluster  of  foramina,  placed  below  those  above  mentioned, 
and  which  correspond  to  the  bottom  of  the  fovea  hemispherica ;  they  are  dis- 
tributed to  the  saccule. 

The  inferior  and  smallest  branch  passes  backAvards  in  a  canal  behind  the 
foramina  for  the  nerves  of  the  saccule,  and  is  distributed  to  the  ampulla  of  the 
posterior  semicircular  canal. 

The  nervous  filaments  enter  the  ampullary  enlargement  at  a  deep  depression 
seen  on  their  external  surface,  and  a  corresponding  elevation  is  seen  within,  the 
nerve-fibres  ending  in  loops,  and  in  free  extremities.  In  the  utricle  and  saccule, 
the  nerve-fibres  spread  out,  some  blending  with  calcareous  matter,  others  radi- 
ating on  the  inner  surface  of  the  wall  of  each  cavity,  becoming  blended  with  a 
layer  of  nucleated  cells,  and  terminating  in  a  thin  fibrous  film. 

The  cochlear  nerve  divides  into  numerous  filaments  at  the  base  of  the  modiolus, 
which  ascend  along  its  canals,  and,  then,  bending  outwards  at  right  angles,  pass 
between  the  plates  of  the  bony  lamina  spiralis,  close  to  its  tympanic  surface. 
Between  the  plates  of  the  spiral  lamina,  the  nerves  form  a  plexus,  which  con- 
tains ganglion  cells;  and  from  the  margin  of  the  osseous  zone,  branches  of  this 
plexus  are  distributed  to  the  membranous  part  of  the  septum,  where  they  are 
arranged  in  small,  conical-shaped  bundles,  parallel  with  one  another.  The  fila- 
ments which  supply  the  apical  portion  of  the  lamina  spiralis,  are  conducted  to 
this  part  through  the  tubulus  centralis  modioli. 


Organs  of  Digestion. 


The  Apparatus  for  Digestion  of  the  food  consists  of  the  alimentary  canal, 
and  of  certain  accessory  organs. 

The  Alimentary  Canal  is  a  musculo-merabranous  tube,  about  thirty  feet  in 
length,  extending  from  the  mouth  to  the  anus,  and  lined  throughout  its  entire 
extent  by  mucous  membrane.  It  has  received  different  names  in  the  various 
parts  of  its  course :  at  its  commencement,  the  mouth,  we  find  provision  made 
for  the  mechanical  division  of  the  food  (mastication),  and  for  its  admixture  with 
a  fluid  secreted  by  the  salivary  glands  (insalivation) ;  beyond  this  are  the  organs 
of  deglutition,  the  pharynx  and  the  oesophagus,  which  convey  the  food  into  that 
part  of  the  alimentary  canal  (the  stomach)  in  which  the  principal  chemical 
changes  occur;  in  the  stomach,  the  reduction  and  solution  of  the  food  take 
place ;  in  the  small  intestines,  the  nutritive  principles  of  the  food  (the  chyle), 
by  its  admixture  with  the  bile  and  pancreatic  fluid,  are  separated  from  that 
portion  which  passes  into  the  large  intestine,  most  of  which  is  expelled  from 
the  system. 


Mouth. 
Pharynx. 
(Esophagus. 
Stomach. 


Teeth. 
Salivary  glands 


Alimentary  Canal. 
Small  intestine 


Large  intestine 

Accessory  Organs. 

{Parotid. 
Submaxillary. 
Sublingual. 

The  Mouth. 


{Duodenum. 
Jejunum. 
Ileum. 
{Caecum. 
Colon. 
Eectum. 


Liver. 

Pancreas. 

Spleen. 


The  Mouth  (Fig.  384)  is  placed  at  the  commencement  of  the  alimentary  canal ; 
it  is  a  nearly  oval-shaped  cavity,  in  which  the  mastication  of  the  food  takes 
place.  It  is  bounded,  in  front  by  the  lips ;  laterally,  by  the  cheeks  and  the 
alveolar  processes  of  the  upper  and  lower  jaw ;  above,  by  the  hard  palate  and 
teeth  of  the  upper  jaw ;  below,  by  the  tongue,  and  by  the  mucous  membrane 
stretched  between  the  under  surface  of  that  organ  and  the  inner  surface  of  the 
jaws,  and  by  the  teeth  of  the  lower  jaw ;  behind,  by  the  soft  palate  and  fauces. 

The  mucous  memlrane  lining  the  mouth,  is  continuous  with  the  integument 
at  the  free  margin  of  the  lips,  and  with  the  mucous  lining  of  the  fauces  behind ; 
it  is  of  a  rose-pink  tinge  during  life,  and  very  thick  where  it  covers  the  hard 
parts  bounding  the  cavity. 

The  Lips  are  two  fleshy  folds,  which  surround  the  orifice  of  the  mouth,  formed 
externally  of  integument,  and  internally  of  mucous  membrane,  between  which 
is  found  the  Orbicularis  Oris  muscle,  the  coronary  vessels,  some  nerves,  areolar 
tissue,  and  fat,  and  numerous  small  labial  glands.  The  inner  surface  of  each 
lip  is  connected  in  the  middle  line  to  the  gum  of  the  corresponding  jaw  by  a 
fold  of  mucous  membrane,  thefrsenum  lahii  superioris  and  inferioris,  the  former 
being  the  larger  of  the  two. 

The  labial  glands  are  situated  between  the  mucous  membrane  and  the  Orbi 

709 


710 


ORGANS    OF    DIGESTION. 


cularis  Oris,  round  the  orifice  of  the  mouth.  They  are  rounded  in  form,  about 
the  size  of  small  peas,  their  ducts  opening  by  small  orifices  upon  the  mucous 
membrane.     In  structure,  they  resemble  the  other  salivary  glands. 

The  Cheeks  form  the  sides  of  the  face,  and  are  continuous  in  front  with  the 
lips.  They  are  composed,  externally,  of  integument ;  internally,  of  mucous 
membrane,  and  between  the  two,  of  a  muscular  stratum,  besides  a  large  quan- 
tity of  fat,  areolar  tissue,  vessels,  nerves,  and  buccal  glands. 

The  mucous  membrane  lining  the  cheek,  is  reflected  above  and  below  upon 
the  gums,  and  is  continuous  behind  with  the  lining  membrane  of  the  soft  palate. 
Opposite  the  second  molar  tooth  of  the  upper  jaw  is  a  papilla,  the  summit  of 
which  presents  the  aperture  of  the  duct  of  the  parotid  gland.  The  principal 
muscle  of  the  cheek  is  the  Buccinator ;  but  several  other  muscles  enter  into 
its  formation ;  viz.,  the  Zygomatici,  Masseter,  and  Platysraa  Myoides. 


Fig.  384.— Sectional  View  of  the  Nose,  Mouth,  Pharynx,  «fec. 


Bnafte 
fias^fd  throuifh 
•Stnw's  ttuet 


The  buccal  glands  are  placed  between  the  mucous  membrane  and  Buccinator 
muscle;  they  are  similar  in  structure  to  the  labial  glands,  but  smaller.  Two 
or  three,  of  larger  size  than  the  rest,  are  placed  between  the  Masseter  and  Buc- 
cinator muscles ;  their  ducts  open  into  the  mouth,  opposite  the  last  molar  tooth. 
They  are  called  molar  glands 

The  Oums  are  composed  of  a  dense  fibrous  tissue,  closely  connected  to  the 
periosteum  of  the  alveolar  processes,  and  surrounding  the  uecks  of  the  teeth. 
They  are  covered  by  smooth  and  vascular  mucous  membrane,  which  is  re- 
markable for  its  limited  sensibility.  Around  the  necks  of  the  teeth,  this  mem- 
brane presents  numerous  fine  papillae;  and  from  this  point  it  is  reflected  into 
the  alveolus,  where  it  is  continuous  with  the  periosteal  membrane  lining  that 
cavitv. 


THE    TEETH. 


ni 


The  Teeth. 

The  human  subject  is  provided  with  two  sets  of  Teeth,  which  make  their 
appearance  at  different  periods  of  life.  The  first  set  appear  in  childhood,  and 
are  called  the  temporary^  deciduous^  or  milk  teeth.  The  second  set,  which  also 
appear  at  an  early  period,  continue  until  old  age,  and  are  noxaQdi  permanent. 

Fig.  385.— The  Permanent  Teeth.     External  View. 

Ujtper    Ja.i» 
■^oftr»  £icttapidt  Canine 

f " 


Tn^itor^ 


WiadoM   taath 


'Tana 


-Nech 


-C  re  ton 


Xiower  Ja,io 


£ieusjiid» 


The  temporary  teeth  are  twenty  in  number ;  four  incisors,  two  canine,  and 
four  molars,  in  each  jaw. 

The  permanent  teeth  are  thirty -two  in  number ;  four  incisors,  two  central 
and  two  lateral,  two  canine,  four  bicuspids,  and  six  molars,  in  each  jaw. 

General  characters.  Each  tooth  consists  of  three  portions;  the  crown  or  body, 
projecting  above  the  gum;  the  root,  or  fang,  entirely  concealed  within  the  alve- 
olus ;  and  the  neck,  the  constricted  portion  between  the  other  two. 

The  roots  of  the  teeth  are  firmly  implanted  within  the  alveoli ;  these  depres- 
sions are  lined  with  periosteum,  which  is  reflected  on  to  the  tooth  at  the  point 
of  the  fang,  and  covers  it  as  far  as  the  neck.  At  the  margin  of  the  alveolus, 
the  periosteum  becomes  continuous  with  the  fibrous  structure  of  the  gums. 

Permanent  Teeth. 

The  Incisors,  or  cutting  teeth,  are  so  named  from  their  presenting  a  sharp, 
cutting  edge,  adapted  for  cutting  the  food.  They  are  eight  in  number,  and 
form  the  four  front  teeth  in  each  jaw. 

The  crown  is  directed  vertically,  is  wedge-like  in  form,  being  bevelled  at  the 
expense  of  its  posterior  surface,  so  as  to  terminate  in  a  sharp,  horizontal  cut- 
ting edge,  which,  before  being  subject  to  attrition,  presents  three  small  promi- 
nent points.  It  is  convex,  smooth,  and  highly  polished  in  front ;  slightly 
concave  behind,  where  it  is  frequently  marked  by  slight  longitudinal  furrows. 

The  nech  is  constricted. 

The  fang  is  long,  single,  conical,  transversely  flattened,  thicker  before  than 
behind,  and  slightly  grooved  on  each  side  in  the  longitudinal  direction. 

The  incisors  of  the  tq)2^er  jaw  are  altogether  larger  and  stronger  than  those 


712'  ORGANS    OF    DIGESTION. 

of  the  lower  jaw.  Thej  are  directed  obliquely  downwards  and  forwards.  The 
two  central  ones  are  larger  than  the  two  lateral,  and  their  free  edges  are  sharp 
and  chisel-like,  being  bevelled  at  the  expense  of  their  posterior  edge :  the  root 
is  more  rounded. 

The  incisors  of  the  lower  jaw  are  smaller  than  the  upper;  the  two  central  ones 
are  smaller  than  the  two  lateral,  and  are  the  smallest  of  all  the  incisor  teeth. 

The  Canine  Teeth  {cuspidati)  are  four  in  number,  two  in  the  upper  and  two  in 
the  lower  jaw  ;  one  being  placed  behind  each  lateral  incisor.  They  are  larger 
and  stronger  than  the  incisors,  especially  the  root,  which  sinks  deeply  into  the 
jaw,  and  causes  a  well-marked  prominence  upon  its  surface. 

The  crown  is  large  and  conical,  very  convex  in  front,  a  little  hollowed  and 
uneven  posteriorly,  and  tapering  to  a  blunted  point,  or  cusp,  which  rises  above 
the  level  of  the  other  teeth. 

The  root  is  single,  but  longer  and  thicker  than  that  of  the  incisors,  conical  in 
form,  compressed  laterally,  and  marked  by  a  slight  groove  on  each  side. 

The  upper  canine  teeth  (vulgarly  called  eye-teeth)  are  larger  and  longer  than 
the  two  lower,  and  situated  a  little  behind  them. 

The  loiuer  canine  teeth  are  placed  in  front  of  the  upper,  so  that  their  summits 
correspond  to  the  interval  between  the  upper  canine  tooth  and  the  neighboring 
incisors  on  each  side. 

The  Bicuspid  T^ee^A  (small,  or  false  molars),  are  eight  in  number,  four  in  each 
jaw,  two  being  placed  immediately  behind  each  of  the  canine  teeth.  They  are 
smaller  and  shorter  than  the  canine. 

The  crown  is  compressed  from  without  inwards,  and  surmounted  by  two 
pyramidal  eminences,  or  cusps,  separated  by  a  groove,  hence  their  name,  bicus- 
pidate.     The  outer  of  these  cusps  is  larger  and  more  prominent  than  the  inner. 

The  neck  is  oval. 

The  root  is  generally  single,  compressed,  and  presents  a  deep  groove  on  each 
side,  which  indicates  a  tendency  in  the  root  to  become  double.  The  apex  is 
generally  bifid. 

The  upper  bicuspids  are  larger,  and  present  a  greater  tendency  to  the  division 
of  their  roots  than  the  lower :  this  is  especially  marked  in  the  second  upper 
bicuspid. 

The  Molar  Teeth  {multicv^pidati,  true,  or  large  molars)  are  the  largest  of  the 
permanent  set,  and  are  adapted,  from  the  great  breadth  of  their  crowns,  for 
grinding  and  pounding  the  food.  They  are  twelve  in  number,  six  in  each  jaw, 
three  being  placed  behind  each  of  the  posterior  bicuspids. 

The  crown  is  nearly  cubical  in  form,  rounded  on  each  of  its  lateral  surfaces, 
flattened  in  front  and  behind ;  the  upper  surface  being  surmounted  by  four 
or  five  tubercles,  or  cusps  (four  in  the  upper,  five  in  the  lower  molars),  sepa- 
rated from  each  other  by  a  crucial  depression,  hence  their  name,  multicusjjidati. 

The  neck  is  distinct,  large,  and  rounded. 

The  ?'oot  is  subdivided  into  from  two  to  five  fangs,  each  of  which  presents  an 
aperture  at  its  summit. 

The  Jirst  molar  tooth  is  the  largest  and  broadest  of  all ;  its  crown  has  usually 
five  cusps,  three  outer  and  two  inner.  In  the  upper  jaw,  the  root  consists  of 
three  fangs,  widely  separated  from  one  another,  two  being  external,  the  other 
internal.  The  latter  is  the  largest  and  the  longest,  slightly  grooved,  and  some- 
times bifid.  In  the  lower  jaw,  the  root  consists  of  two  fangs,  one  being  placed 
in  front,  the  other  behind :  they  are  both  compressed  from  before  backwards, 
and  grooved  on  their  contiguous  faces,  indicating  a  tendency  to  division. 

The  second  molar  is  a  little  smaller  than  the  first. 

The  crown  has  four  cusps  in  the  upper,  and  five  in  the  jowcr  jaw. 

The  root  has  three  fangs  in  the  upper  jaw,  and  two  in  the  lower,  the  characters 
of  which  are  similar  to  the  preceding  tooth. 

The  third  molar  tooth  is  called  the  wisdom  tooth  {dens  sapientiw),  from  its  late 
appearance  through  the  gum.  It  is  smaller  than  the  others,  and  its  axis  is 
directed  inwards. 


TEMPORARY    TEETH. 


13 


The  crown  is  small  and  rounded,  and  furnished  with  three  tubercles. 

The  root  is  generally  single,  short,  conical,  slightly  curved,  and  grooved  so 
as  to  present  traces  of  a  subdivision  into  three  fangs  in  the  upper,  and  two  in 
the  lower  jaw. 

Temporary  Teeth. 

The  Temporary,  or  Milk  Teeth,  are  smaller,  but  resemble  in  form  those  of 
the  permanent  set.  The  hinder  of  the  two  temporary  molars  is  the  largest 
of  all  the  milk  teeth,  and  is  succeeded  by  the  second  permanent  bicuspid.  The 
first  upper  molar  has  only  three  cusps,  two  external,  one  internal :  the  second 
upper  molar  has  four  cusps.     The  first  lower  molar  has  four  cusps :  the  second 

Fig.  386.— The  Temporary,  or  Milk  Teeth.     External  View. 


LoivRf   Jaw 


lower  molar  has  five.  The  fangs  of  the  temporary  molar  teeth  are  smaller,  and 
more  diverging  than  those  of  the  permanent  set :  but,  in  other  respects,  bear  a 
strong  resemblance  to  them. 

Structure.  On  making  a  vertical  section  of  a  tooth  (Fig.  387),  a  hollow  cavity 
will  be  found  in  the  interior.  This  cavity  is  situated  at  the  base  of  the  crown, 
and  is  continuous  with  a  canal  which  traverses  the  centre  of  each  fang,  and 
opens  by  a  minute  orifice  at  its  extremity.  The  shape  of  the  cavity  corre- 
sponds somewhat  with  that  of  the  tooth :  it  forms  what  is  called  the  pulp  cavity, 
and  contains  a  soft,  highly  vascular,  and  sensitive  substance,  the  dental  pulp. 
The  pulp  is  richly  supplied  with  vessels  and  nerves,  which  enter  the  cavity 
through  the  small  apertures  at  the  point  of  each  fang. 

The  solid  portion  of  the  tooth  consists  of  three  distinct  structures,  viz.,  ivory 
(tooth-bone,  or  dentine),  which  forms  the  larger  portion  of  the  tooth ;  enamel, 
which  covers  the  exposed  part,  or  crown;  and  the  cortical 
substance,  or  cement  [crusta  petrosa),  which  is  disposed  as  a 
thin  layer  on  the  surface  of  the  fang. 

The  Ivory,  or  Dentine  (Fig.  388),  forms  the  principal  mass 
of  a  tooth ;  in  its  central  part  is  the  cavity  inclosing  the  pulp. 
It  is  a  modification  of  the  osseous  tissue,  from  which  it  differs, 
however,  in  structure  and  chemical  composition.  On  exami- 
nation with  the  microscope,  it  is  seen  to  consist  of  a  number 
of  minute  wavy  and  branching  tubes,  having  distinct  parietes. 
They  are  called  the  dental  tuhuli,  and  are  imbedded  in  a  dense 
homogeneous  substance,  the  intertubular  tissue. 

The  dental  tubuli  are  placed  parallel  with  one  another,  and 


Fig.  387.— Vertical 
Section  of  a  Mo- 
lar Tooth. 


-  Crcnm 


714 


ORGANS    OF    DIGESTION. 


Fig.  388.— Vertical  Sec 
tion  of  a  Bicuspid  Tooth 
(Magnified.) 


»ek 


fany 


open  at  their  inner  ends  into  the  pulp  cavity.  They  pursue  a  wavy  and  undii- 
lating  course  towards  the  periphery.  The  direction  of  these  tubes  varies;  they 
are  vertical  in  the  upper  portion  of  the  crown,  oblique 
in  the  neck  and  upper  part  of  the  root,  and  towards  the 
lower  part  of  the  root  they  are  inclined  downwards. 
The  tubuli,  at  their  commencement,  are  about  ^j^jjjj  of 
an  inch  in  diameter ;  in  their  course  they  divide  and 
subdivide  dichotomously,  so  as  to  give  to  the  cut  surface 
of  the  dentine  a  striated  appearance.  From  the  sides 
of  the  tubes,  especially  in  the  fang,  ramifications  of  ex- 
treme minuteness  are  given  off,  which  join  together  in 
loops  in  theintertubular  substance,  or  terminate  in  small 
dilatations,  from  which  branches  are  given  off.  Near 
the  periphery  of  the  dentine,  the  finer  ramifications  of 
the  tubuli  terminate  in  a  somewhat  similar  manner.  In 
the  fang,  these  ramifications  occasionally  pass  into  the 
crusta  petrosa.  The  dental  tubuli  have  comparatively 
thick  walls,  and  contain,  according  to  Mr.  Tomes,  slen- 
der cylindrical  prolongations  of  the  pulp-tissue. 

The  iniertuhular  substance  is  translucent,  finely  granu- 
lar, and  contains  the  chief  part  of  the  earthy  matter  of 
the  dentine.  After  the  earthy  matter  has  been  removed, 
by  steeping  a  tooth  in  weak  acid,  the  animal  basis  re- 
maining is  described  by  Henle  as  consisting  of  bundles 
of  pale,  granular,  flattened  fibres,  running  parallel  with 
the  tubes ;  but  by  Mr.  Nasmy th  as  consisting  of  a  mass 
of  brick-shaped  cells  surrounding  the  tubules.  By  Czermak  and  Mr.  Salter  it  is 
supposed  to  consist  of  laminae  which  run  parallel  with  the  pulp  cavity,  across 
the  direction  of  the  tubes. 

Chemical  Composition.  According  to  Berzelius  and  Bibra,  dentine  consists  of 
28  parts  of  animal,  and  72  of  earthy  matter.  The  animal  matter  is  resolvable 
by  boiling  into  gelatin.  The  earthy  matter  consists  of  phosphate  of  lime,  car- 
bonate of  lime,  a  trace  of  fluoride  of  calcium,  phosphate  of  magnesia  and  other 
salts. 

The  Enamel  is  the  hardest  and  most  compact  part  of  a  tooth,  and  forms  a  thin 
crust  over  the  exposed  part  of  the  crown,  as  far  as  the  commencement  of  the 
fang.  It  is  thickest  on  the  grinding  surface  of  the  crown,  until  worn  away  by 
attrition,  and  becomes  thinner  towards  the  neck.  It  consists  of  a  congeries  of 
minute  hexagonal  rods.  They  lie  parallel  with  one  another,  resting  by  one 
extremity  upon  the  dentine,  which  presents  a  number  of  minute  depressions  for 
their  reception ;  and  forming  the  free  surface  of  the  crown  by  the  other  extre- 
mity. These  fibres  are  directed  vertically  on  the  summit  of  the  crown,  horizon- 
tally at  the  sides;  they  are  about  the  gy'jjc  of  an  inch  in  diameter,  and  pursue 
a  more  or  less  wavy  course,  which  gives  to  the  cut  surface  of  the  enamel  the 
appearance  of  a  series  of  concentric  lines. 

Numerous  minute  interstices  intervene  between  the  enamel- fibres  near  their 
dentinal  surface,  a  provision  calculated  to  allow  of  the  permeation  of  fluids  from 
the  dentinal  tubuli  into  the  substance  of  the  enamel.  The  enamel-rods  consist 
of  solid  hexagonal  or  four-sided  prisms,  connected  by  their  surfaces  and  ends, 
and  filled  with  calcareous  matter.  If  the  latter  is  removed,  by  weak  acid,  from 
newly-formed  or  growing  enamel,  it  will  be  found  to  present  a  network  of  deli- 
cate prismatic  cells  of  animal  matter. 

Chemical  Composition.  According  to  Bibra,  enamel  consists  of  96.5  per  cent, 
of  earthy  matter,  and  3,5  per  cent  of  animal  matter.  The  earthy  matter  consists 
of  phosphate  of  lime,  witli  traces  of  fluoride  of  calcium,  carbonate  of  lime,  phos- 
phate of  magnesia,  and  other  salts. 

The  Cortical  Substance,  or  Cement  {crusta  petrosa),  is  disposed  as  a  thin  layer 


DEVELOPMENT    OF    THE    TEETH. 


715 


Development  of  the  Teeth. 
Fig.  389. 


on  the  roots  of  the  teeth,  from  the  termination  of  the  enamel,  as  far  as  the  apex 
of  the  fang,  where  it  is  usually  very  thick.  In  structure  and  chemical  composi- 
tion, it  resembles  bone.  It  contains,  sparingly,  the  lacunse  and  canaliculi  which 
characterize  true  bone :  the  lacunae  placed  near 
the  surface  have  the  canaliculi  radiating  from 
the  side  of  the  lacunee  towards  the  periodontal 
membrane ;  and  those  more  deeply  placed,  join 
with  the  adjacent  dental  tubuli.  In  the  thicker 
portions  of  the  crusta  petrosa,  the  lamellae  and 
Haversian  canals  peculiar  to  bone  are  also  found. 
As  age  advances,  the  cement  increases  in  thick- 
ness, and  gives  rise  to  those  bony  growths,  or  ex- 
ostoses, so  common  in  the  teeth  of  the  aged ;  the 
pulp  cavity  becomes  also  partially  filled  up  by  a 
hard  substance,  intermediate  in  structure  between 
dentine  and  bone  {osteo-dentine^  Owen ;  secondary 
dentine,  Tomes).  It  appears  to  be  formed  by  a 
slow  conversion  of  the  dental  pulp,  which  shrinks, 
or  even  disappears. 


Frimifivt  JJnttal  CrTv<ytt9 


Fi>.  390. 

jPa^Ha ,^(hrm  of  Milh^toal^ 


Fisr.  391. 


circular 


Development  of  the  Teeth.  (Figs.  389  to  394.) 

According  to  the  observations  of  Arnold  and 
Goodsir,  the  teeth  are  developed  from  the  mucous 
membrane  covering  the  edges  of  the  maxillary 
arches.  About  the  sixth  week  of  foetal  life  (Fig. 
389),  the  mucous  membrane  covering  the  edge 
of  the  upper  jaw  presents  a  semicircular  depres- 
sion or  groove:  this  is  the  primitive  dental  groove 
(Goodsir),  from  the  floor  of  which  the  germs  of 
the  ten  deciduous  or  milk-teeth  are  developed. 
The  germ  of  each  tooth  is  formed  by  a  conical 
elevation  or  papilla  of  mucous  membrane  (Fig. 
390)  which  constitutes  the  rudimentary  pulp  of 
a  milk-tooth.  The  germs  of  the  milk-teeth  make 
their  appearance  in  the  following  order:  at  the 
seventh  week,  the  germ  of  the  first  molar  of  the 
upper  jaw  appears ;  at  the  eighth  week,  that  for 
the  canine  tooth  is  developed ;  the  two  incisor 
papillae  appear  about  the  ninth  week  (the  central 
preceding  the  lateral);  lastly,  the  second  molar 
papilla  is  seen  at  the  tenth  week,  behind  the  an- 
terior molar.  The  teeth  of  the  lower  jaw  appear 
rather  later,  the  first  molar  papilla  being  only 
just  visible  at  the  seventh  week ;  and  the  tenth 
papilla  not  being  developed  before  the  eleventh 
week.  This  completes  the  first  or  papillary  stage 
of  their  development. 

The  dental  groove  now  becomes  contracted, 
its  margins  thickened  and  prominent,  and  the 
groove  is  converted  into  follicles  for  the  recep- 
tion of  the  papillae,  by  the  growth  of  membranous 
septa,  which  pass  across  the  groove  between  its 
borders  (Fig.  391).  The  follicles  by  this  means 
become  the  alveoli,  lined  by  periosteum,  from 
the  bottom  of  which  the  process  of  the  mucous 
membrane  of  the  gum  rises,  which  is  the  germ 


Fiff.  392. 


Fig.  393. 


Fig.  394. 

HTu/ttian    ttf 2tiU-toeu>' 


716  ORGANS    OF    DIGESTION. 

of  the  future  tooth.  The  follicle  for  the  first  molar  is  complete  about  the  tenth 
week ;  the  canine  follows  next,  succeeded  by  the  follicles  for  the  incisors,  which 
are  completed  about  the  eleventh  or  twelfth  week ;  and,  lastly,  the  follicle  of 
the  posterior  molar  is  completed  about  the  fourteenth  week.  These  changes 
constitute  the  second  or  follicular  stage. 

About  the  thirteenth  week,  the  papillse  begin  to  grow  rapidly,  project  from 
the  follicles,  and  assume  a  form  corresponding  with  that  of  the  future  teeth  ; 
the  follicles  soon  become  deeper,  and  from  their  margins  small  membranous 
processes,  or  opercula,  are  developed,  which,  meeting,  unite  and  form  a  lid  to 
the  now  closed  cavity  (Fig.  392).  These  processes  correspond  in  shape  to  the 
form  of  the  crown  of  the  tooth,  and  in  number  to  the  tubercles  on  its  surface. 
The  follicles  of  the  incisor  teeth  have  two  opercula,  the  canine  three,  and  the 
molars  four  or  five  each.  The  follicles  are  thus  converted  into  dental  sacs,  and 
the  contained  papillse  become  pulps.  The  lips  of  the  dental  groove  gradually 
advance  over  the  follicles  from  behind  forwards,  and,  uniting,  gradually  oblite- 
rate it.  This  completes  the  third  or  saccular  stage,  which  takes  place  about  the 
end  of  the  fifteenth  week. 

The  deep  portion  of  the  primitive  dental  groove  is  now  closed  in ;  but  the 
more  superficial  portion,  near  the  surface  of  the  gum,  still  remains  open ;  it  is 
called,  by  Mr.  Goodsir,  the  secondary  dental  groove ;  from  it  are  developed  the 
ten  anterior  permanent  teeth.  About  the  fourteenth  week,  certain  lunated 
depressions  are  formed,  one  behind  each  of  the  sacs  of  the  rudimentary  milk- 
teeth.  They  are  ten  in  number  in  each  jaw,  and  are  formed  successively  from 
before  backwards ;  they  are  the  rudimentary  follicles  of  the  four  permanent 
incisors,  the  two  canine,  and  the  four  bicuspids.  As  the  secondary  dental 
groove  closes  in,  the  follicles  become  closed  cavities  of  reserve  (Fig.  392).  The 
cavities  soon  elongate,  and  recede  from  the  surface  into  the  substance  of  the 
gum,  behind  the  sacs  of  the  deciduous  teeth,  and  a  papilla  projects  from  the 
bottom  of  each,  which  is  the  germ  of  the  permanent  tooth ;  at  the  same  time, 
one  or  more  opercula  are  developed  from  the  sides  of  the  cavity ;  and  these 
uniting,  divide  it  into  portions ;  the  lower  portion  containing  the  papilla  of  the 
permanent  tooth,  the  upper  narrower  portion  becoming  gradually  contracted  in 
the  same  way  that  the  primitive  dental  groove  was  obliterated  over  the  sacs  of 
the  deciduous  teeth  (Fig.  393). 

The  six  posterior  permanent  teeth  in  each  jaw,  three  on  each  side,  arise  from 
successive  extensions  backwards  of  the  back  part  of  the  primitive  dental  groove. 
During  the  fourth  month,  that  portion  of  the  dental  groove  which  lies  behind 
the  last  temporary  molar  follicle,  remains  open,  and  from  it  is  developed  the 
papilla,  the  rudiment  of  the  first  permanent  molar.  The  follicle  in  which  it  is 
contained  becomes  closed  by  its  operculum,  and  the  upper  part  of  the  now- 
formed  sac  elongates  backwards  to  form  a  cavity  of  reserve,  in  which  the  papilla 
of  the  second  permanent  molar  appears  at  the  seventh  month  after  birth.  After 
a  considerable  interval,  during  which  the  sacs  of  the  first  and  second  permanent 
molars  have  considerably  increased  in  size,  the  remainder  of  the  cavity  of  re- 
serve presents  for  the  last  time  a  series  of  changes  similar  to  the  preceding,  and 
gives  rise  to  the  sac  and  papilla  of  the  wisdom-tooth,  which  appears  at  the  sixth 
year. 

Growth  of  the  Teeth.  As  soon  as  the  dental  sacs  are  formed  by  the  closing 
in  of  the  follicles,  they  gradually  enlarge,  as  well  as  their  contained  papillae. 
Each  sac  consists  of  two  layers:  an  internal,  highly  vascular  layer  lined  by 
epithelium ;  and  an  external  or  areolo-fibrous  membrane,  analogous  to  the 
corium  of  the  mucous  membrane. 

The  dental  pulps  soon  become  moulded  to  the  form  of  the  future  teeth,  and 
are  adherent  by  their  bases  to  the  bottom  of  the  dental  sacs;  in  the  case  of  the 
molars  the  base  of  the  pulp  is  divided  into  two  or  more  portions,  which  form 
the  future  fangs.  During  the  fourth  or  fifth  month  of  foetal  life,  a  thin  lamina 
or  cap  of  dentine  is  formed  on  the  most  prominent  point  of  the  pulp  of  all  the 


THE    PALATE.  717 

milk-teeth.  In  tlie  incisor  and  canine  teeth,  this  newly-formed  lamina  has  the 
form  of  a  hollow  cone ;  in  the  molar  teeth,  as  many  separate  laminae  are  found 
as  there  are  eminences  upon  its  crown.  These  laminae  grow  at  the  expense  of 
the  pulp-substance,  increasing  in  breadth  by  a  growth  round  their  margins,  and 
in  thickness  by  a  similar  formation  in  its  substance ;  the  separate  cones  (if  a 
molar  tooth)  ultimately  coalesce,  and  the  crown  is  completely  formed.  The 
pulp  now  becomes  constricted,  so  as  to  form  the  cervix ;  and  the  remaining 
portion  becomes  narrow  and  elongated,  to  form  the  fang.  The  growth  of  den- 
tine takes  place  from  the  surface  towards  the  interior,  until  nothing  but  the 
small  pulp-cavity  remains  in  the  centre  of  the  tooth,  communicating  by  the 
aperture  left  at  the  point  of  each  fang  with  the  dental  vessels  and  nerves. 

As  soon  as  the  formation  of  the  dentine  has  commenced,  there  is  developed 
from  the  inner  wall  of  the  dental  sac  a  soft  pulpy  mass,  the  enamel organ^  which 
is  ultimately  united  to  the  surface  of  the  dental  pulp,  or  its  cap  of  dentine.  It 
consists  of  a  mesh  of  fibres,  elastic  and  spongy,  containing  within  its  reticu- 
lations fluid  albumen ;  and  at  the  point  of  junction  of  each  fibre,  a  transparent 
nucleus  is  visible.  The  surface  towards  the  dentinal  pulp  is  covered  by  a  layer 
of  elongated  nucleated  cells,  the  enamel  memhrane.  The  deposition  of  the 
enamel  takes  place  on  the  outer  surface  of  the  cap  of  dentine. 

The  cementum  appears  to  be  formed  at  a  later  period  of  life,  by  the  periodontal 
membrane,  extending  from  the  margin  of  the  enamel  downwards. 

Eruption.  When  the  calcification  of  the  different  tissues  of  the  tooth  is  suffi- 
ciently advanced  to  enable  it  to  bear  the  pressure  to  which  it  will  be  afterwards 
subjected,  its  eruption  takes  place,  the  tooth  making  its  way  through  the  gum. 
The  gum  is  absorbed  by  the  pressure  of  the  crown  of  the  tooth  against  it,  which 
is  itself  pressed  up  by  the  increasing  size  of  the  fang  (Fig.  394).  At  the  same 
time,  the  septa  between  the  dental  sacs,  at  first  fibrous  in  structure,  ossify,  and 
constitute  the  alveoli ;  these  firmly  embrace  the  necks  of  the  teeth,  and  afford 
them  a  solid  basis  of  support. 

The  eruption  of  the  temporary  teeth  commences  at  the  seventh  month,  and 
is  complete  about  the  end  of  the  second  year,  those  of  the  lower  jaw  preceding 
the  upper. 

The  periods  for  the  eruption  of  the  temporary  set  are  : — 

7th  month,  central  incisors.  14th  to  20th  month,  canine. 

7th  to  lOtli  month,  lateral  incisors.        18th  to  36th  month,  posterior  molars. 

12th  to  14th  month,  anterior  molars. 

Calcification  of  the  permanent  teeth  commences  a  little  before  birth,  and  pro- 
ceeds in  the  following  order  in  the  upper  jaw,  in  the  lower  jaw  a  little  earlier. 
First  molar,  five  or  six  months;  the  central  incisor  a  little  later;  lateral  inci- 
sors and  canine,  about  the  eighth  or  ninth  month;  the  bicuspids  at  the  second 
year;  second  molar,  five  or  six  years;  wisdom-tooth,  about  twelve  years. 

Previous  to  the  permanent  teeth  penetrating  the  gum,  the  bony  partitions 
which  separate  their  sacs  from  the  deciduous  teeth  are  absorbed,  the  fangs  of 
the  temporary  teeth  disappear,  and  the  permanent  teeth  become  placed  under 
the  loose  crowns  of  the  deciduous  teeth;  the  latter  finally  become  detached, 
and  the  permanent  teeth  take  their  place  in  the  mouth. 

The  eruption  of  the  permanent  teeth  takes  place  at  the  following  periods, 
the  teeth  of  the  lower  jaw  preceding  those  of  the  upper  by  a  short  interval: — 

6|  years,  first  molars.  10th  year,  second  bicuspid. 

7th  year,  two  middle  incisors.  11th  to  12th  year,  canine. 

8th  year,  two  lateral  incisors.  12th  to  13th  year,  second  molars. 

9th  year,  first  bicuspid.  17th  to  21st  year,  wisdom-teeth. 

The  Palate. 

The  Palate  forms  the  roof  of  the  mouth;  it  consists  of  two  portions,  the  hard 
palate  in  front,  the  soft  palate  behind. 


718  ORGANS    OF    DIGESTION. 

The  hard  palate  is  bounded  in  front  and  at  the  sides  by  the  alveolar  arches 
and  guras ;  behind,  it  is  continuous  with  the  soft  palate.  It  is  covered  by  a 
dense  structure,  formed  by  the  periosteum  and  mucous  membrane  of  the  mouth, 
which  are  intimately  adherent  together.  Along  the  middle  line  is  a  linear 
ridge  or  raphe,  which  terminates  anteriorly  in  a  small  papilla,  corresponding 
with  the  inferior  opening  of  the  anterior  palatine  fossa.  This  papilla  receives 
filaments  from  the  naso-palatine  and  anterior  palatine  nerves.  On  either  side 
and  in  front  of  the  raphe,  the  mucous  membrane  is  thick,  pale  in  color,  and 
corrugated ;  behind,  it  is  thin,  smooth,  and  of  a  deeper  color :  it  is  covered  with 
squamous  epithelium,  and  furnished  with  numerous  glands  (palatal  glands), 
which  lie  between  the  mucous  membrane  and  the  surface  of  the  bone. 

The  soft  palate  (velum  jpenduhim  palati)  is  a  movable  fold,  suspended  from 
the  posterior  border  of  the  hard  palate,  and  forming  an  incomplete  septum 
between  the  mouth  and  pharynx.  It  consists  of  a  fold  of  mucous  membrane, 
inclosing  muscular  fibres,  an  aponeurosis,  vessels,  nerves,  and  mucous  glands. 
"When  occupying  its  usual  position  {i.  e.,  relaxed  and  pendent),  its  anterior  sur- 
face is  concave,  continuous  with  the  roof  of  the  mouth,  and  marked  by  a  median 
ridge  or  raphe,  which  indicates  its  original  separation  into  two  lateral  halves. 
Its  posterior  surface  is  convex,  and  continuous  with  the  mucous  membrane 
covering  the  floor  of  the  posterior  nares.  Its  upper  border  is  attached  to  the 
posterior  margin  of  the  hard  palate,  and  its  sides  are  blended  with  the  pharynx. 
Its  lower  border  is  free. 

Hanging  from  the  middle  of  its  lower  border  is  a  small  conical-shaped  pen- 
dulous process,  the  uvula;  and  arching  outwards  and  downwards  from  the  base 
of  the  uvula  on  each  side  are  two  curved  folds  of  mucous  membrane,  contain- 
ing muscular  fibres,  called  the  arches  or  pillars  of  the  soft  palate. 

The  anterior  pillar  runs  downwards  and  forwards  to  the  side  of  the  base  of 
the  tongue,  and  is  formed  by  the  projection  of  the  Palato-glossus  muscle,  . 
covered  by  mucous  membrane.  I 

The  posterior  pillars  are  nearer  to  each  other  and  larger  than  the  anterior ; 
they  run  downwards  and  backwards  to  the  sides  of  the  pharynx,  and  are  formed 
by  the  projection  of  the  Palato-pharyngei  muscles,  covered  by  mucous  mem- 
brane. The  anterior  and  posterior  pillars  are  separated  below  by  a  triangular 
interval,  in  which  the  tonsil  is  lodged. 

The  space  left  between  the  arches  of  the  palate  on  the  two  sides  is  called  the 
isthmus  of  the  fauces.  It  is  bounded  above  by  the  free  margin  of  the  palate; 
below,  by  the  tongue ;  and  on  each  side,  by  the  pillars  of  the  soft  palate  and 
tonsils. 

The  mucous  m,embrane  of  the  soft  palate  is  thin,  and  covered  with  squamou.s 
epithelium  on  both  surfaces,  excepting  near  the  orifice  of  the  Eustachian  tube, 
where  it  is  columnar  and  ciliated.  The  palatine  glands  form  a  continuous  layer 
on  its  posterior  surface  and  round  the  uvula. 

The  aponeurosis  of  the  soft  palate  is  a  thin  but  firm  fibrous  layer,  attached 
above  to  the  hard  palate,  and  becoming  thinner  towards  the  free  margin  of  the 
velum.  It  is  blended  with  the  aponeurotic  tendon  of  the  Tensor  palati  muscle. 
The  muscles  of  the  soft  palate  are  five  on  each  side;  the  Levator  Pulati,  Ten- 
sor Palati,  Palato-glossus,  Palato-pharyngeus,  and  Azygos  Uvulai  (see  p.  342). 
The  io7isib  {amyrjdalse)  are  two  glandular  organs,  situated  one  on  each  side  of 
the  fauces,  between  the  anterior  and  posterior  pillars  of  the  soft  palate.  They 
are  of  a  rounded  form,  and  vary  considerably  in  size  in  difibrent  individuals. 
Externally,  the  tonsil  is  in  relation  with  the  inner  surface  of  the  Superior  Con-M 
strictor,  and  with  the  internal  carotid  and  ascending  pharyngeal  arteries,  and'" 
corresponds  to  the  angle  of  tlic  lower  jaw.  Its  inner  surface  presents  from 
twelve  to  fifteen  orifices,  leading  into  small  recesses,  from  which  numerous 
follicles  branch  out  into  the  substance  of  the  gland.  These  follicles  are  lined 
by  a  continuation  of  the  mucous  membrane  of  the  pharynx,  covered  with 
eJDithelium,  their  walls  being  formed  by  a  layer  of  closed  capsules  imbedded 


I 


THE    SALIVARY    GLANDS. 


no 


in  the  submucous  tissue.  These  capsules  are  analogous  to  those  of  Peyer's 
glands  ;  they  contain  a  thick  grayish  secretion. 

The  arteries  supplying  the  tonsil  are  the  dorsal  is  linguse  from  the  lingual,  the 
ascending  palatine  and  tonsillar  from  the  facial,  the  ascending  pharyngeal  from 
the  external  carotid,  and  the  descending  palatine  branch  of  the  internal  max- 
illary. 

The  veins  terminate  in  the  tonsillar  plexus,  on  the  outer  side  of  the  tonsil. 

The  nerves  are  derived  from  the  fifth,  and  from  the  glosso-pharyngeal. 

The  Salivaky  Glands.    (Fig.  895.) 

The  principal  Salivary  Glands  communicating  with  the  mouth,  and  pouring 
their  secretion  into  its  cavity,  are  the  parotid,  submaxillary,  and  sublingual. 

The  Parotid  gland,  so  called  from  being  placed  near  the  ear  («opa,  near;  oSj, 
wroj,  the  ear\  is  the  largest  of  the  three  salivary  glands,  varying  in  weight  from 
half  an  ounce  to  an  ounce.  It  lies  upon  the  side  of  the  face,  immediately  below 
and  in  front  of  the  external  ear.     It  is  limited  above  by  the  zygoma;  below, 

Fig.  395.— The  Salivary  Glands. 


by  the  angle  of  the  jaw,  and  by  an  imaginary  line  drawn  between  it  and  the 
Sterno-mastoid  muscle;  posteriorly,  it  is  bounded  by  the  external  meatus,  the 
mastoid  process,  and  the  Sterno-mastoid  and  Digastric  muscles,  slightly  over- 
lapping the  former. 

Its  anterior  surface  is  grooved  to  embrace  the  posterior  margin  of  the  ramus 
of  the  lower  jaw,  and  advances  forwards  beneath  the  ramus,  between  the  two 
Pterygoid  muscles.  Its  outer  surface,  slightly  lobulated,  is  covered  by  the 
integument  and  fascia,  and  has  one  or  two  lymphatic  glands  resting  on  it.  Its 
inner  surface  extends  deeply  into  the  neck,  by  means  of  two  large  processes, 
one  of  which  dips  behind  the  styloid  process,  and  projects  beneath  the  mastoid 
process  and  the  Sterno-mastoid  muscle;  the  other  is  situated  in  front  of  the 
styloid  process,  and  passes  into  the  back  part  of  the  glenoid  fossa,  behind  the 
articulation  of  the  lower  jaw.     Imbedded   in  its  substance  is  the  external 


720  ORGANS    OF    DIGESTION. 

carotid  artery,  which  ascends  behind  the  ramus  of  the  jaw ;  the  posterior  auri- 
cular artery  emerges  from  the  gland  behind;  the  temporal  artery  above;  the 
transverse  facial  in  front;  and  the  internal  maxillary  winds  through  it  inwards, 
behind  the  neck  of  the  jaw.  Superficial  to  the  external  carotid  is  the  trunk 
formed  by  the  union  of  the  temporal  and  internal  maxillary  veii^s ;  a  branch, 
connecting  this  trunk  with  the  internal  jugular,  also  traverses  the  gland.  It  is 
also  traversed,  from  before  backwards,  by  the  facial  nerve  and  its  branches, 
which  emerge  at  its  anterior  border;  the  great  auricular  nerve  pierces  the  gland 
to  join  the  facial,  and  the  temporal  branch  of  the  inferior  maxillary  nerve  lies 
above  the  upper  part  of  the  gland.  The  internal  carotid  artery  and  internal 
jugular  vein  lie  close  to  its  deep  surface. 

The  duct  of  the  parotid  gland  (Steno's)  is  about  two  inches  and  a  half  in 
length.  It  opens  upon  the  inner  surface  of  the  cheek  by  a  small  orifice,  oppo- 
site the  second  molar  tooth  of  the  upper  jaw;  and  from  this  orifice  it  may  be 
traced  obliquely  for  a  short  distance  beneath  the  mucous  membrane,  and  thence 
through  the  substance  of  the  Buccinator  muscle,  and  across  the  Masseter  to  the 
anterior  border  of  the  gland,  in  the  substance  of  which  it  commences  by  nume- 
rous branches.  The  direction  of  the  duct  corresponds  to  a  line  drawn  across 
the  face  about  a  finger's  breadth  below  the  zygoma,  from  the  lower  part  of  the 
concha  to  midway  between  the  free  margin  of  the  upper  lip  and  the  ala  of  the 
nose.  While  crossing  the  Masseter,  it  receives  the  duct  of  a  small  detached 
portion  of  the  gland,  socia  parotidis,  which  occasionally  exists  as  a  separate 
lobe,  just  beneath  the  zygomatic  arch.  The  parotid  duct  is  dense,  of  consider- 
able thickness,  and  its  canal  about  the  size  of  a  crow-quill ;  it  consists  of  an 
external  or  fibrous  coat,  of  considerable  density,  containing  contractile  fibres, 
and  of  an  internal  or  mucous  coat,  lined  with  columnar  epithelium. 

Vessels  and  Nerves.  The  arteries  supplying  the  parotid  gland  are  derived  from 
the  external  carotid,  and  from  the  branches  of  that  vessel  in  or  near  its  sub- 
stance. The  veins  follow  a  similar  course.  The  lymphatics  terminate  in  the 
superficial  and  deep  cervical  glands,  passing  in  their  course  through  two  or 
three  lymphatic  glands,  placed  on  the  surface  and  in  the  substance  of  the 
parotid.  The  nerves  are  derived  from  the  carotid  plexus  of  the  sympathetic, 
the  facial,  the  superficial  temporal,  the  auriculo  temporal,  and  great  auricular 
nerves. 

The  Submaxillary  gland  is  situated  below  the  jaw,  in  the  anterior  part  of  the 
submaxillary  triangle  of  the  neck.  It  is  irregular  in  form,  and  weighs  about 
two  drachms.  It  is  covered  by  the  integument,  Platysma,  deep  cervical  fascia, 
and  the  body  of  the  lower  jaw,  corresponding  to  a  depression  on  the  inner  sur- 
face of  that  bone;  and  lies  upon  the  Mylo-hyoid,  Hyo-glossus,  and  Stylo-glossus 
muscles,  a  portion  of  the  gland  passing  beneath  the  posterior  border  of  the 
Mylo-hyoid.  In  front  of  it  is  the  anterior  belly  of  the  Digastric;  behind,  it  is 
separated  from  the  parotid  gland  by  the  stylo-maxillary  ligament,  and  from  the 
sublingual  gland  in  front  by  the  Mylo-hyoid  muscle.  The  facial  artery  lies 
imbedded  in  a  groove  in  its  posterior  and  upper  border. 

The  duct  of  the  submaxillary  gland  (Wharton's)  is  about  two  inches  in 
length,  and  its  walls  are  much  thinner  than  those  of  the  parotid  duct.  It  opens 
by  a  narrow  orifice  on  the  summit  of  a  small  papilla,  at  the  side  of  the  fra^num 
linguoe.  Traced  from  thence,  it  is  found  to  pass  between  the  sublingual  gland 
and  the  Genio-hyo-glossus  muscle,  then  backwards  and  outwards  between  the 
Mylo-hyoid,  and  the  Hyo-glossus  and  Genio-hyo-glossus  muscles,  and  beneath 
the  gustatory  nerve,  to  the  deep  portion  of  the  gland,  where  it  commences  by 
numerous  branches. 

Vessels  and  Nerves.  The  arteries  supplying  the  submaxillary  gland  are 
branches  of  the  facial  and  lingual.  Its  veins  follow  the  course  of  the  arteries. 
The  7ierves  arc  derived  from  the  submaxillary  ganglion,  from  the  mylo-hyoid 
branch  of  the  inferior  dental,  and  from  the  sympathetic. 

The  SuUinjual  gland  is  the  smallest  of  the  salivary  glands.     It  is  situated 


THE    PHARYNX.  721 

beneatli  tlie  mucous  membrane  of  the  floor  of  the  mouth,  at  the  side  of  the 
fraenum  linguse,  in  contact  with  the  inner  surface  of  the  lower  jaw,  close  to  the 
symphysis.  It  is  narrow,  flattened,  in  shape  somewhat  like  an  almond,  and 
weighs  about  a  drachm.  It  is  in  relation,  above,  with  the  mucous  membrane- 
behw,  with  the  Mylo-hyoid  muscle;  in  front,  with  the  depression  on  the  side 
of  the  symphysis  of  the  lower  jaw,  and  with  its  fellow  of  the  opposite  side; 
behind,  with  the  deep  part  of  the  submaxillary  gland;  and  internally,  with  the 
Genio-hyo-glossus,  from  which  it  is  separated  by  the  lingual  nerve  and  Whar- 
ton's duct.  Its  excretory  ducts  {ductus  Riviniani),  from  eight  to  twenty  in 
number,  open  separately  into  the  mouth,  on  the  elevated  crest  of  mucous  mem- 
brane, caused  by  the  projection  of  the  gland,  on  either  side  of  the  fraenum 
linguae.  One  or  more  join  to  form  a  tube  which  opens  into  the  Whartonian 
duct:  this  is  called  the  duct  of  Bartholine. 

Vesseh  and  Nerves.  The  sublingual  gland  is  supplied  with  blood  from  tho 
sublingual  and  submental  arteries.     Its  nerves  are  derived  from  the  gustatory. 

Structure.  The  salivary  are  conglomerate  glands,  consisting  of  numerous 
lobes,  which  are  made  up  of  smaller  lobules,  connected  together  by  dense  areo- 
lar tissue,  vessels,  and  ducts.  Each  lobule  consists  of  numerous  closed  vesicles, 
which  open  into  a  common  duct:  the  wall  of  each  vesicle  is  formed  of  a  delicate 
basement  membrane,  lined  by  epithelium,  and  covered  on  its  outer  surface  with 
a  dense  capillary  network.  In  the  submaxillary  and  sublingual  glands,  the 
lobes  are  larger  and  more  loosely  united  than  in  the  parotid. 

The  Pharynx. 

The  Pharynx  is  that  part  of  the  alimentary  canal  which  is  placed  behind  the 
nose,  mouth,  and  larynx.  It  is  a  musculo-membranous  sac,  somewhat  conical  in 
form,  with  the  base  upwards,  and  the  apex  downwards,  extending  from  the 
under  surface  of  the  skull  to  the  carotid  cartilage  in  front,  and  the  fifth  cervical 
vertebra  behind. 

The  pharynx  is  about  four  inches  and  a  half  in  length,  and  broader  in  the 
transverse  than  in  the  antero-posterior  diameter.  Its  greatest  breadth  is  oppo- 
site the  cornua  of  the  hyoid  bone;  its  narrowest  point  at  its  termination  in  the 
oesophagus.  It  is  limited,  above,  by  the  basilar  process  of  the  occipital  bone; 
heloio,  it  is  continuous  with  the  oesophagus;  ^posteriorly,  it  is  connected  by  loose 
areolar  tissue  with  the  cervical  portion  of  the  vertebral  column,  and  the  Longi 
Colli  and  Recti  Capitis  Antici  muscles;  anteriorly,  it  is  incomplete,  and  is 
attached  in  succession  to  the  internal  pterygoid  plate,  the  pterygo-maxillary 
ligament,  the  lower  jaw,  the  tongue,  hyoid  bone,  and  larynx;  laterally,  it  is  con- 
nected to  the  styloid  processes  and  their  muscles,  and  is  in  contact  with  the 
common  and  internal  carotid  arteries,  the  internal  jugular  veins,  and  the  eighth, 
ninth,  and  sympathetic  nerves,  and  above,  with  a  small  part  of  the  Internal 
Pterygoid  muscles. 

It  has  seven  openings  communicating  with  it ;  the  two  posterior  nares,  the 
two  Eustachian  tubes,  the  mouth,  larynx,  and  oesophagus. 

The  posterior  nares  are  the  two  large  apertures  situated  at  the  xipper  part  of 
the  anterior  wall  of  the  pharynx. 

The  two  Eustachian  tubes  open  one  at  each  side  of  the  upper  part  of  the 
pharynx,  at  the  back  part  of  the  inferior  meatus.  Below  the  nasal  fosste  is  the 
posterior  surface  of  the  soft  palate  and  uvula,  the  large  aperture  of  the  mouth, 
the  base  of  the  tongue,  the  epiglottis,  and  the  cordiform  opening  of  the  larynx. 

The  oesoj)hageal  opening  is  the  lower  contracted  portion  of  the  pharynx. 

Structure.  The  pharynx  is  composed  of  three  coats  :  a  mucous  coat,  a  mus- 
cular layer,  and  a  fibrous  coat. 

l^hQ  fibrous  coat  is  situated  between  the  mucous  and  muscular  layers,  and  is 
called  the  pharyngeal  aponeurosis.  It  is  thick  above,  where  the  muscular  fibres 
are  wanting,  and  is  firmly  connected  to  the  basilar  process  of  the  occipital  and 
46 


1-32  ORGANS    OF    DIGESTION. 

petrous  portion  of  the  temporal  bones.  As  it  descends,  it  diminislies  in  thick, 
ness,  and  is  gradually  lost. 

The  mucous  coat  is  continuous  with  that  lining  the  Eustachian  tubes,the  nares, 
the  mouth,  and  the  larynx.  It  is  covered  by  columnar  ciliated  epithelium,  as 
low  down  as  on  a  level  with  the  floor  of  the  nares ;  below  that  point,  it  is  of  the 
squamous  variety. 

The  muscular  coat  has  been  already  described  (p.  340). 

mhQ pharyngeal  glands  are  of  two  kinds:  the  simple,  or  compound  follicular, 
which  are  found  in  considerable  numbers  beneath  the  mucous  membrane, 
throughout  the  entire  pharynx;  and  the  racemose,  which  are  especially  nume- 
rous at  the  upper  part  of  the  pharynx,  and  form  a  thick  layer,  across  the  back 
of  the  fauces,  between  the  two  Eustachian  tubes. 

The  (Esophagus. 

The  CEsophagus  is  a  membranous  canal,  about  nine  inches  in  length,  extending 
from  the  pharynx  to  the  stomach.  It  commences  at  the  lower  border  of  the 
cricoid  cartilage,  opposite  the  fifth  cervical  vertebra,  descends  along  the  front 
of  the  spine,  through  the  posterior  mediastinum,  passes  through  the  diaphragm, 
and,  entering  the  abdomen,  terminates  at  the  cardiac  orifice  of  the  stomach, 
opposite  the  ninth  dorsal  vertebra.  The  general  direction  of  the  oesophagus  is 
vertical ;  but  it  presents  two  or  three  slight  curvatures  in  its  course.  At  its 
commencement,  it  is  placed  in  the  median  line ;  but  it  inclines  to  the  left  side 
as  far  as  the  root  of  the  neck,  gradually  passes  to  the  middle  line  again,  and, 
finally,  again  deviates  to  the  left,  as  it  passes  forward  to  the  oesophageal  open- 
ing of  the  Diaphragm.  The  oesophagus  also  presents  an.  antero-posterior  flex- 
ure, corresponding  to  the  curvature  of  the  cervical  and  thoracic  portions  of  the 
spine.  It  is  the  narrowest  part  of  the  alimentary  canal,  being  most  contracted 
at  its  commencement,  and  at  the  point  where  it  passes  through  the  Diaphragm. 

Relations.  In  the  neck^  the  cesophagus  is  in  relation,  in  fronts  with  the  trachea; 
and,  at  the  lower  part  of  the  neck,  where  it  projects  to  the  left  side,  with  the 
thyroid  gland  and  thoracic  duct ;  behind^  it  rests  upon  the  vertebral  column 
and  Longus  Colli  muscle ;  on  each  side,  it  is  in  relation  with  the  common  carotid 
artery  (especially  the  left,  as  it  inclines  to  that  side),  and  part  of  the  lateral  lobes 
of  the  thyroid  gland ;  the  recurrent  laryngeal  nerves  ascend  between  it  and  the 
trachea. 

In  the  thorax,  it  is  at  first  situated  a  little  to  the  left  of^  the  median  line;  it 
then  passes  across  the  left  side  of  the  transverse  part  of  the  aortic  arch,  and 
descends  in  the  posterior  mediastinum,  along  the  right  side  of  the  aorta,  nearly 
to  the  Diaphragm,  where  it  passes  in  front  and  a  little  to  the  left  of  the  artery, 
previous  to  entering  the  abdomen.  It  is  in  relation,  in  front,  with  the  trachea, 
the  arch  of  the  aorta,  the  left  bronchus,  and  the  posterior  surface  of  the  peri- 
cardium ;  behind,  it  rests  upon  the  vertebral  column,  the  Longus  Colli,  and  the 
intercostal  vessels ;  and  below,  near  the  Diaphragm,  upon  the  front  of  the  aorta; 
laterally,  it  is  covered  by  the  pleurae ;  the  vena  azygos  major  lies  on  the  right, 
and  the  descending  aorta  on  the  left  side.  The  pneumogastrio  nerves  descend 
in  close  contact  with  it,  the  right  nerve  passing  down  behind,  and  the  left  nerve 
in  front  of  it. 

Surgical  Anatomy. — The  relations  of  the  cesophagua  are  of  considerable  practical  interest  to 
the  surgeon,  as  he  is  frequently  required,  in  cases  of  stricture  of  this  tube,  to  dilate  the  canal 
by  a  bougie,  when  it  becomes  of  importance  that  the  direction  of  the  oesophagus,  and  its  rela- 
tions to  surrounding  parts,  should  be  remembered.  In  cases  of  malignant  disease  of  the  oeso- 
phagus, -where  its  tissues  have  become  softened  from  infiltration  of  the  morbid  deposit,  the 
greatest  care  is  requisite  in  directing  the  bougie  through  the  strictured  part,  as  a  false  passage 
may  easily  be  made,  and  the  instrument  may  pass  into  the  mediastinum,  or  into  one  or  the  other 
pleural  cavity,  or  even  into  the  pericardium. 

The  student  should  also  remember  that  contraction  of  the  oesophagus,  and  consequent 
symptoms  of  stricture,  arc  occasionally  produced  by  an  aneurism  of  some  part  of  the  aorta 
pressing  upon  this  tube.  In  such  a  case,  the  passage  of  a  bougie  could  only  hasten  the  fatal 
issue. 


THE    ABDOMEN.  Jf93 

It  occasionally  happens  that  a  foreign  body  becomes  impacted  in  the  oesophagus,  which  can 
neither  be  brought  upwards  nor  moved  downwards.  When  all  ordinary  means  for  its  removal 
have  failed,  excision  is  the  only  resource.  This,  of  course,  can  only  be  performed  when  it  is  not 
very  low  down.  If  the  foreign  body  is  allowed  to  remain,  extensive  inflammation  and  ulceration 
of  the  oesophagus  may  ensue.  In  one  case  with  which  I  am  acquainted,  the  foreign  body  ulti- 
mately penetrated  the  intervertebral  substance,  and  destroyed  life  by  inflammation  of  the  mem- 
branes and  substance  of  the  cord. 

The  operation  of  cesophagotomy  is  thus  performed.  The  patient  being  placed  upon  his  back, 
with  the  head  and  shoulders  slightly  elevated,  an  incision,  about  four  inches  in  length,  should  be 
made  on  the  left  side  of  the  trachea,  from  the  thyroid  cartilage  downwards,  dividing  the  skin  and 
Platysma.  The  edges  of  the  wound  being  separated,  the  Omo-hyoid  muscle,  and  the  fibres  of 
the  Sterno-hyoid  and  Sterno-thyroid  muscles,  must  be  drawn  inwards ;  the  sheath  of  the  carotid 
vessels  being  exposed,  should  be  drawn  outwards,  and  retained  in  that  position  by  retractors  ; 
the  oesophagus  will  then  be  exposed,  and  should  be  divided  over  the  foreign  body,  which  should 
then  be  removed.  Great  care  is  necessary  to  avoid  wounding  the  thyroid  vessels,  the  thyroid 
gland,  and  the  laryngeal  nerves. 

Structure.  The  oesophagus  has  three  coats :  an  external,  or  muscular ;  a 
middle,  or  cellular;  and  an  internal,  or  mucous  coat. 

The  muscular  coat  is  composed  of  two  planes  of  fibres  of  considerable  thick- 
ness, an  external  longitudinal,  and  an  internal  circular. 

The  lojigitudinal  fibres  are  arranged  at  the  commencement  of  the  tube,  in  three 
fasciculi :  one  in  front,-  which  is  attached  to  the  vertical  ridge  on  the  posterior 
surface  of  the  cricoid  cartilage ;  and  one  at  each  side,  which  are  continuous  with 
the  fibres  of  the  Inferior  Constrictor ;  as  they  descend  they  blend  together,  and 
form  a  uniform  layer,  which  covers  the  outer  surface  of  the  tube. 

The  circular  fibres  are  continuous  above  with  the  Inferior  Constrictor;  their 
direction  is  transverse  at  the  upper  and  lower  parts  of  the  tube,  but  oblique  in 
the  central  part. 

The  muscular  fibres  in  the  upper  part  of  the  cesophagus  are  of  a  red  color, 
and  consist  chiefly  of  the  striped  variety ;  but  below,  they  consist  entirely  of 
the  involuntary  muscular  fibre. 

The  cellular  coat  connects  loosely  the  mucous  and  muscular  coats. 

The  mucous  coat  is  thick,  of  a  reddish  color  above,  and  pale  below.  It  is 
disposed  in  longitudinal  folds,  which  disappear  on  distension  of  the  tube.  Its 
surface  is  studded  with  minute  papillae,  and  it  is  covered  throughout  with  a 
thick  layer  of  squamous  epithelium. 

The  oesophageal  glands  are  numerous  small  compound  glands,  scattered 
throughout  the  tube ;  they  are  lodged  in  the  subcutaneous  tissue,  and  open 
upon  the  surface  by  a  long  excretory  duct.  They  are  most  numerous  at  the 
lower  part  of  the  tube,  where  they  form  a  ring  round  the  cardiac  orifice. 

The  Abdomen. 

The  Abdomen  is  the  largest  cavity  in  the  body,  and  is  separated,  below,  from 
the  pelvic  cavity  by  the  brim  of  the  pelvis.  It  is  of  an  oval  form,  the  ex- 
tremities of  the  oval  being  directed  upwards  and  downwards ;  it  is  wider  above 
than  below,  and  measures  more  in  the  vertical  than  in  the  transverse  diameter. 

Boundaries.  It  is  bounded,  in  front  and  at  the  sides^  by  the  lower  ribs,  the 
Transversalis  muscle,  and  venter  ilii ;  behind,  by  the  vertebral  column,  and  the 
Psoas  and  Quadratus  Lumborum  muscles;  above,  by  the  Diaphragm;  below,  by 
the  brim  of  the  pelvis.  The  muscles  forming  the  boundaries  of  the  cavities 
are  lined  upon  their  inner  surface  by  a  layer  of  fascia,  diiferently  named  accord- 
ing to  the  part  to  which  it  is  attached. 

The  abdomen  contains  the  greater  part  of  the  alimentary  canal;  some  of  the 
accessory  organs  to  digestion,  viz.,  the  liver,  pancreas,  and  spleen;  and  the 
kidneys  and  suprarenal  capsules.  Most  of  these  structures,  as  well  as  the  wall 
of  the  cavity  in  which  they  are  contained,  are  covered  by  an  extensive  and 
complicated  serous  membrane,  the  'peritoneum. 

The  apertures  found  in  the  walls  of  the  abdomen,  for  the  transmission  of 


724 


ORGANS    OF    DIGESTION. 


structures  to  or  from  it,  are  the  umbilicus,  for  the  transmission  (in  the  foetus)  of 
the  umbilical  vessels ;  the  caval  opening  in  the  Diaphragm,  for  the  transmission 
of  the  inferior  vena  cava;  the  aortic  optning,  for  the  passage  of  the  aorta,  vena 
azygos,  and  thoracic  duct ;  and  the  oesophageal  opening,  for  the  oesophagus  and 
pneumogastric  nerves.  Below,  there  are  two  apertures  on  each  side ;  one  for 
the  passage  of  the  femoral  vessels,  and  the  other  for  the  transmission  of  the 
spermatic  cord  in  the  male,  and  the  round  ligament  in  the  female. 

Regions.  For  convenience  of  description  of  the  viscera,  as  well  as  of  refe- 
rence to  the  morbid  condition  of  the  contained  parts,  the  abdomen  is  artificially 
divided  into  nine  regions.  Thus,  if  two  circular  lines  are  drawn  round  the 
body,  the  one  parallel  with  the  cartilages  of  the  ninth  ribs,  and  the  other  with 
the  highest  point  of  the  crests  of  the  ilia,  the  abdominal  cavity  is  divided  into 
three  zones,  an  upper,  a  middle,  and  a  lower.  If  two  parallel  lines  are  drawn 
from  the  cartilage  of  the  eighth  rib  on  each  side,  down  to  the  centre  of  Pou- 
part's  ligament,  each  of  these  zones  is  subdivided  into  three  parts,  a  middle 
and  two  lateral. 


Fig.  396.— The  Regions  of  the  Abdomen  and  their  Contents.    (Edge  of  Costal  Cartilages  in 

dotted  outline.) 


The  middle  region  of  the  upper  zone  is  called  the  epigastric  {inl,  over ;  your^p, 
ilie  stomach) ;  and  the  two  lateral  region,  the  right  and  left  hypochondriac  (v«6, 
nipkr ;  ;t<>»'3p<«.  the  cartilages).  The  central  region  of  the  middle  zone  is  the  11771- 
hilical;  and  the  two  lateral  regions  the  right  and  left  lumbar.  The  middle  region 
of  the  lower  zone  is  the  hypogastric  or  pubic  region;  and  the  lateral  regions  are 
tlie  right  and  left  inguinal.  The  viscera  contained  in  these  different  regions  are 
ihe  following  (Fig. '396):— 


THE    PERITONEUM. 


725 


Right  Hypochondriac. 

The  right  lobe  of  the 
liver  and  the  gall-bladder, 
the  duodenum,  pancreas, 
hepatic  flexure  of  the 
colon,  upper  part  of  the 
right  kidney,  and  the 
right  suprarenal  capsule. 

Right  Lumbar. 
Ascending  colon,  lower 
part  of  the  right  kidney, 
and  some  convolutions  of 
the  small  intestines. 


Epigastric  Region. 
The  middle  and  pyloric 
end  of  the  stomach,  left 
lobe  of  the  liver  and 
lobulus  Spigelii,  and  the 
pancreas. 


Left  Hypochondriac. 
The  splenic  end  of  the 
stomach,  the  spleen  and 
extremity  of  the  pancreas, 
the  splenic  flexure  of  the 
colon,  upper  half  of  the 
left  kidney,  and  the  left 
suprarenal  capsule. 

Left  Lumbar. 
Descending  colon,  part 
of  the  omentum,  lower 
part  of  the  left  kidney, 
and  some  convolutions  of 
the  small  intestines. 


Right  Inguinal. 
The  csecum,  appendix 
csecii,  and  ureter. 


Ij(?ft  Inguinal. 
Sigmoid  flexure  of  the 
colon,  and  ureter. 


Umbilical  Region. 
The  transverse  colon, 
part  of  the  great  omen- 
tum and  mesentery,  trans- 
verse part  of  the  duode- 
num, and  some  convolu- 
tions of  the  jejunum  and 
ileum. 

Hypogastric  Region. 

Convolutions  of  the 
small  intestines,  the  blad- 
der in  children,  and  in 
adults  if  distended,  and 
the  uterus  during  preg- 
nancy. 

The  Peritoneum. 

The  Peritoneum  {Ttf^itfivtiv^  to  extend  around)  is  a  serous  membrane ;  and,  like 
all  membranes  of  this  class,  a  shut  sac.  In  the  female,  however,  it  is  not  com- 
pletely closed,  the  Fallopian  tubes  communicating  with  it  by  their  free  ex- 
tremities ;  and  thus  the  serous  membrane  is  continuous  with  their  mucous 
lining. 

The  peritoneum  partially  invests  all  the  viscera  contained  in  the  abdominal 
and  pelvic  cavities,  forming  the  visceral  layer  of  the  membrane;  it  is  then  re- 
flected upon  the  internal  surface  of  the  parietes  of  those  cavities,  forming  the 
parietal  layer.  The/ree  surface  of  the  peritoneum  is  smooth,  moist,  and  covered 
by  a  thin  squamous  epithelium;  its  attached  surface  is  rough,  being  connected 
to  the  viscera  and  inner  surface  of  the  parietes  by  means  of  areolar  tissue, 
called  the  subperitoneal  areolar  tissue.  The  parietal  portion  is  loosely  connected 
with  the  fascia  lining  the  abdomen  and  pelvis ;  but  more  closely  to  the  under 
surface  of  the  Diaphragm,  and  in  the  middle  line  of  the  abdomen. 

In  order  to  trace  the  reflections  of  this  membrane  (Fig.  897),  the  abdomen 
having  been  opened,  the  liver  should  be  raised  and  supported  in  that  position, 
and  the  stomach  should  be  depressed,  when  a  thin  membranous  layer  is  seen 
passing  from  the  transverse  fissure  of  the  liver  to  the  upper  border  of  the 
stomach:  this  is  the  lesser  or  gastro-hepatic  omentum.  It  consists  of  two  delicate 
layers  of  peritoneum,  an  anterior  and  a  posterior,  between  which  are  contained 
the  hepatic  vessels  and  nerves.  Of  these  two  layers,  the  anterior  should  first 
be  traced,  and  then  the  posterior. 

The  anterior  layer  descends  to  the  lesser  curvature  of  the  stomach,  and  covers 
its  anterior  surface  as  far  as  the  great  curvature;  it  descends  for  some  distance 
in  front  of  the  small  intestines,  and,  returning  upon  itself  to  the  transverse 
colon,  forms  the  external  layer  of  the  great  omentum;  it  then  covers  the  under 
surface  of  the  transverse  colon,  and,  passing  to  the  back  part  of  the  abdominal 
cavity,  forms  the  inferior  layer  of  the  transverse  meso-colon.  It  then  descends  in 
front  of  the  duodenum,  the  aorta,  and  vena  cava,  as  far  as  the  superior  mesen- 


726 


ORGANS    OF    DIGESTION. 


teric  artery,  along  which  it  passes  to  invest  the  small  intestines,  and,  returning 
to  the  vertebral  column,  form  the  mesentery  ;  whilst,  on  either  side,  it  covers  the 
ascending  and  descending  colon,  and  is  thus  continuous  with  the  peritoneum 
lining  the  walls  of  the  abdomen.  From  the  root  of  the  mesentery,  it  descends 
along  the  front  of  the  spine  into  the  pelvis,  and  surrounds  the  upper  part  of  the 
rectum,  which  it  holds  in  its  position  by  means  of  a  distinct  fold,  the  meso-rectum. 
Its  course  in  the  male  and  female  now  differs. 

In  the  male,  it  forms  a  fold  between  the  rectum  and  bladder,  the  recto-vesi- 
cal  fold,  and  ascends  over  the  posterior  surface  of  the  latter  organ  as  far  as  its 
summit. 

In  the  female,  it  descends  into  the  pelvis  in  front  of  the  rectum,  covers  a 
small  part  of  the  posterior  wall  of  the  vagina,  and  is  then  reflected  on  to  the 
uterus,  the  fundus  and  body  of  which  it  covers.  From  the  sides  of  the  uterus 
it  is  reflected  on  each  side  of  the  wall  of  the  pelvis,  forming  the  broad  liga- 

Fig.  397. — The  Reflections  of  the  Peritoneum,  as  seen  in  a  vertical  Section  of  the  Abdomen. 


ments;  and  from  the  anterior  surface  of  the  uterus  it  ascends  upon  the  posterior 
wall  of  the  bladder,  as  far  as  its  summit.  From  this  point  it  may  be  traced,  as 
in  the  male,  ascending  upon  the  anterior  parietes  of  the  abdomen,  to  the  under 
surface  of  the  Diaphragm;  from  which  it  is  reflected  upon  the  liver,  forming 
the  upper  layer  of  the  coronary,  and  the  lateral  and  longitudinal  ligaments.  It 
then  covers  the  upper  and  under  surfaces  of  the  liver,  and  at  the  transverse 
fissure  becomes  continuous  with  the  anterior  layer  of  the  lesser  omentum,  the 
point  whence  its  reflection  was  originally  traced. 

The  posterior  layer  of  the  lesser  omentum  descends  to  the  lesser  curvature 
of  the  stomach,  and  covers  its  posterior  surface  as  far  as  the  great  curvature; 
it  then  descends  for  some  distance  in  front  of  the  small  intestines,  and,  returning 


THE    PERITONEUM.  121 

■upon  itself  to  the  transverse  colon,  forms  the  internal  layer  of  the  great  olnen- 
tum;  it  covers  the  upper  surface  of  the  transverse  colon,  and,  passing  backwards 
to  the  spine,  forms  the  upper  layer  of  the  transverse  meso-colon.  Ascending  in 
front  of  the  pancreas  and  crura  of  the  Diaphragm,  it  lines  the  back  part  of  the 
under  surface  of  that  muscle,  from  which  it  is  reflected  on  to  the  posterior  bor- 
der of  the  liver,  forming  the  inferior  layer  of  the  coronary  ligament.  From 
the  under  surface  of  the  liver  it  may  be  traced  to  the  transverse  fissure,  where 
it  is  continuous  with  the  posterior  layer  of  the  lesser  omentum,  the  point 
whence  its  reflection  was  originally  traced. 

The  space  included  in  the  reflections  of  this  layer  of  the  peritoneum  is  called 
the  lesser  cavity  of  the  peritoneum^  or  cavity  of  the  great  omentum.  It  is  bounded, 
in  front,  by  the  lesser  omentum,  the  stomach,  and  the  descending  part  of  the 
great  omentum;  behind,  by  the  ascending  part  of  the  great  omentum,  the  trans- 
verse colon,  transverse  meso-colon,  and  its  ascending  layer;  above,  by  the  liver; 
and  below,  by  the  folding  of  the  great  omentum.  This  space  communicates 
with  the  general  peritoneal  cavity  through  the  foramen  of  Winslow,  which  is 
situated  behind  the  right,  or  free  border  of  the  lesser  omentum. 

The  fora7nen  of  Winslow  is  bounded  in  front  by  the  lesser  omentum,  inclosing 
the  vena  portse  and  the  hepatic  artery  and  duct;  behind,  by  the  inferior  vena 
cava;  above,  by  the  lobulus  Spigelii;  below,  by  the  hepatic  artery  curving  for- 
wards from  the  caeliac  axis. 

This  foramen  is  nothing  more  than  a  constriction  of  the  general  peritoneal 
cavity  at  this  point,  caused  by  the  hepatic  and  gastric  arteries  passing  forwards 
from  the  caeliac  axis  to  reach  their  respective  viscera. 

The  viscera  thus  shown  to  be  almost  entirely  invested  by  peritoneum  are  the 
liver,  stomach,  spleen,  first  portion  of  the  duodenum,  the  jejunum,  and  ileum, 
the  transverse  colon,  sigmoid  flexure,  upper  end  of  the  rectum,  the  uterus,  and 
ovaries. 

The  viscera  only  partially  invested  by  peritoneum  are  the  descending  and 
transverse  portions  of  the  duodenum,  the  cgecum,  the  ascending  and  descending 
colon,  the  middle  portion  of  the  rectum,  and  the  upper  part  of  the  vagina  and 
posterior  wall  of  the  bladder.  The  kidneys,  suprarenal  capsules,  and  pancreas 
are  covered  by  the  membrane  without  receiving  any  special  investment  from  it. 

The  lower  end  of  the  rectum,  the  neck,  base,  and  anterior  surface  of  the 
bladder,  the  whole  of  the  front,  and  the  lower  part  of  the  posterior  wall  of  the 
vagina,  have  no  peritoneal  covering. 

Numerous  folds  are  formed  by  the  peritoneum,  extending  between  the  various 
organs.  These  serve  to  hold  them  in  position,  and,  at  the  same  time,  inclose 
the  vessels  and  nerves  proceeding  to  each  part.  Some  of  the  folds  are  called 
ligaments,  from  their  serving  to  support  the  organs  in  position.  Others,  which 
connect  certain  parts  of  the  intestine  with  the  abdominal  wall,  constitute  the 
mesenteries  ;  and  lastly,  those  are  called  omenta,  which  proceed  i'rom  the  stomach 
to  certain  viscera  in  its  neighborhood. 

The  Ligaments,  formed  by  folds  of  the  peritoneum,  include  those  of  the  liver, 
spleen,  bladder,  and  uterus.  They  will  be  found  described  with  their  respective 
organs. 

The  Omenta  are  the  lesser  omentum,  the  great  omentum,  and  the  gastro- 
splenic  omentum. 

The  lesser  omentum  [g astro -hejmtic)  is  the  duplicature  which  extends  between 
the  transverse  fissure  of  the  liver,  and  the  lesser  curvature  of  tlie  stomach.  It 
is  extremely  thin,  and  consists,  as  before  said,  of  two  layers  of  peritoneum.  At 
the  left  border,  its  two  layers  pass  on  to  the  end  of  the  oesophagus ;  but  at  dlie 
right  border,  where  it  is  free,  they  are  continuous,  and  form  a  free  rounded 
margin,  which  contains  between  its  layers  the  hepatic  artery,  the  ductus  commu- 
nis choledochus,  the  portal  vein,  lymphatics,  and  the  hepatic  plexus  of  nerves — • 
all  these  structures  being  inclosed  in  loose  areolar  tissue,  called  GUsson's  capsule. 

The  great  omentum  [gastro-colic)  is  the  largest  peritoneal  fold.     It  consists  of 


128  ORGANS    OF    DIGESTION. 

four  layers  of  peritoneum,  two  of  which  descend  from  the  stomach,  one  from 
its  anterior,  the  other  from  its  posterior  surface,  and,  uniting  at  its  lower  border, 
descend  in  front  of  the  small  intestines,  as  low  down  as  the  pelvis;  they  then 
turn  upon  themselves,  and  ascend  again  as  far  as  the  transverse  colon,  where 
they  separate  and  inclose  that  part  of  the  intestine.  These  separate  layers  may 
be  easily  demonstrated  in  the  young  subject;  but,  in  the  adult,  they  are  more 
or  less  inseparably  blended.  The  left  border  of  the  great  omentum  is  continu- 
ous with  the  gastro-spleuic  omentum ;  its  right  border  extends  as  far  only  as 
the  duodenum.  The  great  omentum  is  usually  thin,  presents  a  cribriform  ap- 
pearance, and  always  contains  some  adipose  tissue,  which,  in  fat  subjects,  accu- 
mulates in  considerable  quantity.  Its  use  appears  to  be  to  protect  the  intestines 
from  cold,  and  to  facilitate  their  movement  upon  each  other  during  their 
vermicular  action. 

The  gastro-splenic  omentum  is  the  fold  which  connects  the  concave  surface  of 
the  spleen  to  the  cul-de-sac  of  the  stomach,  being  continuous  by  its  lower  border 
with  the  great  omentum.     It  contains  the  splenic  vessels  and  vasa  brevia. 

The  Mesenteries  are,  the  mesentery  proper,  the  meso-csecum,  the  ascending, 
transverse,  and  descending  meso-colon,  the  sigmoid  meso-colon,  and  the  meso- 
rectum. 

The  mesentery  {nhov  li/tspoi),  so  called  from  being  connected  to  the  middle  of 
the  cylinder  of  the  small  intestine,  is  the  broad  fold  of  peritoneum  which  con- 
nects the  convolutions  of  the  jejunum  and  ileum  with  the  posterior  wall  of  the 
abdomen.  Its  root,  the  part  connected  with  the  vertebral  column,  is  narrow, 
about  six  inches  in  length,  and  directed  obliquely  from  the  left  side  of  the 
second  lumbar  vertebra  to  the  right  sacro-iliac  symphysis.  Its  intestinal  border 
is  much  longer ;  and  here  its  two  layers  separate,  so  as  to  inclose  the  intestine, 
and  form  its  peritoneal  coat.  Its  breadth,  between  its  vertebral  and  intestinal 
border,  is  about  four  inches.  Its  upper  harder  is  continuous  with  the  under 
surface  of  the  transverse  meso-colon;  its  lower  harder,  with  the  peritoneum 
covering  the  crecum  and  ascending  colon.  It  serves  to  retain  the  small  intes- 
tines in  their  position,  and  contains  between  its  layers  the  mesenteric  vessels 
and  nerves,  the  lacteal  vessels,  and  mesenteric  glands. 

The  meso-csecum,  when  it  exists,  serves  to  connect  the  back  part  of  the  caecum 
with  the  right  iliac  fossa ;  more  frequently,  the  peritoneum  passes  merely  in 
front  of  this  portion  of  the  large  intestine. 

The  ascending  meso-colon  is  the  fold  which  connects  the  back  part  of  the 
ascending  colon  with  the  posterior  wall  of  the  abdomen ;  and  the  descending 
meso-colon  retains  the  descending  colon  in  connection  with  the  posterior  abdomi- 
nal wall :  more  frequently,  the  peritoneum  merely  covers  the  anterior  surface 
and  sides  of  these  two  portions  of  the  intestine. 

The  transverse  meso-colon  is  a  broad  fold,  which  connects  the  transverse  colon 
with  the  posterior  wall  of  the  abdomen.  It  is  formed  by  the  two  ascending 
layers  of  the  great  omentum,  which,  after  separating  to  surround  the  transverse 
colon,  join  behind  it,  and  are  continued  backwards  to  the  spine,  where  they 
diverge  in  front  of  the  duodenum,  as  already  mentioned.  This  fold  contains 
between  its  layers  the  vessels  which  supply  the  transverse  colon. 

The  sigmoid  meso-colon  is  the  fold  of  peritoneum  which  retains  the  sigmoid 
flexure  in  connection  with  the  left  iliac  fossa. 

The  meso-rectum  is  the  narrow  fold  which  connects  the  upper  part  of  the 
rectum  with  the  front  of  the  sacrum.     It  contains  the  hemorrhoidal  vessels. 

The  appendices  epiploicse  are  small  pouches  of  the  peritoneum  tilled  with  fat, 
and  situated  along  the  colon  and  upper  part  of  the  rectum.  They  are  chiefly 
appended  to  the  transverse  colon. 

The  Stomach. 

The  Stomach  is  the  principal  organ  of  digestion.  It  is  the  most  dilated  part 
of  the  alimentary  canal,  serving  for  the  solution  and  reduction  of  the  food, 


I 


THE    STOMACH. 


729 


w'nicTi  constitutes  the  process  of  chymilication.  It  is  situated  in  the  left  hypo- 
chondriac, the  epigastric,  and  part  of  the  right  hypochondriac  regions.  Its 
form  is  irregularly  conical,  curved  upon  itself,  and  presenting  a  rounded  base, 
turned  to  the  left  side.  It  is  placed  immediately  behind  the  anterior  wall  of 
the  abdomen,  above  the  transverse  colon,  below  the  liver  and  the  Diaphragm. 
Its  size  varies  considerably  in  different  subjects,  and  also  according  to  its  state 
of  distension.  When  moderately  full,  its  transverse  diameter  is  about  twelve 
inches,  its  vertical  diameter  about  four.  Its  weight,  according  to  Clendenning, 
is  about  four  ounces  and  a  half.  It  presents  for  examination  two  extremities, 
two  orifices,  two  borders,  and  two  surfaces. 

Its  left  extremity  is  called  the  greater,  or  splenic  end.  This  is  the  largest  part 
of  the  stomach,  and  extends  two  or  three  inches  to  the  left  of  the  point  of 
entrance  of  the  oesophagus.  This  expanded  part  is  called  the  great  cul-de-sac, 
ov  fundus.  It  lies  beneath  the  ribs,  in  contact  with  the  spleen,  to  which  it  is 
connected  by  the  gastro-splenic  omentum. 


The  Mucous  Membrane  of  the  Stomacli  and  Duodenum  with  the  Bile  Ducts. 


Ci/ttli 


The  lesser,  or  pyloric  end,  is  much  smaller  than  the  fundus,  and  situated  on  a 
plane  anterior  and  inferior  to  it.  It  lies  in  contact  with  the  wall  of  the  abdo. 
men,  the  under  surface  of  the  liver,  and  the  neck  of  the  gall-bladder. 

The  oesophageal  or  cardiac  orifice  comanunicates  with  the  oesophagus:  it  is  the 
highest  part  of  the  stomach,  and  somewhat  funnel-shaped. 

The  pyloric  orifice  communicates  with  the  duodenum,  the  aperture  being 
guarded  by  a  kind  of  valve — i\i&  pylorus. 

The  lesser  curvature  extends  between  the  oesophageal  and  pyloric  orifices, 
along  the  upper  border  of  the  organ,  and  is  connected  to  the  under  surface  of 
the  liver  by  the  lesser  omentum. 

The  greater  curvature  extends  between  the  same  points,  along  the  lower  border, 


W  ORGANS    OF    DIGESTION. 

and  gives  attacliment  to  the  great  omentum.     The  surfaces  of  the  organ  are 
limited  by  these  two  curvatures. 

The  anterior  surface  is  directed  upwards  and  forwards,  and  is  in  relation  with 
the  Diaphragm,  the  under  surface  of  the  left  lobe  of  the  liver,  and  with  the 
abdominal  parietes,  in  the  epigastric  region. 

The  jyosterior  surface  is  directed  downwards  and  backwards,  and  is  in  relation 
with  the  pancreas  and  great  vessels  of  the  abdomen,  the  crura  of  the  Diaphragm 
and  the  solar  plexus. 

The  stomach  is  held  in  position  by  the  lesser  omentum,  which  extends  from 
the  transverse  fissure  of  the  liver  to  its  lesser  curvature,  and  by  a  fold  of  peri- 
toneum, which  passes  from  the  Diaphragm  on  to  the  oesophageal  end  of  the 
stomach,  the  gastro-phrenic  ligament;  this  constitutes  the  most  fixed  point  of 
the  stomach,  whilst  the  pyloric  end  and  greater  curvature  are  the  most  movable 
parts:  hence,  when  the  stomach  becomes  greatly  distended,  the  greater  curva- 
ture is  directed  forwards,  whilst  the  anterior  and  posterior  surfaces  are  directed, 
the  former  upwards,  and  the  latter  downwards. 

Alterations  in  Position. — There  is  no  organ  in  the  body  the  position  and  connections  of  which 
present  such  frequent  alterations  as  the  stomach.  During  inspiration,  il  is  displaced  downwards 
by  the  descent  of  the  Diaphragm,  and  elevated  by  the  pressure  of  the  abdominal  muscles  during 
expiration.  Its  position  in  relation  to  the  surrounding  viscera  is  also  changed,  according  to  the 
empty  or  distended  state  of  the  organ.  When  empty,  it  occupies  only  a  small  part  of  the  left 
hypochondriac  region,  the  spleen  lying  behind  it ;  the  left  lobe  of  the  liver  covers  it  in  front,  and 
the  under  surface  of  the  heart  rests  upon  it  above,  and  in  front;  being  separated  from  it  by  the 
left  lobe  of  the  liver,  besides  the  diaphragm  and  pericardium.  This  close  relation  between  the 
stomach  and  the  heart  explains  the  fact  that,  in  gastralgia,  the  pain  is  generally  referred  to  the 
heart,  and  is  often  accompanied  by  palpitation  and  intermission  of  the  pulse.  When  the  stomach, 
is  distended  the  Diaphragm  is  forced  upwards,  contracting  the  cavity  of  the  chest;  hence  the 
dyspnoea  complained  of,  from  inspiration  being  impeded.  The  heart  is  also  displaced  upwards ; 
hence  the  oppression  in  this  region,  and  the  palpitation  experienced  in  extreme  distension  of 
the  stomach.  Pressure  from  without,  as  from  tight  lacing,  pushes  the  stomach  down  towards 
the  pelvis.  In  disease,  also,  the  position  and  connections  of  the  organ  may  be  greatly  changed, 
from  the  accumulation  of  fluid  in  the  chest  or  abdomen,  or  from  alteration  in  size  of  any  of  the 
surrounding  viscera. 

On  looking  into  the  pyloric  end  of  the  stomach,  the  mucous  membrane  is 
found  projecting  inwards  in  the  form  of  a  circular  fold,  the  pylorus,  leaving  a 
narrow  circular  aperture,  about  half  an  inch  in  diameter,  by  which  the  stomach  m 
communicates  with  the  duodenum.  .fl 

The  pylorus  is  formed  by  a  reduplication  of  the  mucous  membrane  of  the 
stomach,  containing  numerous  muscular  fibres,  which  are  aggregated  into  a 
thick  circular  ring,  the  longitudinal  fibres  and  serous  membrane  being  con- 
tinued over  the  fold  without  assisting  in  its  formation.  The  aperture  is  occa- 
sionally oval.  Sometimes,  the  circular  fold  is  replaced  by  two  crescentic  folds, 
placed,  one  above,  and  the  other  below,  the  pyloric  orifice ;  and,  more  rarely, 
there  is  only  one  crescentic  fold. 

Strticture.  The  stomach  consists  of  four  coats :  a  serous,  a  muscular,  a  cellu- 
lar, and  a  mucous  coat,  together  with  vessels  and  nerves. 

The  serous  coat  is  derived  from  the  peritoneum,  and  covers  the  entire  surface 
of  the  organ,  excepting  along  the  greater  and  lesser  curvatures,  at  the  points 
of  attachment  of  the  greater  and  lesser  omenta;  here  the  two  layers  of  peri- 
toneum leave  a  small  triangular  space,  along  which  the  nutrient  vessels  and 
nerves  pa.ss. 

The  muscuhr  coat  (Fig.  399)  is  situated  immediately  beneath  the  serous 
covering.    It  consi.sts  of  three  sets  of  fibres:  longitudinal,  circular,  and  oblique. 

The  longitudinal  fibres  are  most  superficial ;  they  are  continuous  with  the 
longitudinal  fibres  of  the  oesophagus,  radiating  in  a  stellate  manner  from  the 
cardiac  orifice.  They  are  most  distinct  along  the  curvatures,  especially  the 
lesser;  but  are  very  thinly  distributed  over  the  surfaces.  At  the  pyloric  end, 
they  are  more  thickly  distributed,  and  continuous  with  the  longitudinal  fibres 
of  the  small  intestine. 

The  circular  Jibrcs  form  a  uniform  layer  over  the  whole  extent  of  the  stomach. 


•I 


THE    STOMACH.  tSJ 

beneath  the  longitudinal  fibres.  At  the  pylorus  they  are  most  abundant,  and 
are  aggregated  into  a  circular  ring,  which  projects  into  the  cavity,  and  forms, 
with  the  fold  of  raucous  membrane  covering  its  surface,  the  pyloric  valve. 

The  oblique  fibres  are  limited  chiefly  to  the  cardiac  end  of  the  stomach,  where 
they  are  disposed  as  a  thick  uniform  layer  covering  both  surfaces,  somepassino- 
obliquely  from  left  to  right,  others  from  right  to  left,  round  the  cardiac  orifice. 

Fig.  399.— The  Muscular  Coat  of  the  Stomach. 


'•^•AlJT 


The  cellular  coat  consists  of  a  loose,  filamentous,  areolar  tissue,  connecting 
the  mucous  and  muscular  layers.  It  is  sometimes  called  ihesubmucous  coat.  It 
supports  the  bloodvessels  previous  to  their  distribution  to  the  mucous  mem- 
brane ;  hence  it  is  sometimes  called  the  vascular  coat. 

The  mucous  membrane  of  the  stomach  is  thick ;  its  surface  smooth,  soft,  and 
velvety.  During  infancy,  and  immediately  after  death,  it  is  of  a  pinkish  tinge  ; 
but  in  adult  life,  and  in  old  age,  it  becomes  of  a  pale  straw  or  ash-gray  color. 
It  is  thin  at  the  cardiac  extremity,  but  thicker  towards  the  pylorus.  During 
the  contracted  state  of  the  organ,  it  is  thrown  into  numerous  plaits  or  rugfe, 
which,  for  the  most  part,  have  a  longitudinal  direction,  and  are  most  marked 
towards  the  lesser  end  of  the  stomach,  and  along  the  greater  curvature  (Fig. 
398).     These  folds  are  entirely  obliterated  when  the  organ  becomes  distended. 

Structure  of  the  mucous  membrane  (Fig.  400).  When  examined  with  a  lens, 
the  inner  surface  of  the  mucous  membrane  presents  a  peculiar  honeycomb  ap- 
pearance from  being  covered  with  small  shallow  depressions  or  alveoli,  of  a 
polygonal  or  hexagonal  form,  which  vary  from  t^^t  to  t?^^  of  an  inch  in  dia- 
meter, and  are  separated  by  slightly  elevated  ridges.  In  the  bottom  of  the 
alveoli  are  seen  the  orifices  of  minute  tubes,  the  gastric  follicles^  which  are  situ- 
ated perpendicularly  side  by  side,  in  the  entire  substance  of  the  mucous  mem- 
brane. They  are  short,  and  simply  tubular  in  character  towards  the  cardia; 
but  at  the  pyloric  end,  they  are  longer,  more  tliickly  set,  convoluted,  and  ter- 
minate in  dilated  saccular  extremities,  or  are  subdivided  into  from  two  to  six 
tubular  branches.  The  gastric  follicles  are  composed  of  a  homogeneous  base- 
ment membrane,  lined  upon  its  free  surface  by  a  layer  of  cells,  which  differ  in 
their  character  in  different  parts  of  the  stomach.  Towards  the  pylorus,  these 
tubes  are  lined  throughout  with  columnar  epithelium ;  they  are  termed  the 


732 


ORGANS    OF    DIGESTION. 


mucous  glands^  and  are  supposed  to  secrete  the  gastric  mucus.  In  other  parts 
of  the  organ,  the  deep  part  of  each  tube  is  filled  with  nuclei,  and  a  mass  of 
granules ;  above  these  is  a  mass  of  nucleated  cells,  the  upper  fourth  of  the 
tube  being  lined  bj  columnar  epithelium.  These  are  called  the  peptic  glands^ 
and  are  the  supposed  agents  in  the  secretion  of  the  gastric  juice. 

Simple  follicles  are  found  in  greater  or  less  number  over  the  entire  surface  of 
the  mucous  membrane ;  thej  are  most  numerous  near  the  pyloric  end  of  the 
stomach,  and  are  especially  distinct  in  early  life.  The  epithelium  lining  the 
mucous  membrane  of  the  stomach  and  its  alveoli  is  of  the  columnar  variety. 

Fifr.  400. — Minute  Anatomy  of  Mucous  Membrane  of  Stomach. 


mmths  of  Tubult 


fn  tf  Tulm 


EpithtJittl partlcXt* 


Yesseh-  and  Nerves.     The  arteries  supplying  the  stomach  are,  the  coronaria 
ventriculi,  the  pyloric  and  right  gastro-epiploic  branches  of  the  hepatic,  the  left 
gastro-epiploic  and  vasa  brevia  from  the  splenic.     They  supply  the  muscular 
coat,  ramify  in  the  submucous  coat,  and  are  finally  distributed  to  the  mucous 
membrane.     The  veins  accompany  the  arteries,  and  terminate  in  the  splenic 
and  portal  veins.     The  lymphatics  are  numerous ;  they  consist  of  a  superficial 
and  deep  set,  which  pass  through  the  lymphatic  glands  found  along  the  two 
curvatures  of  the  organ.     The  nerves  are  the  terminal  branches  of  the  right  and, 
left  pneumogastric,  the  former  being  distributed  upon  the  back,  and  the  latter! 
upon  the  front  part  of  the  organ.     A  great  number  of  branches  from  the  sym-T 
pathetic  also  supply  the  organ. 

The  Small  Intestines. 

The  Small  Intestine  is  that  part  of  the  alimentary  canal  in  which  the  chyme 
is  mixed  with  the  bile,  the  pancreatic  juice,  and  the  secretions  of  the  various 
glands  imbedded  in  the  mucous  membrane  of  the  intestines,  and  where  the 
separation  of  the  nutritive  principles  of  the  food,  the  chyle,  is  effected ;  this 
constitutes  chylification. 

The  small  intestine  is  a  convoluted  tube,  about  twenty  feet  in  length,  which 
gradually  diminishes  in  size  from  its  commencement  to  its  termination.  It  is 
contained  in  the  central  and  lower  parts  of  the  abdominal  and  pelvic  cavities, 
surrounded  above  and  at  the  sides  by  the  large  intestine;  in  relation,  in  front, 
with  the  great  omentum  and  abdominal  parietes ;  and  connected  to  the  spine 
by  a  fold  of  peritoneum,  the  mesentery.  The  small  intestine  is  divisible  into 
three  portions,  the  duodenum,  jejunum,  and  ileum. 

The  duodenum  has  received  its  name  from  being  about  equal  in  length  to  the 
breadth  of  twelve  fingers  (eight  or  ten  inches).  It  is  the  shortest,  the  widest, 
and  the  most  fixed  part  of  the  small  intestine;  it  has  no  mesentery,  and  is  only 
partially  covered  by  the  peritoneum.  Its  course  presents  a  remarkable  curve, 
somewhat  like  a  horseshoe  in  form;  the  convexity  being  directed  towards  the 
right,  and  the  concavity  to  the  left,  embracing  the  head  of  the  pancreas.  Com- 
mencing at  the  pylorus,  it  ascends  obliquely  upwards  and  backwards  to  the 
under  surface  of  the  liver ;  it  then  descends  in  front  of  the  right  kidney,  and 


SMALL    INTESTINES. 


733 


passes  nearly  transversely  across  the  front  of  the  spine,  terminating  in  the  jeju- 
num on  the  left  side  of  the  second  lumbar  vertebra.  Hence  the  duodenum  has 
been  divided  into  three  portions :  ascending,  descending,  and  transverse. 

The  first,  or  ascending  portion  (Fig.  401),  about  two  inches  in  length,  is  free, 
movable,  and  nearly  completely  invested  by  the  peritoneum.  It  is  in  relation, 
above  and  in  front,  with  the  liver  and  neck  of  the  gall-bladder;  behind,  with 
the  right  border  of  the  lesser  omentum,  the  hepatic  artery  and  duct,  and  vena 
portEe.  This  portion  of  the  intestine  is  usually  found,  after  death,  stained  with 
bile,  especially  on  its  anterior  surface. 

Fig.  401. — Relations  of  the  DuodeQum.     (The  Pancreas  has  been  cut  away,  except  its  head.) 

Cl-aTl 


07V     dlT'a'WTV    cLowTi, 


The  second,  or  descending  portion,  about  three  inches  in  length,  is  firmly  fixed 
by  the  peritoneum  and  pancreas.  It  passes  from  the  neck  of  the  gall-bladder, 
vertically  downwards,  in  front  of  the  right  kidney,  as  far  as  the  third  lumbar 
vertebra.  It  is  covered  by  peritoneum  only  on  its  anterior  surface.  It  is  in 
relation,  in  front,  with  the  right  arch  of  the  colon  and  the  meso-colon  ;  behind, 
with  the  front  of  the  right  kidney  ;  at  its  inner  side  is  the  head  of  the  pancreas, 
and  the  common  choledoch  duct.  The  common  bile  duct  and  the  pancreatic  duct 
perforate  the  inner  side  of  this  portion  of  the  intestine  obliquely,  a  little  below 
its  middle. 

The  third,  or  transverse  portion,  the  longest  and  narrowest  part  of  the  duo- 
denum, passes  across  the  front  of  tlie  spine,  ascending  from  the  third  to  the 
second  lumbar  vertebra,  and  terminating  in  the  jejunum  on  the  left  side  of  that 


734  ORGAXS    OF    DIGESTION. 

bone.  In  front,  it  is  covered  bj  the  descending  layer  of  the  transverse  meso- 
colon, and  crossed  by  the  superior  mesenteric  vessels  ;  behind,  it  rests  upon  the 
aorta,  the  vena  cava,  and  the  crura  of  the  Diaphragm ;  above  it,  is  the  lower 
border  of  the  pancreas,  the  superior  mesenteric  vessels  passing  forwards  be- 
tween the  two. 

Vessels  and  Nerves.  The  arteries  supplying  the  duodenum  are  the  pyloric 
and  pancreatico-duodenal  branches  of  the  hepatic,  and  the  inferior  pancreatico- 
duodenal branch  of  the  superior  mesenteric.  The  veins  terminate  in  the  gastro- 
duodenal  and  superior  mesenteric.  The  nerves  are  derived  from  the  solar  plexus. 

The  jejunum  {jej'unus,  empty),  so  called  from  being  usually  found  empty  after 
death,  includes  the  upper  two-fifths  of  the  rest  of  the  small  intestine.  It  com- 
mences at  the  duodenum  on  the  left  side  of  the  second  lumbar  vertebra,  and 
terminates  in  the  ileum ;  its  convolutions  being  chiefly  confined  to  the  umbilical 
and  left  iliac  regions.  The  jejunum  is  wider,  its  coats  thicker,  more  vascular, 
and  of  a  deeper  color  than  those  of  the  ileum ;  but  there  is  no  characteristic 
mark  to  distinguish  the  termination  of  the  one  and  the  commencement  of  the 
other. 

The  ileum  (tl\nv,  to  twist),  so  called  from  its  numerous  coils  or  convolutions, 
includes  the  remaining  three-fifths  of  the  small  intestine.  It  occupies  chiefly 
the  umbilical,  hypogastric,  right  iliac,  and  occasionally  the  pelvic  regions,  and 
terminates  in  the  right  iliac  fossa  by  opening  into  the  inner  side  of  the  com- 
mencement of  the  large  intestine.  The  ileum  is  narrower,  its  coats  thinner  and 
less  vascular  than  those  of  the  jejunum ;  a  given  length  of  it  weighing  less 
than  the  same  length  of  jejunum. 

Structure.  The  wall  of  the  small  intestine  is  composed  of  four  coats :  serous, 
muscular,  cellular,  and  mucous. 

The  seroxis  coat  is  derived  from  the  peritoneum.  The  first,  or  ascending 
portion  of  the  duodenum,  is  almost  completely  surrounded  by  this  membrane ; 
the  second,  or  descending  portion,  is  covered  by  it  only  in  front;  and  the  third, 
or  transverse  portion  lies  behind  the  descending  layer  of  the  transverse  meso- 
colon, by  which  it  is  covered  in  front.  The  remaining  portion  of  the  small 
intestine  is  surrounded  by  the  peritoneum,  excepting  along  its  attached  or 
mesenteric  border ;  here  a  space  is  left  for  the  vessels  and  nerves  to  pass  to 
the  gut.  ^b 

The  musctdar  coat  consists  of  two  layers  of  fibres,  an  external  or  longitudi™ 
nal,  and  an  internal  or  circular  layer.  The  longitudinal  fibres  are  thinly  scat- 
tered over  the  surface  of  the  intestine,  and  are  most  distinct  along  its  free  border. 
The  circular  fibres  form  a  thick,  uniform  layer;  they  surround  the  cylinder  of 
the  intestine  in  the  greater  part  of  its  circumference,  but  do  not  form  complete 
rings.  The  muscular  coat  is  thicker  at  the  upper  than  at  the  lower  part  of  the 
small  intestine. 

The  cellular^  or  submucous  coat,  connects  together  the  mucous  and  muscular 
layers.  It  consists  of  a  loose,  filamentous,  areolar  tissue,  which  forms  a  nidus 
for  the  subdivision  of  the  nutrient  vessels,  previous  to  their  distribution  to  the 
mucous  surface. 

The  mucotis  membrane  is  thick  and  highly  vascular  at  the  upper  part  of  the 
small  intestine,  but  somewhat  paler  and  thinner  below.  It  presents  for  exami- 
nation the  following  constituents: — 

Epithelium.  Simple  follicles. 

Valvulso  connivcntes.  i  Duodenal  glands. 

Villi.  Glands.  I  Solitary  glands. 

(  Agminate  or  Peyer's  glands. 

The  epithelium,  covering  the  mucous  membrane  of  the  small  intestine,  is  of 
the  columnar  variety. 

Tlie  valvulx  connivenles  (valves  of  Kerkring)  are  reduplications  or  foldings 
of  the  raucous  membrane  and  submucous  tissue,  containing  no  muscular  fibres. 


SMALL    INTESTINES. 


735 


Fig.  402.— Two  Villi  magnified. 


They  extend  transversely  across  the  cylinder  of  the  intestine  for  about  three- 
fourths  or  five-sixths  of  its  circumference.  The  larger  folds  are  about  two 
inches  in  length,  and  two-thirds  of  an  inch  in  depth  at  their  broadest  part ;  but 
the  greater  number  are  of  smaller  size.  The  larger  and  smaller  folds  alternate 
with  each  other.  They  are  not  found  at  the  commencement  of  the  duodenum, 
but  begin  to  appear  about  one  or  two  inches  beyond  the  pylorus.  In  the  lower 
part  of  the  descending  portion,  below  the  point  where  the  common  choledoch 
and  pancreatic  ducts  enter  the  intestine,  they  are  very  large  and  closely  approxi- 
mated. In  the  transverse  portion  of  the  duodenum  and  upper  half  of  the  jeju- 
num, they  are  large  and  numerous ;  and  from  this  point,  down  to  the  middle  of 
they  the  ileum,  they  diminish  considerably  in  size.  In  the  lower  part  of  the 
ileum,  almost  entirely  disappear;  hence  the  comparative  thinness  of  this  portion 
of  the  intestine,  as  compared  with  the  duodenum  and  jejunum.  The  valvulae 
,:;onniventes  retard  the  passage  of  the  food  along  the  intestines,  and  afford  a 
more  extensive  surface  for  absorption. 

The  villi  are  minute,  highly  vascular  processes,  projecting  from  the  mucous 
membrane  of  the  small  intestine  throughout  its  whole  extent,  and  giving  to  its 
surface  a  velvety  appearance.  In  shape,  some  are  triangular  and  laminated, 
others  conical  or  cylindrical,  with  clubbed  or  filiform  extremities.  They  are 
largest  and  most  numerous  in  the  duodenum  and  jejunum,  and  become  fewer 
and  smaller  in  the  ileum.  Krause  estimates  their  number  in  the  upper  part  of 
the  small  intestine  at  from  fifty  to  ninety  in  a  square  line;  and  in  the  lower 
part  from  forty  to  seventy ;  the  total  number  for  the  whole  length  of  the  intes- 
tine being  about  four  millions. 

In  structure  each  villus  consists  of  a  network  of  capillary  and  lacteal  vessels, 
with  nuclear  corpuscles  and  fat-globules  in  their  interstices,  inclosed  in  a  thin 
prolongation  of  basement  membrane  covered , 
by  a  single  layer  of  columnar  epithelium, 
the  particles  of  which  are  arranged  per- 
pendicular to  the  surface.  A  layer  of  or- 
ganic muscular  fibre  has  been  described, 
forming  a  thin  hollow  cone  round  the  cen- 
tral lacteal.  It  is  possible  that  this  assists 
in  the  propulsion  of  the  chyle  along  the 
vessel.  The  mode  of  origin  of  the  lacteals 
within  the  villi  is  unknown. 

The  simple  follicles^  or  crypts  of  Lieber- 
kUhn,  are  found  in  considerable  numbers 
over  every  part  of  the  mucous  membrane 
of  the  small  intestine.  They  consist  of 
minute  tubular  depressions  of  the  mucous 

membrane,  arranged  perpendicularly  to  the  surface,  upon  w^iich  they  open  by 
small  circular  apertures.  They  may  be  seen  with  the  aid  of  a  lens,  their  orifices 
appearing  as  minute  dots,  scattered  between  the  villi.  Their  walls  are  thin, 
consisting  of  a  layer  of  basement  membrane,  lined  by  cylindrical  epithelium, 
and  covered  on  their  exterior  by  capillary  vessels.  Their  contents  vary,  even 
in  health,  and  the  purpose  served  by  their  secretion  is  still  very  doubtful. 

The  duodenal,  or  Brunner's  glands,  are  limited  to  the  duodenum  and  com- 
mencement of  the  jejunum.  They  are  small,  flattened,  granular  bodies, 
imbedded  in  the  submucous  areolar  tissue,  and  open  upon  the  surface  of  the 
mucous  membrane  by  minute  excretory  ducts.  They  are  most  numerous  and 
largest  near  the  pylorus.  They  may  be  compared  to  the  elementary  lobules 
of  a  salivary  gland,  spread  out  over  a  broad  surface,  instead  of  being  collected 
in  a  mass.     In  structure  they  resemble  the  pancreas. 

The  solitary  glands  {glandulva  solitarise)  are  found  scattered  throughout  the 
mucous  membrane  of  the  small  intestine,  but  are  most  numerous  in  the  lower 
part  of  the  ileum.     They  are  small,  round,  whitish  bodies,  from  half  a  line  to  a 


ArUry 


736 


ORGANS    OP    DIGESTION. 


line  in  diameter,  consisting  of  a  closed  saccular  cavity,  having  no  excretory 
duct,  and  containing  an  opaque  white  secretion.  Their  free  surface  is  covered 
with  villi,  and  each  gland  is  surrounded  by  openings  lil^e  those  of  the  follicles 
of  Lieberkiihn.     Their  use  is  .^ot  known. 

Peyerh  glands  may  be  regarded  as  aggregations  of  solitary  glands,  forming 
circular  or  oval  patches  from  twenty  to  thirty  in  number,  and  varying  in  length 
from  half  an  inch  to  four  inches.  They  are  largest  and  most  numerous  in  the 
ileum.  In  the  lower  part  of  the  jejunum  they  are  small,  of  a  circular  form, 
and  few  in  number.  They  are  occasionally  seen  in  the  duodenum.  They  are 
placed  lengthwise  in  the  intestine,  covering  the  portion  of  the  tube  most  distant 
from  the  attachment  of  the  mesentery.  Each  patch  is  formed  of  a  group  of 
small,  round,  whitish  vesicles,  covered  with  mucous  membrane.  Each  vesicle 
consists  of  a  moderately  thick  external  capsule,  having  no  excretory  duct,  and 
containing  an  opaque  white  secretion.  Each  is  surrounded  by  a  zone,  or  wreath 
of  simple  follicles,  and  the  interspaces  between  them  are  covered  with  villi. 
These  vesicles  are  usually  closed;  but  it  is  supposed  they  open  at  intervals  to 
discharge  the  secretion  contained  within  them.  The  mucous  and  submucous 
coats  of  the  intestine  are  intimately  adherent,  and  highly  vascular,  opposite  the 
Peyerian  glands.  Their  use  is  not  known.  They  are  largest  and  most  devel- 
oped during  the  digestive  process. 

The  Large  Intestine. 

The  Large  Intestine  extends  from  the  termination  of  the  ileum  to  the  anus. 
It  is  about  five  feet  in  length,  being  one-fifth  of  the  whole  extent  of  the  intes- 
tinal canal.     It  is  largest  at  its  commencement  at  the  ccecum,  and  gradually, 


Fig.  403.— Patch  of  Peyer's  Glands. 
From  the  lower  part  of  the  Ileum. 


Fig.  404. — A  portion  of  the  above  magnified. 


:^T<w. 


^^^^^''^" 


diminishes  as  far  as  the  rectum,  where  there  is  a  dilatation  of  considerable  size, 
just  above  the  anus.  It  differs  from  the  small  intestine  in  its  greater  size,  its 
more  fixed  position,  and  its  sacculated  form.  The  large  intestine,  in  its  course, 
describes  an  arch,  which  surrounds  the  convolutions  of  the  small  intestine.  It 
commences  in  the  right  iliac  fo.s.sa,  in  a  dilated  part,  the  coecum.  It  ascends 
through  the  right  lumbar  and  hypochondriac  regions  to  the  under  surface  of 
the  liver;  passes  transversely  across  the  abdomen,  on  the  confines  of  the  epi- 
gastric and  umbilical  regions,  to  the  left  hypochondriac  region;  descends 
through  the  left  lumbar  region  to  the  left  iliac  fossa,  where  it  becomes  convo- 
luted, and  forms  the  sigmoid  flexure;  finally,  it  enters  the  pelvis,  and  descends 
along  its  posterior  wall  to  the  aDus.  The  large  intestine  is  divided  into  the 
caecum,  colon,  and  rectum. 


LARGE    INTESTINE.  787 

The  Csectim  {ceecus^  blind)  (Fig.  405)  is  the  large  blind  pouch,  or  cul-de-sac,  in 
which  the  large  intestine  commences.  It  is  the  most  dilated  part  of  the  tube, 
measuring  about  two  and  a  half  inches,  both  in  its  vertical  and  transverse  diame- 
ters. It  is  situated  in  the  right  iliac  fossa,  immediately  behind  the  anterior 
abdominal  wall,  being  retained  in  its  place  by  the  peritoneum,  which  passes 
over  its  anterior  surface  and  sides;  its  posterior  surface  being  connected  by 
loose  areolar  tissue  with  the  iliac  fascia.  Occasionally,  it  is  almost  completely 
surrounded  by  peritoneum,  which  forms  a  distinct  fold,  the  meso-caecum,  con- 
necting its  back  part  with  the  iliac  fossa.  When  this  fold  exists  the  caecum 
obtains  considerable  freedom  of  movement.  Attached  to  its  lower  and  back 
part  is  the  appendix  vermiformis,  a  long,  narrow,  worm-shaped  tube,  the  rudi- 
ment of  the  lengthened  caecum  found  in  all  the  mammalia,  except  the  orang- 
outang and  wombat.  The  appendix  varies  from  three  to  six  inches  in  length, 
its  average  diameter  being  about  equal  to  that  of  a  goose-quill.  It  is  usually 
directed  upwards  and  inwards  behind  the  caecum,  coiled  upon  itself,  and  termi- 
nates in  a  blunt  point,  being  retained  in  its  position  by  a  fold  of  peritoneum, 
which  sometimes  forms  a  mesentery  for  it.  Its  canal  is  small,  and  communi- 
cates with  the  caBCum  by  an  orifice,  which  is  sometimes  guarded  with  an  incom 
plete  valve.  Its  coats  are  thick,  and  its  mucous  lining  furnished  with  a  large 
number  of  solitary  glands. 

Fig.  405. — The  Caecum  and  Colon  laid  open  to  show  Ileo-caecal  Valve. 


Ileo-csecal  Valve.  The  lower  end  of  the  ileum  terminates  at  the  inner  and 
back  part  of  the  large  intestine,  opposite  the  junction  of  the  caecum  with  the 
colon.  At  this  point  the  mucous  membrane  forms  two  valvular  folds,  which 
project  into  the  large  intestine,  and  are  separated  from  each  other  by  a  narrow 
elongated  aperture.  This  is  the  ileo-caecal  valve  {valvula  Bauhini).  Each  fold 
is  semilunar  in  form.  The  upper  one,  nearly  horizontal  in  direction,  is  attached 
by  its  convex  border  to  the  point  of  junction  of  the  ileum  with  the  colon;  the 
lower  segment,  to  the  point  of  junction  of  the  ileum  with  the  caecum.  Their 
free  concave  margins  project  into  the  intestine,  separated  from  one  another  by 
a  narrow  slit-like  aperture,  directed  transversely.  At  each  end  of  this  aperture 
the  two  segments  of  the  valve  coalesce,  and  are  continued,  as  a  narrow  mem- 
branous ridge,  around  the  canal  of  the  intestine  for  a  short  distance,  forming 
47 


788  ORGANS    OF    DIGESTION. 

the  frsena,  or  retinacula  of  the  valve.     The  left  end  of  this  aperture  is  rounded: 
the  right  end  is  narrow  and  pointed. 

Each  segment  of  the  valve  is  formed  by  a  reduplication  of  the  mucous  mem- 
brane, and  of  the  circular  muscular  fibres  of  the  intestine,  the  longitudinal 
fibres  and  peritoneum  being  continued  uninterruptedly  across  from  one  intestine 
to  the  other.  When  these  are  divided  or  removed,  the  ileum  may  be  drawn 
outwards,  and  all  traces  of  the  valve  will  be  lost,  the  ileum  appearing  to  open 
into  the  large  intestine  by  a  funnel-shaped  orifice  of  large  size. 

The  surface  of  each  segment  of  the  valve  directed  towards  the  ileum  is 
covered  with  villi,  and  presents  the  characteristic  structure  of  the  mucous  mem- 
brane of  the  small  intestine;  whilst  that  turned  towards  the  large  intestine  is 
destitute  of  villi,  and  marked  with  the  orifices  of  the  numerous  tubuli  peculiar 
to  the  membrane  in  the  large  intestine.  These  differences  in  structure  continue 
as  far  as  the  free  margin  of  the  valve. 

"When  the  caecum  is  distended,  the  margins  of  the  opening  are  approximated, 
80  as  to  prevent  any  reflux  into  the  ileum. 

The  Colon  is  divided  into  four  parts,  the  ascending,  transverse,  descending, 
and  the  sigmoid  flexure. 

The  ascending  colon  is  smaller  than  the  caecum.  It  passes  upwards,  from  the 
right  iliac  fossa  to  the  under  surface  of  the  liver,  on  the  right  of  the  gall- 
bladder, where  it  bends  abruptly  inwards  to  the  left,  forming  the  hepatic  flexure. 
It  is  retained  in  contact  with  the  posterior  wall  of  the  abdomen  by  the  peri- 
toneum, which  covers  its  anterior  surface  and  sides,  its  posterior  surface  being 
connected  by  loose  areolar  tissue  with  the  Quadratus  Lumborum  and  right 
kidney;  sometimes  the  peritoneum  almost  completely  invests  it,  and  forms  a 
distinct  but  narrow  meso-colon.  It  is  in  relation,  in  front,  with  the  convolu- 
tions of  the  ileum  and  the  abdominal  parietes;  behind,  it  lies  on  the  Quadratu8|L| 
Lumborum  muscle,  and  right  kidney.  W 

The  transverse  colon,  the  longest  part  of  the  large  intestine,  passes  transversely 
from  right  to  left  across  the  abdomen,  opposite  the  confines  of  the  epigastric 
and  umbilical  zones,  into  the  left  hypochondriac  region,  where  it  curves  down- 
wards beneath  the  lower  end  of  the  spleen,  forming  the  splenic  flexure.  In  its 
course  it  describes  an  arch,  the  concavity  of  which  is  directed  backwards 
towards  the  vertebral  column;  hence  the  name,  transverse  arch  of  the  colon. 
This  is  the  most  movable  part  of  the  colon,  being  almost  completely  invested 
by  peritoneum,  and  connected  to  the  spine  behind  by  a  large  and  wide  dupli- 
cature  of  that  membrane,  the  transverse  meso-colon.  It  is  in  relation,  by  its 
upper  surface,  with  the  liver  and  gall-bladder,  the  great  curvature  of  the 
stomach,  and  the  lower  end  of  the  spleen;  by  its  under  surface,  with  the  small 
intestines;  by  its  anterior  surface,  with  the  anterior  layers  of  the  great  omentum 
and  the  abdominal  parietes;  by  its  posterior  surface,  with  the  transverse  meso- 
colon. 

The  descending  colon  passes  almost  vertically  downwards  through  the  left 
hypochondriac  and  lumbar  regions  to  the  upper  part  of  the  left  iliac  fossa, 
where  it  terminates  in  tbe  sigmoid  flexure.  It  is  retained  in  position  by  the 
peritoneum,  which  covers  its  anterior  surface  and  sides,  its  posterior  surface 
being  connected  by  areolar  tissue  with  the  left  crus  of  the  Diaphragm,  the  left 
kidney,  and  the  Quadratus  Lumborum.  It  is  smaller  in  calibre  and  more 
deeply  placed  than  the  ascending  colon. 

The  sigmoid  flexure  is  the  narrowest  part  of  the  colon;  it  is  situated  in  the  left 
iliac  fossa,  commencing  at  the  termination  of  the  descending  colon,  at  the  mar- 
gin of  the  crest  of  the  ilium,  and  ending  in  the  rectum,  opposite  the  left  sacro- 
iliac symphysis.  It  curves  in  the  first  place  upwards,  and  then  descends  verti- 
cally, and  to  one  or  the  other  side,  like  the  letter  S — hence  its  name.  It  is 
retained  in  its  place  by  a  loose  fold  of  peritoneum,  the  sigmoid  meso-colon.  It 
is  in  relation,  in  front,  with  the  small  intestines  and  abdominal  parietes;  behind, 
with  the  iliac  fossa. 


LARGE    INTESTINE.  739 

The  Rectum  is  the  terminal  part  of  the  large  intestine,  and  extends  from  the 
sigmoid  flexure  to  the  anus;  it  varies  in  length  from  six  to  eight  inches,  and 
has  received  its  name  from  being  less  flexuous  than  any  other  part  of'the 
intestinal  canal.  It  commences  opposite  the  left  sacro-iliac  symphysis,  passes 
obliquely  downwards  from  left  to  right  to  the  middle  of  the  sacrum,  forming  a 
gentle  curve  to  the  right  side;  then,  regaining  the  middle  line,  it  descends  in 
front  of  the  lower  part  of  the  sacrum  and  coccyx,  and,  near  the  extremity  of  the 
latter  bone,  inclines  backwards  to  terminate  at  the  anus,  being  curved  both 
in  the  lateral  and  antero-posterior  directions.  The  rectum  is,  therefore,  not 
straight,  the  upper  part  being  directed  obliquely  from  the  left  side  to  the  me-. 
dian  line,  the  middle  portion  being  curved  in  the  direction  of  the  hollow  of  the 
sacrum  and  coccyx,  and  the  lower  portion  presenting  a  short  curve  in  the  oppo- 
site direction.  The  rectum  is  cylindrical,  not  sacculated  like  the  rest  of  the 
large  intestine;  it  is  narrower  at  its  upper  part  than  the  sigmoid  flexure,  gra- 
dually increases  in  size  as  it  descends,  and  immediately  above  the  anus  presents 
a  considerable  dilatation,  capable  of  acquiring  an  enormous  size.  The  rectum 
is  divided  into  three  portions,  upper,  middle,  and  lower. 

The  upper  portion,  which  includes  about  half  the  length  of  the  tube,  extends 
obliquely  from  the  left  sacro-iliac  symphysis  to  the  middle  of  the  third  piece 
of  the  sacrum.  It  is  almost  completely  surrounded  by  peritoneum,  and  con- 
nected to  the  sacrum  behind  by  a  duplicature  of  that  membrane,  the  meso-rectum. 
It  is  in  relation  behind  with  the  Pyriformis  muscle,  the  sacral  plexus  of  nerves, 
and  the  branches  of  the  internal  iliac  artery  of  the  left  side,  which  separate  it 
from  the  sacrum  and  sacro-iliac  symphysis ;  in  front  it  is  separated,  in  the  male, 
from  the  posterior  surface  of  the  bladder:  in  the  female,  from  the  posterior 
surface  of  the  uterus,  and  its  appendages,  by  some  convolutions  of  the  small 
intestine. 

The  middle  portion  of  the  rectum  is  about  three  inches  in  length,  and  extends 
as  far  as  the  tip  of  the  coccyx.  It  is  closely  connected  to  the  concavity  of  the 
sacrum,  and  covered  by  peritoneum  only  on  the  upper  part  of  its  anterior  sur- 
face. It  is  in  relation,  in  front,  in  the  male,  with  the  triangular  portion  of  the 
base  of  the  bladder,  the  vesiculae  seminales,  and  vasa  deferentia ;  more  anteri- 
orly, with  the  under  surface  of  the  prostate.  In  the  female,  it  is  adherent  to 
the  posterior  wall  of  the  vagina. 

The  loiver  p)ortion  is  about  an  inch  in  length ;  it  curves  backwards  at  the  fore 
part  of  the  prostate  gland,  and  terminates  at  the  anus.  This  portion  of  the  in- 
testine receives  no  peritoneal  covering.  It  is  invested  by  the  Internal  Sphinc- 
ter, supported  by  the  Levatores  Ani  muscles,  and  surrounded  at  its  termination 
by  the  External  Sphincter.  In  the  male,  it  is  separated  from  the  membranous 
portion  and  bulb  of  the  urethra  by  a  triangular  space ;  and,  in  the  female,  a 
similar  space?  intervenes  between  it  and  the  vagina.  This  space  forms  by  its 
base  the  perineum. 

Structure.  The  large  intestine  has  four  coats :  serous,  muscular,  cellular,  and 
mucous. 

The  serous  coat  is  derived  from  the  peritoneum,  and  invests  the  different  por- 
tions of  the  large  intestine  to  a  variable  extent.  The  cascum  is  covered  only 
on  its  anterior  surface  and  sides ;  more  rarely,  it  is  almost  completely  invested, 
being  held  in  its  position  by  a  duplicature,  the  meso-caecum.  The  ascending 
and  descending  colon  are  usually  covered  only  in  front.  The  transverse  colon 
is  almost  completely  invested,  the  parts  corresponding  to  the  attachment  of  the 
great  omentum  and  transverse  meso-colon  being  alone  excepted.  The  sigmoid 
flexure  is  nearly  completely  surrounded,  the  point  corresponding  to  the  attach- 
ment of  the  sigmoid  meso-colon  being  excepted.  The  upper  part  of  the  rectum 
is  almost  completely  invested  by  the  peritoneum:  the  middle  portion  is  covered 
only  on  its  anterior  surface ;  and  the  lower  portion  is  entirely  devoid  of  any 
serous  covering.     In  the  course  of  the  colon,  and  upper  part  of  the  rectum,  the 


no  ORGANS    OF    DIGESTION. 

peritoneal  coat  is  thrown  into  a  number  of  small  pouches  filled  with  fat,  called 
appendices  epiphicse.     They  are  chiefly  appended  to  the  transverse  colon. 

The  muscular  coat  consists  of  an  external  longitudinal  and  an  internal  circular 
layer  of  muscular  fibres. 

The  longitudinal  fibres  are  found  as  a  uniform  layer  over  the  whole  surface  of 
the  large  intestine.  In  the  cascum  and  colon,  they  are  especially  collected  into 
three  flat  longitudinal  bands,  each  being  about  half  an  inch  in  width.  These 
bands  commence  at  the  attachment  of  the  appendix  vermiformis  to  the  csecum ; 
one,  the  posterior,  is  placed  along  the  attached  border  of  the  intestine;  the  ante- 
rior band,  the  largest,  becomes  inferior  along  the  arch  of  the  colon,  where  it 
corresponds  to  the  attachment  of  the  great  omentum,  but  is  in  front  in  the 
ascending  and  descending  colon  and  sigmoid  flexure ;  the  third,  or  lateral  band, 
is  found  on  the  inner  side  of  the  ascending  and  descending  colon,  and  on  the 
under  border  of  the  transverse  colon.  These  bands  are  nearly  one-half  shorter 
than  the  other  parts  of  the  intestine,  and  serve  to  produce  the  sacculi  which 
are  characteristic  of  the  caecum  and  colon;  accordingly,  when  they  are  dis- 
sected off,  the  tube  can  be  lengthened,  and  its  sacculated  character  becomes  lost. 
In  the  sigmoid  flexure,  the  longitudinal  fibres  become  more  scattered,  but  upon 
its  lower  part,  and  round  the  rectum,  they  spread  out,  and  form  a  thick  uniform 
layer. 

The  circular  fibres  form  a  thin  layer  over  the  caecum  and  colon,  being  espe- 
cially accumulated  in  the  intervals  between  the  sacculi ;  in  the  rectum,  they 
form  a  thick  layer,  especially  at  its  lower  end,  where  they  become  numerous, 
and  form  the  Internal  Sphincter. 

The  celhilar  coat  connects  the  muscular  and  mucous  layers  closely  together. 
The  mucous  membrane^  in  the  cascum  and  colon,  is  pale,  and  of  a  grayish  or 
pale  yellow  color.  It  is  quite  smooth,  destitute  of  villi,  and  raised  into  nume- 
rous crescentic  folds,  which  correspond  to  the  intervals  between  the  sacculi.  In 
the  rectum,  it  is  thicker,  or  of  a  darker  color,  more  vascular,  and  connected 
loosely  to  the  muscular  coat  as  in  the  oesophagus.  When  the  lower  part  of  the 
rectum  is  contracted,  its  mucous  membrane  is  thrown  into  a  number  of  folds, 
some  of  which  near  the  anus,  are  longitudinal  in  direction,  and  are  effaced  by 
the  distension  of  the  gut.  Besides  these,  there  are  certain  permanent  folds  of  a 
semilunar  shape,  described  by  Mr.  Houston.'  They  are  usually  three  in  num- 
ber ;  sometimes  a  fourth  is  found,  and,  occasionally,  only  two  are  present.  One 
is  situated  near  the  commencement  of  the  rectum,  on  the  right  side ;  another 
extends  inwards  from  the  left  side  of  the  tube,  opposite  the  middle  of  the  sa- 
crum ;  the  largest  and  most  constant  one  projects  backwards  from  the  fore  part 
of  the  rectum,  opposite  the  base  of  the  bladder.  When  a  fourth  is  present,  it 
is  situated  about  an  inch  above  the  anus  on  the  back  of  the  rectum.  These 
folds  are  about  half  an  inch  in  width,  and  contain  some  of  the  circular  fibres  of 
the  gut.  In  the  empty  state  of  the  intestine  they  overlap  each  other,  as  Mr. 
Houston  remarks,  so  effectually  as  to  require  considerable  manoeuvring  to  con- 
duct a  bougie  or  the  finger  along  the  canal  of  the  intestine.  Their  use  seems 
to  be,  "  to  support  the  weight  of  fecal  matter,  and  prevent  its  urging  towards 
the  anus,  where  its  presence  always  excites  a  sensation  demanding  its  discharge." 
The  mucous  membrane  of  the  large  intestine  presents  for  examination,  epithe- 
lium, simple  follicles,  and  solitary  glands. 
The  epithelium  is  of  the  columnar  kind. 

The  simple  follicles  are  minute  tubular  prolongations  of  the  mucous  mem- 
brane, arranged  perpendicularly,  side  by  side,  over  its  entire  surface ;  they  are 
longer,  more  numerous,  and  placed  in  much  closer  apposition  than  those  of  the 
small  intestine;  and  they  open  by  minute  rounded  orifices  upon  the  surface, 
giving  it  a  cribriform  appearance. 

The  solitary  glands  in  the  large  intestine  are  most  abundant  in  the  ctecuin 

\. 

'  Duh.  Hosp.  Reports,  vol.  v.  p.  163. 


THE    LIVER. 


T41 


and  appendix  vermiformis ;  but  are  irregularly  scattered  also  over  the  rest  of 
the  intestine.  They  are  small,  prominent,  flask-shaped  bodies,  of  a  whitish 
color,  perforated  upon  the  central  part  of  their  free  surface  by  a  minute  orifice, 
which,  in  the  majority,  is  permanent. 

Fig.  406. — ]Srinnto  Structure  of  Large  Intestine. 


Jij)ertur»    »f> 
Bolftari/ roOieU 


Tuiu7i  Ttfting  en. 
SiM-hMiuucuM  CeU.  ti'te. 


Station    ^  JiTueoiu  Xtmirajts 


tree    Stnfaec 


Tpik  Liveb. 

^  The  Liver  is  a  glandular  organ  of  large  size,  intended  mainly  for  the  secre- 
tion of  the  bile,  but  effecting  also  important  changes  in  certain  constituents 
of  the  blood  in  their  passage  through  the  gland.  It  is  situated  in  the  right 
hypochondriac  region,  and  extends  across  the  epigastrium  into  the  left  hypo- 
chondrium.  It  is  the  largest  gland  in  the  body,  weighing  from  three  to  four 
pounds  (from  fifty  to  sixty  ounces  avoirdupois).  It  measures,  in  its  transverse 
diameter,  from  ten  to  twelve  inches ;  from  six  to  seven  in  its  antero-posterior ; 
and  is  about  three  inches  thick  at  the  back  part  of  the  right  lobe,  which  is  the 
thickest  part. 

Its  ui-)j)er  surface  is  convex,  directed  upwards  and  forwards,  smooth,  covered 
by  peritoneum.  It  is  in  relation  with  the  under  surface  of  the  Diaphragm  and 
below,  to  a  small  extent,  with  the  abdominal  parietes.  The  surface  is  divided 
into  two  unequal  lobes,  the  right  and  left,  by  a  fold  of  peritoneum,  the  suspen- 
sory or  broad  ligament. 

Its  under  surface  is  concave,  directed  downwards  and  backwards,  and  in  rela- 
tion with  the  stomach  and  duodenum,  the  hepatic  flexure  of  the  colon,  and  the 
right  kidney  and  suprarenal  capsule.  The  surface  is  divided  by  a  longitudinal 
fissure  into  a  right  and  left  lobe. 

The  posterior  horder  is  rounded  and  broad,  and  connected  to  the  Diaphragm 
by  the  coronary  ligament ;  it  is  in  relation  with  the  aorta,  the  vena  cava,  and 
the  crura  of  the  Diaphragm. 

The  anterior  horder  is  thin  and  sharp,  and  marked,  opposite  the  attachment 
of  the  broad  ligament,  by  a  deep  notch.  In  adult  males,  this  border  usually 
corresponds  with  the  margin  of  the  ribs ;  but  in  women  and  children,  it  usually 
projects  below  the  ribs. 

The  right  extremity  of  the  liver  is  thick  and  rounded ;  whilst  the  left  is  thin 
and  flattened. 

Changes  of  Position. — The  student  should  make  himself  acquainted  with  the  different  circum- 
stances under  which  the  liver  clianges  its  position,  as  they  are  of  importance  in  determining  the 
existence  of  enlargement,  or  other  disease  of  the  organ. 

Its  position  varies  according  to  the  posture  of  the  body  ;  in  the  upright  and  sitting  postures, 
its  lower  border  may  be  felt  below  the  edges  of  the  ribs ;  in  the  recumbent  posture,  it  usually 
recedes  behind  the  ribs.  Its  position  varies,  also,  with  the  ascent  or  descent  of  the  Diaphragm. 
In  a  deep  inspiration,  the  liver  descends  below  the  ribs ;  in  expiration,  it  is  raised  to  its  ordinary 
level.  Again,  in  emphysema,  where  the  lungs  are  distended,  and  the  Diaphragm  descends  very 
low,  the  liver  is  pushed  down ;  in  some  other  diseases,  as  phthisis,  where  the  Diaphragm  is  much 
arched,  the  liver  rises  very  high  up.  Pressure  from  without,  as  in  tight  lacing,  by  compreigsing 
the  lower  part  of  the  chest,  displaces  the  liver  considerably,  its  anterior  edge  often  extending  as 
low  as  the  crest  of  the  ilium ;  and  its  convex  surface  is  often,  at  the  same  time,  deeply  indented 


•(42 


ORGANS    OF    DIGESTION. 


from  pressure  of  the  ribs.  Again,  its  position  varies  greatly,  according  to  the  greater  or  less 
distension  of  the  stomach  and  intestines.  When  the  intestines  are  empty,  the  liver  descends  in 
the  abdomen  ;  but  when  they  are  distended,  it  is  pushed  upwards.  Its  relations  to  surrounding 
organs  may  also  be  changed  by  the  growth  of  tumors,  or  by  collections  of  fluid  in  the  thoracic 
or  abdominal  cavities. 

Ligaments.  The  ligaments  of  the  liver  (Fig.  407)  are  five  in  number ;  four 
being  formed  of  folds  of  peritoneum  ;  the  fifth,  the  ligamenturn  teres,  is  a  round, 
fibrous  cord,  resulting  from  the  obliteration  of  the  umbilical  vein.  The  liga- 
ments are  the  longitudinal,  two  lateral,  coronary,  and  round. 

The  longitudinal  ligament  (broad,  falciform,  or  suspensory  ligament)  is  a  broad 
and  thin  antero-posterior  peritoneal  fold,  falciform  in  shape,  its  base  being  di- 
rected forwards,  its  apex  backwards.  It  is  attached  by  one  margin  to  the  under 
surface  of  the  Diaphragm,  and  the  posterior  surface  of  the  sheath  of  the  right 
Eectus  muscle  as  low  down  as  the  umbilicus ;  by  its  hepatic  margin,  it  extends 
from  the  notch  on  the  anterior  margin  of  the  liver,  as  far  back  as  its  posterior 
border.  It  consists  of  two  layers  of  peritoneum  closely  united  together.  Its 
anterior  free  edge  contains  the  round  ligament  between  its  layers. 

Fig.  407.— The  Liver.     Upper  Surfac-o. 


The  lateral  ligaments,  two  in  number,  right  and  left,  are  triangular  in  shape. 
They  are  formed  of  two  layers  of  peritoneum  united,  and  extend  from  the  sides 
of  the  Diaphragm  to  the  adjacent  margins  of  the  posterior  border  of  the  liver 
The  left  is  the  longer  of  the  two,  and  lies  in  front  of  the  oesophageal  opening 
in  the  Diaphragm. 

The  coronary  ligament  connects  the  posterior  border  of  the  liver  to  the 
Diaphragm.  It  is  formed  by  the  reflection  of  the  peritoneum  from  the  Dia- 
phragm on  to  the  upper  and  lower  margins  of  the  posterior  border  of  the  organ. 
The  coronary  ligament  consists  of  two  layers,  which  are  continuous  on  each  side 
with  the  lateral  ligaments;  and  in  front,  with  the  longitudinal  ligament.  Between 
the  layers,  a  large  oval  interspace  is  left  uncovered  by  peritoneum,  .and  con- 
nected to  the  Diaphragm  by  a  firm  areolar  tissue.  This  space  is  subdivided, 
near  its  left  extremity,  into  two  parts  by  a  deep  notch  (sometimes  a  canal),  which 
lodges  the  inferior  vena  cava,  and  into  which  opens  the  hepatic  veins. 

The  round  ligament  (Fig.  408)  is  ji  fibrous  cord  resulting  from  the  obliteration 
of  the  umbilical  vein.  It  ascends  from  the  umbilicus,  in  the  anterior  free 
margin  of  the  longitudinal  ligament,  to  the  notch  in  the  anterior  border  of  the 
liver,  from  which  it  may  be  traced  along  the  longitudinal  fissure  on  the  under 
surface  of  the  liver,  as  far  back  as  the  inferior  vena  cava. 


THE    LIVER. 


743 


Fissures  (Fig.  408).  Five  Fissures  are  seen  upon  the  under  surface  of  the 
liver,  which  serve  to  divide  it  into  five  lobes.  Thej  are  the  longitudinal  fissure, 
the  fissure  of  the  ductus  venosus,  the  transverse  fissure,  the  fissure  for  the  gall- 
bladder, and  the  fissure  for  the  vena  cava. 

The  longitudinal  fissure  is  a  deep  groove,  which  extends  from  the  notch  on 
the  anterior  margin  of  the  liver  to  the  posterior  border  of  the  organ.  It  sepa- 
rates the  right  and  left  lobes;  the  transverse  fissure  joins  it,  at  right  angles, 
about  one-third  from  its  posterior  extremity,  and  divides  it  into  two  parts.  The 
anterior  half  is  called  the  umbilical  fissure ;  it  is  deeper  than  the  posterior  part, 
and  lodges  the  umbilical  vein  in  the  foetus,  or  its  remains  (the  round  ligament) 
in  the  adult.  This  fissure  is  often  partially  bridged  over  by  a  prolongation  of 
the  hepatic  substance,  the  po7is  hepatis. 

The  fissure  of  the  ductus  venosus  is  the  back  part  of  the  longitudinal  fissure ; 
it  is  shorter  and  shallower  than  the  anterior  portiop.  It  lodges  in  the  foetus  the 
ductus  venosus,  and  in  the  adult  a  slender  fibrous  cord,  the  obliterated  remains 
of  that  vessel. 

Fig.  408.— The  Liver.    Under  Surface. 


The  transverse  or  portal  fissure  is  a  short  but  deep  fissure,  about  two  inches  in 
length,  extending  transversely  across  the  under  surface  of  the  right  lobe,  nearer 
to  its  posterior  than  its  anterior  border.  It  joins,  nearly  at  right  angles,  with 
the  longitudinal  fissure.  By  the  older  anatomists,  this  fissure  was  considered 
the  gateway  (porta)  of  the  liver ;  hence  the  large  vein  which  enters  at  this 
point  was  called  the  portal  vein.  Besides  this  vein,  the  fissure  transmits  the 
hepatic  artery  and  nerves,  and  the  hepatic  duct  and  lymphatics.  At  their 
entrance  into  the  fissure,  the  hepatic  duct  lies  in  front  to  the  right,  the  hepatic 
artery  to  the  left,  and  the  portal  vein  behind  (Fig.  412). 

1l\xq  fissure  for  the  gall-bladder  {fossa  cystidis  feUese)  is  a  shallow,  oblong  fossa, 
placed  on  the  under  surface  of  the  right  lobe,  parallel  with  the  longitudinal 
fissure.  It  extends  from  the  anterior  free  margin  of  the  liver,  which  is  occa- 
sionally notched  for  its  reception,  to  near  the  right  extremity  of  the  transverse 
fissure. 

Il^q  fissure  for  the  vena  cava  is  a  short  deep  fissure,  occasionally  a  complete 
canal  which  extends  obliquely  upwards  from  a  little  behind  the  right  extremity 
of  the  transverse  fissure,  to  the  posterior  border  of  the  organ,  where  it  joins 
the  fissure  for  the  ductus  venosus.  On  slitting  open  the  inferior  vena  cava 
which  is  contained  in  it,  a  deep  fossa  is  seen,  at  the  bottom  of  which  the  hepatic 


744  ORGANS    OF    DIGESTION. 

veins  communicate  with  this  vessel.  This  fissure  is  separated  from  the  trans- 
verse fissure  by  the  lobus  caudatus,  and  from  the  longitudinal  fissure  by  the 
lobulus  Spigelii. 

Lobes.  The  Lobes  of  the  liver,  like  the  ligaments  and  fissures,  are  five  in 
number :  the  right  lobe,  the  left  lobe,  the  lobus  quadratus,  the  lobulus  Spigelii, 
and  the  lobus  caudatus. 

The  right  hhe  is  much  larger  than  the  left ;  the  proportion  between  them 
being  as  six  to  one.  It  occupies  the  right  hypochondrium,  and  is  separated  from 
the  left  lobe,  on  its  upper  surface,  by  the  longitudinal  ligament;  on  its  under 
surface,  by  the  longitudinal  fissure ;  and  in  front,  by  a  deep  notch.  It  is  of  a 
quadrilateral  form,  its  under  surface  being  marked  by  three  fissures :  the  trans- 
verse fissure,  the  fissure  for  the  gall-bladder,  and  the  fissure  for  the  inferior 
vena  cava;  and  by  two  shallow  impressions,  one  in  front  {impressio  colica),  for 
the  hepatic  flexure  of  the  colon ;  and  one  behind  {impressio  renalis),  for  the  right 
kidney  and  suprarenal  capsule. 

The  left  hhe  is  smaller  and  more  flattened  than  the  right.  It  is  situated  in 
the  epigastric  and  left  hypochondriac  regions,  sometimes  extending  as  far  as  the 
upper  border  of  the  spleen.  Its  upper  surface  is  convex ;  its  under  concave 
surface  rests  upon  the  front  of  the  stomach ;  and  its  posterior  border  is  in  rela- 
tion with  the  cardiac  orifice  of  the  stomach. 

The  hhus  quadratus,  or  square  lobe,  is  situated  on  the  under  surface  of  the 
right  lobe,  bounded  in  front  by  the  free  margin  of  the  liver ;  behind,  by  the 
transverse  fissure ;  on  the  right,  by  the  fissure  for  the  gall-bladder ;  and,  on  the 
left,  by  the  umbilical  fissure. 

The  lobulus  Spigelii  projects  from  the  back  part  of  the  under  surface  of  the 
right  lobe.  It  is  bounded,  in  front,  by  the  transverse  fissure;  on  the  right,  by 
the  fissure  for  the  vena  cava ;  and,  on  the  left,  by  the  fissure  for  the  ductus 
venosus. 

The  lobus  caudattis,  or  tailed  lobe,  is  a  small  elevation  of  the  hepatic  substance, 
extending  obliquely  outwards,  from  the  base  of  the  lobulus  Spigelii,  to  the 
under  surface  of  the  right  lobe.  It  separates  the  right  extremity  of  the  trans- 
verse tissue  from  the  commencement  of  the  fissure  for  the  inferior  cava. 

Vessels.  The  vessels  connected  with  the  liver  are  also  five  in  number ;  thev 
are  the  hepatic  artery,  the  portal  vein,  the  hepatic  vein,  the  hepatic  duct,  and 
the  lymphatics. 

The  hepatic  artery,  portal  vein,  and  hepatic  duct,  accompanied  by  numerous 
lymphatics  and  nerves,  ascend  to  the  transverse  fissure,  between  the  layers  of 
the  gastro-hepatic  omentum ;  the  hepatic  duct  lying  to  the  right,  the  hepatic 
artery  to  the  left,  and  the  portal  vein  behind  the  other  two.  They  are  enveloped 
in  a  loose  areolar  tissue,  the  capsule  of  Glisson,  which  accompanies  the  vessels 
in  their  course  through  the  portal  canals,  in  the  interior  of  the  organ. 

The  hepatic  veins  convey  the  blood  from  the  liver.  They  commence  at  the 
circumference  of  the  organ,  and  proceed  towards  the  deep  fossa  in  its  posterior 
border,  where  they  terminate  by  two  large  and  several  smaller  branches,  in  tlie 
inferior  vena  cava. 

The  hepatic  veins  have  no  cellular  investment ;  consequently  their  parietes 

are  adherent  to  the  walls  of  the  canals  through  which  they  run ;  so  that,  on  a 

section  of  the  organ,  those  veins  remain  widely  open  and  solitary,  and  may  be 

^  easily  distinguished  from  the  branches  of  the  portal  vein,  which  are  more  or 

less  collapsed,  and  always  accompanied  by  an  artery  and  duct. 

The  lymphatics  are  large  and  numerous,  consisting  of  a  deep  and  superficial 
set.     They  have  been  already  described. 

Nerves.  Tbe  nerves  of  the  liver  are  derived  from  the  hepatic  plexus  of  the 
sympathetic,  from  the  pneumogastric  nerves,  especially  the  left,  and  from  the 
right  phrenic. 

Structure.  The  substance  of  the  liver  is  composed  of  lobules,  held  together 
by  an  extremely  fine  areolar  tissue,  and  of  the  ramifications  of  the  portal  vein, 


STRUCTURE    OF    THE    LITER. 


T49 


hepatic  duct,  hepatic  artery,  hepatic  veins, 
lymphatics,  and  nerves;  the  whole  being  in- 
vested by  a  fibrous  and  a  serous  coat. 

The  serous  coat  is  derived  from  the  perito- 
neum, and  invests  the  entire  surface  of  the 
organ,  excepting  at  the  attachment  of  its 
various  ligaments,  and  at  the  bottom  of  the 
different  fissures,  where  it  is  deficient.  It  is 
intimately  adherent  to  the  fibrous  coat. 

T\\Q  fibrous  coat  lies  beneath  the  serous  in- 
vestment, and  covers  the  entire  surface  of  the 
organ.  It  is  difficult  -of  demonstration,  ex- 
cepting where  the  serous  coat  is  deficient. 
At  the  transverse  fissure,  it  is  continuous  with 
the  capsule  of  Glisson ;  and,  on  the  surface  of 
the  organ,  with  the  areolar  tissue  separating 
the  lobules. 

The  lobules  form  the  chief  .mass  of  the  he- 
patic substance:  they  may  be  seen  either  on 
the  surface  of  the  organ,  or  by  making  a 
section  through  the  gland.  They  are  small 
granular  bodies,  about  the  size  of  a  millet- 
seed,  measuring  from  one-twentieth  to  one- 
tenth  of  an  inch  in  diameter.  If  divided 
longitudinally,  they  have  a  foliated,  and,  if 
transversely,  a  polygonal,  outline.  The  bases 
of  the  lobules  are  clustered  round  the  smallest 
branches  (sublobular)  of  the  hepatic  veins,  to 
which  each  is  connected  by  means  of  a  small 
branch,  which  issues  from  the  centre  of  the 
lobule  (intralobular).  The  remaining  part  of 
the  surface  of  each  lobule  is  imperfectly  iso- 
lated from  the  surrounding  lobules,  by  a  thin 
stratum  of  areolar  tissue,  and  by  the  smaller 
vessels  and  ducts. 

If  one  of  the  hepatic  veins  be  laid  open, 
the  bases  of  the  lobules  may  be  seen  through 
the  thin  wall  of  the  vein,  on  which  they  rest, 
arranged  in  the  form  of  a  tessellated  pave- 
ment, the  centre  of  each  polygonal  space  pre- 
senting a  minute  aperture,  the  mouth  of  a 
sublobular  vein. 

Each  lobule  is  composed  of  a  mass  of  cells; 
of  a  plexus  of  biliary  ducts ;  of  a  venous 
plexus,  formed  by  branches  of  the  portal  vein ; 
of  a  branch  of  an  hepatic  vein  (intralobular); 
of  minute  arteries ;  and,  probably,  of  nerves 
and  lymphatics. 

The  hepatic  cells  form  the  chief  mass  of 
the  substance  of  a  lobule,  and  lie  in  the  inter- 
spaces of  the  capillary  plexus,  being  probably 
contained  in  a  tubular  network,  which  forms 
the  origin  of  the  biliary  ducts.  The  smallest 
branches  of  the  vena  portas  pass  between  the 
lobules,  around  which  they  form  a  plexus,  the 
interlobular.  Branches  from  this  plexus  enter 
the  lobules,  and  form  a  network  in  their  cir- 


H.  Longitudinal  section  of  an  hepatic  vein. 
a.  Portion  of  the  canal,  from  which  the 
vein  has  been  removed  ;  b,  orifices  of  ulti- 
mate twigs  of  the  vein  (sublobular),  situ- 
ated in  the  centre  of  the  lobules.  After 
Kiernan. 

Fig.  410. 


Longitudinal  section  of  a  small  portal  vein 
and  canal,  after  Kiernan.  a.  Portions  of 
the  canal  from  which  the  vein  has  been 
removed  ;  b,  side  of  the  portal  vein  in 
contact  with  the  canal ;  c,  the  side  of  the 
vein  which  is  separated  from  the  canal 
by  the  hepatic  artery  and  duct,  with  are- 
olar tissue  (Glisson's  capsule)  ;  d,  inter- 
nal surface  of  the  portal  vein,  through 
which  are  seen  the  outlines  of  the  lobules 
and  the  openings  («)  of  the  interlobular 
veins  ;/,  vaginal  veins  of  Kiernan  ;  g,  he- 
patic artery  j  h,  hepatic  duct. 


746 


ORGANS    OF    DIGESTION. 


Fig.  411. 


cumference.  ^  The  radicals  of  tbe  portal  vein  communicate  with  those  of  the 
hepatic  vein,  which  occupy  the  centre  of  the  lobule ;  and  the  latter  converge 
to  form  the  intralobular  vein,  which  issues  from  the  base  of  the  lobule,  and 
joins  the  hepatic  vein.  The  portal  vein  carries  the  blood  to  the  liver,  from 
which  the  bile  is  secreted ;  the  hepatic  vein  carries  the  superfluous  blood  from 
the  liver,  and  the  bile-duct  carries  the  bile  secreted  by  the  hepatic  cells. 

The  hepatic  cells  are  of  a  more  or  less  spheroidal  form  ;  but  may  be  rounded, 
flattened,  or  many-sided,  from  mutual  compression.  They  vary  in  size  from 
the  j^ViT  to  the  ^^jVu  of  an  inch  in  diameter,  and  contain  a  distinct  nucleus  in 
the  interior,  or  sometimes  two.  In  the  nucleus  is  a  highly  refracting  nucleolus, 
with  granules.  The  cell-contents  are  viscid,  and  contain  yellow  particles,  the 
coloring  matter  of  the  bile,  and  oil  globules.  Thecellsadheretogether  by  their 
surfaces,  so  as  to  form  rows,  whicb  radiate  from  the  centre  towards  the  circum- 
ference of  the  lobule.  These  cells  are  probably  the  chief  agents  in  the  secre- 
tion of  the  bile. 

Biliary  Ducts.  The  precise  mode  of  origin  of  the  biliary  ducts  is  uncertain. 
Mr.  Kiernan's  original  view,  which  is  supported  by  the  researches  of  Dr.  Beale, 
is  that  the  ducts  commence  within  the  lobules,  in  a  plexiform  network  (lobular 
biliary  plexus),  in  which  the  hepatic  cells  lie.  According  to  Henle,  Handfield 
Jones,  and  Kolliker,  the  cells  are  packed  in  the  interspaces  of  the  capillary 
plexus,  and,  by  means  of  temporary  communications,  transmit  their  contents 
into  the  minute  bile-ducts  which  originate  in  the  spaces  hetiueen  the  lobules, 
never  entering  within  them.  The  ducts  form  a  plexus  (interlobular)  between 
the  lobules ;  and  the  interlobular  branches  unite  and  form  vaginal  branches, 
which  lie  in  the  portal  canals,  with  branches  of  the  portal  vein  and  hepatic  duct. 

The  ducts  finally  form  two  large  trunks,  which 
leave  the  liver  at  the  transverse  fissure,  and 
the  union  of  these  is  the  hepatic  duct. 

The  Portal  Vein,  on  entering  the  liver  at  the 
transverse  fissure,  divides  into  primary  branches, 
which  are  contained  in  the  portal  canals,  to- 
gether with  branches  of  the  hepatic  artery  and 
duct,  and  the  nerves  and  lymphatics.  In  the 
larger  portal  canals,  the  vessels  are  separated 
from  the  parietes,  and  joined  to  each  other  by 
a  loose  cellular  web,  the  capsule  of  Glisson. 
The  veins,  as  they  lie  in  the  portal  canals,  give 
off  vaginal  branches,  which  form  a  plexus  (va- 
ginal plexus)  in  Glisson's  capsule.  From  this 
plexus,  and  from  the  portal  vein  itself,  small 
branches  are  given  off,  which  pass  between  th'fe 
lobules  (interlobular  veins);  these  cover  the 
entire  surface  of  the  lobules,  excepting  their 
bases.  The  lobular  branches  are  derived  from 
the  interlobular  veins  ;  they  penetrate  into  the 
lobule,  and  form  a  capillary  plexus  within  them. 
From  this  plexus  the  intralobular  vein  arises. 
The  Hepatic  Artery  appears  destined  chiefly  for  the  nutrition  of  the  coats  of 
the  large  vessels,  the  ducts,  and  the  investing  membranes  of  the  liver.  It  enters 
the  liver  at  the  transverse  fissure  with  the  portal  vein  and  hepatic  duct,  and 
ramifies  with  these  vessels  through  the  portal  canals.  It  gives  off  vaginal 
branches,  which  ramify  in  the  capsule  of  Glisson ;  and  other  branches  which 
are  distributed  to  the  coats  of  the  vena  portas  and  hepatic  duct.  From  the 
vaginal  plexus,  interlobular  branches  are  given  off,  which  ramify  through  the 
interlobular  fissures,  a  few  branches  being  distributed  to  the  lobules.  Kiernan 
supposes  that  the  branches  of  the  hepatic  artery  terminate  in  a  capillary  plexus, 
which  communicates  with  the  branches  of  the  vena  portas. 


4.-I 


A  transverse  seotion  ot  a  !<mivn  portal 
canal  and  its  vessels,  after  Kiernan.  1. 
Portal  vein  ;  2,  interlobular  branches  ; 
3,  branches  of  the  vein,  termed,  by  Mr. 
Kiernan,  vaginal,  also  giving  off  inter- 
lobular branches  ;  4,  hepatic  duct ;  5, 
hepatio  artery. 


GALL-BLADDER.  141 

The  Hepatic  Veins  commence  in  tlie  interior  of  each  lobule  by  a  plexus,  the 
branches  of  which  converge  to  form  the  intralobular  vein. 

The  intralobular  vein  passes  through  the  centre  of  the  lobule,  and  leaves  it  at 
its  base  to  terminate  in  a  sublobular  vein. 

The  sMi?oJM?rtr  vems  unite  with  neighboring  branches  to  form  larger  veins; 
and  these  join  to  form  the  large  hepatic  trunks,  which  terminate  in  the  vena 
cava. 

Gall-Bladder. 

The  Gall-bladder  is  the  reservoir  for  the  bile;  it  is  a  conical  or  pear-shaped 
membranous  sac,  lodged  in  a  fossa  on  the  under  surface  of  the  right  lobe  of  the 
liver,  and  extending  from  near  the  right  extremity  of  the  transverse  fissure  -to 
the  anterior  free  margin  of  the  organ.  It  is  about  four  inches  in  length,  one 
inch  in  breadth  at  its  w.idest  part,  and  holds  from  eight  to  ten  drachms.  It  is 
divided  into  a  fundus,  body,  and  neck.  ^\\q  fundus^  or  broad  extremity,  is 
divided  downwards,  forwards,  and  to  the  right,  and  occasionally  projects  from 
the  anterior  border  of  the  liver :  the  hody  and  neck  are  directed  upwards  and 
backwards  to  the  left.  The  gall-bladder  is  held  in  its  position  by  the  perito- 
neum, which,  in  the  majority  of  cases,  passes  over  its  under  surface,  but  the 
serous  membrane  occasionally  invests  the  gall-bladder,  which  then  is  connected 
to  the  liver  by  a  kind  of  mesentery. 

Relations.  The  hody  of  the  gall-bladder  is  in  relation,  by  its  upper  surface, 
with  the  liver,  to  which  it  is  connected  by  areolar  tissue  and  vessels;  by  its 
under  surface,  with  the  first  portion  of  the  duodenum,  occasionally  the  pyloric 
end  of  the  stomach,  and  the  hepatic  flexure  of  the  colon.  The/wnJw5  is  com- 
pletely invested  by  peritoneum ;  it  is  in  relation,  in  front,  with  the  abdominal 
parietes,  immediately  below  the  tenth  costal  cartilage ;  behind  with  the  trans- 
verse arch  of  the  colon.  The  neck  is  narrow,  and  curves  upon  itself  like  the 
italic  letter  /;  at  its  point  of  connection  with  the  body  and  with  the  cystic  duct, 
it  presents  a  well-marked  constriction. 

When  the  gall-bladder  is  distended  with  bile  or  calculi,  the  fundus  may  be  felt  through  the 
abdominal  parietes,  especially  in  an  emaciated  subject ;  the  relations  of  this  sac  will  also  serve 
to  explain  the  occasional  occurrence  of  abdominal  biliary  fistulas,  through  which  biliary  calculi 
may  pass  out,  and  of  the  passage  of  calculi  from  the  gall-bladder  into  the  stomach,  duodenum, 
or  colon,  which  occasionally  happens. 

Structure.  The  gall-bladder  consists  of  three  coats;  serous,  fibrous  and  mus- 
cular, and  mucous. 

The  external  or  serous  coat  is  derived  from  the  peritoneum;  it  completely 
invests  the  fundus,  but  covers  the  body  and  neck  only  on  their  under  surface. 

The  middle  ov  fibrous  coat  is  a  thin  but  strong  fibrous  layer,  which  forms  the 
framework  of  the  sac,  consisting  of  dense  fibres  which  interlace  in  all  directions. 
Plain  muscular  fibres  are  also  found  in  this  coat,  disposed  chiefly  in  a  longitu- 
dinal direction,  a  few  running  transversely. 

The  internal  or  mucous  coat  is  loosely  connected  with  the  fibrous  layer.  It  is 
generally  tinged  with  a  yellowish-brown  color,  and  is  everywhere  elevated  into 
minute  rugae,  by  the  union  of  which  numerous  meshes  are  formed ;  the  de- 
pressed intervening  spaces  having  a  polygonal  outline.  The  meshes  are  smaller 
at  the  fundus  and  neck,  being  most  developed  about  the  centre  of  the  sac. 
Opposite  the  neck  of  the  gall-bladder,  the  mucous  membrane  projects  inwards 
so  as  to  form  a  large  valvular  fold. 

The  mucous  membrane  is  covered  with  columnar  epithelium,  and  secretes  an 
abundance  of  thick  viscid  mucus ;  it  is  continuous  through  the  hepatic  duct 
with  the  mucous  membrane  lining  the  ducts  of  the  liver,  and  through  the  duc- 
tus communis  choledochus  with  the  mucous  membrane  of  the  alimentary  canal. 

The  Biliary  Ducts  are,  the  hepatic,  the  cystic,  and  the  ductus  communis 
choledochus. 

The  hepatic  duct  is  formed  of  two  trunks  of  nearly  equal  size,  Avhich  issue 
from  the  liver  at  the  transverse  fissure,  one  from  the  right,  the  other  from  the 


T48 


ORGANS    OF    DIGESTION. 


left  lobe;  these  unite,  and  pass  downwards  and  to  the  right  for  about  an  inch 
and  a  half,  to  join  at  an  acute  angle  with  the  cystic  duct,  and  so  form  the  ductus 
communis  choledochus. 

The  cystic  duct,  the  smallest  of  the  three  biliary  ducts,  is  about  an  inch  in 
length.  It  passes  obliquely  downwards  and  to  the  left  from  the  neck  of  the 
gall-bladder,  and  joins  the  hepatic  duct  to  form  the  common  duct.  It  lies  in 
the  gastro-hepatic  omentum  in  front  of  the  vena  cava,  the  cystic  artery  lying 
to  its  left  side.  The  mucous  membrane  lining  its  interior  is  thrown  into  a  series 
of  crescentic  folds,  from  five  to  twelve  in  number,  which  project  into  the  duct 
in  regular  succession,  and  are  directed  obliquely  round  the  tube,  presenting 
much  the  appearance  of  a  continuous  spiral  valve.  They  exist  only  in  the 
human  subject.  When  the  duct  has  been  distended,  the  interspaces  between 
the  folds  are  dilated,  so  as  to  give  to  its  exterior  a  sacculated  appearance. 

The  ductus  communis  choledochus,  the  largest  of  the  three,  is  the  common  ex- 
cretory duct  of  the  liver  and  gall-bladder.  It  is  about  three  inches  in  length, 
of  the  diameter  of  a  goose-quill,  and  formed  by  the  junction  of  the  cystic  and 
hepatic  ducts.      It  descends  along  the  right  border  of  the  lesser  omentum, 

Fig.  412. — The  Parts  in  the  Gastro-hepatic  Omentum,  its  Anterior  Layer  being  removed. 


behind  the  first  portion  of  the  duodenum,  in  front  of  the  vena  portsB,  and  to 
the  right  of  the  hepatic  artery;  it  then  passes  between  the  pancreas  and  de- 
scending portion  of  the  duodenum,  and,  running  for  a  short  distance  along  the 
right  side  of  the  pancreatic  duct,  near  its  termination,  passes  with  it  obliquely 
between  the  mucous  and  muscular  coats,  the  two  opening  by  a  common  orifice 
upon  the  summit  of  a  papilla,  situated  at  the  inner  side  of  the  descending  por- 
tion of  the  duodenum,  a  little  below  its  middle. 

Structure.  The  coats  of  the  biliary  ducts  are,  an  external  or  fibrous,  and  an 
internal  or  mucous.  The  fibrous  coat  is  composed  of  a  strong  areolar  fibrous 
tissue.  Tlie  mucous  coat  is  continuous  with  the  lining  membrane  of  the  hepatic 
ducts  and  gall-bladder,  and  also  with  that  of  the  duodenum.  It  is  provided 
with  numerous  glands,  the  orifices  of  which  are  scattered  irregularly  in  the 
larger  ducts,  but  in  the  smaller  hepatic  ducts  are  disposed  in  two  longitudinal 
rows,  one  on  each  side  of  the  vessel.  These  glands  are  of  two  kinds.  Some 
are  ramified  tubes,  which  occasionally  anastomose,  and  from  the  sides  of  which 


PANCREAS.  749 

saccular  dilatations  are  given  off;  others  are  small  clustered  cellular  glands, 
which  open  either  separately  into  the  hepatic  duct,  or  into  the  ducts  of  the 
tubular  glands. 

The  Pancreas. 

Dissection.  The  pancreas  may  be  exposed  for  dissection  in  three  different  ways :  1.  By  rais- 
ing the  liver,  drawing  down  the  stomach,  and  tearing  through  the  gastro-hepatic  omentum. 
2.  By  raising  the  stomach,  the  arch  of  the  colon,  and  great  omentum,  and  then  dividing  the 
inferior  layer  of  the  transverse  meso-colon.  3.  By  dividing  the  two  layers  of  peritoneum,  which 
descend  from  the  great  curvature  of  the  stomach  to  form  the  great  omentum;  turning  the  sto- 
mach upwards,  and  then  cutting  through  the  ascending  layer  of  the  transverse  meso-colon. 

The  Pancreas  (rtai/-xpsaj,  all  flesh)  is  a  conglomerate  gland,  analogous  in  its 
structure  to  the  salivary  glands.  In  shape  it  is  transversely  oblong,  flattened 
from  before  backwards,  and  bears  some  resemblance  to  a  dog's  tongue,  its  right 
extremity  being  broad,  and  presenting  a  sort  of  angular  bend  from  above  down- 
wards, called  the  head,  whilst  its  left  extremity  gradually  tapers  to  form  the 
tail,  the  intermediate  portion  being  called  the  body.  It  is  situated  transversely 
across  the  posterior  wall  of  the  abdomen,  at  the  back  of  the  epigastric  and  both 
hypochondriac  regions.  Its  length  varies  from  six  to  eight  inches,  its  breadth 
is  an  inch  and  a  half,  and  its  thickness  from  half  an  inch  to  an  inch,  being 
greater  at  its  right  extremity  and  along  its  upper  border.  Its  weight  varies 
from  two  to  three  and  a  half  ounces,  but  it  may  reach  six  ounces. 

The  right  extremity  or  head  of  the  pancreas  (Fig.  413)  is  curved  upon  itself 
from  above  downwards,  and  is  embraced  by  the  concavity  of  the  duodenum. 

Fig.  413. — The  Pancreas  and  its  Relations. 


The  common  bile-duct  descends  behind,  between  the  duodenum  and  pancreas; 
and  the  pancreatico -duodenal  artery  descends  in  front  between  the  same  parts. 
On  the  posterior  aspect  of  the  pancreas  is  a  lobular  fold  of  the  gland,  which 
passes  transversely  to  the  left,  behind  the  superior  mesenteric  vessels,  forming 
the  back  part  of  the  canal  in  which  they  are  contained.  It  is  sometimes  de- 
tached from  the  rest  of  the  gland,  and  is  called  the  ksset'  pancreas. 

The  lesser  end  or  tail  of  the  pancreas  is  narrow  ;  it  extends  to  the  left  as  far  as 
the  spleen,  and  is  placed  over  the  left  kidney  and  suprarenal  capsule. 


750  ORGANS    OF    DIGESTION. 

The  body  of  the  pancreas  is  convex  in  front,  and  covered  by  the  ascending 
layer  of  the  transverse  meso-colon  and  the  posterior  surface  of  the  stomach. 

The  posterior  surface  is  concave,  and  has  the  following  structures  interposed 
between  it  and  the  first  lumbar  vertebra :  the  superior  mesenteric  artery  and 
vein,  the  commencement  of  the  vena  portae,  the  vena  cava,  the  aorta,  the  left 
kidney,  the  suprarenal  capsule,  and  the  corresponding  renal  vessels. 

The  upper  border  is  tbick,  and  has  resting  upon  it,  near  its  centre,  the  coeliac 
axis ;  the  splenic  artery  and  vein  are  lodged  in  a  deep  groove  or  canal  in  this 
border ;  and  to  the  right,  the  first  part  of  the  duodenum  and  the  hepatic  artery 
are  in  relation  with  it. 

The  lower  border^  thinner  tban  the  upper,  is  separated  from  the  transverse 
portion  of  the  duodenum  by  the  superior  mesenteric  artery  and  vein  ;  to  the  left 
of  these  the  inferior  mesenteric  vein  ascends  behind  the  pancreas  to  join  the 
splenic  vein. 

T\iQ  pancreatic  duct,  called  the  canal  of  Wirsung  from  its  discoverer,  extends 
transversely  from  right  to  left  through  the  substance  of  the  pancreas,  nearer  to 
its  lower  than  .its  upper  border,  and  lying  nearer  its  anterior  than  its  posterior 
surface.  In  order  to  expose  it,  the  superficial  portion  of  the  gland  must  be  re- 
moved. Traced  backwards,  it  is  found  to  commence  by  an  orifice  common  to 
it  and  the  ductus  communis  choledochus,  upon  the  summit  of  an  elevated 
papilla,  situated  at  the  inner  side  of  the  descending  portion  of  the  duodenum,  a 
little  below  its  middle ;  from  this  papilla  it  passes  very  obliquely  through  the 
mucous  and  muscular  coats,  separates  itself  from  the  ductus  communis  chole- 
dochus, and,  ascending  slightly,  runs  from  right  to  left  through  the  middle  of 
the  gland,  giving  off  numerous  branches,  which  commence  in  its  lobules. 

Sometimes  the  pancreatic  duct  and  ductus  communis  choledochus  open  sepa- 
rately into  the  duodenum.  The  excretory  duct  of  the  lesser  pancreas  is  called 
the  ductus  pancreaticus  minor  ;  it  opens  into  the  main  duct  near  the  duodenum, 
and  sometimes  separately  into  that  intestine,  at  a  distance  of  an  inch  or  more 
from  the  termination  of  the  principal  duct. 

The  pancreatic  duct,  near  the  duodenum,  is  about  the  size  of  an  ordinary 
quill ;  its  walls  are  thin,  consisting  of  two  coats,  an  external  fibrous  and  an 
internal  mucous ;  the  latter  is  thin,  smooth,  .and  furnished,  near  its  termination, 
with  a  few  scattered  follicles. 

Sometimes  the  pancreatic  duct  Is  double,  up  to  its  point  of  entrance  into  the 
duodenum. 

In  structure,  the  pancreas  closely  resembles  the  salivary  glands;  but  it  is 
looser  and  softer  in  its  texture.  The  fluid  secreted  by  it  is  almost  identical 
with  saliva. 

Vessels  and  Nerves.  The  arteries  of  the  pancreas  are  derived  from  the  splenic, 
the  pancreatico-duodenal  branch  of  the  hepatic,  and  the  superior  mesenteric. 
Its  veins  open  into  the  splenic  and  superior  mesenteric  veins.  Its  lymphatics 
terminate  in  the  lumbar  glands.  Its  nerves  are  filaments  from  the  splenicf 
plexus. 

The  Spleen. 

The  Spleen  is  usually  classified,  together  with  the  thyroid,  thymus,  and  supra- 
renal capsules,  as  one  of  the  ductless,  or  blood-glands.  It  possesses  no  excre- 
tory duct.  It  is  of  an  oblong  flattened  form,  soft,  of  very  brittle  consistence, 
highly  vascular,  of  a  dark  bluish-red  color,  and  situated  in  the  left  hypochon- 
driac region,  embracing  the  cardiac  end  of  the  stomach.  It  is  invested  by 
peritoneum,  and  connected  with  the  stomach  by  the  gastro-splenic  omentum. 

Relations.  The  external,  surf  ace  \b  convex,  smooth,  and  in  relations  with  the 
under  surface  of  the  Diaphragm,  which  separates  it  from  the  ninth,  tenth,  and 
eleventh  ribs  of  the  left  side.  The  internal  surface  is  slightly  concave,  and 
divided  by  a  vertical  fissure,  the  hilum,  into  an  anterior  or  larger,  and  a  posterior 
or  smaller  portion.     The  hilum  is  pierced  by  several  large  irregular  apertures, 


SPLEEX.  751 

for  the  entrance  and  exit  of  vessels  and  nerves.  At  the  margins  of  the  hilum, 
the  two  layers  of  peritoneum  are  reflected  from  the  surface  of  the  spleen  on  to 
the  cardiac  end  of  the  stomach,  forming  the  gastro-splenic  omentum,  which  con- 
tains between  its  layers  the  splenic  vessels  and  nerves,  and  the  vasa  brevia. 
The  internal  surface  is  in  relation,  in  front,  with  the  great  end  of  the  stomach ; 
below,  with  the  tail  of  the  pancreas ;  and  behind,  with  the  left  crus  of  the  Dia- 
phragm and  corresponding  suprarenal  capsule.  The  upper  end,  thick  and 
rounded,  is  in  relation  with  the  Diaphragm,  to  which  it  is  connected  by  a  fold 
of  peritoneum,  the  suspensory  ligament.  The  hiuer  end  is  pointed  ;  it  is  in  re- 
lation with  the  left  extremity  of  the  transverse  arch  of  the  colon.  The  anterior 
margin  is  free,  rounded,  and  often  notched,  especially  below.  The  posterior 
margin  is  rounded,  and  lies  in  relation  with  the  left  kidney,  to  which  it  is  con- 
nected by  loose  areolar  tissue. 

The  spleen  is  held  in  its  position  by  two  folds  of  peritoneum ;  one,  the  gastro- 
splenic  omentum,  connects  it  with  the  stomach  ;  and  the  other,  the  suspensory  liga- 
ment, with  the  under  surface  of  the  Diaphragm. 

Fig.  414. — Transverse  Section  of  the  Spleen,  showing  the  Trabecular  Tissue  and  the  Splenic 

Vein  and  its  Branches. 


The  size  and  weight  of  the  spleen  are  liable  to  very  extreme  variations  at 
different  periods  of  life,  in  different  individuals,  and  in  the  same  individual 
under  different  conditions.  In  the  adult,  in  whom  it  attains  its  greatest  size,  it 
is  usually  about  five  inches  in  length,  three  or  four  inches  in  breadth,  and  an 
inch  or  an  inch  and  a  half  in  thickness,  and  weighs  about  seven  ounces.  At 
birth,  its  weight,  in  proportion  to  the  entire  body,  is  almost  equal  to  what  is 
observed  in  the  adult,  being  as  1  to  350 ;  whilst  in  the  adult  it  varies  from  1  to 
320  and  400.  In  old  age,  the  organ  not  only  decreases  in  weight,  but  decreases 
considerably  in  proportion  to  the  entire  body,  being  as  1  to  700.  The  size  of 
the  spleen  is  increased  during  and  after  digestion,  and  varies  considerabl}'-, 
according  to  the  state  of  nutrition  of  the  body,  being  large  in  highly-fed,  and 
small  in  starved  animals.  In  intermittent  and  other  fevers,  it  becomes  much 
enlarged,  weighing  occasionally  from  18  to  20  pounds. 

Structure.  The  spleen  is  invested  by  two  coats ;  an  external  serous,  and  an 
internal  fibrous  elastic  coat. 

The  external,  or  serom  coat,  is  derived  from  the  peritoneum ;  it  is  thin,  smooth, 
and  in  the  human  subject  intimately  adherent  to  the  fibrous  elastic  coat.  It 
invests  almost  the  entire  organ ;  being  reflected  from  it,  at  the  hilum,  on  to  the 


752 


ORGANS    OF    DIGESTION. 


great  end  of  the  stomach,  and  at  the  upper  end  of  the  organ  on  to  the  Dia- 
phragm. 

The  fibrous  elastic  coat  forms  the  framework  of  the  spleen.  It  invests  the 
exterior  of  the  organ,  and  the  hilum  is  reflected  inwards  upon  the  vessels  in 
the  form  of  vaginae  or  sheaths.  From  these  sheaths,  as  well  as  from  the  inner 
surface  of  the  fibro-elastic  coat,  numerous  small  fibrous  bands,  traheculse  (Fig. 
414),  are  given  off  in  all  directions ;  these  uniting,  constitute  the  areolar  frame- 
work of  the  spleen.  The  proper  coat,  the  sheaths  of  the  vessels,  and  the  trabe- 
culae,  consist  of  a  dense  mesh  of  white  and  yellow  elastic  fibrous  tissues,  the 
latter  considerably  predominating.  It  is  owing  to  the  presence  of  this  tissue, 
that  the  spleen  possesses  a  considerable  amount  of  elasticity,  to  allow  of  the 
very  considerable  variations  in  size  that  it  presents  under  certain  circumstances. 
In  some  of  the  mammalia,  in  addition  to  the  usual  constituents  of  this  tunic, 
there  are  found  numerous  pale,  flattened,  spindle-shaped,  nucleated  fibres,  like 
unstriped  muscular  fibres.  It  is  probably  owing  to  this  structure  that  the  spleen 
possesses,  when  acted  upon  by  the  galvanic  current,  faint  traces  of  contractility. 

The  proper  substance  of  the  spleen  occupies  the  interspaces  of  the  areolar 
framework  of  the  organ ;  it  is  a  soft,  pulpy  mass,  of  a  dark  reddish-brown  color, 
consisting  of  colorless  and  colored  elements. 

The  colorless  elements  consist  of  granular  matter*;  nuclei,  about  the  size  of  the 
red  blood-disks,  homogeneous  or  granular  in  structure ;  and  nucleated  vesicles 

Fig.  415. — The  Malpighian  Corpuscles,  and  their  Relation  with  the  Splenic  Artery  and  its 

Branches. 


in  small  numbers.  These  elements  form,  probably,  one-half  or  two-thirds  of 
^the  whole  substance  of  the  pulp,  filling  up  the  interspaces  formed  by  the  par- 
titions of  the  spleen,  and  lying  in  close  contact  with  the  walls  of  the  capillary 
vessels,  so  as  to  be  readily  acted  upon  by  the  nutrient  fluid  which  permeates 
them.  Thus  in  well-nourished  animals,  they  form  a  large  part  of  the  entire  bulk 
of  the  spleen,  whilst  they  diminish  in  number,  and  occasionally  are  wanting  in  W 
starved  animals.  The  application  of  chemical  tests  shows  that  they  are  essen-™ 
tially  a  proteine  compound. 

The  colored  elements  of  the  pulp  consist  of  red  blood-globules  and  of  colored 
corpuscles,  either  free,  or  included  iu  cells.     Sometimes,  unchanged  blood-disks 


STRUCTURE    OF    THE    SPLEEX.  753 

are  seen  included  in  a  cell ;  but  more  frequently  the  included  blood-disks  are 
altered  both  in  form  and  color.  Besides  these,  numerous  deep-red,  or  reddish- 
yellow,  or  black  corpuscles  and  crystals,  either  single  or  aggregated  in  masses, 
are  seen  diffused  throughout  the  pulp-substance:  these,  in  chemical  composi- 
tion, are  closely  allied  to  the  hsematin  of  the  blood. 

Malpighian  Corpuscles.  On  examining  the  cut  surface  of  a  healthy  spleen,  a 
number  of  small  semi-opaque  bodies,  of  gelatinous  consistence,  are  seen  dis- 
seminated throughout  its  substance;  these  are  the  splenic  or  Malpighian  cor- 
puscles (Fig.  415).  They  may  be  seen  at  al'l  periods  of  life;  but  they  are  more 
distinct  in  early  than  in  adult  life  or  old  age;  and  they  are  much  smaller  in 
man  than  in  most  mammalia.  They  are  of  a  spherical  or  ovoid  form,  vary  con- 
siderably in  size  and  number,  and  are  of  a  semi-opaque  whitish  color.  They  are 
appended  to  the  sheaths  of  the  smaller  arteries  and  their  branches,  presenting  a 
resemblance  to  the  buds  of  the  moss  rose.  Each  consists  of  a  membranous  cap- 
sule, composed  of  fine  pale  fibres,  which  interlace  in  all  directions.  In  man, 
the  capsule  is  homogeneous  in  structure,  and  formed  by  a  prolongation  from 
the  sheaths  of  the  small  arteries  to  which  the  corpuscles  are  attached.  The 
bloodvessels  ramifying  on  the  surface  of  the  corpuscles,  consist  of  the  larger 
ramifications  of  the  arteries  to  which  the  sacculus  is  connected;  and  also  of  a 
delicate  capillary  plexus,  similar  to  that  surrounding  the  vesicles  of  other 
glands.  These  vesicles  have  also  a  close  relation  with  the  veins  (Fig.  416). 
The  latter  vessels,  which  are  of  considerable  size  even  at  their  origin,  com- 
mence on  the  surface  of  each  vesicle  throughout  the  whole  of  its  circumference, 
forming  a  dense  mesh  of  veins,  in  which  the  Malpighian  corpuscle  is  inclosed. 

Fig.  416. — One  of  the  Splenic  Corpuscles,  showing  its  Relations  with  the  Bloodvessels. 


It  is  probable  that,  from  the  blood  contained  in  the  capillary  network,  the 
material  is  separated  which  is  occasionally  stored  up  in  the  cavity  of  the  cor- 
puscle ;  the  veins  being  so  placed  as  to  carry  off,  under  certain  conditions,  those 
contents  to  be  discharged  again  into  the  circulation.  Each  capsule  contains  a 
soft,  white,  semi-fluid  substance,  consisting  of  granular  matter,  nuclei  similar  to 
those  found  in  the  pulp,  and  a  few  nucleated  cells,  the  composition  of  which  is 
apparently  albuminous.  These  bodies  are  very  large  after  digestion  is  com- 
48 


754 


.ORGANS    OF    DIGESTION. 


plcted,  in  well-fed  animals,  and  especially  in  those  fed  upon  albuminous  diet. 
In  starved  animals,  they  disappear  altogether. 

The  splenic  artery  is  remarkable  for  its  large  size,  in  proportion  to  the  size 
of  the  organ;  and  also  for  its  tortuous  course.  It  divides  into  from  four  to  six 
branches,  which  enter  the  hilum  of  the  organ,  and  ramify  throughout  its  sub- 
stance (Fig.  417),  receiving  sheaths  from  an  involution  of  the  external  fibrous 
tunic,  the  same  sheaths  also  investing  the  nerves  and  veins.  Each  branch  runs 
in  the  transverse  axis  of  the  organ,  from  within  outwards,  diminishing  in  size 
during  its  transit,  and  giving  off,  in  its  passage,  smaller  branches,  some  of  which 
pass  to  the  anterior,  others  to  the  posterior  part;  these  ultimately  terminate  in 
the  proper  substance  of  the  spleen,  in  small  tufts  or  pencils  of  capillary  vessels, 
which  lie  in  direct  contact  with  the  pulp.  Each  of  the  larger  branches  of  the 
arteries  supplies  chiefly  that  region  of  the  organ  in  which  the  branch  ramifies, 
having  no  anastomosis  with  the  majority  of  the  other  branches. 

Fig.  417. — Transverse  Section  of  the  Human  Spleen,  showing  the  Distribution  of  the  Splenic 
»  Artery  and  its  Branches. 


The  capillaries^  supported  by  the  minute  trabeculse,  traverse  the  pulp  in  all 
directions,  and  terminate  either  directly  in  the  veins,  or  open  into  lacunar] 
spaces,  from  which  the  veins  originate. 

The  veins  are  of  large  size,  as  compared  with  the  size  of  the  organ;  and  their  i 
distribution  is  limited,  like  that  of  the  arteries,  to  the  supply  of  a  particular ' 
j)art  of  the  gland;  they  are  much  larger  and  more  numerous  than  the  arteries.' 
They  originate,  1st,  as  continuations  of  the  capillaries  of  the  arteries;  2d,  by 
intercellular  spaces  communicating  with  each  other;    3d,  by  distinct  cajcal 
pouches.     By  their  junction  they  form  from  four  to  six  branches,  which  emerge 
from  the  hilum;  and  these  uniting,  form  the  splenic  vein,  the  largest  branch 
of  the  vena  portae. 

The  lymphatics  form  a  deep  and  superficial  set;  they  pass  through  the  lym- 
phatic glands  at  the  hilum,  and  terminate  in  the  thoracic  duct. 

The  nerves  are  derived  from  branches  of  the  right  and  left  semilunar  ganglia, 
and  right  pneumogastric  nerve. 


The  Thorax. 

The  Thorax  is  a  conical  framework,  formed  partly  of  bones,  and  partly  of 
tlie  soft  tissues  by  which  they  are  connected  together.  It  is  supported  and  its 
back  part  is  formed  by  the  middle,  or  dorsal,  region  of  the  spine.  It  is  narrow 
above,  broad  below,  flattened  before  and  behind,  and  somewhat  cordiform  on  a 
transverse  section. 

Boundaries.  The  thorax  is  bounded  in  front  by  the  sternum,  the  six  upper 
costal  cartilages,  the  ribs,  and  intercostal  muscles ;  at  the  sides,  by  the  ribs  and 
intercostal  muscles ;  and  behind,  by  the  same  structures  and  the  dorsal  portion 
of  the  vertebral  column. 

The  superior  opening  of  the  thorax  is  bounded  on  each  side  by  the  first  rib ; 
in  front,  by  the  upper  border  of  the  sternum ;  and  behind,  by  the  first  dorsal 
vertebra.  It  is  broader  from  side  to  side  than  from  before  backwards ;  and  its 
direction  is  backwards  and  upwards. 

The  lower  opening,  or  hase,  is  bounded  in  front  by  the  ensiform  cartilage ; 
behind,  by  the  last  dorsal  vertebra;  and  on  each  side  by  the  last  rib,  the 
Diaphragm  filling  in  the  intervening  space.  Its  direction  is  obliquely  down- 
wards and  backwards ;  so  that  the  cavity  of  the  thorax  is  much  deeper  on  the 
posterior  than  on  the  anterior  wall.  It  is  wider  transversely  than  from  before 
backwards.  Its  outer  surface  is  convex ;  but  it  is  more  flattened  at  the  centre 
than  at  the  sides.  Its  floor  is  higher  on  the  right  than  on  the  left  side,  corre- 
sponding in  the  dead  body  to  the  upper  border  of  the  fifth  costal  cartilage  on 
the  right  side ;  and  to  the  corresponding  part  of  the  sixth  cartilage  on  the  left 
side. 

The  parts  which  pass  through  the  upper  opening  of  the  thorax  are,  from  before 
backwards,  the  Sterno-hyoid  and  Sterno-thyroid  muscles,  the  remains  of  the 
thymus  gland,  the  trachea,  oesophagus,  thoracic  duct,  and  the  Longus  Colli 
muscles  on  each  side ;  on  the  sides,  the  arteria  innominata,  the  left  carotid  and 
left  subclavian  arteries,  the  internal  mammary  and  superior  intercostal  arteries, 
the  right  and  left  venae  innominate,  and  the  inferior  thyroid  veins,  the  pneumo- 
gastric,  sympathetic,  phrenic,  and  cardiac  nerves,  the  anterior  branch  of  the.first 
dorsal  nerve,  and  the  recurrent  laryngeal  nerve  of  the  left  side.  The  apex  of 
each  lung,  covered  by  the  pleura,  also  projects  through  this  aperture,  a  little 
above  the  margin  of  the  first  rib. 

The  viscera  contained  in  the  thorax  are,  the  heart,  inclosed  in  its  membranous 
bag,  the  pericardium ;  and  the  lungs,  invested  by  the  pleurge. 

The  Pekicardium. 

The  Pericardium  is  a  conical  membranous  sac,  in  which  the  heart  and  the 
commencement  of  the  great  vessels  are  contained.  It  is  placed  behind  the 
sternum,  and  the  cartilages  of  the  third,  fourth,  fifth,  sixth,  and  seventh  ribs  of 
the  left  side,  in  the  interval  between  the  pleurae. 

Its  apex  is  directed  upwards,  and  surrounds  the  great  vessels  about  two  inches 
above  their  origin  from  the  base  of  the  heart.  Its  base  is  attached  to  the  central 
tendon  of  the  Diaphragm,  extending  a  little  farther  to  the  left  than  the  right  side. 
Tn  front,  it  is  separated  from  the  sternum  by  the  remains  of  the  thymus  gland 
above,  and  a  little  loose  areolar  tissue  below ;  and  is  covered  by  the  margins  of 
the  lungs,  especially  the  left.  Behind,  it  rests  upon  the  bronchi,  the  a3sophagus, 
and  the  descending  aorta.  Laterally,  it  i"s  covered  by  the  pleurae ;  the  phrenic 
vessels  and  nerve  descending  between  the  two  membranes  on  either  side. 

755 


756 


THE    THORAX. 


The  pericardium  is  a  fibro-serous  membrane,  and  consists,  tlierefore,  of  two 
layers ;  an  external  fibrous,  and  an  internal  serous. 

ThQ  fibrous  layer  is  a  strong,  dense  membrane.  Above,  it  surrounds  the  great 
vessels  arising  from  the  base  of  the  heart,  on  which  it  is  continued  in  the  form 
of  tubular  prolongations,  Avhich  are  gradually  lost  upon  their  external  coats ; 
the  strongest  being  that  which  incloses  the  aorta.  The  pericardium  may  be 
traced,  over  these  vessels,  to  become  continuous  with  the  deep  layer  of  the 
cervical  fascia.  Below,  it  is  attached  to  the  central  tendon  of  the  Diaphragm ; 
and,  on  the  left  side,  to  its  muscular  fibres. 

The  vessels  receiving  fibrous  prolongations  from  this  membrane  are  the  aorta, 
the  superior  vena  cava,  and  the  pulmonary  arteries  and  veins.     As  the  inferior 

Fig,  418. — Front  View  of*the  Thorax.    The  Ribs  and  Sternum  arc  represented  in  Relation  to 
the  Lungs,  Heart,  and  other  Internal  Organs, 


vena  cava  enters  the  pericardium,  through  the  central  tendon  of  the  Diaphragm, 
it  receives  no  covering  from  the  fibrous  layer. 

The  serous  layer  invests  the  heart,  and  is  then  reflected  on  the  inner  surface  of 
the  pericardium.  It  consists,  therefore,  of  a  visceral  and  a  parietal  portion 
The  former  invests  the  surface  of  the  heart,  and  the  commencement  of  the  great 
vessels,  to  the  extent  of  two  inches  from  their  origin;  from  these,  it  is  reflected 
upon  the  inner  surface  of  the  fibrous  layer,  lining,  below,  the  upper  surface  of 
the  central  tendon  of  tlie  Diaphragm.  The  serous  membrane  incloses  the  aortj 
and  pulmonary  artery  in  a  single  tube ;  but  it  only  partially  covers  the  superio 


1. 

I 


HEART.  75Y 

and  inferior  vena  cava  and  the  four  pulmonary  veins.  Its  inner  surface  is 
smooth  and  glistening,  and  secretes  a  thin  fluid,  which  serves  to  facilitate  the 
movements  of  the  heart. 

The  arteries  of  the  pericardium  are  derived  from  the  internal  mammary,  the 
bronchial,  the  oesophageal,  and  the  phrenic. 

The  Heaet. 

The  Heart  is  a  hollow  muscular  organ  of  a  conical  form,  placed  between  the 
lungs,  and  inclosed  in  the  cavity  of  the  pericardium. 

Position.  The  heart  is  placed  obliquely  in  the  chest :  the  broad  attached  end, 
or  base,  is  directed  upwards  and  backwards  to  the  right,  and  corresponds  to  the 
interval  between  the  fifth  and  eighth  dorsal  vertebrae :  the  apex  is  directed  for- 
wards and  to  the  left,  and  corresponds  to  the  interspace  between  the  cartilage  of 
the  fifth  and  sixth  ribs,  one  inch  to  the  inner  side,  and  two  inches  below  the 
left  nipple.  The  heart  is  placed  behind  the  lower  two-thirds  of  the  sternum, 
and  projects  further  into  the  left  than  into  the  right  cavity  of  the  chest,  extend- 
ing from  the  median  line  about  three  inches  in  the  former  direction,  and  only 
one  and  a  half  in  the  latter.  Its  upper  border  would  correspond  to  a  line  drawn 
across  the  sternum,  on  a  level  with  the  upper  border  of  ihe  third  costal  carti- 
lages ;  and  its  lower  border,  to  a  line  drawn  across  the  lower  end  of  the  gladiolus, 
from  the  costo-xiphoid  articulation  of  the  right  side,  to  4;he  point  above  men- 
tioned, as  the  situation  of  the  apex.  Its  anterior  surface  is  rounded  and  convex,, 
directed  upwards  and  forwards,  and  formed  chiefly  by  the  right  ventricle  and 
part  of  the  left.  Its  posterior  surface  is  flattened,  and  rests  upon  the  Diaphragm, 
and  is  formed  chiefly  by  the  left  ventricle.  The  right  border  is  long,  thin,  and 
sharp ;  the  left  border  short,  but  thick  and  round. 

Size.  The  heart,  in  the  adult,  measures  about  five  inches  in  length,  three 
inches  and  a  half  in  breadth  in  its  broadest  part,  and  two  inches  and  a  half  in 
thickness.  The  prevalent  weight,  in  the  male,  varies  from  ten  to  twelve  ounces  ; 
in  the  female,  from  eight  to  ten ;  its  proportion  to  the  body  being  as  1  to  169 
in  males;  1  to  149  in  females.  The  heart  continues  increasing  in  weight,  and 
also  in  length,  breadth  and  thickness,  up  to  an  advanced  period  of  life ;  this 
increase  is  more  marked  in  men  than  in  women. 

Component  parts.  The  heart  is  subdivided  by  a  longitudinal  muscular  septum 
into  two  lateral  halves,  which  are  named  respectively,  from  their  position,  right 
and  left ;  and  a  transverse  constriction  divides  each  half  of  the  organ  into  two 
cavities,  the  upper  cavity  on  each  side  being  called  the  auricle,  the  lower  the 
ventricle.  The  right  is  the  venous  side  of  the  heart,  receiving  into  its  auricle 
the  dark  venous  blood  from  the  entire  body,  by  the  superior  and  inferior  vena 
cava,  and  coronary  sinus.  From  the  auricle,  the  blood  passes  into  the  right 
ventricle ;  and  from  the  right  ventricle,  through  the  pulmonary  artery  into  the 
lungs.  The  blood,  arterialized  by  its  passage  through  the  lungs,  is  returned  to 
the  left  side  of  the  heart  by  the  pulmonary  veins,  which  open  into  the  left 
auricle ;  from  the  left  auricle  the  blood  passes  into  the  left  ventricle,  and  from 
the  left  ventricle  is  distributed,  by  the  aorta  and  its  subdivisions,  through  the 
entire  body.     This  constitutes  the  circulation  of  the  blood  in  the  adult. 

This  division  of  the  heart  into  four  cavities  is  indicated  by  grooves  upon  its 
surface.  The  great  transverse  groove  separating  the  auricles  from  the  ventri- 
cles, is  called  the  auriculo-ventricular  groove.  It  is  deficient,  in  front,  from 
being  crossed  by  the  root  of  the  pulmonary  artery,  and  contains  the  trunk  of 
the  nutrient  vessels  of  the  heart.  The  auricular  portion  occupies  the  base  of 
the  heart,  and  is  subdivided  into  two  cavities  by  a  median  septum.  The  two 
ventricles  are  also  separated  into  a  right  and  left,  by  two  longitudinal  furrows, 
which  are  situated  one  on  the  anterior,  the  other  on  the  posterior  surface :  these 
extend  from  the  base  to  the  apex  of  the  organ :  the  former  being  situated  nearer 
to  the  left  border  of  the  heart,  and  the  latter  to  the  right.    It  follows,  therefore, 


758 


THE    THORAX. 


that  the  right  ventricle  forms  the  greater  portion  of  the  anterior  surface  of  the 
heart,  and  the  left  ventricle  more  of  its  posterior  surface. 

Each  of  these  cavities  should  now  be  separately  examined. 

The  Right  Atiricle  is  a  little  larger  than  the  left,  its  walls  somewhat  thinner, 
measuring  about  one  line ;  and  its  cavity  is  capable  of  containing  about  two 
ounces.  It  consists  of  two  parts,  a  principal  cavity,  or  sinus,  and  an  appendix 
auriculae. 

The  sinus  is  the  large  quadrangular  cavity,  placed  between  the  two  vence  cavae ; 
its  walls  are  extremely  thin :  it  is  connected  below  with  the  right  ventricle,  and 
internally  with  the  left  auricle,  being  free  in  the  rest  of  its  extent. 


Fig.  419. — The  Right  Auricle  and  Ventricle  laid  open,  the  Anterior  Walls  of  both  being  removed. 


Might  JbM.TUuU-'VtmtrUulaj'  tfnuiu 


The  appendix  auriculse,  so  called  from  its  fancied  resemblance  to  a  dog's  ear, 
is  a  small  conical  muscular  pouch,  the  margins  of  which  present  a  dentated  edge. 
It  projects  from  the  sinus  forwards  and  to  the  left  side,  overlapping  the  root  of 
the  pulmonary  artery. 

To  examine  the  interior  of  the  auricle,  a  transverse  incision  should  be  made  along  its  ventricular 
margin,  from  its  right  border  to  the  appendix  ;  and,  from  the  middle  of  this,  a  second  incision 
should  be  carried  upwards,  along  the  inner  side  of  the  two  venai  cavae. 

The  following  parts  present  themselves  for  examination : — 


Openings. 


Superior  cava. 
Inferior  cava. 

Coronary  sinus.  Valves. 

Foramina  Thebesii. 
Auriculo-ventricular. 
Relics  of  fcetal  j  Annulus  ovalis. 
structure.       (  Fossa  ovalis. 
Musculi  pectinati. 


(  Eustachian. 
I  Coronary. 


HEART— RIGHT    AURICLE.  759 

Openings.  The  superior  vena  cava  returns  the  blood  from  the  upper  half  of 
the  body,  and  opens  into  the  upper  and  front  part  of  the  auricle,  the  direction 
of  its  orifice  being  downwards  and  forwards. 

The  inferior  vena  cava,  larger  than  the  superior,  returns  the  blood  from  the 
lower  half  of  the  body,  and  opens  into  the  lowest  part  of  the  auricle,  near  the 
septum,  the  direction  of  its  orifice  being  upwards  and  inwards.  The  direction 
of  a  current  of  blood  through  the  superior  vena  cava  would  consequently  be 
towards  the  auriculo-ventricular  orifice ;  whilst  the  direction  of  the  blood 
through  the  inferior  cava  would  be  towards  the  auricular  septum.  This  is  the 
normal  direction  of  the  two  currents  in  foetal  life. 

The  tuherculum  Loiveri  is  a  small  projection  on  the  right  wall  of  the  auricle, 
between  the  two  cavae.  This  is  most  distinct  in  the  hearts  of  quadrupeds ;  in 
man,  it  is  scarcely  visible.  It  was  supposed  by  Lower  to  direct  the  blood  fron* 
the  superior  cava  towards  the  auriculo-ventricular  opening. 

The  coronary  sinus  opens  into  the  auricle,  between  the  inferior  vena  cava  and 
the  auriculo-ventricular  opening.  It  returns  the  blood  from  the  substance  of 
the  heart,  and  is  protected  by  a  semicircular  fold  of  the  lining  membrane  of 
the  auricle,  the  coronary  valve.  The  sinus,  before  entering  the  auricle,  is  con- 
siderably dilated.  Its  wall  is  partly  muscular,  and, 'at  its  junction  with  the 
great  coronary  vein,  is  somewhat  constricted,  and  furnished  with  a  valve,  con- 
sisting of  two  unequal  segments. 

The /oramma  ThehesH  are  numerous  minute  apertures,  the  mouths  of  small 
veins  {vense  cordis  minimse),  which  open  on  various  parts  of  the  inner  surface  of 
the  auricle.  They  return  the  blood  directly  from  the  muscular  substance  of  the 
heart.  Some  of  these  foramina  are  minute  depressions  in  the  walls  of  the  heart, 
presenting  a  closed  extremity. 

The  auriculo-ventricular  opening  is  the  large  oval  aperture  of  communication 
between  the  auricle  and  ventricle,  to  be  presently  described. 

Valves.  The  Eustachian  valve  is  situated  between  the  anterior  margin  of  the 
inferior  cava  and  the  auriculo-ventricular  orifice.  It  is  semilunar  in  form,  its 
convex  margin  being  attached  to  the  wall  of  the  vein  ;  its  concave  margin, 
which  is  free,  terminating  in  two  cornua,  of  which  the  left  is  attached  to  the 
anterior  edge  of  the  annulus  ovalis  ;  the  right  being  lost  on  the  wall  of  the 
auricle.  The  valve  is  formed  by  a  duplicature  of  the  lining  membrane  of  the 
auricle,  containing  a  few  muscular  fibres. 

In  the/ce^w5,  this  valve  is  of  large 'size,  and  serves  to  direct  the  blood  from 
the  inferior  cava,  through  the  foramen  ovale,  into  the  left  auricle. 

In  the  adult,  it  is  occasionally  persistent,  and  may  assist  in  preventing  the 
reflux  of  blood  into  the  inferior  cava ;  more  commonly,  it  is  small,  and  its  free 
margin  presents  a  cribriform,  or  filamentous  appearance ;  occasionally,  it  is 
altogether  wanting. 

The  coronary  valve  is  a  semicircular  fold  of  the  lining  membrane  of  the  auri- 
cle, protecting  the  orifice  of  the  coronary  sinus.  It  prevents  the  regurgitation 
of  blood  into  the  sinus  during  the  contraction  of  the  auricle.  This  valve  is 
occasionally  double. 

The  fossa  ovalis  is  an  oval  depression,  corresponding  to  the  situation  of  the 
foramen  ovale  in  the  foetus.  It  is  situated  at  the  lower  part  of  the  septum  auri- 
cularum,  above  the  orifice  of  the  inferior  vena  cava. 

The  annulus  ovalis  is  the  prominent  oval  margin  of  the  foramen  ovale.  It  is 
most  distinct  above,  and  at  the  sides;  below  it  is  deficient.  A  small  slit-like 
valvular  opening  is  occasionally  found,  at  the  upper  margin  of  the  fossa  ovalis, 
which  leads  upwards,  beneath  the  annulus,  into  the  left  auricle,  and  is  the  re- 
mains of  the  aperture  between  the  two  auricles  in  the  foetus. 

The  musculi peciinati  are  small,  prominent  muscular  columns,  which  run  across 
the  inner  surface  of  the  appendix  auriculae  and  adjoining  portion  of  the  wall  of 
the  sinus.  They  have  received  the  name  pectinatUxom  the  fancied  resemblance 
they  bear  to  the  teeth  of  a  comb. 


760  THE    THORAX. 

The  Right  Ventricle  is  triangular  in  form,  and  extends  from  the  right-  auricle 
to  near  the  apex  of  the  heart.  Its  anterior  or  upper  surface  is  rounded  and 
convex,  and  forms  the  larger  part  of  the  front  of  the  heart.  Its  posterior  or 
under  surface  is  flattened,  rests  upon  the  Diaphragm,  and  forms  only  a  small 
part  of  the  back  of  the  heart.  Its  inner  wall  is  formed  by  the  partition  be- 
tween the  two  ventricles,  the  septum  ventricdorum,  the  surface  of  which  is 
convex,  and  bulges  into  the  cavity  of  the  right  ventricle.  Superiorly,  the  ven- 
tricle forms  a  conical  prolongation,  the  infundihuhim,  or  conus  arteriosus,  from 
which  the  pulmonary  artery  arises.  The  walls  of  the  right  ventricle  are  thinner 
than  those  of  the  left,  the  proportion  between  them  being  as  1  to  2  (Bizot). 
The  wall  is  thickest  at  the  base,  and  gradually  becomes  thinner  towards  the 
apex.  The  cavity,  which  equals  that  of  the  left  ventricle,  is  capable  of  -con- 
taining about  two  fluidounces. 

To  examine  the  interior,  an  incision  should  be  made  a  little  to  the  rip^ht  of  the  anterior  ven- 
tricular groove  from  the  pulmonary  artery  to  the  apex  of  the  heart,  and  should  be  carried  up 
from  thence  along  the  right  border  of  the  ventricle,  as  far  as  the  auriculo-ventricular  opening. 

The  following  parts  present  themselves  for  examination : — 

r\       •  '     j  Auriculo-ventricular. 

P        S      •     •    I  Opening  of  the  pulmonary  artery. 

Valves    .     .     .       Tricu^F^- 
(  berailunar. 

And  a  muscular  and  tendinous  apparatus  connected  with  the  tricuspid  valve : — 

Columnae  carneae.  Chordae  tendineas. 

The  auriculo-ventricular  orifice  is  the  large  oval  aperture  of  communication 
between  the  auricle  and  ventricle.  It  is  situated  at  the  base  of  the  ventricle, 
near  the  right  border  of  the  heart,  and  corresponds  to  the  centre  of  the  sternum 
between  the  third  costal  cartilages.  The  opening  is  about  an  inch  in  diameter,' 
oval  from  side  to  side,  surrounded  by  a  fibrous  ring,  covered  by  the  lining  mem- 
brane of  the  heart,  and  rather  larger  than  the  corresponding  aperture  on  the 
left  side,  being  sufficiently  large  to  admit  the  ends  of  three  fingers.  It  is 
guarded  by  the  tricuspid  valve. 

The  opening  of  the  ptdmonary  artery  is  circular  in  form,  and  situated  at  the 
summit  of  the  conus  arteriosus,  close  to  the  septum  ventriculorum.  It  is  placed 
on  the  left  side  of  the  auriculo-ventricular  opening,  upon  the  anterior  aspect  of 
the  heart,  and  corresponds  to  the  upper  border  of  the  third  costal  cartilage  of 
the  left  side,  close  to  the  sternum.  Its  orifice  is  guarded  by  the  pulmonary 
semilunar  valves. 

The  tricuspid  valve  consists  of  three  segments  of  a  triangular  or  trapezoidal 
shape,  formed  by  a  duplicature  of  the  lining  membrane  of  the  heart,  strength- 
ened by  a  layer  of  fibrous  tissue,  and  containing,  according  to  Kiirsehner  and 
Senac,  muscular  fibres.  These  segments  are  connected  by  their  bases  to  the 
auriculo-ventricular  orifice,  and  by  their  sides  with  one  another,  so  as  to  form 
a  continuous  annular  membrane,  which  is  attached  round  the  margin  of  the 
auriculo-ventricular  opening,  their  free  margins  and  ventricular  surfaces  afford- 
ing attachment  to  a  number  of  delicate  tendinous  cords,  the  chordse  tendinese. 
The  largest  and  most  movable  segment  is  placed  towards  the  left  side  of  the 
auriculo-ventricular  opening ;  interposed  between  that  opening  and  the  pulmo- 

'  In  the  Pathological  Transactions,  vol.  vi.  p.  119,  Dr.  Peacock  has  given  some  careful  re- 
searches upon  the  weight  and  dimensions  of  the  heart  in  iicaltli  and  disease,  lie  states  as  the 
result  of  his  investigations,  that,  in  the  healthy  adult  heart,  the  riglit  auriculo-ventricular  aper- 
ture has  a  mean  circumference  of  .")4.4  lines,  or  4J'J  inches  ;  the  left  auricnhi-ventricular  aperture 
a  mean  circumference  of  44.3  lines,  35  J  inches  ;  the  pulmonic  orifice  of  40  lines,  or  3^2  iuches ; 
and  the  aortic  orifice  of  35..')  lines,  or  'in*x  inches;  hut  the  dimensions  of  the  orifice  varied 
greatly  in  different  cases,  the  right  auriculo-ventricular  aperture  having  a  range  of  from  43  to  60 
lines,  and  the  others  in  the  same  proportion. 


HEART  — LEFT    AURICLE.  761 

nary  artery.  Another  segment  corresponds  to  the  front  of  the  ventricle ;  and 
a  third  to  its  posterior  wall.  The  central  part  of  each  segment  is  thick  and 
strong  ;  the  lateral  margins  are  thin  and  indented.  The  chordae  tendine^e  are 
connected  with  the  adjacent  margins  of  the  principal  segments  of  the  valve,  and 
are  further  attached  to  each  segment  in  the  following  manner,:  I.  Three  or  four 
reach  the  attached  margin  of  each  segment,  where  they  are  continuous  with 
the  auriculo-ventricular  tendinous  ring.  2.  Others,  four  to  six  in  number,  are 
attached  to  the  central  thickened  part  of  each  segment.  3.  The  most  numerous 
and  finest  are  connected  with  the  marginal  portion  of  each  segment. 

The  cohminse  carnese  are  the  rounded  muscular  columns  which  project  from 
nearly  the  whole  of  the  inner  surface  of  the  ventricle,  excepting  near  the  open- 
ing of  the  pulmonary  artery.  They  may  be  classified,  according  to  their  mode 
of  connection  with  the  ventricle,  into  three  sets.  The  first  set  merely  form 
prominent  ridges  on  the  inner  surface  of  the  ventricle,  being  attached  by  their 
entire  length  on  one  side,  as  well  as  by  their  extremities.  The  second  set  are 
attached  by  their  two  extremities,  but  are  free  in  the  rest  of  their  extent;  whilst 
the  third  set  {coliimnse  2^apiU(i?^es),  three  or  four  in  number,  are  attached  by  one 
extremity  to  the  wall  of  the  heart,  the  opposite  extremity  giving  attachment  to 
the  chordse  tendinese. 

The  semilunar  valves^  three  in  number,  guard  the  orifice  of  the  pulmonary 
artery.  They  consist  of  three  semicircular  folds,  formed  by  a  duplicature  of  the 
lining  membrane,  strengthened  by  fibrous  tissue.  They  are  attached,  by  their 
convex  margins,  to  the  wall  of  the  artery,  at  its  junction  with  the  ventricle,  the 
straight  border  being  free,  and  directed  upwards  in  the  course  of  the  vessel, 
against  the  sides  of  which  the  valve-flaps  are  pressed  during  the  passage  of  the 
blood  along  the  artery.  The  free  margin  of  each  is  somewhat  thicker  than  the 
rest  of  the  valve,  is  strengthened  by  a  bundle  of  tendinous  fibres;  and  presents, 
at  its  middle,  a  small  projecting  fibro-cartilaginous  nodule,  called  corpus  Arantii. 
From  this  nodule,  tendinous  fibres  radiate  through  the  valve  to  its  attached 
margin,  and  these  fibres  form  a  constituent  part  of  its  substance  throughout  its 
whole  extent,  excepting  two  narrow  lunated  portions,  placed  one  on  either  side 
of  the  nodule,  immediately  behind  the  free  margin ;  here,  the  valve  is  thin,  and 
formed  merely  by  the  lining  membrane.  During  the  passage  of  the  blood 
along  the  pulmonary  artery,  these  valves  are  pressed  against  the  sides  of  its 
cylinder,  and  the  course  of  the  blood  along  the  tube  is  uninterrupted;  but 
during  the  ventricular  diastole,  when  the  current  of  blood  along  the  pulmonary 
artery  is  checked,  and  partly  thrown  back  by  its  elastic  walls,  these  valves 
become  immediately  expanded,  and  effectually  close  the  entrance  of  the  tube. 
When  the  valves  are  closed,  the  lunated  portions  of  each  are  brought  into  con- 
tact with  one  another  by  their  opposed  surfaces,  the  three  fibro-cartilaginous 
nodules  filling  up  the  small  triangular  space  that  would  be  otherwise  left  by 
the  approximation  of  the  three  semilunar  folds. 

Between  the  semilunar  valves  and  the  commencement  of  the  pulmonary 
artery  are  three  pouches  or  dilatations,  one  behind  each  valve.  These  are  the 
pulmonary  sinuses  {sinuses  of  Valsalva).  Similar  sinuses  exist  between  the 
semilunar  valves  and  the  commencement  of  the  aorta;  they  are  larger  than  the 
pulmonary  sinuses.  The  blood,  in  its  regurgitation  towards  the  heart,  finds  its 
way  into  these  sinuses,  and  so  shuts  down  the  valve-flaps. 

The  Left  Auricle  is  rather  smaller  but  thicker  than  the  right,  measuring 
about  one  line  and  a  half;  it  consists,  like  the  right,  of  two  parts,  a  principal 
cavity  or  sinus,  and  an  appendix  auriculae. 

The  sinus  is  cuboidal  in  form,  and  concealed  in  front  by  the  pulmonary 
artery  and  aorta;  internally,  it  is  separated  from  the  right  auricle  by  the  septum 
auricularum;  behind,  it  receives  on  each  side  the  pulmonary  veins,  being  free 
in  the  rest  of  its  extent. 

The  appendix  auriculse  is  somewhat  constricted  at  its  junction  with  the  auri- 


762 


THE    THORAX. 


cle;  it  is  longer,  narrower,  and  more  curved  than  that  of  the  right  side,  and  its 
margins  more  deeply  indented,  presenting  a  kind  of  foliated  appearance.  Its 
direction  is  forwards  and  towards  the  right  side,  overlapping  the  root  of  the 
pulmonary  artery. 

In  order  to  examine  its  interior,  a  horizontal  incision  should  be  made  alonof  the  attached 
border  of  the  auricle  to  the  ventricle ;  and  from  the  middle -of  this,  a  second  incision  should  be 
carried  upwards. 

The  following  parts  then  present  themselves  for  examination : — 

The  openings  of  the  four  pulmonary  veins. 
Auriculo-ventricular  opening. 
Musculi  pectinati. 

7he  pulmonary  veins,  four  in  number,  open,  two  into  the  right,  and  two  into 
the  left  side  of  the  auricle.  The  two  left  veins  frequently  terminate  by  a  com- 
mon opening.     They  are  not  provided  with  valves. 

Fig.  420.— The  Left  Auricle  and  Ventricle  laid  open,  the  Anterior  Walls  of  both  being  removed. 


£rft  Aurteula-Ttftt)* 


patted  theAorlic  opening 


The  auriculo-ventricular  opening  is  the  large  oval  aperture  of  communication 
between  the  auricle  and  ventricle.  It  is  rather  smaller  than  the  corresponding 
opening  on  the  opposite  side. 

The  musculi  pectinati  are  fewer  in  number  and  smaller  than  on  the  right  side; 
they  are  confined  to  the  inner  surface  of  the  appendix. 

On  the  inner  surface  of  the  septum  auricular um  may  be  seen  a  lunated  impres- 
sion, bounded  below  by  a  crescentic  ridge,  the  concavity  of  which  is  turned 
upwards.     The  depression  is  just  above  the  fossa  ovalis  in  the  right  auricle. 

The  Left  Ventricle  is  longer  and  more  conical  in  shape  than  the  right  ven- 
tricle. It  forms  a  small  part  of  the  left  side  of  the  anterior  surface  of  the  heart, 
and  a  considerable  part  of  its  ])osterior  surface.  It  also  forms  the  apex  of  the 
heart  by  its  projection  beyond  the  right  ventricle.  Its  walls  are  much  thicker 
than  those  of  the  right  ventricle,  the  proportion  being  at  least  3  to  1.      They 


HEART— LEFT    YENTRICLE.  T63 

are  also  thickest  in  the  broadest  part  of  the  ventricle,  becoming  gradually  thin- 
ner towards  the  base,  and  also  towards  the  apex,  which  is  the  thinnest  part. 

Its  cavity  should  be  opened,  by  making  an  incision  through  its  anterior  wall  along  the  left 
side  of  the  ventricular  septum,  and  carrying  it  round  the  apex  and  along  its  posterior  surface  to 
the  auriculo-ventricular  opening. 

The  following  parts  present  themselves  for  examination : — 

Q       .         j  Auriculo-ventricular.  -yr  -i        j  Mitral. 

"  (  Aortic.  '  (  Semilunar. 

Chordae  tendinege.  Columnse  carneae. 

The  auriculo-ventricular  opening  is  placed  to  the  left  of  the  aortic  orifice, 
beneath  the  right  auriculo-ventricular  opening,  opposite  the  centre  of  the  ster- 
num. It  is  a  little  smaller  than  the  corresponding  aperture  of  the  opposite  side; 
and,  like  it,  is  broader  in  the  transverse  than  in  the  antero-posterior  diameter. 
It  is  surrounded  by  a  dense  fibrous  ring,  covered  by  the  lining  membrane  of 
the  heart,  and  guarded  by  the  mitral  valve. 

The  aortic  opening  is  a  small  circular  aperture,  in  front  and  to  the  right  side 
of  the  auriculo-ventricular,  from  which  it  is  separated  by  one  of  the  segments 
of  the  mitral  valve.  Its  orifice  is  guarded  by  the  semilunar  valves.  Its  position 
corresponds  to  the  sternum,  on  a  line  with  the  lower  border  of  the  third  left 
costal  cartilage. 

The  mitral  valve  is  attached  to  the  circumference  of  the  auriculo-ventricular 
orifice,  in  the  same  way  that  the  tricuspid  valve  is  on  the  opposite  side.  It  is 
formed  by  a  duplicature  of  the  lining  membrane,  strengthened  by  fibrous  tissue, 
and  contains  a  few  muscular  fibres.  It  is  larger  in  size,  thicker,  and  altogether 
stronger  than  the  tricuspid,  and  consists  of  two  segments  of  unequal  size.  The 
larger  segment  is  placed  in  front,  between  the  auriculo-ventricular  and  aortic 
orifices,  and  is  said  to  prevent  the  filling  of  the  aorta  during  the  distension  of 
the  ventricle.  Two  smaller  segments  are  usually  found  at  the  angle  of  junction 
of  the  larger.  The  mitral  valve  flaps  are  furnished  with  chorda?  tendineas;  the 
mode  of  attachment  of  which  is  precisely  similar  to  those  on  the  right  side; 
but  they  are  thicker,  stronger,  and  less  numerous. 

The  semilunar  valves  surround  the  orifice  of  the  aorta;  they  are  similar  in 
structure,  and  in  their  mode  of  attachment,  to  those  of  the  pulmonary  artery. 
They  are,  however,  larger,  thicker,  and  stronger  than  those  of  the  right  side; 
the  lunulas  are  more  distinct,  and  the  corpora  Arantii  larger  and  more  promi- 
nent. Between  each  valve  and  the  cylinder  of  the  aorta  is  a  deep  depression, 
the  sinus  aortici  (sinuses  of  Valsalva) ;  they  are  larger  than  those  at  the  root  of 
the  pulmonary  artery. 

The  columnse  carnese  admit  of  a  subdivision  into  three  sets,  like  those  upon 
the  right  side ;  but  they  are  smaller,  more  numerous,  and  present  a  dense  inter- 
lacement, especially  at  the  apex,  and  upon  the  posterior  wall.  Those  attached 
by  one  extremity  only,  the  niusculi  p)apillares,  are  two  in  number,  being  con- 
nected one  to  the  anterior,  the  other  to  the  posterior  wall ;  they  are  of  large 
size,  and  terminate  by  free  rounded  extremities,  from  which  the  chordae  tendineas 
arise. 

The  Endocardium  is  the  serous  membrane  which  lines  the  internal  surface  of 
the  heart ;  it  assists  in  forming  the  valves  by  its  reduplications,  and  is  continu- 
ous with  the  lining  membrane  of  the  great  bloodvessels.  It  is  a  thin,  smooth, 
transparent  membrane,  giving  to  the  inner  surface  of  the  heart  its  glistening 
appearance.  It  is  more  opaque  on  the  left  than  on  the  right  side  of  the  heart, 
thicker  in  the  auricles  than  in  the  ventricles,  and  thickest  in  the  left  auricle.  It 
is  thin  on  the  musculi  pectinati,  and  on  the  columnae  carnese;  but  thicker  on 
the  smooth  part  of  the  auricular  and  ventricular  walls,  and  on  the  tips  of  the 
musculi  papillares. 

Structure  of  the  Heart.  The  heart  consists  of  muscular  fibres,  and  of  fibrous 
rings  which  serve  for  their  attachment. 


764  THE    THORAX. 

The  Jihrons  rings  surround  the  auriculo-ventricular  and  arterial  orifices;  tliej 
are  stronger  upon  the  left  than  on  the  right  side  of  the  heart.  The  auriculo- 
ventricular  rings  serve  for  the  attachment  of  the  muscular  fibres  of  the  auricles 
and  ventricles,  and  also  for  the  mitral  and  tricuspid  valves;  the  ring  on  the 
left  side  is  closely  connected,  by  its  right  margin,  with  the  aortic  arterial  ring. 
Between  these  and  the  right  auriculo-ventricular  ring,  is  a  fibro-cartilaginous 
mass ;  and  in  some  of  the  larger  animals,  as  the  ox  and  elephant,  a  portion  of 
bone. 

The  fibrous  rings  surrounding  the  arterial  orifices,  serve  for  the  attachment 
of  the  great  vessels  and  semilunar  valves.  Each  ring  receives,  by  its  ventricu- 
lar margin,  the  attachment  of  the  muscular  fibres  of  the  ventricles ;  its  opposite 
margin  presents  three  deep  semicircular  notches,  within  which  the  middle  coat 
of  the  artery  (which  presents  three  convex  semicircular  segments)  is  firmly 
fixed ;  the  attachment  of  the  artery  to  its  fibrous  ring  being  strengthened  by  the 
thin  cellular  coat  and  serous  membrane  externally,  and  by  the  endocardium 
within.  It  is  opposite  the  margins  of  these  semicircular  notches,  in  the  arterial 
rings,  that  the  endocardium,  by  its  reduplication,  forms  the  semilunar  valves, 
the  fibrous  structure  of  the  ring  being  continued  into  each  of  the  segments  of 
the  valve  at  this  part.  The  middle  coat  of  the  artery  in  this  situation  is  thin, 
and  the  sides  of  the  vessel  dilated  to  form  the  sinuses  of  Valsalva. 

The  muscuJor  structure  of  the  heart  consists  of  bands  of  fibres,  which  present 
an  exceedingly  intricate  interlacement.  They  are  of  a  deep  red  color,  and 
marked  with  transverse  strias. 

The  muscular  fibres  of  the  heart  admit  of  a  subdivision  into  two  kinds; 
those  of  the  auricles,  and  those  of  the  ventricles;  which  are  quite  independent 
of  one  another. 

Fibres  of  (he  auricles.  These  are  disposed  in  two  layers;  a  superficial  layer 
common  to  both  cavities,  and  a  deep  layer  proper  to  each.  The  superficial  fibres 
are  more  distinct  on  the  anterior  surface  of  the  auricles,  across  the  bases  of 
which  they  run  in  a  transverse  direction,  forming  a  thin,  but  incomplete  layer. 
Some  of  these  fibres  pass  into  the  septum  auricularum.  The  internal  or  deep 
fibres  proper  to  each  auricle  consist  of  two  sets,  looped  and  annular  fibres. 
The  looped  fibres  pass  upwards  over  each  auricle,  being  attached  by  both  ex- 
tremities to  the  corresponding  auriculo-ventricular  rings,  in  front  and  behind. 
The  annular  fibres  surround  the  whole  extent  of  the  appendices  auriculoB,  and 
are  continued  upon  the  walls  of  the  vena3  cava?  and  coronary  sinus  on  the  right 
side,  and  upon  the  pulmonary  veins  on  the  left  side,  at  their  connection  with 
the  heart.     In  the  appendices,  they  interlace  with  the  longitudinal  fibres. 

Fibres  of  the  ventricles.  These,  as  in  the  auricles,  are  disposed  in  layers,  some 
of  which  are  common  to  both  ventricular  cavities,  whilst  others  belong  exclu- 
sively to  one  ventricle,  the  latter  being  chiefly  found  towards  the  base  of  the 
heart.  The  greater  majority  of  these  fibres  are  connected  by  both  ends  with 
the  auriculo-ventricular  fibrous  rings,  either  directly  or  indirectly  through  the 
chorda3  tcndinete;  some,  however,  are  attached  to  the  fibrous  rings  surrounding 
the  arterial  orifices. 

The  superficial  fibres  are  either  longitudinal,  or  more  commonly  oblique  or 
spiral  in  their  direction,  and  towards  the  apex  are  arranged  in  the  form  of 
twisted  loops  ;  the  deeper  fibres  are  circular. 

The  spiral  fibres  are  disposed  in  layers  of  various  degrees  of  thickness;  the 
most  superficial,  on  the  front  of  the  ventricles,  run  obliquely  from  right  to  left, 
and  from  above  downwards.  On  the  back  of  the  ventricles  they  are  directed 
more  vertically,  and  pass  from  left  to  right. 

The  superficial  fibres  coil  inwards  at  the  apex  of  the  heart,  round  which  they 
are  arranged  in  a  whorl-like  form,  called  the  vortex^  dipping  beneath  the  edge 
of  the  deeper  and  shorter  layers.  If  these  fibres  are  carefully  uncoiled,  in  a 
heart  previously  boiled,  the  cavity  of  the  left,  and  then  that  of  the  right  ven- 
tricle, will  be  exposed  at  this  point.     The  layers  of  fibres  successively  met  with 


VASCULAR    SYSTEM    OF    FCETUS.  765 

have  a  similar  arrangement;  the  more  superficial  and  longer  turning  inwards, 
and  including  the  deeper  and  shorter  bands.  All  these  fibres  ascend  and  spread 
out  upon  the  inner  surface  of  the  ventricles,  forming  the  walls,  the  septum,  and 
the  musculi  papillares,  which  project  from  these  cavities ;  and  thej  are  finally 
inserted  into  the  auriculo-ventricular  fibrous  rings  directly,  or,  indirectly, 
through  the  chordae  tendinese.  Of  these  spiral  fibres,  some  enter  at  the  inter- 
ventricular furrows,  and  surround  either  ventricle  singly ;  others  pass  across 
the  furrows  and  embrace  both  cavities.  On  tracing  those  which  form  the  vortex 
back  into  the  interventricular  septum,  they  are  found  to  be  interlaced  with 
similar  fibres  from  the  right  ventricle,  and  ascend  vertically  upon  the  right  side 
of  the  septum,  as  far  as  its  base,  in  the  form  of  a  long  and  broad  band. 

Circular  fibres.  The  circular  fibres  are  situated  deeply  in  the  substance  of 
the  heart ;  towards  the  base  they  enter  the  anterior  and  posterior  longitudinal 
furrows,  so  as  to  include  each  cavity  singly,  or,  passing  across  them,  surround 
both  ventricles,  more  fibres  passing  across  the  posterior  than  the  anterior  fur- 
row. They  finally  ascend  in  the  substance  of  the  ventricle,  to  be  inserted  into 
the  fibrous  rings  at  its  base. 

Vessels  and  Nerves.  The  arteries  supplying  the  heart  are  the  left  or  anterior 
and  the  right  or  posterior  coronary. 

The  veins  accompany  the  arteries,  and  terminate  in  the  right  auricle.  They 
are  the  great  cardiac  vein,  the  small,  or  anterior  cardiac  veins,  and  the  venae 
cordis  minimee  (venx  Thehesii). 

The  lymphatics  terminate  in  the  thoracic  and  right  lymphatic  ducts. 

The  nerves  are  derived  from  the  cardiac  plexuses,  which  are  formed  partly 
from  the  cranial  nerves,  and  partly  from  the  sympathetic.  They  are  freely 
distributed  both  on  the  surface,  and  in  the  substance  of  the  heart ;  the  separate 
filaments  being  furnished  with  small  ganglia.' 

Peculiarities  in  the  Vascular  System  of  the  Fcetus. 

The  chief  Peculiarities  in  the  Heart  of  the  Foetus  are  the  direct  communica- 
tion between  the  two  auricles  through  the  foramen  ovale,  and  the  large  size  of 
the  Eustachian  valve.  There  are  also  several  minor  peculiarities.  Thus,  the 
position  of  the  heart  is  vertical  until  the  fourth  month,  when  it  commences  to 
assume  an  oblique  direction.  Its  size  is  also  very  considerable,  as  compared 
with  the  body,  the  proportion  at  the  second  month  being  as  1  to  50 :  at  birth 
it  is  as  1  to  120:  whilst,  in  the  adult,  the  average  is  about  1  to  160.  At  an 
early  period  of  foetal  life,  the  auricular  portion  of  the  heart  is  larger  than  the 
ventricular,  the  right  auricle  being  more  capacious  than  the  left ;  but,  towards 
birth,  the  ventricular  portion  becomes  the  larger.  The  thickness  of  both  ven- 
tricles is,  at  first,  about  equal ;  but,  towards  birth,  the  left  becomes  much  the 
thicker  of  the  two. 

The /ommen  ovale  is  situated  at  the  lower  and  back  part  of  the  septum  auricu- 
larum,  forming  a  communication  between  the  auricles.  It  attains  its  greatest 
size  at  the  sixth  month. 

The  Eustachian  valve  is  developed  from  the  anterior  border  of  the  inferior 
vena  cava,  at  its  entrance  into  the  auricle.  It  is  directed  upwards  on  the  lelt 
side  of  the  opening  of  this  vein,  and  serves  to  direct  the  blood  from  the  inferior 
vena  cava  through  the  foramen  ovale  into  the  left  auricle. 

The  peculiarities  in  the  arterial  system  of  the  foetus  are  the  communication 
between  the  pulmonary  artery  and  descending  part  of  the  arch  of  the  aorta,  by 
means  of  the  ductus  arteriosus,  and  the  communication  between  the  internal 
iliac  arteries  and  the  placenta,  by  means  of  the  umbilical  arteries. 

The  diLctus  arteriosus  is  a  short  tube,  about  half  an  inch  in  length  at  birth, 
and  of  the  diameter  of  a  goose-quill.     In  the  early  condition,  it  forms  the  con- 

'  For  full  and  accurate  descriptinns  of  tho  nerves  and  ganglia  of  the  heart,  the  student  is 
referred  to  Dr.  11.  Lee's  papers  on  the  subject. 


766 


THE    THORAX. 


tinuation  of  the  pulmonary  artery,  and  opens  into  the  arch  of  the  aorta,  just 
below  the  origin  of  the  left  subclavian  artery ;  and  so  conducts  the  chief  part 
of  the  blood  from  the  right  ventricle  into  the  descending  aorta.  When  the 
branches  of  the  pulmonary  artery  have  become  larger  relatively  to  the  ductus 
arteriosus,  the  latter  is  chiefly  connected  to  the  left  pulmonary  artery;  and  the 
fibrous  cord,  which  is  all  that  remains  of  the  ductus  arteriosus  in  later  life,  will 
be  found  to  be  attached  to  the  root  of  that  vessel. 


Fig.  421.— Plan  of  the  Foetal  Circulation. 


Inl^nal  JUac  ^ 


In  this  plan  the  figured  arrows  represent  the  kind  of  blood,  as  well  as  the  direction  which  it 

takes  in  the  vessels.   Thus— arterial  blood  is  figured  x> ••>;  venous  blood,  >» >  ; 

mixed  (arterial  and  venous  blood),  ^^•— •^•>'. 


FCETAL    CIRCULATION.  767 

The  umbilical,  or  hypogastric  arteries,  arise  from  the  internal  iliacs,  in  addition 
to  the  branches  given  off  from  those  vessels  in  the  adult.  Ascending  along  the 
sides  of  the  bladder  to  its  fundus,  they  pass  out  of  the  abdomen  at  the  umbili- 
cus, and  are  continued  along  the  umbilical  cord  to  the  placenta,  coiling  round 
the  umbilical  vein.  They  return  to  the  placenta  the  blood  which  has  circulated 
in  the  system  of  the  foetus. 

The  peculiarity  in  the  venous  system  of  the  foetus  is  the  communication 
established  between  the  placenta  and  the  liver  and  portal  vein,  through  the 
umbilical  vein,  and  with  the  inferior  vena  cava  by  the  ductus  venosus. 

The  arterial  blood  destined  for  the  nutrition  of  the  foetus,  is  carried  from  the 
placenta  to  the  foetus,  along  the  umbilical  cord,  by  the  umbilical  vein.  The 
umbilical  vein  enters  the  abdomen  at  the  umbilicus,  and  passes  upwards  along 
the  free  margin  of  the  suspensory  ligament  of  the  liver,  to  the  under  surface  of 
that  organ,  where  it  gives  off  two  or  three  branches  to  the  left  lobe,  one  of  which 
is  of  large  size ;  and  others  to  the  lobus  quadratus  and  lobulus  Spigelii.  At  the 
transverse  fissure  it  divides  into  two  branches ;  of  these,  the  larger  is  joined  by 
the  portal  vein,  and  enters  the  right  lobe :  the  smaller  branch  continues  on- 
wards, under  the  name  of  the  ductus  venosus,  and  joins  the  left  hepatic  vein  at 
the  point  of  junction  of  that  vessel  with  the  inferior  vena  cava.  The  blood, 
therefore,  which  traverses  the  umbilical  vein,  reaches  the  inferior  cava  in  three 
different  ways.  The  greater  quantity  circulates  through  the  liver  with  the 
portal  venous  blood,  before  entering  the  vena  cava  by  the  hepatic  veins :  some 
enters  the  liver  directly,  and  is  also  returned  to  the  inferior  cava  by  the  hepatic 
veins:  the  smaller  quantity  passes  directly  into  the  vena  cava,  by  the  junction 
of  the  ductus  venosus  with  the  left  hepatic  vein. 

In  the  inferior  cava,  the  blood  carried  by  the  ductus  venosus  and  hepatic 
veins,  becomes  mixed  with  that  returning  from  the  lower  extremities  and  vis- 
cera of  the  abdomen.  It  enters  the  right  auricle,  and,  guided  by  the  Eustachian 
valve,  passes  through  the  foramen  ovale  into  the  left  auricle,  where  it  becomes 
mixed  with  a  small  quantity  of  blood  returned  from  the  lungs  by  the  pulmo- 
nary veins.  From  the  left  auricle  it  passes  into  the  left  ventricle ;  and,  from 
the  left  ventricle,  into  the  aorta,  from  whence  it  is  distributed  almost  entirely 
to  the  head  and  upper  extremities,  a  small  quantity  being  probably  carried  into 
the  descending  aorta.  From  the  head  and  upper  extremities,  the  blood  is  re- 
turned by  the  branches  of  the  superior  vena  cava  to  the  right  auricle,  where  it 
becomes  mixed  with  a  small  portion  of  the  blood  from  the  inferior  cava.  From 
the  right  auricle  it  descends  over  the  Eustachian  valve  into  the  right  ventricle; 
and,  from  the  right  ventricle,  passes  into  the  pulmonary  artery.  The  lungs  of 
the  foetus  being  solid,  and  almost  impervious,  only  a  small  quantity  of  the 
blood  of  the  pulmonary  artery  is  distributed  to  them,  by  the  right  and  left  pul- 
monary arteries,  which  is  returned  by  the  pulmonary  veins  to  the  left  auricle : 
the  greater  part  passes  through  the  ductus  arteriosus  into  the  commencement 
of  the  descending  aorta,  where  it  becomes  mixed  with  a  small  quantity  of  blood 
transmitted  by  the  left  ventricle  into  the  aorta.  Along  this  vessel  it  descends 
to  supply  the  lower  extremities  and  viscera  of  the  abdomen  and  pelvis,  the  chief 
portion  being,  however,  conveyed  by  the  umbilical  arteries  to  the  placenta. 

From  the  preceding  account  of  the  circulation  of  the  blood  in  the  foetus,  it 
will  be  seen  : — 

1.  That  the  placenta  serves  the  double  purpose  of  a  respiratory  and  nutritive 
organ,  receiving  the  venous  blood  from  the  foetus,  and  returning  it  again  reoxy- 
genated,  and  charged  with  additional  nutritive  material, 

2.  That  nearly  the  whole  of  the  blood  of  the  umbilical  vein  traverses  the  liver 
before  entering  the  inferior  cava  ;  hence  the  large  size  of  this  organ,  especially 
at  an  early  period  of  foetal  life. 

3.  That  the  right  auricle  is  the  point  of  meeting  of  a  double  current,  the 
blood  in  the  inferior  cava  being  guided  by  the  Eustachian  valve  into  the  left 
auricle,  whilst  that  in  the  superior  cava  descends  into  the  right  ventricle.     At 


T68  THE    THORAX. 

an  early  period  of  foetal  life,  it  is  highly  probable  that  the  two  streams  are  quite 
distinct;  for  the  inferior  cava  opens  almost  directly  into  the  left  auricle  and 
the  Eustachian  valve  would  exclude  the  current  along  the  vein  from  enterino- 
the  right  ventricle.  At  a  later  period,  as  the  separation  between  the  two  auri- 
cles becomes  more  distinct,  it  seems  probable  that  some  fixture  of  the  two 
streams  must  take  place. 

4.  The  blood  carried  from  the  placenta  to  the  foetus  by  the  umbilical  vein, 
mixed  with  the  blood  from  the  inferior  cava,  passes  almost  directly  to  the  arch 
of  the  aorta,  and  is  distributed  by  the  branches  of  that  vessel  to  the  head  and 
upper  extremities :  hence  the  large  size  and  perfect  development  of  those  parts 
at  birth. 

5.  The  blood  contained  in  the  descending  aorta,  chiefly  derived  from  that 
which  has  already  circulated  through  the  head  and  limbs,  together  with  a  small 
quantity  from  the  left  ventricle,  is  distributed  to  the  lower  extremities :  hence 
the  small  size  and  imperfect  development  of  these  parts  at  birth. 

Changes  in  the  Yascular  System  at  Birth. 

•  At  birth,  when  respiration  is  established,  an  increased  amount  of  blood  from 
the  pulmonary  artery  passes  through  the  lungs,  which'  now  perform  their  office 
as  respiratory  organs,  and,  at  the  same  time,  the  placental  circulation  is  cut  off. 
The  foramen  ovale  becomes  gradually  closed-in  by  about  the  tenth  day  after 
birth,  a  valvular  fold  rises  up  on  the  left  side  of  its  margin,  and  ultimately 
above  its  upper  part ;  this  valve  becomes  adherent  to  the  margins  of  the  fora- 
men for  the  greater  part  of  its  circumference,  but,  above,  a  valvular  opening  is 
left  between  the  two  auricles,  which  sometimes  remains  persistent. 

The  ductus  arteriosus  begins  to  contract  immediately  after  respiration  is  estab- 
lished, becomes  completely  closed  from  the  fourth  to  the  tenth  day,  and  ulti- 
mately degenerates  into  an  impervious  cord,  which  serves  to  connect  the  left  .  . 
pulmonary  artery  to  the  concavity  of  the  arch  of  the  aorta.  vl 

Of  the  umbilical  or  hypogastric  arteries^  the  portion  continued  on  to  the  bladder 
from  the  trunk  of  the  corresponding  internal  iliac  remains  pervious,  as  the  supe- 
rior vesical  artery ;  and  the  part  between  the  fundus  of  the  bladder  and  the 
umbilicus  becomes  obliterated  between  the  second  and  fifth  days  after  birth, 
and  forms  the  anterior  true  ligament  of  the  bladder. 

The  iLinhilical  vein  and  ductus  venosus  become  completely  obliterated  between 
the  second  and  fifth  days  after  birth,  and  ultimately  dwindle  to  fibrous  cords; 
the  former  becoming  tlie  round  ligament  of  the  liver,  the  latter,  the  fibrous  cord, 
which,  in  the  adult,  may  be  traced  along  the  fissure  of  the  ductus  veuosus. 


i| 


Organs  of  Voice  and  Respiration. 


The  Larynx. 

The  Larynx  is  the  organ  of  voice,  placed  at  the  upper  part  of  the  air-passage. 
It  is  situated  between  the  trachea  and  base  of  the  tongue,  at  the  upper  and  fore 
part  of  the  neck,  where  it  forms  a  considerable  projection  in  the  middle  line. 
On  either  side  of  it  lie  the  great  vessels  of  the  neck  ;  behind,  it  forms  part  of 
the  boundary  of  the  pharynx,  and  is  covered  by  the  mucous  membrane  lining 
that  cavity. 

The  larynx  is  narrow  and  cylindrical  below,  but  broad  above,  where  it  pre- 
sents the  form  of  a  triangular  box,  flattened  behind  and  at  the  sides,  whilst  in 
front  it  is  bounded  by  a  prominent  vertical  ridge.  It  is  composed  of  carti- 
lages, which  are  connected  together  by  ligaments  and  moved  by  numerous  mus- 
cles ;  the  interior  is  lined  by  mucous  membrane,  and  supplied  with  vessels  and 
nerves. 

The  Cartilages  of  the  larynx  are  nine  ia  number,  three  single,  and  three 
pairs : — 


Thyroid. 

Cricoid, 

Epiglottis. 


Two  Arytenoid. 

Two  Cornicula  Laryngis. 

Two  Cuneiform. 


Fig.  422.— Side  View  of  the  Thyroid 
and  Cricoid  Cartilages. 


The  Thyroid  (svpso?,  a  shield)  is  the  largest  cartilage  of  the  larynx.  It  consists 
of  two  lateral  lamellae  or  al«,  united  at  an  acute  angle  in  front,  forming  a  vertical 
projection  in  the  middle  line,  which  is  promi- 
nent above,  and  called  the  pomum  Adami.  This 
projection  is  subcutaneous,  more  distinct  in  the 
male  than  in  the  female,  and  occasionally  sepa- 
rated from  the  integument  by  a  bursa  mucosa. 

Each  lamella  is  quadrilateral  in  form.  Its 
outer  surface  presents  an  oblique  ridge,  which 
passes  downwards  and  forwards  from  a  tubercle, 
situated  near  the  root  of  the  superior  cornu. 
This  ridge  gives  attachment  to  the  Sterno-thy- 
roid  and  Thyro-hyoid  muscles ;  the  portion  of 
cartilage  included  between  it  and  the  posterior 
border,  to  part  of  the  Inferior  Constrictor 
muscle. 

The  inner  surface  of  each  ala  is  smooth,  con- 
cave, and  covered  by  mucous  membrane  above 
and  behind ;  but  in  front,  in  the  receding  angle 
formed  by  their  junction,  is  attached  the  epiglot- 
tis, the  true  and  false  chordas  vocales,  the  Thyro- 
arytenoid, and  Thyro-epiglottidean  muscles. 

The  upper  border  of  the  thyroid  cartilage  is 
deeply  notched  in  the  middle  line  immediately 
above  the  pomum  Adami,  whilst  on  either  side 
it  is  slightly  concave.  This  border  gives  attach- 
ment throughout  its  whole  extent  to  the  thyro- 
hyoid membrane. 

The  lower  border  is  connected  to  the  cricoid  cartilage,  in  the  median  line,  by 
the  crico-thyroid  membrane  ;  and,  on  each  side,  by  the  Crico-thyroid  muscle. 
49  769 


•10 


ORGANS    OF    VOICE    AND    RESPIRATION. 


The  posterior  borders,  thick  and  rounded,  terminate,  above,  in  the  superior 
cornua  ;  and,  below,  in  the  inferior  cornua.  The  two  superior  cornua  are  long 
and  narrow,  directed  backwards,  upwards,  and  inwards;  and  terminate  in  a 
conical  extremity,  which  gives  attachment  to  the  thyro-hyoid  ligament.     The 

two  inferior  cornua  are  short  and 


Fig.  423.— The  Cartilapes  of  the  Larynx. 

Posterior  View. 


CPiauoTTis 


OnMMtZa  tarngU 


thick  ;  they  pass  forwards  and  in- 
wards, and  present,  on  their  inner 
surfaces,  a  small,  oval,  articular 
facet  for  articulation  with  the  side 
of  the  cricoid  cartilage.  The  pos- 
terior border  receives  the  insertion 
of  the  Stylo-pharyngeus  and  Pa- 
lato-pharyngeus  muscles  on  each 
side. 

The  Cricoid  Cartilage  is  so  called 
from  its  resemblance  to  a  signet 
ring  (xptxoj,  a  ring).  It  is  smaller 
but  thicker  and  stronger  than  the 
thyroid  cartilage,  and  forms  the 
lower  and  back  part  of  the  cavity 
of  the  larynx. 

Its  anterior  half  is  narrow,  con- 
vex, affording  attachment  in  front 
and  at  the  sides  to  the  Crico-thy- 
roid  muscles,  and,  behind  those,  to 
part  of  the  Inferior  Constrictor. 

Its  posterior  half  is  very  broad, 
both  from  side  to  side  and  from 
above  downwards  ;  it  presents  in 
the  middle  line  a  vertical  ridge  for 
the  attachment  of  the  longitudinal 
fibres  of  the  oesophagus;  and  on 
either  side  a  broad  depression  for 
the  Crico-arytaenoideus  Posticus 
muscle. 

At  the  point  of  junction  of  the 
two  halves  of  the  cartilage  on 
either  side,  is  a  small  round  ele- 
vation, for  articulation  with  the 
inferior  cornu  of  the  thyroid  carti- 
lage. 

The  lower  border  of  the  cricoid 
cartilage  is  horizontal,  and  con- 
nected to  the  upper  ring  of  the 
trachea  by  fibrous  membrane. 
Its  upper  border  is  directed  ob- 
liquely upwards  and  backwards,  owing  to  the  great  depth  of  its  posterior  sur- 
face. It  gives  attachment,  in  front,  to  the  crico-thyroid  membrane ;  at  the  sides, 
to  part  of  the  same  membrane  and  to  the  lateral  Crico-arytenoid  muscle ;  be- 
hind, the  highest  point  of  the  upper  border  is  surmounted  on  each  side  by  a 
smooth  oval  surface,  for  articulation  with  the  arytenoid  cartilage.  Between 
the  articular  surfaces  is  a  slight  notch,  for  the  attachment  of  part  of  the  Ary- 
ticnoideus  muscle. 

The  i7i»er  surface  of  the  cricoid  cartilage  is  smooth,  and  lined   by  mucous 
membrane. 

The  Arytenoid  Cartilages  are  so  called  from  the  resemblance  they  bear,  when 
approximated,  to  the  mouth  of  a  pitcher  (dpwrotvo,  a  pitcher).     They  are  two  in 


cmco-AiirTiiMero 


Aiyttntid  CartV^  lam 


^  Thyroid  C. 


CARTILAGES    AND    LIGAMENTS    OF    LARYNX.  in 

number,  and  situated  at  the  upper  border  of  the  cricoid  cartilage,  at  the  back 
of  the  larynx.  Each  cartilage  is  pyramidal  in  form,  and  presents  for  examina- 
tion three  surfaces,  a  base,  and  an  apex. 

The  posterior  surface  is  triangular,  smooth,  concave,  and  lodges  part  of  the 
Arytenoid  muscle. 

The  anterior  surface,  somewhat  convex  and  rough,  givea  attachment  to  the 
Thyro-arytenoid  muscle,  and  to  the  false  vocal  cord. 

The  internal  sar/ace  is  narrow,  smooth,  and  flattened,  covered  by  mucous  mem- 
brane, and  lies  almost  in  apposition  with  the  cartilage  of  the  opposite  side. 

The  base  of  each  cartilage  is  broad,  and  presents  a  concave  smooth  surface, 
for  articulation  with  the  cricoid  cartilage.  Of  its  three  angles,  the  external  is 
short,  rounded,  and  prominent,  receiving  the  insertion  of  the  posterior  and 
lateral  Crico-arytenoid  muscles.  The  anterior  angle,  also  prominent,  but  more 
pointed,  gives  attachment  to  the  true  vocal  cord. 

The  apex  of  each  cartilage  is  pointed,  curved  backwards  and  inwards,  and 
surmounted  by  a  small  conical-shaped,  cartilaginous  nodule,  corniculum  lai>jngis 
(cartilage  of  Santorini).  This  cartilage  is  sometimes  united  to  the  arytenoid, 
and  serves  to  prolong  it  backwards  and  inwards.  To  it  is  attached  the  aryteno- 
epiglottidean  fold. 

The  cuneiform,  cartilages  (cartilages  of  Wrisberg)  are  two  small,  elongated, 
cartilaginous  bodies,  placed  one  on  each  side,  in  the  fold  of  mucous  membrane 
which  extends  from  the  apex  of  the  arytenoid  cartilage  to  the  side  of  the 
epiglottis  (aryteno-epiglottideanfokl)-  they  give  rise  to  small  whitish  elevations 
on  the  inner  surface  of  the  mucous  membrane,  just  in  front  of  the  arytenoid 
cartilages. 

The  epiglottis  is  a  thin  lamella  of  fibro-cartilage,  of  a  yellowish  color,  shaped 
like  a  leaf,  and  placed  behind  the  tongue  in  front  of  the  superior  opening  of  the 
larynx.  During  respiration,  its  direction  is  vertically  upwards,  its  free  ex- 
tremity curving  forwards  towards  the  base  of  the  tongue;  but  when  the  larynx 
is  drawn  up  beneath  the  base  of  the  tongue  during  deglutition,  it  is  carried 
downwards  and  backwards,  so  as  to  completely  close  the  opening  of  the 
larynx.  Its  free  extremity  is  broad  and  rounded ;  its  attached  end  is  long  and 
narrow,  and  connected  to  the  receding  angle  between  the  two  alee  of  the  thy- 
roid cartilage,  just  below  the  median  notch,  by  a  long,  narrow,  ligamentous 
band,  the  thyro-epiglottic  Ugamejit.  It  is  also  connected  to  the  posterior  surface 
of  the  body  of  the  hyoid  bone,  by  an  elastic  ligamentous  band,  the  hyo-epiglottic 
ligament. 

Its  anterior  or  lingual  surface  is  curved  forwards  towards  the  tongue,  and 
covered  by  mucous  membrane,  which  is  reflected  on  to  the  sides  and  base  of  the 
organ,  forming  a  median  and  two  lateral  folds,  the  glosso-epiglottidean  ligaments. 

Its  piosierior  or  laryngeal  surface  is  smooth,  concave  from  side  to  side,  convex 
from  above  downwards,  and  covered  by  mucous  membrane;  when  this  is 
removed,  the  surface  of  the  cartilage  is  seen  to  be  studded  with  a  number  of 
small  mucous  glands,  which  are  lodged  in  little  pits  upon  its  surface.  To  its 
sides  the  aryteno-epiglottidean  folds  are  attached. 

Structure.  The  epiglottis,  cuneiform  cartilages,  and  cornicula  laryngis  are 
composed  of  yellow  cartilage,  which  shows  little  tendency  to  ossification;  but 
the  other  cartilages  resemble  in  structure  the  costal  cartilages,  becoming  more 
or  less  ossified  in  old  age. 

Ligaments  of  the  larynx.  The  ligaments  of  the  larynx  are  extrinsic,  i.  e.,  those 
connecting  the  thyroid  cartilage  with  the  os  hyoides;  a.n(iintrinsic,  those  which 
connect  the  several  cartilaginous  segments  to  each  other. 

The  ligaments  connecting  the  thyroid  cartilage  with  the  os  hyoides  are  three 
in  number;  the  thyro-hyoid  membrane,  and  the  two  lateral  thyro-hyoid  liga- 
ments. 

The  thyro-hyoid  membrane  is  a  broad,  fibro-elastic,  membranous  layer,  attached 
below  to  the  upper  border  of  the  thyroid  cartilage,  and  above  to  the  upper 


772 


ORGANS    OF    VOICE    AND    RESPIRATION. 


border  of  the  inner  surface  of  the  hyoid  bone:  being  separated  from  the  poste- 
rior surface  of  the  hyoid  bone  by  a  synovial  bursa.  It  is  thicker  in  the  middle 
line  than  at  either  side,  in  which  situation  it  is  pierced  by  the  superior  laryn- 
geal vessels  and  nerve. 

The  two  lateral  thyro-Tiyoid  ligaments  are  rounded,  elastic  cords,  which  pass 
between  the  superior  cornua  of  the  thyroid  cartilage  and  the  extremities  of  the 
greater  cornua  of  the  hyoid  bone.  A  small  cartilaginous  nodule  (carlilago 
triticea),  sometimes  bony,  is  found  in  each. 

The  ligaments  connecting  the  thyroid  cartilage  to  the  cricoid  are  also  three 
in  number;  the  crico-thyroid  membrane,  and  the  capsular  ligaments  and  syno- 
vial membrane. 

The  crico-thyroid  membrane  is  composed  mainly  of  yellow  elastic  tissue.  It  is 
of  triangular  shape;  thick  in  front,  where  it  connects  together  the  contiguous 
margins  of  the  thyroid  and  cricoid  cartilages;  thinner  at  each  side,  where  it 
extends  from  the  superior  border  of  the  cricoid  cartilage,  to  the  inferior  margin 
of  the  true  vocal  cords,  with  which  it  is  closely  united  in  front. 

The  anterior  portion  of  the  crico-thyroid  membrane  is  convex,  concealed  on 
each  side  by  the  Crico-thyroid  muscle,  subcutaneous  in  the  middle  line,  and 
crossed  horizontally  by  a  small  anastomotic  arterial  arch,  formed  by  the  junc- 
tion of  the  two  crico-thyroid  arteries. 

The  lateral  portions  are  lined  internally  by  mucous  membrane,  and  covered 
by  the  lateral  Crico-arytenoid  and  Thyro-arytenoid  muscles. 

A  capsular  ligament  incloses  the  articulation  of  the  inferior  cornu  of  the 
thyroid  with  the  cricoid  cartilage  on  each  side.  The  articulation  is  lined  by 
synovial  membrane. 

The  ligaments  connecting  the  arytenoid  cartilages  to  the  cricoid,  are  two 
thin  and  loose  capsular  ligaments  connecting  together  the  articulating  surfaces 
lined  internally  by  synovial  membrane,  and  strengthened  behind  by  a  strong 

posterior  crico-arytenoid  liga- 

Fig.  424. — The  Larynx  and  adjacent  parts,  as  seen 
from  above. 


Aryttnn'i.  cart  ' 


ment,  which  extends  from  the 
cricoid  to  the  inner  and  back 
part  of  the  base  of  the  aryte- 
noid cartilage. 

The  ligaments  of  the  epiglot- 
tis are  the  hyo-epiglottic,  the 
thyro-epiglottic,  and  the  three 
glosso-epiglottic  folds  of  mu- 
cous membrane  which  connect 
the  epiglottis  to  the  sides  and 
base  of  the  tongue.  The  latter 
have  been  already  described. 

The  hyo-epightlic  ligament  is 
an  elastic  fibrous  band,  which 
extends  from  the  anterior  sur- 
face of  the  epiglottis,  near  its 
apex,  to  the  posterior  surface 
of  the  body  of  the  hyoid  bone. 
The  thyro-epiglottic  ligament 
is  a  long,  slender,  elastic  cord, 

which  connects  the  apex  of  the  epiglottis  with  the  receding  angle  of  the  thyroid 

cartilage,  immediately  beneath  the  median  notch,  above  the  attachment  of  the 

vocal  cords. 

Interior  of  the  larynx.     The  superior  aj>erture  of  the  larynx  (Fig.  424)  is  a 

triangular  or  cordiform  opening,  wide  in  front,  narrow  behind,  and  sloping 

obliquely  downwards  and  backwards.     It  is  bounded  in  front  by  the  epiglottis; 

behind,  by  the  apices  of  the  arytenoid  cartilages,  and  the  cornicula  laryngis; 

and  laterally,  oy  a  fold  of  mucous  membrane,  inclosing  ligamentous  and  mus- 


CAVITY    OF    LARYNX— GLOTTIS— TOCAL    CORDS.      773 


Fig.  425. — Vertical  Section  of  the  La- 
rynx and  Upper  part  of  the  Trachea. 


cular  fibres,  stretched  between  the  sides  of  the  epiglottis  and  the  apex  of  the 
arytenoid  cartilage :  these  are  the  aryteno-epiglottidean  folds,  on  the  margins 
of  which  the  cuneiform  cartilages  form  a  more  or  less  distinct  whitish  promi- 
nence. 

The  cavity  of  the  larynx  extends  from  the  aperture  behind  the  epiglottis  to 
the  lower  border  of  the  cricoid  cartilage.  It  is  divided  into  two  parts  by  the 
projection  inwards  of  the  vocal  cords,  and  Thyro-arytenoid  muscles^  between 
the  two  cords  is  a  long  and  narrow  triangular  fissure  or  chink,  the  ulottts^  or 
rima  ghtiidis.  The  portion  of  the  cavity  of  the  larynx  above  the  glottis,  is 
broad  and  triangular  in  shape  above,  and  corresponds  to  the  interval  between 
the  alee  of  the  thyroid  cartilage ;  the  portion  below  the  glottis  is  at  first  of  an 
elliptical,  and  lower  down  of  a  circular  form. 

The  glottis  {rima  glottidis)  is  the  interval  between  the  inferior,  or  true,  vocal 
cords.  The  two  superior  or  false  vocal  cords  are  placed  above  the  latter,  and 
are  formed  almost  entirely  by  a  folding  inwards  of  the  miucous  membrane ; 
whilst  the  two  inferior  or  true  vocal  cords  are  thick,  strong,  and  formed  partly 
by  mucous  membrane,  and  partly  by  ligamentous  fibres.  Between  the  true  and 
false  vocal  cords,  on  each  side,  is  an  oval  depression,  the  sinus,  or  ventricle  of 
the  larynx,  which  leads  upwards,  on  the  outer  side  of  the  superior  vocal  cord, 
into  a  ceecal  pouch  of  variable  size,  the  sacculiis  laryngis. 

The  rima  glottidis  is  the  narrow  fissure  or  chink  between  the  inferior  or  true 
vocal  cords.  It  is  the  narrowest  part  of  the  cavity  of  the  larynx,  and  corre- 
sponds to  the  lower  level  of  the  arytenoid 
cartilages.  Its  length,  in  the  male,  measures 
rather  less  than  an  inch,  its  breadth,  when 
dilated,  varying  at  its  widest  part  from  a 
third  to  half  an  inch.  In  the  female,  these 
measurements  are  less  by  two  or  three  lines. 
The  form  of  the  glottis  varies.  In  its  half- 
closed  condition,  it  is  a  narrow  fissure,  a  lit- 
tle enlarged  and  rounded  behind.  In  quiet 
breathing,  it  is  widely  open,  somewhat  tri- 
angular, the  base  of  the  triangle  directed 
backwardsi,  and  corresponding  to  the  space 
between  the  separated  arytenoid  cartilages. 
In  forcible  expiration,  it  is  smaller  than  dur- 
ing inspiration.  When  sound  is  produced, 
it  is  more  narrowed,  the  margins  of  the  ary- 
tenoid cartilages  being  brought  into  contact, 
and  the  edges  of  the  vocal  cords  approxi- 
mated and  made  parallel,  the  degree  of  ap- 
proximation and  tension  corresponding  to 
the  height  of  the  note  produced.^ 

The  sui^erior  or  false  vocal  cords,  so  called 
because  they  are  not  directly  concerned  in 
the  production  of  the  voice,  are  two  folds  of 
mucous  membrane,  inclosing  a  delicate  nar- 
row fibrous  band,  the  superior  thyro-arytenoid 
ligament.  This  ligament  consists  of  a  thin 
band  of  elastic  tissue,  attached  in  front  to 
the  angle  of  the  thyroid  cartilage  below  the 

epiglottis,  and  behind  to  the  anterior  surface  of  the  arytenoid  cartilage.  The 
lower  border  of  this  ligament,  inclosed  in  mucous  membrane,  forms  a  free 
crescentic  margin,  which  constitutes  the  upper  boundary  of  the  ventricle  of  the 
larynx. 

«  On  the  shape  of  the  glottis  in  the  various  conditions  of  breathing  and  speaking,  see  "  Cze^ 
mak  on  the  Laryngoscope,"  translated  for  the  New  Sydenham  Socitti/. 


eartf- 


774  ORGANS    OF    VOICE    AND    RESPIRATION. 

The  inferior  or  trne  vocal  cords,  so  called  from  their  being  concerned  in  the 
production  of  sound,  are  two  strong  fibrous  bands  {inferior  thyro-arytenoid  liga- 
ments), covered  on  their  surface  bj  a  thin  layer  of  mucous  membrane.  Each 
ligament  consists  of  a  band  of  yellow  elastic  tissue,  attached  in  front  to  the 
depression  between  the  two  alse  of  the  thyroid  cartilage,  and  behind  to  the  ante- 
rior angLe  of  the  base  of  the  arytenoid.  Its  lower  border  is  continuous  with 
the  thin  lateral  part  of  the  crico-thyroid  membrane.  Its  upper  border  forms 
the  lower  boundary  of  the  ventricle  of  the  larynx.  Externally,  the  Thyro- 
aryta3noid«us  muscle  lies  parallel  with  it.  It  is  covered  internally  by  mucous 
membrane,  which  is  extremely  thin,  and  closely  adherent  to  its  surface. 

The  ventricle  of  the  larynx  is  an  oblong  fossa,  situated  between  the  superior 
and  inferior  vocal  cords  on  each  side,  and  extending  nearly  their  entire  length. 
This  fossa  is  bounded  above  by  the  free  crescentic  edge  of  the  superior  vocal 
cord;  below,  by  the  straight  margin  of  the  true  vocal  cord;  externally,  by  the 
corresponding  Thyro-arytaenoideus  muscle.  The  anterior  part  of  the  ventricle 
leads  up  by  a  narrow  opening  into  a  csecal  pouch  of  mucous  membrane  of 
variable  size,  called  the  laryngeal  pouch. 

The  sacculus  laryngis,  or  laryngeal  pouch,  is  a  membranous  sac,  placed  between 
the  superior  vocal  cord  and  the  inner  surface  of  the  thyroid  cartilage,  occasion- 
ally extending  as  far  as  its  upper  border ;  it  is  conical  in  form,  and  curved 
slightly  backwards,  like  a  Phrygian  cap.  On  the  surface  of  its  mucous  mem- 
brane are  the  openings  of  sixty  or  seventy  small  follicular  glands,  which  are 
lodged  in  the  submucous  areolar  tissue.  This  sac  is  inclosed  in  a  fibrous  capsule, 
continuous  below  with  the  superior  thyro-arytenoid  ligament;  its  laryngeal 
surface  is  covered  by  the  Arytseno-epiglottideus  Inferior  muscle  {Compressor 
Sacculi  Laryngis,  Hilton);  whilst  its  exterior  is  covered  by  the  Thyro-epiglot- 
tideus  muscle.  These  muscles  compress  the  sacculus  laryngis,  and  discharge 
the  secretion  it  contains  upon  the  chordas  vocales,  the  surface  of  which  it  is 
intended  to  lubricate. 

Muscles.  The  intrinsic  muscles  of  the  larynx  are  eight  in  number ;  five  of 
which  are  the  muscles  of  the  chordae  vocales  and  rima  glottidis;  three  are  con- 
nected with  the  epiglottis. 

The  five  muscles  of  the  chordae  vocales  and  rima  glottidis  are  the 


Crico-thyroid.  Arytaenoideus. 

Crico-arytsenoideus  Posticus.  Thyro-arytaenoideus. 

Crico-arytsenoideus  Lateralis. 


sidaSI 


The  Crico-thyroid  is  triangular  in  form,  and  situated  at  the  fore  part  and 
of  the  cricoid  cartilage.  It  arises  from  the  front  and  lateral  part  of  the  cricoid 
cartilage;  its  fibres  diverge,  passing  obliquely  upwards  and  outwards,  to  be 
inserted  into  the  lower  and  inner  borders  of  the  thyroid  cartilage,  from  near  the 
median  line  in  front,  as  far  back  as  the  inferior  cornu. 

The  inner  borders  of  these  two  muscles  are  separated  in  the  middle  line  by  n 
triangular  interval,  occupied  by  the  crico-thyroid  membrane. 

The  Crico-arytsenoideus  Posticus  arises  from  the  broad  depression  occupying 
each  lateral  half  of  the  posterior  surface  of  the  cricoid  cartilage ;  its  fibres  pass 
upwards  and  outwards,  and  converge  to  be  inserted  into  the  outer  angle  of  the 
base  of  the  arytenoid  cartilage.  The  upper  fibres  are  nearly  horizontal,  the 
middle  oblique,  and  the  lower  almost  vertical.* 

•  Dr.  Mcrkel  of  Lcipsic  has  lately  described  a  muscular  slip  •which  occasionally  extends  be- 
tween the  outer  border  of  the  posterior  surface  of  the  cricoid  cartilage,  and  the  posterior  marjjia 
of  the  inferior  cornu  of  the  thyroid ;  this  he  calls  the  "  Musculus  Kerato-cricoideus."  It  is  not 
found  in  every  larvnx,  and  when  present  exists  usually  only  on  one  side,  but  is  occasionally  found 
on  both  sides.  ^Ir.  Turner  {Edinburgh  Medical  Journal,  Feb.  I860)  states  that  it  is  found  in 
about  one  case  in  five.  Its  action  is  to  fix  the  lower  horn  of  the  thyroid  cartilage  backwards 
and  downwards,  opposing  in  some  measure  the  part  of  the  crico-thyroid  muscle,  which  is  con- 
nected to  the  anterior  margin  of  the  horn. 


I 


INTRINSIC    MUSCLES    OF    LARYNX. 


775 


Fipr.  426. — Muscles  of  Larynx.     Side  Yiew. 
Bight  Ala  of  Thyroid  Cartilage  removed. 


The  Crico-arylsenoideus  Lateralis  is  smaller  thaa  the  preceding,  and  of  an 
r)blong  form.  It  arises  from  the  upper  border  of  the  side  of  the  cricoid  carti- 
lage, and,  passing  obliquely  upwards  and  backwards,  is  inserted  into  the  outer 
angle  of  the  base  of  the  arytenoid  cartilage,  in  front  of  the  preceding  muscle. 

The  Tliyro-arytsenoideus  is  a  broad,  flat  muscle,  which  lies  parallel  with  the 
outer  side  of  the  true  vocal  cord.  It 
arises  in  front  from  the  lower  half  of  the 
receding  angle  of  the  thyroid  cartilage, 
and  from  the  crioo-thyroid  membrane. 
Its  fibres  pass  horizontally  backwards 
and  outwards,  to  be  inserted  into  the 
base  and  anterior  surface  of  the  arytenoid 
cartilage.  This  muscle  consists  of  two 
fasciculi.  The  inferior^  the  thicker,  is 
inserted  into  the  anterior  angle  of  the 
base  of  the  arytenoid  cartilage,  and  into 
the  adjacent  portion  of  its  anterior  sur- 
face; it  lies  parallel  with  the  true  vocal 
cord,  to  which  it  is  occasionally  adherent. 
The  superior  fasciculus,  the  thinner,  is 
inserted  into  the  anterior  surface  and 
outer  border  of  the  arytenoid  cartilage 
above  the  preceding  fibres ;  it  lies  on  the 
outer  side  of  the  sacculus  laryngis,  imme- 
diately beneath  its  mucous  lining. 

The  Arytsenoideus  is  a  single  muscle, 
filling  up  the  posterior  concave  surface 
of  the  arytenoid  cartilages.  It  arises 
from  the  posterior  surface  and  outer 
border  of  one  arytenoid  cartilage,  and  is 
inserted  into  the  corresponding  parts  of 
the  opposite  cartilage.  It  consists  of 
three  planes  of  fibres :  two  oblique,  and 
one  transverse.  The  ohlique  fibres,  the 
most  superficial,  form  two  fasciculi,  which 
pass  from  the  base  of  one  cartilage  to 
the  apex  of  the  opposite  one.  The 
transverse  fibres,  the  deepest  and  most 
numerous,  pass  transversely  across  be- 
tween the  two  cartilages;  hence  the 
ArytEenoideus  was  formerly  considered 
as  several  muscles,  under  the  names  of 
transversi  and  obliqui.  A  few  of  the 
oblique  fibres  are  occasionally  continued 
round  the  outer  margin  of  the  cartilage, 
and  blend  with  the  Thyro-arytenoid  or 
the  Arytasno-epiglottideus  muscle. 

The  muscles  of  the  epiglottis  are,  the 

Thyro-epiglottideus. 
Arytseno-epiglottideus  Superior. 
Arytgeno-epiglottideus  Inferior. 

The  Tliyro-ej)iglottideus  is  a  delicate 
fasciculus,  which  arises  from  the  inner 
surface  of  the  thyroid  cartilage,  just  ex- 
ternal to  the  origin  of  the  Thyro-aryte- 
noid muscle,  and  spreading  out  upon  the 


JirHeulitr  facet' 
TXyrotd  Ca.tt't 


Fig.  427. — Interior  of  the  Larynx,  seen 
from  above.     (Enlarged.) 


776  ORGANS    OF    VOICE    AND    RESPIRATION. 

outer  surface  of  the  sacculus  laryngis,  some  of  its  fibres  are  lost  in  the  aryteno- 
epiglottidean  fold,  whilst  others  are  continued  forwards  to  the  margin  of  the 
epiglottis  [Depressor  EjngloUidis). 

The  Arytseno-epiglottideiis  Superior  consists  of  a  few  delicate  muscular  fasciculi, 
which  arise  from  the  apex  of  the  arytenoid  cartilage,  and  become  lost  in  the 
fold  of  mucous  membrane  extending  between  the  arytenoid  cartilage  and  side 
of  the  epiglottis  {aryteno-epiglottidean  folds). 

The  Arytseno-epiglottideus  Inferior  {Compressor  Sacculi  Laryngis^  Hilton)  arises 
from  the  arytenoid  cartilage,  just  above  the  attachment  of  the  superior  vocal 
cord ;  passing  forwards  and  upwards,  it  spreads  out  upon  the  inner  and  upper 
part  of  the  sacculus  laryngis,  and  is  inserted,  by  a  broad  attachment,  into  the 
margin  of  the  epiglottis.  This  muscle  is  separated  from  the  preceding  by  an 
indistinct  areolar  interval. 

Actions.  In  considering  the  action  of  the  muscles  of  the  larynx,  they  may 
be  conveniently  divided  into  two  groups,  viz:  1.  Those  which  open  and  close 
the  glottis.     2.  Those  which  regulate  the  degree  of  tension  of  the  vocal  cords. 

1.  The  muscles  which  open  the  glottis  are  the  Crico-arytasnoidei  Postici ;  and 
those  which  close  it,  are  the  Arytaenoideus,  and  the  Crico-arytaenoidei  Laterales. 
2.  The  muscles  which  regulate  the  tension  of  the  vocal  cords  are,  the  Crico- 
thyroidei,  which  tense  and  elongate  them;  and  the  Thyro-arytsenoidei,  which 
relax  and  shorten  them.  The  Thyro-epiglottideus  is  a  depressor  of  the  epiglottis, 
and  the  Arytseno-epiglottidei  constrict  the  superior  aperture  of  the  larynx, 
compress  the  sacculi  laryngis,  and  empty  them  of  their  contents. 

The  Crico-artftcenotdet  Postici  separate  the  chordae  vocales,  and,  consequently,  open  the 
glottis,  by  rotating  the  base  of  the  arytenoid  cartilages  outwards  and  backwards  ;  so  that  their 
anterior  angles,  and  the  ligaments  attached  to  them,  become  widely  separated,  the  vocal  cords, 
at  the  same  time,  being  made  tense. 

The  Grico-arytcenoidei  Laterales  close  the  glottis,  by  rotating  the  base  of  the  arytenoid  carti- 
lages inwards,  so  as  to  approximate  their  anterior  angles. 

The  Arytaenoideus  muscle  approximates  the  arytenoid  cartilages,  and  thus  closes  the  opening 
of  the  glottis,  especially  at  its  back  part. 

The  Crico4hyroid  muscles  produce  tension  and  elongation  of  the  vocal  cords,  by  drawing 
down  the  thyroid  cartilage  over  the  cricoid. 

The  Thyro-arytcenoidei  muscles  draw  the  arytenoid  cartilages,  together  with  the  part  of  the 
cricoid  to  which  they  are  connected,  forwards  towards  the  thyroid,  and  thus  shorten  and  relax 
the  vocal  cords. 

The  Thyro-epiglottidei  depress  the  epiglottis,  and'  assist  in  compressing  the  sacculi  laryngis. 
The  Arytajno-epiglottideus  Superior  constricts  the  superior  aperture  of  the  larynx,  when  it  is 
drawn  upwards,  during  deglutition,  and  the  opening  closed  by  the  epiglottis.  The  Arytteno- 
epiglottideus  Inferior,  together  with  some  fibres  of  the  Thyro-arytsenoidei,  compress  the  sacculus 
laryngis. 

The  Mticons  Membrane  of  the  Larynx  is  continuous,  above,  with  that  lining 
the  mouth  and  pharynx,  and  is  prolonged  through  the  trachea  and  bronchi  into 
the  lungs.  It  lines  both  surfaces  of  the  epiglottis,  to  which  it  is  closely  adhe- 
rent, and  forms  the  aryteno-epiglottidean  folds,  which  encircle  the  superior 
aperture  of  the  larynx.  It  lines  the  whole  of  the  cavity  of  the  larynx ;  forms, 
by  its  reduplication,  the  chief  part  of  the  superior,  or  false,  vocal  cord;  and, 
from  the  ventricle,  is  continued  into  the  sacculus  laryngis.  It  is  then  reflected 
over  the  true  vocal  cords,  where  it  is  thin,  and  very  intimately  adherent;  covers 
the  inner  surface  of  the  crico-thyroid  membrane,  and  cricoid  cartilage ;  and  is 
ultimately  continuous  with  the  lining  membrane  of  the  trachea.  It  is  covered 
with  columnar  ciliated  epithelium,  below  the  superior  vocal  cord ;  but,  above 
this  point,  the  ciliae  are  found  only  in  front,  as  high  as  the  middle  of  the 
epiglottis.     In  the  rest  of  its  extent,  the  epithelium  is  of  the  squamous  variety. 

Olands.  The  mucous  membrane  of  the  larynx  is  furnished  with  numerous 
muciparous  glands,  the  orifices  of  which  are  found  in  nearly  every  part :  they 
are  very  numerous  upon  the  epiglottis,  being  lodged  in  little  pits  in  its  sub- 
stance ;  they  are  also  found  in  large  numbers  along  the  posterior  margin  of  the 
aryteno-epiglottidean  fold,  in  front  of  the  arytenoid  cartilages,  where  they  are 


VESSELS    AND    NERVES    OF    LARYNX. 


Ill 


termed  tlie  arytenoid  glands.     They  exist  also  in  large  numbers  upon  the  inner 
surface  of  the  sacculus  laryngis.     None  are  found  on  the  vocal  cords. 

Vessels  and  Nerves.  The  arteries  of  the  larynx  are  the  laryngeal  branches 
derived  from  the  superior  and  inferior  thyroid.  The  veins  empty  themselves 
into  the  superior,  middle,  and  inferior  thyroid  veins.  The  lymphatics  terminate 
in  the  deep  cervical  glands.  The  nerves  are  the  superior  laryngeal,  and  the  in- 
ferior or  recurrent  laryngeal  branches  of  the  pueumogastric  nerves,  joined  by 
filaments  from  the  sympathetic.  The  superior  laryngeal  nerves  supply  the 
mucous  membrane  of  the  larynx,  and  the  Crico-thyroid  muscles.  The  inferior 
laryngeal  nerves  supply  the  remaining  muscles.  The  Arytenoid  muscle  is 
supplied  by  both  nerves. 

The  Trachea.    (Fig.  428). 

The  Trachea,  or  air-tube,  is  a  cartilaginous  and  membranous  cylindrical  tube, 
flattened   posteriorly,  which  extends  from  the  lower  part  of  the  larynx,  on  a 

Fi^,  428. — Front  View  of  Cartilarres  of  Larynx;  the  Trachea  and  Bronchi. 


Superior 
Cornu 


level   with   the   fifth  cervical  vertebra,  to  opposite  the  third  dorsal,  where  it 
divides  into  the  two  bronchi,  one  for  each  lung.     Tlie  trachea  measures  about 


778  ORGANS    OF    VOICE    AND    RESPIRATION. 

f(5ur  inches  and  a  half  in  length  ;  its  diameter,  from  side  to  side,  is  from  three- 
quarters  of  an  inch  to  an  inch,  being  always  greater  in  the  male  than  in  the 
female. 

Relations.  The  anterior  surface  of  the  trachea  is  convex,  and  covered,  in  the 
neck,  from  above  downwards,  by  the  isthmus  of  the  thyroid  gland,  the  inferior 
thyroid  veins,  the  arteria  thyroidea  ima  (when  that  vessel  exists),  the  Sterno- 
hyoid and  Sterno-thyroid  muscles,  the  cervical  fascia  (in  the  interval  between 
those  muscles),  and,  more  superficially,  by  the  anastomosing  branches  between 
the  anterior  jugular  veins  ;  in  the  thorax,  it  is  covered  from  before  backwards 
by  the  first  piece  of  the  sternum,  the  remains  of  the  thymus  gland,  the  arch  of 
the  aorta,  the  innominate  and  left  carotid  arteries,  and  the  deep  cardiac  plexus. 
It  lies  upon  the  oesophagus,  which  is  directed  to  the  left,  near  the  arch  of  the 
aorta ;  laterally,  in  the  neck,  it  is  in  relation  with  the  common  carotid  arteries, 
the  lateral  lobes  of  the  thyroid  gland,  the  inferior  thyroid  arteries,  and  recur- 
rent laryngeal  nerves ;  and,  in  the  thorax,  it  lies  in  the  interspace  between  the 
pleuras,  having  the  pneumogastric  nerve  on  each  side  of  it. 

The  Bight  Bronchus,  wider,  shorter,  and  more  horizontal  in  direction  than  the 
left,  is  about  an  inch  in  length,  and  enters  the  right  lung,  opposite  the  fourth 
dorsal  vertebra.  The  vena  azygos  arches  over  it,  from  behind ;  and  the  right 
pulmonary  artery  lies  below,  and  then  in  front  of  it. 

The  Left  Bronchus  is  smaller,  more  oblique,  and  longer  than  the  right,  being 
nearly  two  inches  in  length.  It  enters  the  root  of  the  left  lung,  opposite  the 
fifth  dorsal  vertebra,  about  an  inch  lower  than  the  right  bronchus.  It  crosses 
in  front  of  the  oesophagus,  the  thoracic  duct,  and  the  descending  aorta;  passes 
beneath  the  arch  of  the  aorta,  and  has  the  left  pulmonary  artery  lying  at  first 

above,  and   then   in  front  of  it.     If  a 

Fig.  429.— Transverse  Section  of  the  Trachea,     transverse  section  is  made  across  the 

just  above  its  Bifurcation,  with  a  bird's  eye    trachea,  a  short  distance  above  its  point 

view  of  the  interior.  n  -.-p  '      ,.  -,         i  •   j)  • 

oi  bifurcation,  and   a   bird  s  eye  view 

taken  of  its  interior  (Fig.  429),  the  sep-  - - 
tum  placed  at  the  bottom  of  the  trachea  ■I 
and  separating  the  two  bronchi  will  be 
seen  to  occupy  the  left  of  the  median  line, 
as  was  first  shown  by  Mr.  Goodall,  of 
Dublin,  so  that  any  solid  body  dropping 
into  the  trachea,  would  naturally  be  di- 
rected towards  the  right  bronchus,  and 
this  tendency  is  undoubtedly  aided  by 
the  larger  size  of  this  tube,  as  compared  with  its  fellow.     This  fact  serves  to 
explain  why  a  foreign  substance  in  the   trachea  generally  falls  into  the  right 
bronchus. 

The  trachea  is  composed  of  imperfect  cartilaginous  rings,  fibrous  membrane, 
muscular  fibres,  longitudinal  yellow  elastic  fibres,  mucous  membrane,  and  glands. 
The  Cartilages  y&ry  from  sixteen  to  twenty  in  number;  each  forms  an  im- 
perfect ring,  which  surrounds  about  two-thirds  of  the  cylinder  of  the  trachea, 
being  imperfect  behind,  where  the  tube  is  completed  by  fibrous  membrane.  The 
cartilages  are  placed  horizontally  above  each  other,  separated  by  narrow  mem- 
branous intervals.  They  measure  about  two  lines  in  depth,  and  half  a  line  in 
thickness.  Their  outer  surfaces  are  flattened,  but,  internally,  they  are  convex, 
from  being  thicker  in  the  middle  than  at  the  margins.  The  cartilages  are  con- 
nected together  at  their  margins,  by  an  elastic  fibrous  membrane,  which  covers 
both  their  surfaces ;  and  in  the  space  between  tlieir  extremities,  behind,  forms 
a  distinct  layer.     The  peculiar  cartilages  are  the  first  and  the  last.  fll 

Thejirst  cartilage  is  oroader  than  the  rest,  and  sometimes  divided  at  one  end:  ■■ 
it  is  connected  by  fibrous  membrane  with  the  lower  border  of  the  cricoid  car- 
tilage, with  which,  or  with  the  succeeding  cartilage,  it  is  sometimes  blended. 
The  last  cartilage  is  thick  and  broad  in  the  middle,  in  consequence  of  its  lower 


I 
I 


TRACHEA.  779 

border  being  prolonged  downwards,  and,  at  the  same  time,  curved  backwards, 
at  the  point  of  bifurcation  of  the  trachea.  It  termiuates  on  each  side  in  an  im- 
perfect ring,  which  incloses  the  commencement  of  the  bronchi.  The  cartilage 
above  the  last  is  somewhat  broader  than  the  rest  at  its  centre.  Two  or  more 
of  the  cartilages  often  unite,  partially  or  completely,  and  are  sometimes  bifur- 
cated at  their  extremities.  They  are  highly  elastic,  and  seldom  ossify,  even  in 
advanced  life.  In  the  right  bronchus,  the  cartilages  vary  in  number  from  six 
to  eight;  in  the  left,  from  nine  to  twelve.  They  are  shorter  and  narrower  than 
those  of  the  trachea. 

The  Muscular  Fibres  are  disposed  in  two  layers,  longitudinal  and  transverse. 
The  longitudinal  fibres  are  the  most  external,  and  arise  by  minute  tendons  from 
the  termination  of  the  tracheal  cartilages,  and  from  the  fibrous  membrane. 

The  transverse  fibres  (Trachealis  muscle,  Todd  and  Bowman),  the  most  inter- 
nal, form  a  thin  layer,  which  extends  transversely  between  the  ends  of  the  car- 
tilages, at  the  posterior  part  of  the  trachea.  The  muscular  fibres  are  of  the 
unstriped  variety. 

The  Elastic  Fibres  are  situated  beneath  the  mucous  membrane,  inclosing  the 
entire  cylinder  of  the  trachea;  they  are  most  abundant  at  its  posterior  part, 
where  they  are  collected  into  longitudinal  bundles. 

The  Mucous  Membrane  lining  the  tube  is  covered  with  columnar  ciliated 
epithelium.  It  is  continuous  above  with  that  of  the  larynx,  and  below  with 
that  of  the  lungs. 

The  Tracheal  Glands  are  found  in  great  abundance  at  the  posterior  part  of  the 
trachea.  They  are  small,  flattened,  ovoid  bodies,  placed  between  the  fibrous 
and  muscular  coats,  each  furnished  with  an  excretory  duct,  which  opens  on  the 
surface  of  the  mucoas  membrane.  Some  glands  of  smaller  size  are  also  found 
at  the  sides  of  the  trachea,  between  the  layers  of  fibrous  tissue  connecting  the 
rings,  and  others  immediately  beneath  the  mucous  coat.  The  secretion  from 
these  glands  serves  to  lubricate  the  inner  surface  of  the  trachea. 

Vessels  and  Nerves.  The  trachea  is  supplied  with  blood  by  the  inferior  thy- 
roid arteries.  The  veins  terminate  in  the  thyroid  venous  plexus.  The  nerves 
are  derived  from  the  pneumogastric  and  its  recurrent  branches,  and  from  the 
sympathetic. 

Surgical  Anatomy.  The  air-passage  may  be  opened  in  three  different  situations  :  through 
the  crlco-thyroid  membrane  [laryngotomy),  through  the  cricoid  cartilage  and  upper  ring  of  the 
trachea  [laryngo-tracheotomy),  or  through  the  trachea  below  the  isthmus  of  the  thyroid  gland 
{iracheotomy).  The  student  should,  therefore,  carefully  consider  the  relative  anatomy  of  the 
air-tube  in  each  of  these  situations. 

Beneath  the  integument  of  the  laryngo-tracheal  region,  on  either  side  of  the  median  line,  are 
the  two  anterior  jugular  veins.  Their  size  and  position  vary;  there  is  nearly  always  one,  and 
frequently  two  :  at  the  lower  part  of  the  neck  they  diverge,  passing  beneath  the  Sterno-raastoid 
muscles,  and  are  frequently  connected  by  a  transverse  communicating  branch.  These  veins 
should,  if  possible,  always  be  avoided  in  any  operation  on  the  larynx  or  trachea.  If  cut  through, 
considerable  hemorrhage  occurs. 

Beneath  the  cervical  fascia  are  the  Sterno-hyoid  and  Stemo-thyroid  muscles,  the  contiguous 
edges  of  the  former  being  near  the  median  line;  and  beneath  these  muscles  the  following  parts 
are  met  with,  from  above  downwards :  the  thyroid  cartilage,  the  crico-thyroid  membrane,  the 
cricoid  cartilage,  the  trachea,  and  the  isthmus  of  the  thyroid  gland. 

The  crico-thyroid  space  is  very  superficial,  and  may  be  easily  felt  beneath  the  skin  as  a  depres- 
sion, about  an  inch  below  the  pomum  Adami;  it  is  crossed  transversely  by  a  small  artery,  the 
crico-thyroid,  the  division  of  which  is  seldom  accompanied  by  any  troublesome  hemorrhage. 

The  isthmus  of  the  thyroid  gland  usually  crosses  the  second  and  third  rings  of  the  trachea; 
above  it,  is  found  a  large  transverse  communicating  branch  between  the  superior  thyroid  veins, 
and  the  isthmus  is  covered  by  a  venous  plexus,  formed  between  the  thyroid  veins,  of  opposite 
sides.  On  the  sides  of  the  thyroid  gland,  and  below  it,  the  veins  converge  to  a  single  median 
vessel,  or  to  two  trunks  which  descend  along  the  median  line  of  the  front  of  the  trachea,  to  open 
into  the  innominate  veins  by  valved  orifices.  In  the  infant,  the  thymus  gland  ascends  a  variable 
distance  along  the  front  of  the  trachea :  and  the  innominate  artery  crosses  the  tube  obliquely  at 
the  root  of  the  neck,  from  left  to  right.  The  anterior  thyroidea  ima,  when  that  vessel  exists, 
passes  from  below  upwards  along  the  front  of  the  trachea.  The  upper  part  of  the  trachea  lies 
comparatively  superficial ;  but  the  lower  part  passes  obliquely  downwards  and  backwards,  so  as 
to  be  deeply  placed  between  the  converging  Sterno-mastoid  muscles.     In  the  child,  the  trachea 


•780  ORGANS    OF    VOICE    AND    RESPIRATION. 

is  smaller,  more  deeply  placed,  and  more  movable  than  in  the  adult.  In  fat,  or  short-necked 
people,  or  in  those  in  whom  the  muscles  of  the  neck  are  prominently  developed,  the  trachea  is 
more  deeply  placed  than  in  the  opposite  conditions. 

From  these  observations,  it  must  be  evident  that  laryngotomy  is  anatomically  the  most  simple 
operation,  can  most  readily  be  performed,  and  should  always  be  preferred  when  particular  cir- 
cumstances do  not  render  the  operation  of  tracheotomy  absolutely  necessary.  The  operation  is 
performed  thus :  The  head  being  thrown  back  and  steadied  by  an  assistant,  the  finger  is  passed 
over  the  front  of  the  neck,  and  the  crico-thyroid  depression  felt  for.  A  vertical  incision  is  then 
made  through  the  skin,  in  the  middle  line  over  this  spot,  and  the  crico-thyroid  membrane  is 
divided  to  a  suflScient  extent  to  allow  of  the  introduction  of  a  large  curved  tube.  The  crico- 
thyroid artery  is  the  only  vessel  of  importance  crossing  this  space.  If  it  should  be  of  large  size, 
its  division  might  produce  troublesome  hemorrhage. 

Fig.  430.— Surgical  Anatomy  of  Laryngo-tracheal  Region,  in  the  Infant. 


Crieo-tluiriiid  Hinabmti* 
'  le  Art»ry 
Cruroui  Ca'TtUagi 
ffiLp&rior  TTtyroid  vt-in 


Laryngchtracheotomy,  anatomically  considered,  is  more  dangerous  than  tracheotomy,  on 
account  of  the  small  interspace  between  the  cricoid  cartilage  and  the  isthmus  of  the  thyroid 
gland :  the  communicating  branches  between  the  superior  thyroid  veins,  which  cover  this  spot, 
can  hardly  fail  to  be  divided ;  and  the  greatest  care  will  not,  in  some  cases,  prevent  the  division 
of  part  of  the  thyroid  isthmus.  If  either  of  these  structures  is  divided,  the  hemorrhage  may  be 
considerable. 

Tracheotomy  below  the  isthmus  of  the  thyroid  gland  is  performed  thns :  The  head  being  thrown 
back  and  steadied  by  an  assistant,  an  incision,  an  inch  and  a  half  or  two  inches  in  length,  is 
made  through  the  skin,  in  the  median  line  of  the  neck,  from  a  little  below  the  cricoid  cartilage, 
to  the  top  of  the  sternum.  The  anterior  jugular  veins  should  be  avoided,  by  keeping  exactly  in 
the  median  line;  the  deep  fascia  should  then  be  divided,  and  the  contiguous  borders  of  the 
Sterno-hyoid  muscles  separated  from  each  other.  A  quantity  of  loose  areolar  tissue,  containing 
the  inferior  thyroid  veins,  must  then  be  separated  from  the  front  of  the  trachea,  with  the  handle 
of  the  scalpel ;  and  M'hen  the  trachea  is  well  exposed,  it  should  be  opened  by  inserting  the  knife 
into  it,  dividing  two  or  three  of  its  rings  from  below  upwards.  It  is  a  matter  of  the  greatest 
importance  to  restrain,  if  possible,  all  hemorrhage  before  the  tube  is  opened ;  otherwise,  blood 
may  pass  into  the  trachea,  and  suffocate  the  patient. 

The  Pleura. 

Each  lung  is  invested,  upon  its  external  surface,  by  an  exceedingly  delicate 
serous  membrane,  the  Pleura,  which  incloses  the  organ  as  far  as  its  root,  and  is 
then  reflected  upon  the  inner  surface  of  the  thorax.  The  portion  of  the  serous 
membrane  investing  the  surface  of  the  lung  is  called  the  2)?ewra  pulmonalis 
(visceral  layer  of  pleura);  whilst  that  which  lines  the  inner  surface  of  the 
chest  is  called  the  pleura  costalis  (parietal  layer  of  pleura).  The  interspace  or 
cavity  between  these  two  layers  is  called  the  cavity  of  the  pleura.     Each  pleura 


PLEURA. 


781 


is  therefore  a  shut  sac,  one  occupying  the  right,  the  other  the  left  half  of  the 
thorax ;  and  they  are  perfectly  separate,  not  communicating  with  each  other. 
The  two  pleurae  do  not  meet  in  the  middle  line  of  the  chest,  excepting  at  one 
point  in  front ;  an  interspace  being  left  between  them,  which  contains  all  the 
viscera  of  the  thorax,  excepting  the  lungs :  this  is  the  mediastinum. 

Reflections  of  the  pleura  (Fig.  431).  Commencing  at  the  sternum,  the  pleura 
passes  outwards,  covers  the  costal  cartilages,  the  inner  surface  of  the  ribs  and 
Intercostal  muscles,  and  at  the  back  of  the  thorax  passes  over  the  thoracic 
ganglia  and  their  branches,  and  is  reflected  upon  the  sides  of  the  bodies  of  the 
vertebrae,  where  it  is  separated  by  a  narrow  interspace  from  the  opposite  pleura, 
the  posterior  mediastinum.  From  the  vertebral  column  the  pleura  passes  to  the 
side  of  the  pericardium,  which  it  covers  to  a  slight  extent ;  it  then  covers  the 
back  part  of  the  root  of  the  lung,  from  the  lower  border  of  which  a  triangular 
fold  descends  vertically  by  the  side  of  the  posterior  mediastinum  to  the  Dia- 
phragm.    This  fold  is  the  broad  ligament  of  the  lung,  the  ligamentum  latum 


Fig.  431. — A  Transverse  Section  of  the  Thorax,  showing  the  relative  Position  of  the  Yiscera, 

and  the  Reflections  of  the  Pleura. 


TRIANaUUAdlS      STERN 

Jntemal  Mammary  Vttttls 


ZafiJ^rtme  lftrv» 


tHfu^n.  fiut-monaliB 
Pleura    Coslalit 


-_   ,.  \Su<mpa.thttio  iTervt 

Meataitttnum   ( 

'  Thoracio  Du 


Vena.  Axyyo 
Pneumogaitrtt. 


pulmonis,  and  serves  to  retain  the  lower  part  of  that  organ  in  position.  From 
the  root,  the  pleura  may  be  traced  over  the  convex  surface  of  the  lung,  the 
summit  and  base,  and  also  over  the  sides  of  the  fissures  between  the  lobes.  It 
covers  its  anterior  surface,  and  the  front  part  of  its  root,  and  is  reflected  upon 
the  side  of  the  pericardium  to  the  inner  surface  of  the  sternum.  Behw,  it 
covers  the  upper  surface  of  the  Diaphragm.  Above,  its  apex  projects,  in  the 
form  of  a  cul-de-sac,  through  the  superior  opening  of  the  thorax  into  the  neck, 
extending  about  an  inch  above  the  margin  of  the  first  rib,  and  receives  the 
summit  of  the  corresponding  lung ;  this  sac  is  strengthened,  according  to  Dr. 
Sibson,  by  a  dome-like  expansion  of  fascia,  derived  from  the  lower  part  of  the 
Scaleni  muscles. 

A  little  above  the  middle  of  the  sternum,  the  contiguous  surfaces  of  the  two 
pleurae  are  sometimes  in  contact  for  a  slight  extent;  but  above  and  below  this 
point,  the  interval  left  between  them  forms  the  anterior  mediastinum. 


782  ORGANS    OF    YOICE    AND    RESPIRATION. 

The  inner  surface  of  the  pleura  is  smooth,  polished,  and  moistened  by  a 
serous  fluid.  Its  outer  surface  is  intimately  adherent  to  the  surface  of  the  lung, 
and  to  the  pulmonary  vessels  as  they  emerge  from  the  pericardium;  it  is  also 
adherent  to  the  upper  surface  of  the  Diaphragm :  throughout  the  rest  of  its 
extent,  it  is  somewhat  thicker,  and  may  be  separated  from  the  adjacent  parts 
with  extreme  facility. 

The  right  pleural  sac  is  shorter,  wider,  and  reaches  higher  in  the  neck  than 
the  left. 

Vessels  and  Nerves.  The  arteries  of  the  pleura  are  derived  from  the  inter- 
costal, the  internal  mammary,  the  phrenic,  inferior  thyroid,  thymic,  pericardiac, 
and  bronchial.  The  veins  correspond  to  the  arteries.  The  lymphatics  are  very 
numerous.  The  nerves  are  derived  from  the  phrenic  and  sympathetic  (Luschka). 
Kiilliker  states  that  nerves  accompany  the  ramifications  of  the  bronchial  arteries 
in  the  pleura  pulmonalis. 

Mediastinum. 

The  Mediastinum  is  the  space  left  in  the  median  line-of  the -chest  by  the  non- 
approximation  of  the  two  pleurae.  It  extends  from  the  sternum  in  front  to  the 
spine  behind,  and  contains  all  the  viscera  in  the  thorax,  excepting  the  lungs. 
The  mediastinum  is  subdivided,  for  convenience  of  description,  into  the  anterior, 
middle,  and  posterior. 

The  anterior  mediastinum  is  bounded  in  front  by  the  sternum,  on  each  side  by 
the  pleura,  and  behind  by  the  pericardium.  Owing  to  the  oblique  position  of 
the  heart  towards  the  left  side,  this  space  is  not  parallel  with  the  sternum,  but 
directed  obliquely  from  above  downwards,  and  to  the  left  of  the  median  line; 
it  is  broad  below,  narrow  above,  very  narrow  opposite  the  second  piece  of  the 
sternum,  the  contiguous  surfaces  of  the  two  pleurae  being  occasionally  united 
over  a  small  space.  The  anterior  mediastinum  contains  the  origin  of  the  Sterno-  _ - 
hyoid  and  Sterno-thyroid  muscles,  the  Triangularis  Sterni,  the  internal  mam-ftl 
mary  vessels  of  the  left  side,  the  remains  of  the  thymus  gland,  and  a  quantity 
of  loose  areolar  tissue,  in  which  some  lymphatic  vessels  are  found  ascending 
from  the  convex  surface  of  the  liver. 

The  middle  mediastinum  is  the  broadest  part  of  the  interpleural  space.  It 
contains  the  heart  inclosed  in  the  pericardium,  the  ascending  aorta,  the  superior 
vena  cava,  the  bifurcation  of  the  trachea,  the  pulmonary  arteries  and  veins,  and 
the  phrenic  nerves. 

The  posterior  mediastinum  is  an  irregular  triang]ar  space,  running  parallel 
with  the  vertebral  column ;  it  is  bounded  in  front  by  the  pericardium  and  roots 
of  the  lungs,  behind  by  the  vertebral  column,  and  on  either  side  by  the  pleura. 
It  contains  the  descending  aorta,  the  greater  and  lesser  azygos  veins  and  left 
superior  intercostal  vein,  the  pneumogastric  and  splanchnic  nerves,  the  oesopha- 
gus, thoracic  duct,  and  some  lymphatic  glands. 


I 


The  Lungs. 

The  Lungs  are  the  essential  organs  of  respiration;  they  are  two  in  number; 
placed  one  in  each  of  the  lateral  cavities  of  the  chest,  separated  from  each  other 
by  the  heart  and  other  contents  of  the  mediastinum.  Each  lung  is  conical  in 
shape,  and  presents  for  examination  an  apex,  a  base,  two  borders,  and  two  sur- 
faces (see  Fig.  418,  p.  756). 

The  apex  forms  a  tapering  cone,  which  extends  into  the  root  of  the  neck, 
about  an  inch  to  an  inch  and  a  half  above  the  level  of  the  first  rib. 

The  hase  is  broad,  concave,  and  rests  upon  the  convex  surface  of  the  Dia- 
phragm ;  its  circumference  is  thin,  and  fits  into  the  space  between  the  lower 
ribs  and  the  costal  attachment  of  the  Diaphragm,  extending  lower  down  exter- 
nally and  behind  than  in. front. 


I 


THE    LUNGS, 


Fi":.  432. — The  Posterior  Mediastinum. 


783 


The  external  or  thoracic  surface  is  smooth,  convex,  of  considerable  extent,  and 
corresponds  to  the  form  of  the  cavity  of  the  cliest,  being  deeper  behind  than 
in  front. 

The  inner  surface  is  concave.  It  presents,  in  front,  a  depression  correspond- 
ing to  the  convex  surface  of  the  pericardium,  and  behind,  a  deep  fissure  (the 
hilum  pulmonis)  which  gives  attachment  to  the  root  of  the  lung. 

^h.Q  posterior  border  is  rounded  and  broad,  and  is  received  in  the  deep  con- 


784 


ORGANS    OF    VOICE    AND    RESPIRATION. 


cavity  on  either  side  of  the  spinal  column.  It  is  much  longer  than  the  anterior 
border,  and  projects  below  between  the  ribs  and  the  Diaphragm. 

The  anterior  border  is  thin  and  sharp,  and  overlaps  the  front  of  the  peri- 
cardium. 

The  anterior  border  of  the  right  lung  corresponds  to  the  median  line  of  the 
sternum,  and  is  in  contact  with  its  fellow,  the  pleurae  being  interposed,  as  low 
as  the  fourth  costal  cartilage ;  below  this,  the  contiguous  borders  are  separated 
by  an  irregularly  shaped  interval,  formed  at  the  expense  of  the  anterior  border 
of  the  left  lung,  and  in  which  the  pericardium  is  exposed. 

Fig.  433. — ^Front  View  of  the  Heart  and  Lungs. 


Duetia  Arteria 


Each  lung  is  divided  into  two  lobes,  an  tipper  and  lower,  by  a  long  and  deep 
fissure,  which  extends  from  the  upper  part  of  the  posterior  border  of  tlie  organ, 
about  three  inches  from  its  apex,  downwards  and  forwards,  to  the  lower  part  of  fll 
its  anterior  border.  This  fissure  penetrates  nearly  to  the  root.  In  the  right 
lung  the  upper  lobe  is  partially  divided  by  a  second  and  shorter  fissure,  which 
extends  from  the  middle  of  the  preceding,  forwards  and  upwards,  to  the  anterior 
margin  of  the  organ,  marking  ofi'a  small  triangular  portion,  the  middle  lobe. 

The  rvjht  lung  is  the  largest;  it  is  broader  than  the  left,  owing  to  the  inclina- 
tion of  the  heart  to  the  left  side;  it  is  also  shorter  by  an  inch,  in  consequence 
of  the  Diaphragm  rising  higher  on  the  right  side  to  accommodate  the  liver.  The 
right  lung  has  three  lobes. 

The  left  lung  is  smaller,  narrower,  and  longer  than  the  right,  and  has  only 
two  lobes. 

A  little  above  the  middle  of  the  inner  surface  of  each  lung,  and  nearer  its 
posterior  than  its  anterior  border,  is  its  root,  by  which  tlie  lung  is  connected  to 
the  heart  and  the  tracliea.  The  root  is  formed  by  the  bronchial  tube,  the  pul- 
monary artery,  the  pulmonary  veins,  the  bronchial  arteries  and  veins,  the  pul- 


THE    LUNGS.  Y85 

monary  plexus  of  nerves,  lymphatics,  bronchiar  glands,  and  areolar  tissue,  all 
of  which  are  inclosed  by  a  reflection  of  the  pleura.  The  root  of  the  right  lung 
lies  behind  the  superior  cava  and  upper  part  of  the  right  auricle,  and  below  the 
yena^azygos.  That  of  the  left  lung  passes  beneath  the  arch  of  the  aorta,  and 
in  front  of  the  descending  aorta;  the  phrenic  nerve  and  the  anterior  pulmonary 
plexus  lie  in  front  of  each,  and  the  pneumogastric  and  posterior  pulmonary- 
plexus  behind  each. 

The  chief  structures  composing  the  root  of  each  lung  are  arranged  in  a  similar 
manner  from  before  backwards  on  both  sides,  viz  :  the  pulmonary  veins  most 
anterior ;  the  pulmonary  artery  in  the  middle ;  and  the  bronchus,  together  with 
the  bronchial  vessels,  behind.  From  above  downwards,  on  the  two  sides,  their 
arrangement  differs,  thus: — 

On  the  right  side,  their  position  is,  bronchus,  pulmonary  artery,  pulmonary 
veins;  but  on  the  left  side  their  position  is,  pulmonary  artery,  bronchus,  pul- 
monary veins  ;  which  is  accounted  for  by  the  bronchus  being  placed  on  a  lower 
level  on  the  left  than  on  the  right  side. 

The  weight  of  both  lungs  together  is  about  forty-two  ounces,  the  right  lung 
being  two  ounces  heavier  than  the  left ;  but  much  variation  is  met  with  accord- 
ing to  the  amount  of  blood  or  serous  fluid  they  may  contain.  The  lungs  are 
heavier  in  the  male  than  in  the  female,  their  proportion  to  the  body  being,  in 
the  former,  as  1  to  37,  in  the  latter  as  1  to  43.  The  specific  gravity  of  the  lung- 
tissue  varies  from  345  to  746,  water  being  1000. 

The  color  of  the  lungs  at  birth  is  a  pinkish  white ;  m  adult  life,  a  dark  slate 
color,  mottled  in  patches ;  and,  as  age  advances,  this  mottling  assumes  a  black 
color.  The  coloring  matter  consists  of  granules  of  a  carbonaceous  substance, 
deposited  in  the  areolar  tissue  near  the  surface  of  the  organ.  It  increases  in 
quantity  as  age  advances,  and  is  more  abundant  in  males  than  in  females.  The 
posterior  border  of  the  lung  is  usually  darker  than  the  anterior.  The  surface 
of  the  lung  is  smooth,  shining,  and  marked  out  into  numerous  polyhedral  spaces, 
indicating  the  lobules  of  the  organ :  the  area  of  each  of  these  spaces  is  crossed 
by  numerous  lighter  lines. 

The  substance  of  the  lung  is  of  a  light,  porous,  spongy  texture ;  it  floats  in 
water,  and  crepitates  when  handled,  owing  to  the  presence  of  air  in  the  tissue ; 
it  is  also  highly  elastic ;  hence  the  collapsed  state  of  these  organs  when  they 
are  removed  from  the  closed  cavity  of  the  thorax. 

Structure.  The  lungs  are  composed  of  an  external  serous  coat,  a  subserous 
areolar  tissue,  and  the  pulmonary  substance  or  parenchyma. 

The  serous  coat  is  derived  from  the  pleura;  it  is  thin,  transparent,  and  invests 
the  entire  organ  as  far  as  the  root. 

The  subserous  areolar  tissue  contains  a  large  proportion  of  elastic  fibres;  it 
invests  the  entire  surface  of  the  lung,  and  extends  inwards  between  the  lobules. 
The  parenchyma  is  composed  of  lobules,  which,  although  closely  connected 
together  by  an  interlobular  areolar  tissue,  are  quite  distinct  from  one  another, 
and  are  easily  separable  in  the  foetus.  The  lobules  vary  in  size;  those  on  the 
surface  are  large,  of  a  pyramidal  form,  the  base  turned  towards  the  surface ; 
those  in  the  interior  smaller,  and  of  various  forms.  Each  lobule  is  composed 
of  one  of  the  ramifications  of  the  bronchial  tube  and  its  terminal  air-cells,  and 
of  the  ramifications  of  the  pulmonary  and  bronchial  vessels,  lymphatics,  and 
nerves:  all  of  these  structures  being  connected  together  by  areolar  fibrous 
tissue. 

The  bronchus  upon  entering  the  substance  of  the  lung,  divides  and  subdivides 
dichotomously  throughout  the  entire  organ.  Sometimes  three  branches  arise 
together,  and  occasionally  small  lateral  branches  are  given  off  from  the  sides 
of  a  main  trunk.  Each  of  the  smaller  subdivisions  of  the  bronchi  enters  a 
pulmonary  lobule  (lobular  bronchial  tube),  and,  again  subdividing,  ultimately 
terminates  in.  the  intercellular  passages  and  air-cells  of  which  the  lobule  is  com 
50 


186  ORGANS    OF    VOICE    AND    RESPIRATION. 

posed.  "Within  the  lungs  the  bronchial  tubes  are  circular,  not  flattened,  and 
their  constituent  elements  present  the  following  peculiarities  of  structure. 

The  cartilages  are  not  imperfect  rings,  but  consist  of  thin  laminae,  of  varied 
form  and  size,  scattered  irregularly  along  the  sides  of  the  tube,  being  most  dis- 
tinct at  the  points  of  division  of  the  bronchi.  They  may  be  traced  into  tTibes, 
the  diameter  of  which  is  only  one-fourth  of  a  line.  Beyond  this  point,  the  tubes 
are  wholly  membranous.  The  fibrous  coat,  and  longitudinal  elastic  fibres,  are 
continued  into  the  smallest  ramifications  of  the  bronchi.  The  muscular  coat  is 
disposed  in  the  form  of  a  continuous  layer  of  annular  fibres,  which  may  be 
traced  upon  the  smallest  bronchial  tubes ;  they  consist  of  the  unstriped  variety 
of  muscular  fibre.  The  mucous  membrane  lines  the  bronchi  and  its  ramifica- 
tions throughout,  and  is  covered  with  columnar  ciliated  epithelium. 

According  to  the  observations  of  Mr.  Eainey,^  the  lobular  bronchial  tubes, 
on  entering  the  substance  of  the  lobules,  divide  and  subdivide  from  four  to  nine 
times,  according  to  the  size  of  the  lobule,  continuing  to  diminish  in  size  until 
they  attain  a  diameter  of  3'^th  to  -g'f^th  of  an  inch.  They  then  become  changed 
in  structure,  losing  their  cylindrical  form,  and  are  continued  onwards  as  irregular 
passages  (intercellular  passages,  Eainey — air-sacs.  Waters),  through  the  sub- 
stance of  the  lobule,  their  sides  and  extremities  being  closely  covered  by  nume- 
rous saccular  dilatations,  the  air-cells.  This  arrangement  resembles  most  closely 
the  naked  eye  appearances  observed  in  the  reticulated  structure  of  the  lung  of 
the  tortoise,  and  other  reptilia.  Opinions  have  differed  as  to  the  existence  of 
communications  or  anastomoses  between  the  intercellular  passages,  or  air-sacs. 
According  to  Dr.  Waters,^  these  airsacs,  as  he  terms  them,  are  arranged  in 
groups,  or  "  lobulettes"  of  five  or  six,  which  spring  from  the  terminal  dilatation 
of  a  single  bronchial  tube,  but  have  no  other  communication  with  each  other, 
or  with  neighboring  lobulettes,  than  that  which  is  afforded  by  their  common 
connection  with  the  bronchial  tubes. 

The  air-cells^  or  alveoli  (Waters),  are  small,  polyhedral,  alveolar  recesses, 
separated  from  each  other  by  thin  septa,  and  communicating  freely  with  the 
intercellular  passages  or  air-sacs.  They  are  well  seen  on  the  surface  of  the  lung, 
and  vary  from  n^^th  to  ^\i\i.  of  an  inch  in  diameter;  being  largest  on  the  surface, 
at  the  thin  borders,  and  at  the  apex;  and  smallest  in  the  interior. 

At  the  termination  of  the  bronchial  tubes,  in  the  intercellular  passages,  their 
constituent  elements  become  changed :  their  walls  are  formed  by  an  interlacing 
of  the  longitudinal  elastic  bundles  with  fibrous  tissue;  the  muscular  fibres  dis- 
appear, and  the  mucous  membrane  becomes  thin  and  delicate,  and  lined  with  a 
layer  of  squamous  epithelium.  The  latter  membrane  lines  the  air-cells,  and 
forms  by  its  reduplications  the  septa  intervening  between  them. 

The  Pulmonary  Artery  conveys  the  venous  blood  to  the  lungs  :  it  divides  into 
branches  which  accompany  the  bronchial  tubes,  and  terminates  in  a  dense  capil- 
lary network  upon  the  walls  of  the  intercellular  passages  and  air-cells.  From 
this  network,  the  radicles  of  the  pulmonary  veins  arise;  coalescing  into  large 
branches  they  accompany  the  arteries,  and  return  the  blood,  purified  by  its 
passage  through  the  capillaries,  to  the  left  auricle  of  the  heart.  In  the  lung, 
the  branches  of  the  pulmonary  artery  are  usually  above  and  in  front  of  a  bron- 
chial tube,  the  vein  below. 

The  Pulmonary  Capillaries  form  plexuses  which  lie  immediately  beneath  the 
mucous  membrane,  on  the  walls  and  septa  of  the  air-cells,  and  upon  the  walls 
of  the  intercellular  passages.  In  the  septa  between  the  cells,  the  capillary  net- 
work forms  a  single  layer.  The  capillaries  form  a  very  minute  network,  the 
meshes  of  which  are  smaller  than  the  vessels  themselves:^  their  walls  are  also 
exceedingly  thin.     The  vessels  of  neighboring  lobules  are  distinct  from  each 

«  Medico-Chirurgical  Trnnmcttnns,  vol.  xxviii.  1845. 
«  "The  Anatomy  of  the  Human  Lung,"  1860,  pp.  130 — 150. 

»  The  meshes  are  only  0.00'/"  to  0.008'"  in  width,  whilo  the  vessels  arc  0.003'"  to  0.005'". 
Kiilliker,  Human  Microscopic  Anatomy. 


THYROID    GLAND.  •^87 

otber,  and  do  not  anastomose;  and,  according  to  Dr.  "Waters,  those  of  the  sepa- 
rate groups  of  intercellular  passages,  or  air-sacs  (which  groups  he  denominates 
lobulettes),  are  also  independent ;  so  that  in  the  septa  between  two  adjoining 
lobulettes,  there  would  be  a  double  layer  of  capillaries,  one  layer  belonging  to 
each  of  the  adjacent  air-sacs,  or  intercellular  passages.  If  this  is  really  the 
arrangement  of  the  vessels,  it  would  follow,  that  in  the  septa  between,  the  air- 
cells  (or  alveoli),  the  blood  in  the  capillaries  would  be  exposed  on  all  sides  to 
the  action  of  the  air,  since  it  is  circulating  in  a  single  layer  of  vessels,  which  is 
in  contact  with  the  membrane  of  the  air-passages  on  both  sides;  but  that,  in 
the  septa  between  the  intercellular  passages  (or  air-sacs)  the  blood  in  the  double 
layer  of  capillaries  will  be  in  contact  with  the  air  on  one  side  only. 

The  Bronchial  Arteries  supply  blood  for  the  nutrition  of  the  lung :  they  are 
derived  from  the  thoracic  aorta,  and,  accompanying  the  bronchial  tubes,  are 
distributed  to  the  bronchial  glands,  and  upon  the  walls  of  the  larger  bronchial 
tubes  and  pulmonary  vessels,  and  terminate  in  the  deep  bronchial  veins.  Others 
are  distributed  in  the  interlobular  areolar  tissue,  and  terminate  partly  in  the 
deep,  partly  in  the  superficial,  bronchial  veins.  Lastly,  some  ramify  upon  the 
walls  of  the  smallest  bronchial  tubes,  and  terminate  in  the  pulmonary  veins. 

The  Superficial  and  Deep  Bronchial  Veins  unite  at  the  root  of  the  lung,  and 
terminate  on  the  right  side  in  the  vena  azygos;  on  the  left  side,  in  the  superior 
intercostal  vein. 

According  to  Dr.  "Waters,  the  bronchial  veins  do  not  exist  within  the  proper 
substance  of  the  lung,  but  commence  at  or  near  the  root  of  the  lung,  by  branches 
which  lie  on  the  large  bronchial  tubes.  He  also  denies  that  the  bronchial  arte- 
ries contribute  to  the  formation  of  the  pulmonary  plexus,  believing  that  the 
communication  between  the  bronchial  and  pulmonary  system  of  vessels  takes 
place  in  the  pulmonary  veins.  If  this  view  be  correct,  almost  the  whole  of  the 
blood  carried  by  the  bronchial  arteries  must  be  returned  to  the  heart  by  the 
pulmonary  veins,  and  thus  the  great  mass  of  pure,  or  arterial  blood  which  is 
carried  by  the  pulmonary  veins,  would  be  adulterated  by  a  small  quantity  of 
carbonized  or  venous  blood,  which  has  passed  through  the  bronchial  circulation. 

The  Lymphatics  consist  of  a  superficial  and  deep  set :  they  terminate  at  the 
root  of  the  lung,  in  the  bronchial  glands. 

Nerves.  The  lungs  are  supplied  from  the  anterior  and  posterior  pulmonary 
plexuses,  formed  chiefly  by  branches  from  the  sympathetic  and  pneumogastric. 
The  filaments  from  these  plexuses  accompany  the  bronchial  tubes,  upon  which 
they  are  lost.     Small  ganglia  are  found  upon  these  nerves. 

Thyroid  Gland. 

The  Thyroid  Gland  bears  much  resemblance  in  structure  to  other  glandulap 
organs,  and  is  usually  classified  together  with  the  thymus,  suprarenal  capsules, 
and  spleen,  under  the  head  of  ductless  glands^  since  it  has  no  excretory  duct.  Its 
function  is  unknown,  but,  from  its  situation  in  connection  with  the  trachea  and 
larynx,  the  thyroid  body  is  usually  described  with  those  organs,  although  it 
takes  no  part  in  the  function  of  respiration.  It  is  situated  at  the  upper  part  of 
the  trachea,  and  consists  of  two  lateral  lobes,  placed  one  on  each  side  of  that 
tube,  and  connected  together  by  a  narrow  transverse  portion,  the  isthmus. 

Its  anterior  surface  is  convex,  and  covered  by  the  Sterno-hyoid,  Sterno-thy- 
roid,  and  Omo-hyoid  muscles. 

Its  lateral  surfaces,  also  convex,  lie  in  contact  with  the  sheath  of  the  common 
carotid  artery. 

Its  posterior  surface  is  concave,  and  embraces  the  trachea  and  larynx.  The 
posterior  borders  of  the  gland  extend  as  far  back  as  the  lower  part  of  the 
pharynx. 

The  thyroid  is  of  a  brownish-red  color.  Its  weight  varies  from  one  to  two 
ounces.    It  is  larger  in  females  than  in  males,  and  becomes  slightly  increased  in 


T88  ORGANS    OF    VOICE    AND    RESPIRATION. 

size  during  menstruation.  It  occasionally  becomes  enormously  hypertrophied, 
constituting  the  disease  called  bronchocele,  or  goitre.  Each  lobe  is  somewhat 
conical  in  shape,  about  two  inches  in  length,  and  three-quarters  of  an  inch  in 
breadth,  the  right  lobe  being  rather  the  larger  of  the  two. 

The  isthmus  connects  the  lower  third  of  the  two  lateral  lobes ;  it  measures 
about  half  an  inch  in  breadth,  and  the  same  in  depth,  aud  usually  covers  the 
second  and  third  rings  of  the  trachea.  Its  situation  presents,  however,  many 
variations,  a  point  of  importance  in  the  operation  of  tracheotomy.  Sometimes 
the  isthmus  is  altogether  wanting. 

A  third  lobe,  of  conical  shape,  called  the  pyramid^  occasionally  arises  from 
the  left  side  of  the  upper  part  of  the  isthmus,  or  from  the  left  lobe,  and  ascends 
as  high  as  the  hyoid  bone.  It  is  occasionally  quite  detached,  or  divided  into 
two  parts,  or  altogether  wanting. 

A  few  muscular  bands  are  occasionally  found  attached,  above,  to  the  body  of 
the  hyoid  bone,  and  below,  to  the  isthmus  of  the  gland,  or  its  pyramidal  pro- 
cess. These  form  a  muscle,  which  was  named  by  Stimmerring  the  Levator 
Olandulve  Thyroidese. 

Structure.  The  thyroid  consists  of  numerous  minute  closed  vesicles,  composed 
of  a  homogeneous  membrane,  inclosed  in  a  dense  capillary  plexus,  and  connected 
together  into  imperfect  lobules,  by  areolar  tissue.  These  vessels  are  spherical 
or  oblong,  perfectly  distinct,  and  contain  a  yellowish  fluid,  in  which  are  found 
floating  numerous  "dotted  corpuscles"  and  cells.  The  fluid  coagulates  by  heat 
or  alcohol,  but  preserves  its  transparency.  In  the  foetus,  and  in  young  subjects, 
the  corpuscles  lie  in  a  single  layer,  in  contact  with  the  inner  surface  of  these 
cavities,  and  become  detached  during  the  process  of  growth. 

Vessels  and  Nerves.  The  arteries  supplying  the  thyroid,  are  the  superior  and 
inferior  thyroid,  and  sometimes  an  additional  branch  (thyroidea  media,  t.  ima) 
from  the  arteria  innominata,  or  the  arch  of  the  aorta,  which  ascends  upon  the 
front  of  the  trachea.  The  arteries  are  remarkable  for  their  large  size  and 
frequent  anastomoses.  The  veins  form  a  plexus  on  the  surface  of  the  gland, 
and  on  the  front  of  the  trachea,  from  which  arise  the  superior,  middle,  and 
inferior  thyroid  veins;  the  two  former  terminating  in  the  internal  jugular,  the 
latter  in  the  vena  innominata.  The  lymphatics  are  numerous,  of  large  size,  and 
terminate  in  the  thoracic  and  right  lymphatic  ducts.  The  nerves  are  derived 
from  the  pneumogastric,  and  from  the  middle  and  inferior  cervical  ganglia  of 
the  sympathetic. 

Chemical  Composition.  The  thyroid  gland  consists  of  albumen,  traces  of 
gelatine,  stearine,  oleine,  extractive  ftiatter,  alkaline,  and  earthy  salts,  and 
water.  The  salts  are  chloride  of  sodium,  alkaline  sulphate,  phosphate  of  potash, 
lime,  magnesia,  and  a  trace  of  oxide  of  iron. 

Thymus  Gland. 

The  Thymus  Gland  presents  much  resemblance  in  structure  to  other  glandular 
organs,  and  is  another  of  the  organs  denominated  ductless  glands. 

The  thymus  gland  is  a  temporary  organ,  attaining  its  full  size  at  the  end  of 
the  second  year,  when  it  ceases  to  grow,  and  gradually  dwindles,  until,  at 
puberty,  it  has  almost  disappeared.  If  examined  when  its  growth  is  most 
active,  it  will  be  found  to  consist  of  two  lateral  lobes,  placed  in  close  contact 
along  the  middle  line,  situated  partly  in  the  anterior  mediastinum,  partly  in  the 
neck,  and  extending  from  the  fourth  costal  cartilage  upwards,  as  high  as  the 
lower  border  of  the  thyroid  gland.  It  is  covered  by  the  sternum,  and  by  the 
origins  of  the  Storno-hyoid  and  Sterno-thyroid  muscles.  In  the  mediastinum, 
it  rests  upon  the  pericardium,  being  separated  from  the  arch  of  the  aorta  and 
great  vessels  by  the  thoracic  fascia.  In  the  neck,  it  lies  on  the  front  and  sides 
of  the  trachea,  behind  the  Sterno-hyoid  and  Sterno-thyroid  muscles.  The  two 
lobes  generally  differ  in  size ;  they  are  occasionally  united,  so  as  to  form  a  single 


THYMUS    GLAND.  789 

mass ;  and  sometimes  separated  by  an  intermediate  lobe.  The  thymus  is  of  a 
pinkish-gray  color,  soft,  and  lobulated  on  its  surfaces.  It  is  about  two  inches 
in  length,  one  and  a  half  in  breadth,  below,  and  about  three  or  four  lines  in 
thickness.     At  birth,  it  weighs  about  half  an  ounce. 

Structure.  Each  lateral  lobe  is  composed  of  numerous  lobules,  held  together 
by  delicate  areolar  tissue;  the  entire  gland  being  inclosed  in  an  investing  cap- 
sule of  a  similar,  but  denser  structure.  The  primary  lobules  vary  in  size  from 
a  pin's  head  to  a  small  pea.  Each  lobule  contains,  in  its  interior,  a  small  cavity, 
which  is  surrounded  with  smaller  or  secondary  lobules,  also  hollow.  The 
cavities  of  the  secondary  and  primary  lobules  communicate ;  those  of  the  latter 
opening  into  the  great  central  cavity,  or  reservoir  of  the  thymus^  which  extends 
through  the  entire  length  of  each  lateral  half  of  the  gland.  The  central  cavity 
is  lined  by  a  vascular  membrane,  which  is  prolonged  into  all  the  subordinate 
cavities,  and  contains  a  milk-white  fluid  resembling  chyle. 

If  the  investing  capsule  and  vessels,  as  well  as  the  areolar  tissue  connecting 
the  lobules,  are  removed  from  the  surface  of  either  lateral  lobe,  it  will  be  seen 
that  the  central  cavity  is  folded  upon  itself,  and  admits  of  being  drawn  out  into 
a  lengthened  tubular  cord,  around  which  the  primary  lobules  are  attached  in  a 
spiral  manner,  like  knots  upon  a  rope.  Such  is  the  condition  of  the  organ,  at 
an  early  period  of  its  development ;  for  Mr.  Simon  has  shown,  that  the  primi- 
tive form  of  the  thymus  is  a  linear  tube,  from  which,  as  its  development  pro- 
ceeds, lateral  diverticula  lead  outwards,  the  tube  ultimately  becoming  obscure, 
from  its  surface  being  covered  with  numerous  lobules. 

According  to  Oesterlen  and  Mr.  Simon,  the  cavities  in  the  secondary  lobules 
are  surrounded  by  rounded  saccular  dilatations  or  vesicles,  which  open  into  it. 
These  vesicles  are  formed  of  a  homogeneous  membrane,  inclosed  in  a  dense 
capillary  plexus. 

The  whitish  fluid  contained  in  the  vesicles  and  central  cavity  of  the  thymus, 
contain  numerous  dotted  corpuscles,  similar  to  those  found  in  the  chyle.  The 
corpuscles  are  flattened  circular  disks,  measuring  about  xTjVTr  of  3,n  inch  in 
diameter. 

Vessels  and  Nerves.  The  arteries  supplying  the  thymus  are  derived  from  the 
internal  mammary,  and  from  the  superior  and  inferior  thyroid.  The  veins 
terminate  in  the  left  vena  innominata,  and  in  the  thyroid  veins.  The  lymphatics 
are  of  large  size,  arise  in  the  substance  of  the  gland,  and  are  said  to  terminate 
in  the  internal  jugular  vein.  Sir  A.  Cooper  believed  that  these  vessels  carried 
into  the  blood  the  secretion  formed  in  the  substance  of  the  thj^mus.  The  nerves 
are  exceedingly  minute;  they  are  derived  from  the  pneumogastric  and  sympa- 
thetic. Branches  from  the  descendens  noni  and  phrenic  reach  the  investing 
capsule,  but  do  not  penetrate  into  the  substance  of  the  gland. 

Chemical  Composition.  The  solid  animal  constituents  of  the  thymus  are  albu- 
men and  fibrine  in  large  quantities,  gelatine  and  other  animal  matters.  The 
salts  are  alkaline  and  earthy  phosphates,  with  chloride  of  potassium.  It  con- 
tains about  80  per  cent,  of  water. 


The  Urinary  Organs.. 


The  Kidneys. 

The  Kidneys  are  glandular  organs,  intended  for  the  secretion  of  the  urine. 
They  are  situated  at  the  back  part  of  the  abdominal  cavity,  behind  the  perito- 
neum, one  in  each  lumbar  region,  extending  from  the  eleventh  rib  to  near  the 
crest  of  the  ilium;  the  right  being  lower  than  the  left,  in  consequence  of  the 
large  size  of  the  liver.  They  are  usually  surrounded  by  a  considerable  quan- 
tity of  fat,  and  are  retained  in  their  position  by  the  vessels  which  pass  to  and 
from  them. 

Relations.  The  anterior  surface  of  the  kidney  is  convex,  partially  covered  by 
the  peritoneum,  and  is  in  relation,  on  the  right  side,  with  the  back  part  of  the 
right  lobe  of  the  liver,  the  descending  portion  of  the  duodenum,  and  the  ascend- 
ing colon;  and  on  the  left  side  with  the  great  end  of  the  stomach,  the  lower  end 
of  the  spleen,  the  tail  of  the  pancreas,  and  the  descending  colon. 

The  'posterior  surface  is  flattened,  and  rests  upon  the  corresponding  crus  of  the 
Diaphragm,  in  front  of  the  eleventh  and  twelfth  ribs,  on  the  anterior  lamella 
of  the  aponeurosis  of  the  trans versalis,  which  separates  the  kidney  from  the 
Quadratus  Lumborum,  and  on  the  Psoas  Magnus. 

The  superior  extremity,  directed  inwards,  is  thick  and  rounded,  and  embraced 
by  the  suprarenal  capsule.  It  corresponds,  on  the  left  side,  to  the  upper  border 
and  on  the  right  side  to  the  lower  border  of  the  eleventh  rib. 

The  inferior  extremity,  small  and  flattened,  extends  nearly  as  low  as  the  crest 
of  the  ilium. 

The  external  border  is  convex,  and  directed  outwards  towards  the  parietes 
of  the  abdomen. 

The  internal  border  is  concave,  and  presents  a  deep  notch,  the  hilum  of  the 
kidney,  more  marked  behind  than  in  front.  At  the  hilum,  the  vessels,  excre- 
tory duct  and  nerves,  pass  into  or  from  the  organ;  the  branches  of  the  renal 
vein  lying  in  front,  the  artery  and  its  branches  next,  the  excretory  duct  or 
ureter  behind  and  below.  On  the  vessels  the  nerves  and  lymphatics  ramify, 
and  much  cellular  tissue  and  fat  surround  the  whole.  The  hilum  leads  into  a 
hollow  space,  the  sinus,  which  occupies  the  interior  of  the  gland. 

Each  kidney  is  about  four  inches  in  length,  two  inches  in  breadth,  and  about 
one  inch  in  thickness;  the  left  being  somewhat  longer  and  thinner  than  the 
right.  The  weight  of  the  kidney  in  the  adult  male  varies  from  4J  oz.  to  6  oz.; 
in  the  female,  from  4  oz.  to  5|  oz.  The  left  kidney  is  nearly  always  heavier 
than  the  right,  by  about  two  drachms.  Their  weight  in  proportion  to  the  body 
is  about  1  to  240.  The  renal  substance  is  dense,  firm  to  the  touch,  but  very 
fragile,  and  of  a  deep-red  color. 

The  kidney  is  invested  by  a  fibrous  capsule,  formed  of  dense  fibro-areolar 
tissue.  This  capsule  is  thin,  smooth,  and  easily  removed  from  the  surface  of 
the  kidney,  to  which  it  is  connected  by  fine  fibrous  processes  and  vessels;  and 
at  the  hilum  is  continued  inwards,  lining  the  sides  of  the  sinus,  and  at  the  bot- 
tom of  that  cavity  forms  sheaths  around  the  bloodvessels,  and  the  subdivisions 
of  the  excretory  duct. 

On  making  a  vertical  section  through  the  organ,  from  its  convex  to  its  con- 
cave border,  it  appears  to  consist  of  two  different  substances,  viz.,  an  external 
or  cortical,  anJ  an  internal  or  medullary,  substance. 

The  -cortical  substance  forms  about  three-fourths  of  the  gland.  It  occupies  the 
surface  of  the  kidney,  forming  a  layer  about  two  lines  in  thickness,  where  it 

790 


THE    KIDNEYS. 


101 


Fig.  434. — Vertical  Section  of  Kidney. 


covers  tbe  pyramids,  and  sends  numerous  prolongations  inwards,  towards  the 
sinus  between  the  pyramids. 

The  cortical  substance  is  soft,  reddish,  granular,  easily  lacerated,  and  contains 
numerous  small,  red  bodies  scattered  through  it  in  every  part,  excepting  towards 
the  free  surface.  These  are  the  Malpighian  bodies.  The  cortical  substance  is 
composed  of  a  mass  of  convoluted  tubuli  uri- 
niferi,  bloodvessels,  lymphatics,  and  nerves, 
connected  together  by  a  firm,  transparent, 
granular  substance,  which  contains  small 
graaular  cells. 

The  medullary  substance  consists  of  pale, 
reddish-colored,  conical  masses,  the  jyyramicls 
of  Malpighi;  they  vary  in  number  from  eight 
to  eighteen;  their  bases  are  directed  towards 
the  circumference  of  the  organ;  whilst  their 
apices,  which  are  free  from  the  cortical  sub- 
stance, converge  towards  the  sinus,  and  termi- 
nate in  smooth,  rounded  extremities,  called 
the  papillss  (mammillae)  of  the  kidney.  Some- 
times, two  of  the  masses  are  joined,  and  have 
between  them  only  one  papilla.  The  kidney 
is  thus  seen  to  consist  of  a  number  of  conical- 
shaped  masses,  each  inclosed,  excepting  at  the 
apex,  by  an  investment  of  the  cortical  substance: 
these  represent  the  separate  lobules  of  which 
the  human  kidney  in  the  foetus  consists,  a  con- 
dition which  is  permanent  in  the  kidneys  of 
many  of  the  lower  animals.  As  the  human  kid- 
ney becomes  developed,  the  adjacent  lobules 
coalesce,  so  as  to  form  a  single  gland,  the  surface 
of  which,  even  in  the  adult,  occasionally  pre- 
sents faint  traces  of  a  lobular  subdivision. 

The  medullary  substance  is  denser  in  structure  than  the  cortical,  darker  in 
color,  and  presents  a  striated  appearance,  from  being  composed  of  a  number  of 
minute  converging  tubes  {tubuli  uriniferi).  If  traced  backwards  the  tubuli 
uriniferi  are  found  to  commence  at  the  apices  of  the  cones  by  small  orifices, 
which  vary  from  ^^n  to  5'^  of  an  inch;  as  they  pass  up 
in  the  medullary  substance,  towards  the  periphery,  they 
pursue  a  diverging  course,  dividing  and  subdividing  at 
very  acute  angles,  until  they  reach  the  cortical  sub- 
stance, where  they  become  convoluted,  anastomose  freely 
with  each  other,  and  retain  the  same  diameter.  The 
number  of  orifices  on  the  entire  surface  of  a  single  pa- 
pilla is,  according  to  Buschke,  about  a  thousand;  from 
four  to  five  hundred  large,  and  as  many  smaller  ones. 
The  tubuli  uriniferi  are  formed  of  a  transparent  homo- 
geneous basement  membrane,  lined  by  spheroidal  epi- 
thelium, which  occupies  about  two-thirds  of  the  diameter 
of  the  tube.  The  tubes  are  separated  from  one  another, 
in  the  medullary  cones,  by  capillary  vessels,  which  form 
oblong  meshes  parallel  with  the  tubuli,  and  by  an  inter- 
mediate parenchymatous  substance  composed  of  cells. 

As  soon  as  the  tubuli  uriniferi  enter  the  cortical  sub- 
stance (Fig.  435),  they  become  convoluted,  and  anastomose  freely  with  each 
other;  they  are  sometimes  called  the  tubes  of  Ferrein.     At  the  bases  of  the 
pyramids,  the  straight  tubes  are  described  as  being  collected  into  small  conical 
bundles,  the  tortuous  tubuli  corresponding  to  which  are  prolonged  upwards 


Fig.  43.^. — Minute  Struc- 
ture of  Kidney. 


t93  URINARY    ORGANS. 

into  the  cortical  portion  of  the  kidney  as  far  as  the  surface,  forming  a  number 
of  small  conical  masses,  which  are  named  the  pyramids  of  Ferrein,  several  of 
•which  correspond  to  each  medullary  cone  and  its  corresponding  portion  of  cor- 
tical substance.  According  to  Mr.  Bowman,  the  tubuli  uriniferi  commence  in 
the  cortical  substance  as  small,  dilated,  membranous  capsules,  the  capsules  of 
the  Malpighian  bodies;  they  also  form  loops,  either  by  the  junction  of  adjacent 
tubes,  or,  according  to  Toynbee,  by  the  union  of  two  branches  proceeding  from 
the  same  tube ;  they  have  also  been  seen  to  arise  by  free  closed  extremities. 

The  Malpighian  bodies  are  found  only  in  the  cortical  substance  of  the  kidney. 
They  are  small  round  bodies,  of  a  deep  red  color,  and  of  the  average  diameter 
of  the  Tjnth  of  an  inch.  Each  body  is  composed  of  a  vascular  tuft  inclosed  in 
a  thin  membranous  capsule,  the  dilated  commencement  of  a  uriniferous  tubule. 
The  vascular  tuft  consists  of  the  ramifications  of  a  minute  artery,  the  afferent 
vessel^  which,  after  piercing  the  capsule,  divides,  in  a  radiated  manner,  into 
several  branches,  which  ultimately  terminate  in  a  finer  set  of  capillary  vessels. 
From  these,  a  small  vein,  the  efferent  vessel^  proceeds ;  this  pierces  the  capsule 
near  the  artery,  and  forms  a  close  venous  plexus,  with  the  efferent  vessels  from 
other  Malpighian  bodies,  round  the  adjacent  tubuli. 

The  capsular  dilatation  of  the  Malpighian  body  is  not  always  placed  at  the 
commencement  of  the  tube;  it  may  occupy  one  side  (Gerlach):  hence  their 
subdivision  into  lateral  or  terminal.  The  membrane  composing  it  is  thicker 
than  that  of  the  tubule ;  the  epithelium  lining  its  inner  surface  is  thin,  and,  in 
the  frog,  provided  with  cilia  at  the  neck  of  the  dilated  portion;  but  in  the  human 
subject  cilia  have  not  been  detected.  According  to  Mr.  Bowman,  the  surface  of 
the  vascular  tuft  lies  free  and  uncovered  in  the  interior  of  its  capsule ;  but, 
according  to  Gerlach,  it  is  covered  with  a  thick  layer  of  nucleated  cells,  similar 
to  those  lining  the  inner  surface  of  the  capsule. 

Ducts.  The  ureter,  as  it  approaches  the  hilum,  becomes  dilated  into  a  funnel- 
shaped  membranous  sac,  i\\Q  pelvis.  It  then  enters  the  sinus,  and  subdivides 
usually  into  three  prolongations,  the  infundibula ;  one  placed  at  each  extremity, 
and  one  in  the  middle  of  the  organ  ;  these  subdivide  into  from  seven  to  thirteen 
smaller  tubes,  the  ealices,  each  of  which  embraces  the  base  of  one  of  the  papillae. 
Sometimes,  a  calix  incloses  two  or  more  papillae.  The  ureter,  the  pelvis,  and 
the  calices  consist  of  three  coats :  fibrous,  muscular,  and  mucous. 

The  exteryial  ov  fihro-elaf<tic  coat  is  continuous,  round  the  bases  of  the  papilloa, 
with  the  tunica  propria  investing  the  surface  of  the  organ. 

The  mtiscular  coat  is  placed  between  the  fibrous  and  mucous  coats.  It  con- 
sists of  an  external  or  longitudinal,  and  an  internal  or  circular  stratum. 

H^he  internal  or  rmicous  coat  invests  the  papilloe  of  the  kidney,  and  is  continued 
into  the  orifices  upon  their  surfaces.  It  is  lined  by  epithelium  of  the  spheroidal 
kind. 

Vessels  and  nerves.  The  renal  artery  is  large  in  proportion  to  the  size  of  the 
organ  which  it  supplies.  Each  vessel  divides  into  four  or  five  branches,  which 
enter  the  hilum,  and  are  invested  by  sheaths  derived  from  the  fibrous  capsule; 
they  penetrate  the  substance  of  the  organ  between  the  papilla),  and  enter  the 
cortical  substance  in  the  intervals  between  the  medullary  cones;  dividing  and 
subdividing  in  their  course  towards  the  bases  of  the  pyramids,  where  they  form 
arches  by  their  anastomoses ;  from  these  arclies,  numerous  vessels  are  distributed 
to  the  cortical  substance,  some  of  which  enter  the  Malpighian  corpuscles;  whilst 
others  form  a  capillary  network  round  the  uriniferous  tubes. 

The  veins  of  the  kidney  commence  upon  the  surface  of  the  organ,  where  they 
have  a  stellate  arrangement;  they  pass  inwards,  and  open  into  larger  veins, 
which  unite  into  arches  round  the  bases  of  the  medullary  cones.  After  receiv- 
ing the  venous  plexus  from  the  tubular  portion,  they  accompany  the  branches 
of  the  arteries  of  the  sinus  of  the  kidney,  where  they  finally  unite  to  form  a 
single  vein,  which  terminates  in  the  inferior  vena  cava. 


URETERS— SUPRARENAL    CAPSULES.  793 

Tlie  lymphatics  of  the  kidney  consist  of  a  superficial  and  deep  set ;  they 
accompany  the  bloodvessels,  and  terminate  in  the  lumbar  glands. 

The  7ierves  are  derived  from  the  renal  plexus,  which  is  formed  by  filaments 
from  the  solar  plexus  and  lesser  splanchnic  nerve  ;  they  accompany  the  branches 
of  the  arteries.  From  the  renal  plexus,  some  filaments  pass  to  the  spermatic 
plexus  and  ureter. 

The  Uretees. 

The  Ureter  is  the  excretory  duct  of  the  kidney.  It  is  a  cylindrical  membra- 
nous tube,  from  sixteen  to  eighteen  inches  in  length,  and  of  the  diameter  of  a 
goose-quill.  It  is  placed  at  the  back  part  of  the  abdomen,  behind  the  perito- 
neum: and  extends  obliquely  downwards  and  inwards,  from  the  lower  part  of 
the  pelvis  of  the  kidney,  enters  the  cavity  of  the  pelvis,  and  then  passes  down- 
wards, forwards,  and  inwards,  to  the  base  of  the  bladder,  into  which  it  opens  by 
a  constricted  orifice,  after  passing  obliquely,  for  nearly  an  inch,  between  its 
muscular  and  mucous  coats. 

Relations.  In  its  course  from  above  downwards,  it  rests  upon  the  Psoas 
muscle,  being  covered  by  the  peritoneum,  and  crossed  in  front  very  obliquely 
by  the  spermatic  vessels ;  the  right  ureter  lying  close  to  the  outer  side  of  the 
inferior  vena  cava.  Opposite  the  sacrum,  it  crosses  the  common  or  the  external 
iliac  artery,  lying  behind  the  ileum  on  the  right  side,  and  the  sigmoid  flexure 
of  the  colon  on  the  left.  In  the  pelvis,  it  enters  the  posterior  false  ligament  of 
the  bladder,  below  the  obliterated  hypogastric  artery ;  the  vas  deferens,  in  the 
male,  passing  between  it  and  the  bladder.  In  the  female,  the  ureter  passes  along 
the  sides  of  the  cervix  uteri  and  upper  part  of  the  vagina.  At  the  base  of  the 
bladder,  it  is  situated  about  two  inches  from  its  fellow ;  lying,  in  the  male, 
about  an  inch  and  a  half  behind  the  base  of  the  prostate,  at  the  posterior  angle 
of  the  trigone. 

Structure.  The  ureter  is  composed  of  three  coats:  fibrous,  muscular,  and 
mucous. 

1l^\\q  fihrous  coat  is  continuous  with  that  surrounding  the  pelvis  of  the  kidney. 

The  muscular  coat  consists  of  two  layers  of  longitudinal  fibres,  and  an  inter- 
mediate transverse  layer.  , 

The  mucous  coat  is  smooth,  and  presents  a  few  longitudinal  folds,  which  be- 
come effaced  by  distension.  It  is  continuous  with  the  mucous  membrane  of 
the  bladder  below ;  whilst,  above,  it  is  prolonged  over  the  papillae  into  the 
tubuli  uriniferi.     The  epithelial  cells  lining  it  are  spheroidal. 

The  arteries  supplying  the  ureter  are  branches  of  the  renal,  spermatic,  internal 
iliac,  and  inferior  vesical. 

The  nerves  are  derived  from  the  inferior  mesenteric,  spermatic,  and  hypogas- 
tric plexuses. 

Suprarenal  Capsules. 

The  Suprarenal  Capsules  are  usually  classified,  together  with  the  spleen,  thy- 
mus, and  thyroid,  under  the  head  of  "ductless  glands,"  as  they  have  no  excretory 
duct.  They  are  two  small  flattened  glandular  bodies,  of  a  yellowish  color,  situ- 
ated at  the  back  part  of  the  abdomen,  behind  the  peritoneum,  and  immediately 
in  front  of  the  upper  end  of  either  kidney ;  hence  their  name.  The  right  one 
is  somewhat  triangular  m  shape,  bearing  a  resemblance  to  a  cocked  hat;  the 
left  is  more  semilunar,  and  usually  larger  and  higher  than  the  right.  They 
vary  in  size  in  different  individuals,  being  sometimes  so  small  as  to  be  scarcely 
detected ;  their  usual  size  is  from  an  inch  and  a  quarter  to  nearly  two  inches  in 
length,  rather  less  in  width,  and  from  two  to  three  lines  in  thickness.  In  weight 
they  vary  from  one  to  two  drachms. 

Relations.  The  anterior  surface  is  in  relation,  on  the  right  side,  with  the  under 
surface  of  the  liver;  and  on  the  left,  with  the  pancreas  and  spleen.     ^\\q poste- 


794  URINARY    ORGANS. 

rior  surface  rests  upon  the  crus  of  the  Diaphragm,  opposite  the  tenth  dorsal 
vertebra.  The  xipper  thin  convex  border  is  directed  upwards  and  inwards.  The 
lower  thick  concave  border  rests  upon  the  upper  end  of  the  kidney,  to  which  it 
is  connected  by  areolar  tissue.  The  inner  border  is  in  relation  with  the  great 
splanchnic  nerve  and  semilunar  ganglion,  and  lies  in  contact  on  the  right  side 
with  the  inferior  vena  cava,  and  on  the  left  side  with  the  aorta.  The  surface 
of  the  suprarenal  gland  is  surrounded  by  areolar  tissue  containing  much  fat, 
and  closely  invested  by  a  thin  fibrous  coat,  which  is  difficult  to  remove,  on 
account  of  the  numerous  fibrous  processes  and  vessels  which  enter  the  organ 
through  the  furrows  on  its  anterior  surface  and  base. 

Structure.  On  making  a  perpendicular  section,  the  gland  is  seen  to  consist 
of  two  substances :  external  or  cortical,  and  internal  or  medullary. 

The  cortical  substance  forms  the  chief  part  of  the  organ  ;  it  is  of  a  deep  yellow 
color,  and  consists  of  narrow  columnar  masses  placed  perpendicularly  to  the 
surface. 

The  medullary  substance  is  soft,  pulpy,  and  of  a  dark  brown  or  black  color ; 
hence  the  name,  atrabiliary  capsules^  formerly  given  to  these  organs.  In  the 
centre  is  often  seen  a  space  formed  by  the  breaking  down  of  the  component 
parts  of  the  tissue. 

According  to  the  researches  of  Oesterlen  and  Mr.  Simon,  the  narrow  columnar 
masses  of  which  the  cortical  substance  is  composed  measure  about  ^Jtoth  of  an 
inch  in  diameter,  and  consists  of  small  closed  parallel  tubes  of  limitary  mem- 
brane containing  dotted  nuclei,  together  with  much  granular  matter,  oil  globules, 
and  nucleated  cells.  According  to  Ecker,  the  apparently  tubular  canals  con- 
sist of  rows  of  closed  vesicles  placed  endwise,  so  as  to  resemble  tubes ;  whilst 
Kiilliker  states,  that  these  vesicles  are  merely  loculi  or  spaces  in  the  stroma  of 
the  organ,  having  no  limitary  membrane,  which,  from  being  situated  endwise, 
present  the  appearance  of  linear  tubes.  Nucleated  cells  exist  in  large  numbers 
in  the  suprarenal  glands  of  ruminants,  more  sparingly  in  man  and  other  animals, 
but  the  granular  matter  appears  to  form  the  chief  constituent  of  the  gland ;  the 
granules  vary  in  size,  and  they  present  the  singular  peculiarity  of  undergoing 
no  change  when  acted  upon  by  most  chemical  reagents.  The  columnar  masses 
are  surrounded  by  a  close  capillary  network,  which  runs  parallel  with  them. 

The  medullary  substance  consists  of  nuclei  and  granular  matter,  uniformly 
scattered  throughout  a  plexus  of  minute  veins. 

T^\iQ  arteries  supplying  the  suprarenal  capsules  are  numerous  and  of  large  size, 
they  are  derived  from  the  aorta,  the  phrenic,  and  the  renal ;  they  subdivide  iuto—. 
numerous  minute  branches  previous  to  entering  the  substance  of  the  gland.       HI 

The  suprarenal  vein  returns  the  blood  from  the  medullary  venous  plexus,  and 
receives  several  branches  from  the  cortical  substance ;  it  opens  on  the  right  side 
into  the  inferior  vena  cava,  on  the  left  side  into  the  renal  vein.  ^\ 

The  lymphatics  terminate  in  the  lumbar  glands.  ^Bl 

The  nerves  are  exceedingly  numerous;  they  are  derived  from  the  solar  and 
renal  plexuses,  and,  according  to  Bergmann,  from  the  phrenic  and  pneumogas 
trie  nerves.     They  have  numerous  small  ganglia  developed  upon  them. 

THE  PELVIS. 

The  Cavity  of  the  Pelvis  is  that  part  of  the  general  abdominal  cavity  which: 
is  below  the  level  of  the  linea  ilio-pectinea  and  the  promontory  of  the  sacrum. 

Boundaries.     It  is  bounded,  behind,  by  the  sacrum,  the  coccyx,  and  the  great] 
sacro-sciatic  ligaments ;  in  front  and  at  the  sides,  by  the  pubes  and  ischia,  cov- 
ered by  the  Obturator  muscles;  above,  it  communicates  with  the  cavity  of  thai 
abdomen;  and  below,  it  is  limited  by  the  Levatores  Ani  and  Coccygei  muscles,j 
and  the  visceral  layer  of  the  pelvic  fascia,  which  is  reflected  from  the  wall  of 
the  pelvis  on  to  the  viscera. 

Contents.     The  viscera  contained  in  this  cavity  are  the  urinary  bladder,  th( 


■I 

\ 


THE    BLADDER. 


t95 


rectum,  and  some  of  the  generative  organs  peculiar  to  each  sex:  they  are  par- 
tially covered  by  the  peritoneum,  and  supplied  with  blood  and  lymphatic  vessels 
and  nerves. 

The  Bladder. 

The  Bladder  is  the  reservoir  for  the  urine.  It  is  a  musculo-membranous  sac, 
situated  in  the  pelvis,  behind  the  pubes,  and  in  front  of  the  rectum  in  the  male, 
the  uterus  and  vagina  intervening  between  it  and  that  intestine  in  the  female. 
The  shape,  position,  and  relations  of  the  bladder  are  greatly  influenced  by  age, 
sex,  and  the  degree  of  distension  of  the  organ.  During  infancy,  it  is  conical  in 
shape,  and  projects  above  the  upper  border  of  the  pubes  into  the  hypogastric 
region.     In  the  adult,  when  quite  empty  and  contracted,  it  is  a  small  triangular 

Fig.  436. — Vertical  Section  of  Bladder,  Penis,  aad  Urethra. 


Prtpii-oa 


sac,  placed  deeply  in  the  pelvis,  flattened  from  before  backwards,  its  apex  reaching 
as  high  as  the  upper  border  of  the  symphysis  pubis.  When  slightly  distended, 
it  has  a  rounded  form,  and  partially  fills  the  pelvic  cavity;  and  when  greatly 
distended,  it  is  ovoid  in  shape,  rising  into  the  abdominal  cavity,  and  often  ex- 
tending nearly  as  high  as  the  umbilicus.  It  is  larger  in  its  vertical  diameter 
than  from  side  to  side,  and  its  long  axis  is  directed  from  above  obliquely  down- 
wards and  backwards,  in  a  line  directed  from  some  point  between  the  pubes 
and  umbilicus  (according  to  its  distension)  to  the  end  of  the  coccyx.  The 
bladder,  when  distended,  is  slightly  curved  forwards  towards  the  anterior  wall 
of  the  abdomen,  so  as  to  be  more  convex  behind  than  in  front.  In  the  female, 
it  is  larger  in  the  transverse  than  in  the  vertical  diameter,  and  its  capacity  is 
said  to  be  greater  than  in  the  male.  When  moderately  distended,  it  measures 
about  five  inches  in  length,  and  three  inches  across,  and  the  ordinary  amount 
which  it  contains  is  about  a  pint. 

The  bladder  is  divided  into  a  summit,  body,  base,  and  neck. 

The  summit,  or  apex,  of  the  bladder  is  rounded  and  directed  forwards  and 
upwards;  it  is  connected  to  the  umbilicus  by  a  fibro-muscular  cord,  the  urachus, 


196  URINARY    ORGANS. 

and  also  by  means  of  two  rounded  fibrous  cords,  the  obliterated  portions  of  the 
hypogastric  arteries,  which  are  placed  one  on  each  side  of  tlie  urachus.  The 
summit  of  the  bladder  behind  the  urachus  is  covered  by  peritoneum,  whilst  the 
portion  in  front  of  the  urachus  has  no  peritoneal  covering,  but  rests  upon  the 
abdominal  wall. 

The  urachus  is  the  obliterated  remains  of  a  tubular  canal  which  exists  in  the 
embryo,  and  connects  the  cavity  of  the  bladder  with  a  membranous  sac  placed 
external  to  the  abdomen,  opposite  the  umbilicus,  called  the  allantois.  In  the 
infant,  at  birth,  it  is  occasionally  found  pervious,  so  that  the  urine  escapes  at 
the  umbilicus,  and  calculi  have  been  found  in  its  canal. 

The  body  of  ibe  bladder  in  front  is  not  covered  by  peritoneum,  and  is  in 
relation  with  the  trianguJar  ligament  of  the  urethra,  the  posterior  surface  of 
the  symphysis  pubis,  the  Internal  Obturator  muscles,  and,  when  distended,  with 
the  abdominal  parietes. 

The  posterior  surface  is  covered  by  peritoneum  throughout.  It  corresponds, 
in  the  male,  with  the  rectum ;  in  the  female,  with  the  uterus,  some  convolu- 
tions of  the  small  intestine  being  interposed. 

The  side  of  the  bladder  is  crossed  obliquely  from  below,  upwards  and  for- 
wards, by  the  obliterated  hypogastric  artery;  above  and  behind  this  cord,  the 
bladder  is  covered  by  peritoneum;  but  below  and  in  front  of  it,  the  serous 
covering  is  wanting,  and  it  is  connected  to  the  pelvic  fascia.  The  vas  deferens 
passes,  in  an  arched  direction,  from  before  backwards,  along  the  side  of  the 
bladder,  towards  its  base,  crossing  in  its  course  the  obliterated  hypogastric 
artery,  and  passing  along  the  inner  side  of  the  ureter. 

The  base  {fundus)  of  the  bladder  is  directed  downwards  and  backwards.  It 
varies  in  extent  according  to  the  state  of  distension  of  the  organ,  being  very 
broad  when  full,  but  much  narrower  when  empty.  In  the  male,  it  rests  upon 
the  second  portion  of  the  rectum,  from  which  it  is  separated  by  a  reflection  of 
the  recto-vesical  fascia.  It  is  covered  posteriorly,  for  a  slight  extent,  by  the 
peritoneum,  which  is  reflected  from  it  upon  the  rectum,  forming  the  recto- 
vesical fold.  The  portion  of  the  bladder  in  relation  with  the  rectum  corresponds 
to  a  triangular  space,  bounded  behind  by  the  recto-vesical  fold ;  on  either  side, 
by  the  vesicula  seminalis  and  vas  deferens;  and  touching  the  prostate  gland  in 
front.  When  the  bladder  is  very  full,  the  peritoneal  fold  is  raised  with  it, 
and  the  distance  between  its  reflection  and  the  anus  is  about  four  inches;  but 
this  distance  is  much  diminished  when  the  bladder  is  empty  and  contracted. 
In  the  female^  the  base  of  the  bladder  lies  in  contact  with  the  lower  part  of  the 
cervix  uteri,  is  adherent  to  the  anterior  wall  of  the  vagina,  and  separated  from 
the  upper  part  of  the  anterior  surface  of  the  cervix  uteri  by  a  fold  of  the 
peritoneum. 

The  neck  {cervix)  of  the  bladder  is  the  constricted  portion  continuous  with 
the  urethra.     In  the  male,  its  direction  is  oblique  in  the  erect  posture,  and  it  is 
surrounded  by  the  prostate  gland.     In  the  female,  its  direction  is  obliquely  j 
downwards  and  forwards. 

Ligaments.  The  bladder  is  retained  in  its  place  by  ligaments,  which  are 
divided  into  true  and  false.  The  true  ligaments  are  five  in  number,  two  ante- 
rior, and  two  lateral,  formed  by  the  recto-vesical  fiiscia,  and  the  uraclius.  The 
false  ligaments,  also  five  in  number,  are  formed  by  folds  of  the  peritoneum.       |H 

The  anterior  li(/nments  {pnbo-prostatic)  extend  from  the  back  of  the  pubes,  " 
one  on  each  side  of  the  symphysis,  to  the  front  of  the  neck  of  the  bladder,  and 
uf)per  surface  of  the  prostate  gland.     These  ligaments  contain  a  few  muscular  h 
fibres,  prolonged  from  the  bladder.  -^P 

•  The  lateral  ligaments,  broader  and  thinner  than  the  preceding,  are  attached  to 
the  lateral  parts  of  the  prostate,  and  to  the  sides  of  the  base  of  the  bladder. 

The  urachus  is  the  fibro-muscular  cord  already  mentioned,  extending  between 
the  summit  of  the  bladder  and  the  umbilicus.  It  is  broad  below,  at  its  attach- 
ment to  the  bladder,  and  becomes  narrower  as  it  ascends. 


1 


BLADDER.  797 

The  false  ligaments  of  the  bladder  are,  two  posterior,  two  lateral,  and  one 
superior. 

The  two  posterior  pass  forwards,  in  the  male,  from  the  sides  of  the  rectum ;  in 
the  female,  from  the  sides  of  the  uterus,  to  the  posterior  and  lateral  aspect  of 
the  bladder ;  they  form  the  lateral  boundaries  of  the  recto-vesical  fold  of  peri- 
toneum, and  contain  the  obliterated  hypogastric  arteries,  and  the  ureters,  beside 
vessels  and  nerves. 

The  two  lateral  ligaments  are  reflections  of  the  peritoneum,  from  the  iliac 
fossee  to  the  sides  of  the  bladder. 

The  superior  ligament  is  the  prominent  fold  of  peritoneum  extending  from  the 
summit  of  the  bladder  to  the  umbilicus.  It  covers  the  urachus,  and  the  oblite- 
rated hypogastric  arteries. 

Structure.  The  bladder  is  composed  of  four  coats :  a  serous,  a  muscular,  a 
cellular,  and  a  mucous  coat. 

The  serous  coat  is  partial,  and  derived  from  the  peritoneum.  It  invests  the 
posterior  surface,  from  opposite  the  termination  of  the  two  ureters  to  its  sum- 
mit, and  is  reflected  from  this  point  and  from  the  sides,  on  to  the  abdominal  and 
pelvic  walls. 

The  muscular  coat  consists  of  two  layers  of  unstriped  muscular  fibre,  an 
external  layer,  composed  of  longitudinal  fibres,  and  an  internal  layer  of  circular 
fibres. 

The  longitudinal  fibres  are  most  distinct  on  the  anterior  and  posterior  sur- 
faces of  the  organ.  They  arise  in  front,  from  the  anterior  ligaments  of  the 
bladder,  from  the  neck  of  the  bladder,  and,  in  the  male,  from  the  adjacent  por- 
tion of  the  prostate  gland.  They  spread  out,  and  form  a  plexiform  mesh,  on 
the  anterior  surface  of  the  bladder,  being  continued  over  the  posterior  surface 
and  base  of  the  organ  to  the  neck,  where  they  are  inserted  into  the  prostate,  in 
the  male,  and  into  the  vagina  in  the  female. 

Other  longitudinal  fibres  arise,  in  the  male,  from  the  sides  of  the  prostate, 
and  spread  out  upon  the  sides  of  the  bladder,  intersecting  with  one  another. 

The  circular  fibres  are  very  thinly  and  irregularly  scattered  on  the  body  of 
the  organ ;  but,  towards  its  lower  part,  round  the  cervix  and  commencement 
of  the  urethra,  they  are  disposed  as  a  thick  circular  layer,  forming  the  sphincter 
vesicne,  which  is  continuous  with  the  muscular  fibres  of  the  prostate  gland. 

Two  bands  of  oblique  fibres,  originating  behind  the  orifices  of  the  ureters, 
converge  to  the  back  part  of  the  prostate  gland,  and  are  inserted,  by  means  of 
a  fibrous  process,  into  the  middle  lobe  of  that  organ.  They  are  the  muscles  of 
the  ureters^  described  by  Sir  C.  Bell,  who  supposed  that,  during  the  contraction 
of  the  bladder,  they  served  to  retain  the  oblique  -direction  of  the  ureters,  and 
so  prevent  the  reflux  of  urine  into  them. 

The  cellular  coat  consists  of  a  layer  of  areolar  tissue,  connecting  together  the 
muscular  and  mucous  coats,  and  intimately  united  to  the  latter. 

The  mucous  coat  is  thin,  smooth,  and  of  a  pale  rose  color.  It  is  continuous 
through  the  ureters  with  the  lining  membrane  of  the  uriniferons  tubes,  and 
below,  with  that  of  the  urethra.  It  is  connected  loosely  to  the  muscular  coat, 
by  a  layer  of  areolar  tissue,  excepting  at  the  trigone,  where  its  adhesion  is 
more  close.  It  is  provided  with  a  few  mucous  follicles ;  and  numerous  small 
racemose  glands,  lined  with  columnar  epithelium,  exist  near  the  neck  of  the 
organ.  The  epithelium  covering  it  is  intermediate  in  form  between  the  columnar 
and  squamous  varieties. 

Interior  of  the  bladder.  Upon  the  inner  surface  of  the  base  of  the  bladder, 
immediately  behind  the  urethral  orifice,  is  a  triangular,  smooth  surface,  the  apex 
of  which  is  directed  forwards ;  this  is  the  trigonum  vesicse,  or  trigone  vesicale. 
It  is  paler  in  color  than  the  rest  of  the  mucous  membrane,  and  never  presents 
any  rugae,  even  in  the  collapsed  condition  of  the  organ,  owing  to  its  intimate 
adhesion  to  the  subjacent  tissues.  It  is  bounded  on  each  side  by  two  slight 
ridges,  which  pass  backwards  and  outwards  to  the  orifices  of  the  ureters,  and 


798 


URINARY    ORGANS. 


Fig.  437.— The  "Bladder  and  Urethra 
laid  open.    "Seen  from  above. 


correspond  with  the  muscles  of  these  tubes  ;  and  at  each  posterior  angle,  by  the 
orifices  of  the  ureters,  which  are  placed  nearly  two  inches  from  each  other,  and 
about  an  inch  and  a. half  behind  the  orifice  of  the  urethra.  The  trigone  cor- 
responds with  the  interval  at  the  base  of  the  bladder,  bounded  by  the  pro.state 

in  front,  and  the  vesiculae  and  vasa  deferentia 
on  the  sides.  Projecting  from  the  lower  and 
anterior  part  of  the  bladder,  into  the  orifice  of 
the  urethra,  is  a  slight  elevation  of  mucous 
membrane,  called  the  uvula  vesicae.  It  is  formed 
by  a  thickening  of  the  prostate. 

The  arteries  supplying  the  bladder  are  the 
superior,  middle,  and  inferior  vesical,  in  the 
male,  with  additional  branches  from  the  uterine, 
in  the  female.  They  are  all  derived  from  the 
anterior  trunk  of  the  internal  iliac. 

The  veins  form  a  complicated  plexus  round 
the  neck,  sides,  and  base  of  the  bladder,  and 
terminate  in  the  internal  iliac  vein. 

The  lymphatics  accompany  the  bloodvessels, 
passing  through  the  glands  surrounding  them. 
The  nerves  are  derived  from  the  hypogastric 
and  sacral  plexuses;  the  former  supplying  the 
upper  part  of  the  organ,  the  latter  its  base  and 
neck. 


fu-pti'*  ClanJ. 


Qrlfltm  <f  ituet*. 


Male  Ukethra. 


Jl 


'11 

1 


The  Urethra  extends  from  the  neck  of  th< 
bladder  to  the  meatus  urinarius.  It  presents  a 
double  curve  in  the  flaccid  state  of  the  penis, 
but  in  the  erect  state  it  forms  only  a  single 
curve,  the  concavity  of  which  is  directed  up- 
wards (Fig.  436).  Its  length  varies  from  eight 
to  nine  inches;  and  it  is  divided  into  three  por- 
tions, the  prostatic,  membranous,  and  spongy, 
the  structure  and  relations  of  which  are  esseu^ 
tially  different. 

The  prostatic  portion  is  the  widest  and  most 
dilatable  part  of  the  canal.     It  passes  through 
the  prostate  gland,  from  its  base  to  its  apex, 
lying  nearer  its  upper  than  its  lower  surface. 
It  is  about  an  inch  and  a  quarter  in  length ; 
the  form  of  the  canal  is  spindle-shaped,  being 
wider  in  the  middle  than  at  either  extremity,  and  narrowest  in  front,  where 
it  joins  the  membranous  portion.     A  transverse  section  of  the  canal  in  this 
situation  is  triangular,  the  apex  directed  downwards.  mt 

Upon  the  floor  of  the  canal  is  a  narrow  longitudinal  ridge,  the  verumontanufn^^^ 
or  caput  gallinayinisy  formed  by  an  elevation  of  the  mucous  membrane  and  its 
subjacent  tissue.     It  is  eight  or  nine  lines  in  length,  and  a  line  and  a  half  in_, 
height;  and  contains,  according  to  Kobelt,  muscular  and  erectile  tissues.    WhenMl 
distended,  it  may  serve  to  prevent  the  passage  of  the  semen  backwards  into  the"' 
bladder.     On  each  side  of  the  verumontanum  is  a  slightly  depressed  fossa,  the 
prostatic  simis,  the  floor  of  which  is  perforated  by  numerous  apertures,  th« 
orifices  of  the  prostatic  ducts,  the  ducts  of  the  middle  lobe  opening  behind  th< 
crest.     At  the  fore  part  of  the  verumontanum,  in  the  middle  line,  is  a  depres^ 
sion,  the  sinu^  pocularis  (vesicula  prostatica) ;  and  upon  or  within  its  margins  are 
the  slit-like  openings  of  the  ejaculatory  ducts.     The  sinus  pocularis  forms  a 


ilcalui 


le 

1 


URETHRA.  Y99 

cul-de-sac  about  a  quarter  of  an  inch  in  length,  which  runs  upwards  and  back- 
wards in  the  substance  of  the  prostate,  beneath  the  middle  lobe;  its  prominent 
upper  wall  partly  forms  the  verumontanum.  Its  walls  are  composed  of  fibrous 
tissue,  muscular  fibres,  and  mucous  membrane;  and  numerous  small  glands 
open  on  its  inner  surface.  It  has  been  called  by  Weber,  who  discovered  it,  the 
tUerus  mascuUnus,  from  its  supposed  homology  with  the  female  organ. 

The  membranous  portion  of  the  urethra  extends  between  the  apex  of  the  pros- 
tate and  the  bulb  of  the  corpus  spongiosum.  It  is  the  narrowest  part  of  the 
canal  (excepting  the  orifice),  and  measures  three-quarters  of  an  inch  aloncr  its 
upper  and  half  an  inch  along  its  lower  surface,  in  consequence  of  the  bulb 
projecting  backwards  beneath  it  below.  Its  upper  concave  surface  is  placed 
about  an  inch  beneath  the  pubic  arch,  from  which  it  is  separated  by  the  dorsal 
vessels  and  nerves  of  the  penis,  and  some  muscular  fibres.  Its  lower  convex 
surface  is  separated  from  the  rectum  by  a  triangular  space,  which  constitutes 
the  perineum.  The  membranous  portion  of  the  urethra  perforates  the  deep 
perineal  fascia;  and  two  layers  from  this  membrane  are  prolonged  round  it,  the 
one  forwards,  the  other  backwards;  it  is  also  surrounded  by  the  Compressor 
Urethrae  muscle.  Its  coverings  are  mucous  membrane,  elastic  fibrous  tissue,  a 
thin  layer  of  erectile  tissue,  muscular  fibres,  and  a  prolongation  from  the  deep 
perineal  fascia. 

The  spongy  portion  is  the  longest  part  of  the  urethra,  and  is  contained  in 
the  corpus  spongiosum.  It  is  about  six  inches  in  length,  and  extends  from 
the  termination  of  the  membranous  portion  to  the  meatus  urinarius.  Com- 
mencing below  the  symphysis  pubis,  it  ascends  for  a  short  distance,  and  then 
curves  downwards.  It  is  narrow,  and  of  uniform  size  in  the  body  of  the  penis, 
measuring  about  a  quarter  of  an  inch  in  diameter;  being  dilated  behind, 
within  the  bulb;  and  again  anteriorly  within  the  glans  penis,  forming  the  fossa 
navicularis.  A  cross  section  of  this  canal  in  the  body  of  the  penis  has  its  long 
diameter  transverse;  but  in  the  glans,  that  diameter  is  directed  vertically. 

The  bulbous  portion  is  a  name  given,  in  some  descriptions  of  the  urethra,  to 
the  posterior  dilated  part  of  the  spongy  portion  contained  within  the  bulb. 

The  meatus  uriyiarius  is  the  most  contracted  part  of  the  urethra;  it  is  a  verti- 
cal slit,  about  three  lines  in  length,  bounded  on  each  side  by  two  small  labia. 
The  inner  surface  of  the  lining  membrane  of  the  urethra,  especially  on  the  floor 
of  the  spongy  portion,  presents  the  orifices  of  numerous  mucous  glands  and 
follicles,  situated  in  the  submucous  tissue,  and  named  the  glands  of  Littre.  They 
vary  in  size,  and  their  orifices  are  directed  forwards,  so  that  they  may  easily 
intercept  the  point  of  a  catheter  in  its  passage  along  the  canal.  One  of  these 
iacunoe,  larger  than  the  rest,  is  situated  on  the  upper  surface  of  the  fossa  navi- 
cularis, about  an  inch  and  a  half  from  the  orifice;  it  is  called  the  lacuna  magna. 
Into  the  bulbous  portion  are  found  opening  the  ducts  of  Cowper's  glands. 

Structure.  The  urethra  is  composed  of  three  coats :  a  mucous,  muscular,  and 
erectile. 

The  mucous  coat  forms  part  of  the  genito-urinary  mucous  membrane.  It  is 
continuous  with  the  mucous  membrane  of  the  bladder,  ureters,  and  kidneys; 
externally,  with  the  integument  covering  the  glans  penis;  and  is  prolonged  into 
the  ducts  of  the  glands  which  open  into  the  urethra,  viz.,  Cowper's  glands,  the 
prostate  gland,  and  the  vasa  deferentia  and  vesiculae  seminales,  through  the 
ejaculatory  ducts.  In  the  spongy  and  membranous  portions  the  mucous  mem- 
brane is  arranged  in  longitudinal  folds  when  the  organ  is  contracted.  Small 
papillte  are  found  upon  it,  near  the  orifice;  and  its  epithelial  lining  is  of  the 
columnar  variety,  excepting  near  the  meatus,  where  it  is  laminated. 

The  mziscular  coat  consists  of  two  layers  of  plain  muscular  fibres,  an  external 
longitudinal  layer,  and  an  internal  circular.  The  muscular  tissue  is  most 
abundant  in  the  prostatic  portion  of  the  canal. 

A  thin  layer  of  erectile  tissue  is  continued  from  the  corpus  spongiosum  round 
the  membranous  and  prostatic  portions  of  the  urethra  to  the  neck  of  the  bladder. 


Male   Organs    of   Generation. 

Prostate  Gland. 

The  Prostate  Gland  (jtpoiorj^/ii,  to  .stand  he/ore)  is  a  pale,  firm,  glandular  body, 
which  surrounds  the  neck  of  the  bladder  and  commencement  of  the  urethra. 
It  is  placed  in  the  pelvic  cavity,  behind  and  below  the  symphysis  pubis,  poste- 
rior to  the  deep  perineal  fascia,  and  upon  the  rectum,  through  which  it  may 
be  distinctly  felt,  especially  when  enlarged.  In  shape  and  size  it  resembles  a 
horse-chestnut. 

Its  base  is  directed  backwards  towards  the  neck  ot  the  bladder. 

The  o/jex  is  directed  forwards  to  the  deep  perineal  fascia,  which  it  touches. 

Its  under  surface  is  smooth,  and  rests  on  the  rectum,  to  which  it  is  connected 
by  dense  areolar  fibrous  tissue. 

Its  upper  surface  is  flattened,  marked  by  a  slight  longitudinal  furrow,  and 
placed  about  three-quarters  of  an  inch  below  the  pubic  symphysis. 

It  measures  about  an  inch  and  a  half  in  its  transverse  diameter  at  the  base, 
an  inch  in  its  antero-posterior  diameter,  and  three-quarters  of  an  inch  in  depth. 
Its  weight  is  about  six  drachms.  It  is  held  in  its  position  by  the  anterior  liga- 
ments of  the  bladder  (pubo -prostatic)',  by  the  posterior  layer  of  the  deep  perineal 
fascia,  which  invests  the  commencement  of  the  membranous  portions  of  the 
urethra  and  prostate  gland;  and  by  the  anterior  portion  of  the  Levator  Ani 
muscle  {Levator  Prostatoe),  which  passes  down  on  each  side  from  the  symphysis 
pubis  and  anterior  ligament  of  the  bladder  to  the  sides  of  the  prostate. 

The  prostate  consists  of  three  lobes:  two  lateral  and  a  middle  lobe. 

The  two  lateral  lobes  are  of  equal  size,  separated  behind  by  a  deep  notch,  and 
marked  by  a  slight  furrow  upon  their  upper  and  lower  surface,  which  indicates 
the  bi-lobed  condition  of  the  organ  in  some  animals. 

The  third,  or  middle  lobe,  is  a  small  transverse  band,  occasionally  a  rounded 
or  triangular  prominence,  placed  between  the  two  lateral  lobes,  at  the  under 
and  posterior  part  of  the  organ.  It  lies  immediately  beneath  the  neck  of  the 
bladder,  behind  the  commencement  of  the  urethra,  and  above  the  ejaculatory 
ducts.  Its  existence  is  not  constant;  but  it  is  occasionally  found  at  an  early 
period  of  life,  as  well  as  in  adults  and  in  old  age.  In  advanced  life  it  often 
becomes  considerably  enlarged,  and  projects  into  the  bladder,  so  as  to  impede 
the  passage  of  the  urine.  According  to  Dr.  Messer's  researches,  conducted  at 
Greenwich  Hospital,'  it  would  seem  that  this  obstruction  exists  in  20  per  cent, 
of  all  prostates  over  sixty  years  of  age. 

The  prostate  gland  is  perforated  by  the  urethra  and  common  seminal  ducts. 
The  urethra  usually  lies  about  one-third  nearer  its  upper  than  its  lower  sur- 
face; occasionally  the  prostate  surrounds  only  the  lower  three-fourths  of  this 
tube,  and  more  rarely  the  urethra  runs  through  the  lower  instead  of  the  upper 
part  of  the  gland.  The  ejaculatory  ducts  pass  forwards  obliquely  through  a 
conical  canal,  situated  in  the  lower  part  of  the  prostate,  and  open  into  the  pros- 
tatic portion  of  the  urethra. 

Structure.  The  prostate  is  inclosed  in  a  thin  but  firm  fibrous  capsule,  dis- 
tinct from  thatxlerived  from  the  posterior  layer  of  the  deep  perineal  fascia,  and 
separated  from  it  by  a  plexus  of  veins.  Its  .substance  is  of  a  pale  reddish-gray 
color,  very  friable,  but  of  great 'density.  It  consists  of  glandular  substance  and 
muscular  tissue. 


I 
I 


'  Med.-Chir.  Trans.,  vol.  xliii.  p.  152. 
800 


I 


PENIS.  801 

The  glandular  siibstance  is  composed  of  numerous  follicular  pouches,  opening 
into  elongated  canals,  which  join  to  form  from  twelve  to  twenty  small  excre- 
tory ducts.  The  follicles  are  connected  together  by  areolar  tissue,  supported 
by  prolongations  from  the  fibrous  capsule,  and  inclosed  in  a  delicate  capillary 
plexus.  The  epithelium  lining  the  canals  is  columnar,  whilst  that  in  the  termi- 
nal vesicles  is  of  the  sqaumous  variety. 

The  muscular  tissue  of  the  prostate  is  arranged  in  the  form  of  circular  bands 
round  the  urethra  ;  it  is  continuous  behind  with  the  circular  fibres  of  the 
sphincter  vesicse,  and  in  front  with  the  circular  fibres  of  the  urethra.  The  mus- 
cular fibres  are  of  the  involuntary  kind.  The  prostatic  ducts  open  into  the 
floor  of  the  prostatic  portion  of  the  urethra. 

Vessels  and  Nerves.  The  arteries  supplying  the  prostate  are  derived  from  the 
internal  pudic,  vesical,  and  ha3morrhoidal.  Its  veins  form  a  plexus  around  the 
sides  and  base  of  the  gland  ;  they  communicate  in. front  with  the  dorsal  vein  of 
the  penis,  and  terminate  in  the  internal  iliac  vein.  The  nerves  are  derived 
from  the  hypogastric  plexus. 

The  Prostatic  Secretion  is  a  milky  fluid,  having  an  acid  reaction,  and  presenting, 
on  microscopic  examination,  molecular  matter,  the  squamous  and  columnar  forms 
of  epithelium,  and  granular  nuclei.  In  old  age,  this  gland  is  liable  to  be  en- 
larged, and  its  ducts  are  often  filled  with  innumerable  small  concretions,  of  a 
brownish-red  color,  and  of  the  size  of  a  millet  seed,  composed  of  carbonate  of 
lime  and  animal  matter. 

Cowper's  Glands. 

Cowper's  Glands  are  two  small  rounded  and  somewhat  lobulated  bodies,  of  a 
yellowish  color,  about  the  size  of  peas,  placed  beneath  the  fore  part  of  the  mem- 
branous portion  of  the  urethra,  between  the  two  layers  of  the  deep  perineal 
fascia.  They  lie  close  behind  the  bulb,  and  are  inclosed  by  the  transverse  fibres 
of  the  Compressor  Urethrse  muscle.  Each  gland  consists  of  several  lobules, 
held  together  by  a  fibrous  investment.  The  excretory  duct  of  each  gland, 
nearly  an  inch  in  length,  passes  obliquely  forwards  beneath  the  mucous  mem- 
brane, and  opens  by  a  minute  orifice  on  the  floor  of  the  bulbous  portion  of  the 
urethra.  Their  existence  is  said  to  be  constant ;  they  gradually  diminish  in 
size  as  age  advances. 

The  Penis. 

The  Penis  is  the  organ  of  copulation,  and  contains  in  its  interior  the  larger 
portion  of  the  urethra.  It  consists  of  a  root,  body,  and  extremity  or  glans 
penis. 

The  root  is  broad,  and  firmly  connected  to  the  rami  of  the  pubes  by  two  strong 
tapering  fibrous  processes,  the  crura,  and  to  the  front  of  the  symphysis  pubis 
by  a  fibrous  membrane,  the  suspensory  ligament. 

The  extremity^  or  glans  jjenis,  presents  the  form  of  art  obtuse  cone,  flattened 
from  above  downwards.  At  its  summit  is  a  vertical  fissure,  the  orifice  of  the 
urethra  (meatus  urinarius) ;  at  the  back  part  of  this  orifice  a  fold  ot  mucous 
membrane  passes  backwards  to  the  bottom  of  a  depressed  raphe,  where  it  is 
continuous  with  the  prepuce;  this  fold  is  termed  the //•a??iMW  prejmtii.  The  base 
of  the  glans  forms  a  rounded  projecting  border,  the  corona  glandis  ;  and  behind 
the  corona  is  a  deep  constriction,  the  cervix.  Upon  both  of  these  parts  nume- 
rous small  lenticular  sebaceous  glands  are  found,  the  glandulse  Tysonii^  g.odoriferse. 
They  secrete  a  sebaceous  matter  of  very  peculiar  odor,  which  probably  con- 
tains caseine,  and  becomes  easily  decomposed. 

The  hody  of  the  penis  is  the  part  between  the  root  and  the  extremity.    In  the 

flaccid  condition  of  the  organ  it  is  cylindrical,  but  when  erect  has  a  triangular 

prismatic  form  with  rounded  angles,  the  broadest  side  being  turned  upwards, 

and  called  the  dorsum.     It  is  covered  by  integument  remarkable  for  its  thin- 

51  ^         ^ 


802  MALE    ORGANS    OF    GENERATION. 

ness,  its  dark  color,  and  its  looseness  of  connection  with  the  deeper  parts  of  the 
organ,  and  containing  no  adipose  tissue.  At  the  root  of  the  penis  the  integu- 
ment is  continuous  with  that  upon  the  pubes  and  scrotum ;  and  at  the  neck  of 
the  glans  it  leaves  the  surface,  and  becomes  folded  upon  itself  to  form  the  pre- 
puce. 

The  internal  layer  of  the  prepuce,  which  also  becomes  attached  to  the  cervix, 
approaches  in  character  to  a  mucous  membrane  ;  it  is  reflected  over  the  glans 
penis,  and  at  the  meatus  urinarius  is  continuous  with  the  mucous  lining  of  the 
urethra. 

The  mucous  membrane  covering  the  glans  penis  contains  no  sebaceous  glands ; 
but  projecting  from  its  free  surface  are  a  number  of  small,  highly  sensitive 
papillae. 

The  penis  is  composed  of  a  mass  of  erectile  tissue,  inclosed  in  three  cylin- 
drical fibrous  compartments.  Of  these,  two,  the  corpora  cavernosa,  are  placed 
side  by  side  along  the  upper  part  of  the  organ ;  the  third,  or  corpus  spongiosum, 
incloses  the  urethra,  and  is  placed  below. 

The  Corpora  Cavernosa  form  the  chief  part  of  the  body  of  the  penis.  They 
consist  of  two  fibrous  cylindrical  tubes,  placed  side  by  side,  and  intimately 
connected  along  the  median  line  for  their  anterior  three-fourths,  their  posterior 
fourth  being  separated  to  form  the  two  crura,  by  which  the  penis  is  connected 
to  the  rami  of  the  pubes.  Each  crus  commences  by  a  thick-pointed  process  in 
front  of  the  tuberosity  of  the  ischium ;  and,  near  its  junction  with  its  fellow, 
presents  a  slight  enlargement,  named,  by  Kobelt,  the  hulh  of  the  corpus  caver- 
nosum.  Just  beyond  this  point  they  become  constricted,  and  retain  an  equal 
diameter  to  their  anterior  extremity,  where  they  form  a  single  rounded  end, 
which  is  received  into  a  fossa  in  the  base  of  the  glans  penis.  A  median  groove 
on  the  upper  surface  lodges  the  dorsal  vein  of  the  penis,  and  the  groove  on  the 
under  surface  receives  the  corpus  spongiosum.  The  root  of  the  penis  is  con- 
nected to  the  symphysis  pubis  by  the  suspensory  ligament. 

/Structure.  Each  corpus  cavernosum  consists  of  a  strong  fibrous  envelope, 
inclosing  a  fibrous  reticular  structure,  which  contains  erectile  tissue  in  its 
meshes.     It  is  separated  from  its  fellow  by  an  incomplete  fibrous  septum. 

The  fibrous  investment  is  extremely  dense,  of  considerable  thickness,  and 
highly  elastic ;  it  not  only  invests  the  surface  of  the  organ,  but  sends  off  nume- 
rous fibrous  bands  {traheculse)  from  its  inner  surface,  as  well  as  from  the  surface 
of  the  septum,  which  cross  its  interior  in  all  directions,  subdividing  it  into  a 
number  of  separate  compartments,  which  present  a  spongy  structure,  in  which 
the  erectile  tissue  is  contained. 

The  trabecular  structure  fills  the  interior  of  the  corpora  cavernosa.    Its  com 
ponent  fibres  are  larger  and  stronger  round  the  circumference  than  at  the  centre 
of  the  corpora  cavernosa ;  they  are  also  thicker  behind  than  in  front.     The  iii-fll 
terspaces,  on  the  contrary,  are  larger  at  the  centre  than  at  the  circumference,"" 
their  long  diameter  being  directed  transversely  ;  and  they  are  largest  anteriorly. 
They  are  lined  by  a  layer  of  squamous  epithelium. 

l^\iQ  fibrous  septum  forms  an  imperfect  partition  between  the  two  corpora  caver- 
nosa; it  is  thick  and  complete  behind ;  but  in  front  it  is  incomplete,  and  consists 
of  a  number  of  vertical  bands  of  fibrous  tissue,  which  are  arranged  like  the 
teeth,  of  a  comb,  hence  the  name,  septum  piecliniforme ;  these  bands  extend  be- 
tween the  dorsal  and  urethral  surface  of  the  corpora  cavernosa. 

The  fibrous  investment  and  septum  consist  of  longitudinal  bands  of  white 
fibrous  tissue,  with  numerous  elastic  and  muscular  fibres.  The  trabeculre  also 
consist  of  white  fibrous  tissue,  elastic  fibres,  and  plain  muscular  fibres,  and  in- 
close arteries  and  nerves. 

The  Corpus  Spongiosum  incloses  the  urethra,  and  is  situated  in  the  groove  on 
the  under  surface  of  the  corpora  cavernosa.  It  commences  posteriorly  in  front 
of  the  deep  perineal  fascia,  between  the  diverging  crura  of  the  corpora  caver- 
nosa, where  it   forms  a  rounded   enlargement,  the  bulb ;  and  terminates,  ante- 


II 


II 


II 


PENIS.  803 

riorly,  in  anotlier  expansion,  the  glans  penis,  whicTi  overlaps  the  anterior 
rounded  extremity  of  the  corpora  cavernosa.  The  central  portion,  or  body  of 
the  corpus  spongiosum,  is  cylindrical,  and  tapers  slightly  from  behind  forwards. 

The  hulb  varies  in  size  in  different  subjects;  it  receives  a  fibrous  investment 
from  the  anterior  layer  of  the  deep  perineal  fascia,  and  is  surrounded  by  the 
Accelerator  UrinaB  muscle.  The  urethra  enters  the  bulb  nearer  its  upper  than 
its  lower  surface,  being  surrounded  by  a  layer  of  erectile  tissue,  a  thin  prolon- 
gation of  which  is  continued  backwards  round  the  membranous  and  prostatic 
portions  of  the  canal  to  the  neck  of  the  bladder,  lying  immediately  beneath 
the  mucous  membrane.  The  portion  of  the  bulb  below  the  urethra  presents  a 
partial  division  into  two  lobes,  being  marked  externally  by  a  linear  raphe, 
whilst  internally  there  projects  inwards  for  a  short  distance  a  thin  fibrous  sep- 
tum, more  distinct  in  early  life. 

Structure.  The  corpus  spongiosum  consists  of  a  strong  fibrous  envelope,  in- 
closing a  trabecular  structure,  which  contains  in  its  meshes  erectile  tissue.  The 
fibrous  envelope  is  thinner,  whiter  in  color,  and  more  elastic  than  that  of  the 
corpus  cavernosum.  The  trabeculse  are  delicate,  uniform  in  size,  and  the  meshes 
between  them  small ;  their  long  diameter,  for  the  most  part,  corresponding  with 
that  of  the  penis.  A  thin  layer  of  muscular  fibres,  continuous  behind  with  those 
of  the  bladder,  forms  part  of  the  outer  coat  of  the  corpus  spongiosum. 

Erectile  tissue  consists  essentially  of  an  intricate  venous  plexus,  lodged  in  the 
interspaces  between  the  trabeculae.  The  veins  forming  this  plexus  are  so 
numerous,  and  communicate  so  freely  with  one  another,  as  to  present  a  cellular 
appearance  when  examined  by  means  of  a  section ;  their  walls  are  extremely 
thin,  and  lined  by  squamous  epithelium.  The  veins  are  smaller  in  the  glans 
penis,  corpus  spongiosum,  and  circumference  of  the  corpora  cavernosa,  than  in 
the  central  part  of  the  latter,  where  they  are  of  large  size,  and  much  dilated. 
They  return  the  blood  by  a  series  of  vessels,  some  of  which  emerge  in  con- 
siderable numbers  from  the  base  of  the  glans  penis,  and  converge  on  the  dorsum 
of  the  organ  to  form  the  dorsal  vein  ;  others  pass  out  on  the  upper  surface  of 
the  corpora  cavernosa,  and  join  the  dorsal  vein ;  some  emerge  from  the  under 
surface  of  the  corpora  cavernosa,  and,  receiving  branches  from  the  corpus  spon- 
giosum, wind  round  the  sides  of  the  penis  to  terminate  in  the  dorsal  vein ;  but 
the  greater  number  pass  out  at  the  root  of  the  penis,  and  join  the  prostatic 
plexus  and  pudendal  veins. 

The  arteries  of  the  penis  are  derived  from  the  internal  pudic.  Those  supplying 
the  corpora  cavernosa  are  the  arteries  of  the  corpora  cavernosa,  and  branches 
from  the  dorsal  artery  of  the  penis,  which  perforate  the  fibrous  capsule  near  the 
fore  part  of  the  organ.  Those  to  the  corpus  spongiosum  are  the  arteries  of  the 
bulb.  Additional  branches  are  described,  by  Kobelt,  as  arising  from  the  trunk 
of  the  internal  pudic  ;  they  enter  the  bulbous  enlargements  on  the  corpora  ca- 
vernosa and  corpus  spongiosum.  The  arteries,  on  entering  the  cavernous  struc- 
ture, divide  into  branches,  which  are  supported  and  inclosed  by  the  trabeculae; 
according  to  Miiller,  some  of  these  branches  terminate  in  a  capillary  network, 
which  communicates  with  the  veins  as  in  other  parts ;  whilst  others  are  more 
convoluted,  and  assume  a  tendril-like  appearance ;  hence  the  name,  helicine 
arteries,  which  is  given  to  these  vessels.  The  helicine  arteries  are  more  abund- 
ant in  the  back  part  of  the  corpora  cavernosa  and  corpus  spongiosum ;  they 
have  not  been  §een  in  the  glans  penis.  They  are  small  twigs,  given  off  in 
bunches  from  the  sides  of  the  arteries  as  they  lie  on  the  trabeculse,  and  they 
terminate  in  dilated  extremities  hanging  down  into  the  cavity  of  a  vein. 
Whether  the  extremities  of  the  twigs  are  open  or  closed,  appears  uncertain. 
The  existence  of  these  vessels  is  denied  by  Valentin,  who  describes  the  smallest 
branches  of  the  arteries  as  terminating  by  wide,  funnel-shaped  orifices,  which 
open  directly  into  the  venous  cavities. 

The  lymphatics  of  the  penis  consist  of  a  superficial  and  deep  set ;  the  former 
terminate  in  the  inguinal  glands ;  the  latter  emerge  from  the  corpora  cavernosa 


804  MALE    ORGANS    OF    GENERATION. 

and  corpus  spongiosum,  and,  passing  beneath  the  pubic  arch,  join  the  deep  lym- 
phatics of  the  pelvis. 

The  nerves  are  derived  from  the  internal  pudic  nerve  and  the  hypogastric 
plexus.  On  the  glans  and  bulb  some  filaments  of  the  cutaneous  nerves  have 
Pacinian  bodies  connected  with  them. 

The  Testes  and  their  Coverings. 

The  Testes  are  two  small  glandular  organs,  which  secrete  the  semen ;  they 
are  situated  in  the  scrotum,  being  suspended  by  the  spermatic  cords.  At  an 
early  period  of  foetal  life,  the  testes  are  contained  in  the  abdominal  cavity,  be- 
hind the  peritoneum.  Before  birth,  they  descend  to  the  inguinal  canal,  along 
which  they  pass  with  the  spermatic  cord,  and,  emerging  at  the  external  abdomi- 
nal ring,  they  descend  into  the  scrotum,  becoming  invested  in  their  course  by 
numerous  coverings,  derived  from  the  serous,  muscular,  and  fibrous  layers  of 
the  abdominal  parietes,  as  well  as  by  the  scrotum.  The  coveriugs  of  the  testis 
are,  the 

Dartos    }   ^^'°^^^- 

Intercolumnar,  or  External  spermatic  fascia. 

Cremaster  muscle. 

Infundibuliform,  or  Fascia  propria  (Internal  spermatic  fascia). 

Tunica  vaginalis. 

The  Scrotum  is  a  cutaneous  pouch,  which  contains  the  testes  and  part  of  the 
spermatic  cords.  It  is  divided  into  two  lateral  halves,  by  a  median  line,  or 
raphe,  which  is  continued  forwards  to  the  under  surface  of  the  penis,  and  back- 
wards along  the  middle  line  of  the  perineum  to  the  anus.  Of  these  two  lateral 
portions,  the  left  is  longer  than  the  right,  and  corresponds  with  the  greater 
length  of  the  spermatic  cord  on  the  left  side.  Its  external  aspect  varies  under 
different  circumstances :  thus,  under  the  influence  of  warmth,  and  in  old  and 
debilitated  persons,  it  becomes  elongated  and  flaccid :  but,  under  the  influence 
of  cold,  and  in  the  young  and  robust,  it  is  short,  corrugated,  and  closely  applied 
to  the  testes. 

The  scrotum  consists  of  two  layers,  the  integument  and  the  dartos. 

The  integu,nent  is  very  thin,  of  a  brownish  color,  and  generally  thrown  into 
folds  or  rugas.  It  is  provided  with  sebaceous  follicles,  the  secretion  of  which 
has  a  peculiar  odor,  and  is  beset  with  thinly  scattered,  crisp  hairs,  the  roots  of 
which  are  seen  through  the  skin. 

The  dartos  is  a  thin  layer  of  loose  reddish  tissue,  endowed  with  contractility ; 
it  forms  the  proper  tunic  of  the  scrotum,  is  continuous,  around  the  base  of  the 
scrotum,  with  the  superficial  fascia  of  the  groin,  perineum,  and  inner  side  of  the 
thighs,  and  sends  inwards  a  distinct  septum,  septum  scroti,  which  divides  it  into 
two  cavities  for  the  two  testes,  the  septum  extending  between  the  raphe  and  the 
under  surface  of  the  penis,  as  far  as  its  root. 

The  dartos  is  closely  united  to  the  skin  externally,  but  connected  with  the 
subjacent  parts  by  delicate  areolar  tissue,  upon  which  it  glides  with  the  greatest 
facility.  The  dartos  is  very  vascular,  and  consists  of  a  loose  areolar  tissue,  con- 
taining unstriped  muscular  fibre.  Its  contractility  is  slow,  and  excited  by  cold 
and  mechanical  stimuli,  but  not  by  electricity. 

The  intercolumnar  fascia  is  a  thin  membrane,  derived  from  the  margin  of  the 
pillars  of  the  external  abdominal  ring,  during  the  descent  of  the  testis  in  the 
foetus,  being  prolonged  downwards  around  the  surface  of  the  cord  and  testis. 
It  is  separated  from  the  dartos  by  loose  areolar  tissue,  which  allows  of  consider- 
able movement  of  the  latter  upon  it,  but  is  intimately  connected  with  the  suc- 
ceeding layer. 

The  cremasteric  fascia  consists  of  scattered  bundles  of  muscular  fibres  {Cre- 


SPERMATIC    CORD  — TESTES.  806 

master  muscle),  derived  from  the  lower  border  of  the  Internal  Oblique  muscle, 
during  the  descent  of  the  testis  (p.  826). 

The  fascia  propria  is  a  thin  membranous  layer,  which  loosely  invests  the 
surface  of  the  cord.  It  is  a  continuation  downwards  of  the  infundibuliform 
process  of  the  fascia  transversalis,  and  is  also  derived  during  the  descent  of  the 
testis  in  the  fcetus. 

The  tunica  vaginalis  is  described  with  the  proper  coverings  of  the  testis.  A 
more  detailed  account  of  the  other  coverings  of  the  testis  will  be  found  in  the 
description  of  the  surgical  anatomy  of  inguinal  hernia. 

Vessels  and  Nerves.  The  arteries  supplying  the  coverings  of  the  testis  are : 
the  superficial  and  deep  external  pudic,  from  the  femoral ;  the  superficial  peri- 
neal branch  of  the  internal  pudic ;  and  the  cremasteric  branch  from  the  epigas- 
tric. The  veins  follow  the  course  of  the  corresponding  arteries.  The  lymphatics 
terminate  in  the  inguinal  glands.  Thewerwsare:  the  ilio-inguinal  and  ilio- 
hypogastric branches  of  the  lumbar  plexus,  the  two  superficial  perineal  branches 
of  the  internal  pudic  nerve,  the  inferior  pudendal  branch  of  the  small  sciatic 
nerve,  and  the  genital  branch  of  the  genito-crural  nerve. 

The  Sperinatic  Cord  extends  from  the  internal  abdominal  ring,  where  the 
structures  of  which  it  is  composed  converge,  to  the  back  part  of  the  testicle. 
It  is  composed  of  arteries,  veins,  lymphatics,  nerves,  and  the  excretory  duct, 
of  the  testicle.  These  structures  are  connected  together  by  areolar  tissue,  and 
invested  by  the  fascias  brought  down  by  the  testicle  in  its  descent.  In  the 
abdominal  wall  the  cord  passes  obliquely  along  the  inguinal  canal,  lying  at  first 
beneath  the  Internal  Oblique,  and  upon  the  fascia  transversalis;  but  nearer  the 
pubes,  it  rests  upon  Poupart's  ligament,  having  the  aponeurosis  of  the  External 
Oblique  in  front  of  it,  and  the  conjoined  tendon  behind  it.  It  then  escapes  at 
the  external  ring,  and  descends  nearly  vertically  into  the  scrotum.  The  left 
cord  is  rather  longer  than  the  right,  consequently  the  left  testis  hangs  some- 
what lower  than  its  fellow. 

The  arteries  of  the  cord  are  the  spermatic,  from  the  aorta;  the  artery  of  the 
vas  deferens,  from  the  superior  vesical ;  and  the  cremasteric,  from  the  epigastric 
artery. 

The  spermatic  artery  supplies  the  testicle.  On  approaching  the  gland,  it 
gives  off  some  branches  which  supply  the  epididymis,  and  others  which  per- 
forate the  tunica  albuginea  behind,  and  spread  out  on  its  inner  surface,  or  pass 
through  the  fibrous  septum  in  its  interior,  to  be  distributed  on  the  membranous 
septa  between  the  lobes. 

The  artery  of  the  vas  deferens  is  a  long  slender  vessel,  which  accompanies 
the  vas  deferens,  ramifying  upon  the  coats  of  that  duct,  and  anastomosing  with 
the  spermatic  artery  near  the  testis. 

The  cremasteric  branch  from  the  epigastric  supplies  the  Cremaster  muscle, 
and  other  coverings  of  the  cord. 

The  spermatic  veins  leave  the  back  part  of  the  testis,  and  receiving  branches 
from  the  epididymis,  unite  to  form  a  plexus  {pampiniform  plexus),  which  forms 
the  chief  mass  of  the  cord.  They  pass  up  in  front  of  the  vas  deferens,  and  unite 
to  form  a  single  trunk,  which  terminates,  on  the  right  side,  in  the  inferior  vena 
cava,  on  the  left  side,  in  the  left  renal  vein. 

The  lymphatics  are  of  large  size,  accompany  the  bloodvessels,  and  terminate 
in  the  lumbar  glands. 

The  nerves  are  the  spermatic  plexus  from  the  sympathetic.  This  plexus  is 
derived  from  the  renal  and  aortic  plexuses,  joined  by  filaments  from  the  hypo- 
gastric plexus,  which  accompany  the  artery  of  the  vas  deferens. 

Each  testis  is  of  an  oval  form,  compressed  laterally  and  behind,  and  having 
an  oblique  position  in  the  scrotum ;  the  upper  extremity  being  directed  forwards 
and  a  little  outwards;  the  lo^/er,  backwards  and  a  little  inwards;  the  anterior 


806 


MALE    ORGANS    OF    GENERATION. 


convex  border  looks  forwards  and  downwards,  the  posterior  or  straight  border, 
to  which  the  cord  is  attached,  backwards  and  upwards. 

The  anterior  and  lateral  surfaces,  as  well  as  both  extremities  of  the  organ, 
are  convex,  free,  smooth,  and  invested  by  the  tunica  vaginalis.  The  posterior 
border,  to  which  the  cord  is  attached,  receives  only  a  partial  investment  from 
that  membrane.  Lying  upon  the  outer  edge  of  this  border,  is  a  long,  narrow, 
flattened  body,  named,  from  its  relation  to  the  testis,  the  epididymis  {bCivnoc^ 
testis).  It  consists  of  a  central  portion,  or  body,  an  upper  enlarged  extremity, 
the  globus  major,  or  head;  and  a  lower  pointed  extremity,  the  tail,  or  globus 
minor.  The  globus  major  is  intimately  connected  with  the  upper  end  of  the 
testicle  by  means  of  its  efferent  ducts;  and  the  globus  minor  is  connected  with 
its  lower  end  by  cellular  tissue,  and  a  reflection  of  the  tunica  vaginalis.  The 
outer  surface  and  upper  and  lower  ends  of  the  epididymis  are  free  and  covered 
by  serous  membrane;  the  body  is  also  completely  invested  by  it,  excepting 
along  its  posterior  border,  and  connected  to  the  back  of  the  testis  by  a  fold  of 
the  serous  membrane.  Attached  to  the  upper  end  of  the  testis,  or  to  the  epi- 
didymis, is  a  small  pedunculated  body,  the  use  of  which  is  unknown. 

Size  and  Weight.  The  average  dimensions  of  this  gland  are  from  one  and  a 
half  to  two  inches  in  length,  one  inch  in  breadth,  and  an  inch  and  a  quarter  in 
the  antero-posterior  diameter;  and  the  weight  varies  from  six  to  eight  drachms, 
the  left  testicle  being  a  little  the  larger. 

The  testis  is  invested  by  three  tunics,  the  tunica  vaginalis,  tunica  albuginea, 
and  tunica  vasculosa. 

The  Tunica  Vaginalis  is  the  serous  covering  of  the  testis.  It  is  a  pouch  of 
serous  membrane,  derived  from  the  peritoneum  during  the  descent  of  the  testis 
in  the  foetus,  from  the  abdomen  into  the  scrotum.  After  its  descent,  that  por- 
tion of  the  pouch  which  extends  from  the  internal  ring  to  near  the  upper  part 

of  the  gland  becomes  obliterated,  the  lower  por- 
tion remaining  as  a  shut  sac,  which  invests  the 
outer  surface  of  the  testis,  and  is  reflected  on  the 
internal  surface  of  the  scrotum;  hence  it  may  be 
described  as  consisting  of  a  visceral  and  parietal 
portion. 

The  visceral  portion  {tunica  vaginalis  propria), 
covers  the  outer  surface  of  the  testis,  as  well  as 
the  epididymis,  connecting  the  latter  to  the  testis 
by  means  of  a  distinct  fold.  From  the  posterior 
border  of  the  gland,  it  is  reflected  on  to  the  inter- 
nal surface  of  the  scrotum. 

The  p>arietal  portion  of  the  serous  membrane 
[tunica  vaginalis  rejlexa)  is  far  more  extensive 
than  the  visceral  portion,  extending  upwards  for 
some  distance  in  front,  and  on  the  inner  side  of 
the  cord,  and  reaching  below  the  testis.  The 
inner  surface  of  the  tunica  vaginalis  is  free, 
smooth,  and  covered  by  a  layer  of  squamous 
epithelium.  The  interval  between  the  visceral 
and  parietal  layers  of  this  membrane  constitutes  ^| 
the  cavity  of  the  tunica  vaginalis.  Vl 

The  Tunica  Albuginea  is  the  fibrous  covering 
of  the  testis.  It  is  a  dense  fibrous  membrane,  of  a  bluish-white  color,  composed 
of  bundles  of  white  fibrous  tissue,  which  interlace  in  every  direction.  Its  outer 
surface  is  covered  by  tlie  tunica  vaginalis,  except  along  its  posterior  border, 
and  at  tlie  points  of  attachment  of  the  epididymis;  hence  the  tunica  albuginea 
is  usually  considered  as  a  fibro-serous  membrane,  like  the  dura  mater  and  peri-  A| 
cardium.  This  membrane  surrounds  the  glandular  structure  of  the  testicle,  ■! 
and,  at  its  posterior  and  upper  border,  is  reflected  into  the  interior  of  the  gland, 


Fip.  438.— The  Testis  in  Situ. 
The  Tunica  Vaginalis  having  been 
laid  open. 


Jrtery 
of  Curd 


TESTES. 


807 


forming  an  incomplete  vertical  septum,  called  the  mediastinum  testis  {corpus 
Highinorianum). 

The  mediastinum  testis  extends  from  the  upper,  nearly  to  the  lower  border 
of  the  gland,  and  is  wider  above  than  below.  From  the  front  and  sides  of  this 
septum,  numerous  slender  fibrous  cords  (traheculse)  are  given  off",  which  pass  to 
be  attached  to  the  inner  surface  of  the  tunica  albuginea:  they  serve  to  maintain 
the  form  of  the  testis,  and  join  with  similar  cords  given  off  from  the  inner  sur- 
face of  the  tunica  albuginea,  to  form  spaces  which  inclose  the  separate  lobules 
of  the  organ.  The  mediastinum  supports  the  vessels  and  ducts  of  the  testis  in 
their  passage  to  and  from  the  substance  of  the  gland. 

The  Tunica  Vasculosa  {pia  mater  testis),  is  the  vascular  layer  of  the  testis, 
consisting  of  a  plexus  of  bloodvessels,  held  together  by  a  delicate  areolar  tissue. 
It  covers  the  inner  surface  of  the  tunica  albuginea,  sending  off  numerous  pro- 
cesses between  the  lobules,  which  are  supported  by  the  fibrous  prolongations 
from  the  mediastinum  testis. 

Structure.  The  glandular  structure  of  the  testis  consists  of  numerous  lobules 
{lohuli  testis).  Their  number,  in  a  single  testis,  is  estimated  by  Berres  at  250, 
and  by  Krause  at  400.  They  differ  in  size  according  to  their  position,  those  in 
the  middle  of  the  gland  being  larger  and  longer.  The  lobules  are  conical  in 
shape,  the  base  being  directed  towards  the  circumference  of  the  organ,  the  apex 
towards  the  mediastinum.  Each  lobule  is  contained  in  one  of  the  intervals 
between  the  fibrous  cords  and  vascular  processes,  which  extend  between  the 
mediastinum  testis  and  the  tunica  albuginea,  and  consists  of  from  one  to  three, 
or  more,  minute  convoluted  tubes,  the  tubuli  seminiferi.  The  tubes  may  be 
separately  unravelled,  by  careful  dissection  under  water,  and  may  be  seen  to 
commence  either  by  free  ceecal  ends,  or  by  anastomotic  loops.  The  total  num- 
ber of  tubes  is  considered  by  Monro  to  be  about  300,  and  the  length  of  each 
about  sixteen  feet:  by  Lauth,  their  number  is  estimated  at  840,  and  their 
average  length  two  feet  and  a  quarter 
-fl^th  of  an  inch.  The  tubuli  are  pale  in  color  in 
early  life,  but,  in  old  age,  they  acquire  a  deep  yellow 
tinge,  from  containing  much  fatty  matter.  They 
consist  of  a  basement  membrane,  lined  by  epithe- 
lium, consisting  of  nucleated  granular  corpuscles, 
and  are  inclosed  in  a  delicate  plexus  of  capillary 
vessels.  In  the  apices  of  the  lobules,  the  tubuli 
become  less  convoluted,  assume  a  nearly  straight 
course,  and  unite  together  to  form  from  twenty  r«»/<..^.'%,Y» 
to  thirty  larger  ducts,  of  about  ^gth  of  an  inch  in 
diameter,  and  these,  from  their  straight  course, 
are  called  vasa  recta. 

The  vasa  recta  enter  the  fibrous  tissue  of  the 
mediastinum,  and  pass  upwards  and  backwards, 
forming,  in  their  ascent,  a  close  network  of  anas- 
tomosing tubes,  with  exceedingly  thin  parietes; 
this  constitutes  the  rete  testis.  At  the  upper  end 
of  the  mediastinum,  the  vessels  of  the  rete  testis 
terminate  in  from  twelve  to  fifteen  or  twenty 
ducts,  the  vasa  efferentia:  they  perforate  the  tunica 
albuginea,  and  carry  the  seminal  fluid  from  the 
testis  to  the  epididymis.  Their  course  is  at  first 
straight;  they  then  become  enlarged,  exceedingly 
convoluted,  and  form  a  series  of  conical  masses, 
the  coni  vasculosis  which,  together,  constitute  the 
globus  major  of  the  epididymis.  Each  cone  con- 
sists of  a  single  convoluted  duct,  from  six  to  eight  inches  in  length,  the  dia 
meter  of  which  gradually  decreases  from  the  testis  to  the  epididymis.     Op 


Their  diameter  varies  from  ^l^ih.  to 


Figr.  439.— Vertical  Section  of 
the  Testicle,  to  show  the  arrange- 
ment of  the  Ducts. 


808 


iMALE    ORGANS    OP    GENERATION. 


posite  the  bases  of  the  cones,  the  eflferent  vessels  open  at  narrow  intervals  into 
a  single,  duct,  which  constitutes,  by  its  complex  convolutions,  the  body  and 
globus  minor  of  the  epididymis.  When  the  convolutions  of  this  tube  are 
unravelled,  it  measures  upwards  of  twenty  feet  in  length,  and  increases  in 
breadth  and  thickness  as  it  approaches  the  vas  deferens.  The  convolutions  are 
held  together  by  fine  areolar  tissue,  and  by  bands  of  fibrous  tissue.  A  long 
narrow  tube,  the  vasculum  aherrans  of  Haller,  is  occasionally  found  connected 
with  the  lower  part  of  the  canal  of  the  epididymis,  or  with  the  commencement 
of  the  vas  deferens,  and  extending  up  into  the  cord  for  about  two  or  three 
inches,  where  it  terminates  by  a  blind  extremity,  which  is  occasionally  bifur- 
cated. Its  length  varies  from  an  inch  and  a  half  to  fourteen  inches,  and  some- 
times it  becomes  dilated  towards  its  extremity:  more  commonly,  it  retains  the 
same  diameter  throughout.  Its  structure  is  similar  to  that  of  the  vas  deferens. 
Occasionally,  it  is  found  unconnected  with  the  epididymis. 

The  Vas  Deferens^  the  excretory -duct  of  the  testis,  is  the  continuation  of  the 
epididymis.  Commencing  at  the  lower  part  of  the  globus  minor,  it  ascends 
along  the  posterior  and  inner  side  of  the  testis  and  epididymis,  and  along  the 
back  part  of  the  spermatic  cord,  through  the  spermatic  canal,  to  the  internal 
abdominal  ring.  From  the  ring  it  descends  into  the  pelvis,  crossing  the  exter- 
nal iliac  vessels,  and  curves  round  the  outer  side  of  the  epigastric  artery:  at  the 
side  of  the  bladder,  it  arches  backwards  and  downwards  to  its  base,  crossing 
outside  the  obliterated  hypogastric  artery,  and  to  the  inner  side  of  the  ureter. 
At  the  base  of  the  bladder,  it  lies  between  that  viscus  and  the  rectum,  running 
along  the  inner  border  of  the  vesicula  seminalis.  In  this  situation,  it  becomes 
enlarged  and  sacculated;  and,  becoming  narrowed,  at  the  base  of  the  prostate, 
unites  with  the  duct  of  the  vesicula  seminalis  to  form  the  ejaculatory  duct. 
The  vas  deferens  presents  a  hard  and  cord-like  sensation  to  the  fingers;  it  is 
about  two  feet  in  length,  of  cylindrical  form,  and  about  a  line  and  a  quarter  in 
diameter.  Its  walls  are  of  extreme  density  and  thickness,  measuring  one-third 
of  a  line;  and  its  canal  is  extremely  small,  measuring  about  half  a  line. 

Fig,  440, — Base  of  the  Bladder,  with  the  Vasa  Deferentia  and  Vesiculae  Seminales. 


d,ict 


In  structure,  the  vas  deferens  consists  of  three  coats:  1.  An  external,  or  cel- 
lular coat;  2,  A  muscular  coat,  which  is  thick,  dense,  elastic,  and  consists  of 
two  longitudinal,  and  an  intermediate  circular  layer  of  muscular  fibres;  3.  An 
internal,  or  mucous  coat,  which  is  pale,  and  arranged  in  longitudinal  folds;  its 
epithelial  covering  is  of  the  columnar  variety. 


YESICUL^    SEMINALES.  800 


Vesicul^  Seminales. 


The  Seminal  Vesicles  are  two  lobulated  membranous  pouches,  placed  between 
the  base  of  the  bladder  and  the  rectum,  serving  as  reservoirs  for  the  semen,  and 
secreting  some  fluid  to  be  added  to  that  of  the  testicles.  Each  sac  is  somewhat 
pyramidal  in  form,  the  broad  end  being  directed  backwards,  and  the  narrow 
end  forwards  towards  the  prostate.  They  measure  about  two  and  a  half  inches 
in  length,  about  five  lines  in  breadth,  and  from  two  to  three  lines  in  thickness. 
They  vary,  however,  in  size,  not  only  in  different  individuals,  but  also  in  the 
same  individual  on  the  two  sides.  Their  upper  surface  is  in  contact  with  the 
base  of  the  bladder,  extending  from  near  the  termination  of  the  ureters  to  the 
base  of  the  prostate  gland.  Their  under  surface  rests  upon  the  rectum,  from 
which  they  are  separated  by  the  recto- vesical  fascia.  Their  posterior  extremities 
diverge  from  each  other.  Their  anterior  extremities  are  pointed,  and  converge 
towards  the  base  of  the  prostate  gland,  where  each  joins  with  the  corresponding 
vas  deferens  to  form  the  ejaculatory  duct.  Along  the  inner  margin  of  each 
vesicula  runs  the  enlarged  and  convoluted  vas  deferens.  The  inner  border  of 
the  vesiculje,  and  the  corresponding  vas  deferens,  form  the  lateral  boundary 
of  a  trianglar  space,  limited  behind  by  the  recto-vesical  peritoneal  fold;  the 
portion  of  the  bladder  included  in  this  space  rests  on  the  rectum,  and  corres- 
ponds with  the  trigonum  vesicae  in  its  interior. 

Structure.  Bach  vesicula  consists  of  a  single  tube,  coiled  upon  itself,  and 
giving  off  several  irregular  caical  diverticula ;  the  separate  coils,  as  well  as  the 
diverticula,  being  connected  together  by  fibrous  tissue.  When  uncoiled,  this 
tube  is  about  the  diameter  of  a  quill,  and  varies  in  length  from  four  to  six 
inches;  it  terminates  posteriorly  in  a  cul-de-sac;  its  anterior  extremity  becomes 
constricted  into  a  narrow  straight  duct,  which  joins  on  its  inner  side  with  the 
corresponding  vas  deferens,  and  forms  the  ejaculatory  duct. 

The  Ejaculatory  Ducts^  two  in  number,  one  on  each  side,  are  formed  by  the 
junction  of  the  duct  of  the  vesicula  seminalis  with  the  vas  deferens.  Each  duct 
is  about  three-quarters  of  an  inch  in  length ;  it  commences  at  the  base  of  the 
prostate,  and  runs  forwards  and  upwards  in  a  canal  in  its  substance,  and  along 
the  side  of  the  utriculus,  to  terminate  by  a  separate  slit-like  orifice  upon  or 
within  the  margins  of  the  sinus  pocularis.  The  ducts  diminish  in  size,  and 
converge  towards  their  termination. 

Structure.  The  vesiculae  seminales  are  composed  of  three  coats:  an  external  or 
fibro-celhdar,  derived  from  the  recto-vesical  fascia;  a  middle  or  fibrous  coat,  which 
is  firm,  dense,  fibrous  in  structure,  somewhat  elastic,  and  contains,  according  to 
E.  H.  Weber,  muscular  fibres ;  and  an  internal  or  mucous  coat,  which  is  pale,  of  a 
whitish-brown  color,  and  presents  a  delicate  reticular  structure,  like  that  seen  in 
the  gall-bladder,  but  the  meshes  are  finer.  The  epithelium  is  squamous.  The 
coats  of  the  ejaculatory  ducts  are  extremely  thin,  the  outer  fibrous  layer  being 
almost  entirely  lost  after  their  entrance  into  the  prostate,  a  thin  layer  of  muscular 
fibres  and  the  mucous  membrane  forming  the  only  constituents  of  the  tubes. 

Vessels  and  nerves.  The  arteries  supplying  the  vesiculse  seminales  are  derived 
from  the  inferior  vesical  and  middle  hasmorrhoidal.  The  veins  and  lymphatics 
accompany  the  arteries.     The  nerves  are  derived  from  the  hypogastric  plexus. 

The  Semen  is  a  thick  whitish  fluid,  having  a  peculiar  odor.  It  consists  of  a 
fluid,  the  liquor  seminis,  and  solid  particles,  the  seminal  granules,  and  sperma- 
tozoa. 

The  liquor  semiyiis  is  transparent,  colorless,  and  of  an  albuminous  composition, 
containing  particles  of  squamous  and  columnar  epithelium,  with  oil-globules 
and  granular  matter  floating  in  it,  besides  the  above-mentioned  solid  elements. 

The  seminal  granules  are  round,  finely-granular  corpuscles,  measuring  j^j^tfth 
of  an  inch  in  diameter. 

The  spermatozoa,  or  spermatic  filaments,  are  the  essential  agents  in  producing 
fecundation.    They  are  minute  elongated  particles,  consisting  of  a  small  flattened 


810  MALE    ORGANS    OF    GENERATION. 

oval  extremity  or  body,  and  a  long  slender  caudal  filament.  A  small  circular 
spot  is  observed  in  the  centre  of  the  body,  and  at  its  point  of  connection  with  the 
tail  there  is  frequently  seen  a  projecting  rim  or  collar.  The  movements  of  these 
bodies  are  remarkable,  and  consist  of  a  lashing  or  undulatory  motion  of  the  tail. 

Descent  of  the  Testes. 

The  testes,  at  an  early  period  of  foetal  life,  are  placed  at  the  back  part  of  the 
abdominal  cavity,  behind  the  peritoneum,  in  front  and  a  little  below  the  kid- 
neys. The  anterior  surface  and  sides  are  invested  by  peritoneum  ;  the  blood- 
vessels and  efferent  ducts  are  connected  with  their  posterior  surface;  and 
attached  to  the  lower  end  is  a  peculiar  structure,  the  gubernaculum  testis,  which 
is  said  to  assist  in  their  descent. 

The  Gubernaculum  Testis  attains  its  full  development  between  the  fifth  and 
sixth  months ;  it  is  a  conical-shaped  cord,  attached  above  to  the  lower  end  of 
the  epididymis,  and  below  to  the  bottom  of  the  scrotum.  It  is  placed  behind 
the  peritoneum,  lying  upon  the  front  of  the  Psoas  muscle,  and  completely  filling 
the  inguinal  canal.  It  consists  of  a  soft  transparent  areolar  tissue  within,  which 
often  appears  partially  hollow,  surrounded  by  a  layer  of  striped  muscular  fibres, 
the  Cremaster,  which  ascends  upon  this  body  to  be  attached  to  the  testis. 
According  to  Mr.  Curling,  the  gubernaculum,  as  well  as  these  muscular  fibres, 
divides  below  into  three  processes ;  the  external  and  broadest  process  is  con- 
nected with  Poupart's  ligament  in  the  inguinal  canal ;  the  middle  process  descends 
along  the  inguinal  canal  to  the  bottom  of  the  scrotum,  where  it  joins  the  dartos ; 
the  internal  one  is  firmly  attached  to  the  os  pubis  and  sheath  of  the  Rectus 
muscle;  some  fibres,  moreover,  are  reflected  from  the  Internal  Oblique  on  to 
the  front  of  the  gubernaculum.  Up  to  the  fifth  month,  the  testis  is  situated  in 
the  lumbar  region,  covered  in  front  and  at  the  sides  by  peritoneum,  and  sup- 
ported in  its  position  by  a  fold  of  that  membrane,  called  the  mesorchium  ;  between 
the  fifth  and  sixth  months  the  testis  descends  to  the  iliac  fossa,  the  gubernaculum 
at  the  same  time  becoming  shortened ;  during  the  seventh  month,  it  enters  the 
internal  abdominal  ring,  a  small  pouch  of  peritoneum  {processus  vaginalis)  pre- 
ceding the  testis  in  its  course  through  the  canal.  By  the  end  of  the  eighth  month, 
the  testis  has  descended  into  the  scrotum,  carrying  down  Avith  it  a  lengthened 
pouch  of  peritoneum,  which  communicates  by  its  upper  extremity  with  the 
peritoneal  cavity.  Just  before  birth,  the  upper  part  of  this  pouch  usually 
becomes  closed,  and  this  obliteration  extends  gradually  downwards  to  within  a 
short  distance  of  the  testis.  The  process  of  peritoneum  surrounding  the  testis, 
which  is  now  entirely  cut  off  from  the  general  peritoneal  cavity,  constitutes  the 
tunica  vaginalis} 

Mr.  Curling  believes  that  the  descent  of  the  testis  is  effected  by  means  of  the 
ipuscular  fibres  of  the  gubernaculum ;  those  fibres  which  proceed  from  Poupart  s 
ligament  and  theObliquusInternus  are  said  to  guide  the  organ  into  the  inguinal 
canal ;  those  attached  to  the  pubis  draw  it  below  the  external  abdominal  ring ; 
and  those  attached  to  the  bottom  of  the  scrotum  complete  its  descent.  During 
the  descent  of  the  organ  these  muscular  fibres  become  gradually  everted,  form- 
ing a  muscular  layer,  which  becomes  placed  external  to  the  process  of  the  peri- 
toneum, surrounding  the  gland  and  spermatic  cord,  and  constitutes  the  Cremaster. 
In  the  female,  a  small  cord,  corresponding  to  tlie  gubernaculum  in  the  male, 
descends  to  the  inguinal  region,  and  ultimately  forms  the  round  ligament  of  the 
uterus.  A  pouch  of  peritoneum  accompanies  it  along  the  inguinal  canal, 
analogous  to  the  processus  vaginalis  in  the  male ;  it  is  called  the  canal  of  Nuck. 

•  The  obliteration  of  the  process  of  peritoneum  which  accompanies  the  cord,  and  is  hence 
called  the  funicular  process,  is  often  incomplete.  For  an  account  of  the  various  conditions 
produced  by  such  incomplete  obliteration  (which  are  of  preat  importance  in  the  patholo<rical 
anatomy  of  Infjninal  Hernia),  the  student  is  referred  to  the  Essay  on  Hernia,  by  Mr.  Birkett,  iu 
"A  .Sy.stem  of  Surgery,"  edited  by  T.  Holmes,  vol.  iv. 


Female  Organs  of  Generation. 

The  External  Organs  of  Generation  in  the  female,  are  the  mons  Veneris,  the 
labia  majora  and  minora,  the  clitoris,  the  meatus  urinarius,  and  the  orifice  of 
the  vagina.  The  term  "vulva"  or  "pudendum,"  as  generally  applied,  includes 
all  these  parts. 

The  mons  Veneris  is  the  rounded  eminence  in  front  of  the  pubes,  formed  by  a 
collection  of  fatty  tissue  beneath  the  integument.  It  surmounts  the  vulva,  and 
is  covered  with  hair  at  the  time  of  puberty. 

Fig.  441.— The  Vulva.    External  Female  Organs  of  Generation. 


The  labia  majora  are  two  prominent  longitudinal  cutaneous  folds,  extending 
downwards  from  the  mons  Veneris  to  the  anterior  boundary  of  the  perineum, 
and  inclosing  an  elliptical  fissure,  the  common  urino-sexual  opening.  Each 
labium  is  formed  externally  of  integument,  covered  with  hair ;  internally,  of 
mucous  membrane,  which  is  continuous  with  the  genito-urinary  mucous  tract ; 
and  between  the  two,  of  a  considerable  quantity  of  areolar  tissue,  fat,  and  a 
tissue  resembling  the  dartos  of  the  scrotum,  besides  vessels,  nerves,  and  glands. 
The  labia  are  thicker  in  front  than  behind,  and  joined  together  at  each  extre- 

811 


812  FEMALE    ORGANS    OF    GENERATION. 

mity,  forming  the  anterior  and  posterior  commissures.  The  interval  left  between 
the  posterior  commissure  and  the  margin  of  the  anus  is  about  an  inch  in  length, 
and  constitutes  the  perineum.  Just  within  the  posterior  commissure  is  a  small 
transverse  fold,  the  frsenuhtm  pudendi  ov  fourchette^  which  is  commonly  ruptured 
in  the  first  parturition,  and  the  space  between  it  and  the  commissure  is  called 
the  fossa  naviculans.     The  labia  are  analogous  to  the  scrotum  in  the  male. 

The  labia  minora  or  nymphse  are  two  small  folds  of  mucous  membrane,  situ- 
ated within  the  labia  majora,  extending  from  the  clitoris  obliquely  doAvnwards 
and  outwards  for  about  an  inch  and  a  half  on  each  side  of  the  orifice  of  the 
vagina,  on  the  sides  of  which  they  are  lost.  They  are  continuous  externally 
Avith  the  labia  majora,  internally  with  the  inner  surface  of  the  vagina.  As  they 
converge  towards  the  clitoris  in  front,  each  labium  divides  into  two  folds,  which 
surround  the  glans  clitoridis,  the  superior  folds  uniting  to  form  the  prseputium 
clitoridis,  the  inferior  folds  being  attached  to  the  glans,  and  forming  the  fraenura. 
The  nymphoe  are  composed  of  mucous  membrane,  covered  by  a  thin  epithelial 
layer.  They  contain  a  plexus  of  vessels  in  their  interior,  and  are  provided  with 
numerous  large  mucous  crypts  which  secrete  abundance  of  sebaceous  matter. 

The  clitoris  is  an  erectile  structure,  analogous  to  the  corpora  cavernosa  of  the 
penis.  It  is  situated  beneath  the  anterior  commissure,  partly  hidden  between 
the  anterior  extremities  of  the  labia  minora.  It  is  an  elongated  organ,  con- 
nected to  the  rami  of  the  pubes  and  ischia  on  each  side  by  two  crura ;  the  body 
is  short,  and  concealed  beneath  the  labia ;  the  free  extremity,  or  glans  clitoridis, 
is  a  small  rounded  tubercle,  consisting  of  spongy  erectile  tissue,  and  highly 
sensitive.  The  clitoris  consists  of  two  corpora  cavernosa,  composed  of  erectile 
tissue  inclosed  in  a  dense  layer  of  fibrous  membrane,  united  together  along  their 
inner  surfaces  by  an  incomplete  fibrous  pectiniform  septum.  It  is  provided, 
like  the  penis,  with  a  suspensory  ligament,  and  with  two  small  muscles,  the 
Erectores  Clitoridis,  which  are  inserted  into  the  crura  of  the  corpora  cavernosa. 

Between  the  clitoris,  and  the  entrance  of  the  vagina,  is  a  triangular  smooth 
surface,  bounded  on  each  side  by  the  nympha) :  this  is  the  vestibule. 

The  orifice  of  the  urethra  {meatus  urinarius)  is  situated  at  the  back  part  of 
the  vestibule,  about  an  inch  below  the  clitoris,  and  near  the  margin  of  the 
vagina,  surrounded  by  a  prominent  elevation  of  the  mucous  membrane.  Below 
the  meatus  urinarius,  is  the  orifice  of  the  vagina,  an  elliptical  aperture,  more 
or  less  closed  in  the  virgin,  by  a  membranous  fold,  the  hymen. 

The  hymen  is  a  thin  semilunar  fold  of  mucous  membrane,  stretched  across  the 
lower  part  of  the  orifice  of  the  vagina ;  its  concave  margin  being  turned  up- 
wards towards  the  pubes.  Sometimes  this  membrane  forms  a  complete  septum 
across  the  orifice  of  the  vagina:  a  condition  known  as  imperforate  hymen. 
Occasionally,  it  forms  a  circular  septum,  perforated  in  the  centre  by  a  round 
opening;  sometimes  it  is  cribriform,  or  its  free  margin  forms  a  membranous 
fringe,  or  it  may  be  entirely  absent.  It  may  also  persist  after  copulation.  The 
hymen  cannot,  consequently,  be  considered  as  a  test  of  virginity.  Its  rupture, 
or  the  rudimentary  condition  of  the  membrane  above  referred  to,  gives  rise  to 
those  small  rounded  elevations  which  surround  the  opening  of  the  vagina,  the 
carunculse  m.yrtiformes. 

Glands  of  Bartholine.  On  each  side  of  the  commencement  of  the  vagina  is  a 
round  or  oblong  body,  of  a  reddish-yellow  color,  and  of  the  size  of  a  horse-bean, 
analogous  to  Cowper's  gland  in  the  male.  It  is  called  the  gland  of  Bartholine. 
Each  gland  opens  by  means  of  a  long  single  duct,  upon  the  inner  side  of  the 
nymphie,  external  to  the  hymen.  Extending  from  the  clitoris,  along  cither 
side  of  the  vestibule,  and  lying  a  little  behind  the  nympha),  are  two  largo  oblong 
masses,  about  an  inch  in  length,  consisting  of  a  plexus  of  veins,  inclosed  in  a 
thin  layer  of  fibrous  membrane.  These  bodies  are  narrow  in  front,  rounded 
below,  and  are  connected  with  the  crura  of  the  clitoris  and  rami  of  the  pubes, 
they  arc  termed  by  Kobelt  the  bulbi  vestibnli ;  and  he  considers  them  analogous 
to  the  bulb  of  the  corpus  spongiosum  in  the  male.  Immediately  in  front  of  these 


BLADDER— URETHRA. 


813 


bodies  is  a  smaller  venous  plexus,  continuous  with  the  bulbi  vestibuli  behind 
and  the  glans  clitoridis  in  front;  it  is  called  by  Kobelt  thenars  intermedia,  and  is 
considered  by  him  as  analogous  to  that  part  of  the  body  of  the  corpus  spono-io- 
sura  which  immediately  succeeds  the  bulb.  ^ 

Fig.  4i2.— Section  of  Female  Pelvis,  showing  Position  of  Viscera. 


The  Bladder. 

The  Bladder  is  situated  at  the  anterior  part  of  the  pelvis.  It  is  in  relation, 
in  front,  with  the  os  pubis ;  behind,  with  the  uterus,  some  convolutions  of  the 
small  intestine  being  interposed  ;  its  base  lies  in  contact  with  the  neck  of  the 
uterus,  and  with  the  anterior  wall  of  the  vagina.  The  bladder  is  said  to  be 
larger  in  the  female  than  in  the  male,  and  is  very  broad  in  its  transverse  dia- 
meter. 

The  Urethea. 

The  Urethra  is  a  narrow  membranous  canal,  about  an  inch  and  a  half  in 
length,  extending  from  the  neck  of  the  bladder  to  the  meatus  urinarius.  It  is 
placed  beneath  the  symphysis  pubis,  imbedded  in  the  anterior  w.all  of  the  va- 
gina ;  and  its  direction  is  obliquely  downwards  and  forwards,  its  course  being 
slightly  curved,  the  concavity  directed  forwards  and  upwards.  Its  diameter, 
when  undilated,  is  about  a  quarter  of  an  inch.  The  urethra  perforates  the  tri- 
angular ligament,  precisely  as  in  the  male,  and  is  surrounded  by  the  muscular 
fibres  of  the  Compressor  IJrethroe. 

Structure.  The  urethra  consists  of  three  coats;  muscular,  erectile,  and 
mucous. 

The  muscular  coat  is  continuous  with  that  of  the  bladder ;  it  extends  the  whole 
length  of  the  tube,  and  consists  of  a  thick  stratum  of  circular  fibres. 


814  FEMALE    ORGANS    OF    GENERATION. 

A  thin  layer  of  spongy,  erectile  tissue,  intermixed  witli  much  elastic  tissue, 
lies  immediately  beneath  the  mucous  coat. 

The  mucous  coat  is  pale,  continuous,  externally  with  that  of  the  vulva,  and 
internally  with  that  of  the  bladder-  It  is  thrown  into  longitudinal  folds,  one 
of  which,  placed  along  the  floor  of  the  canal*,  resembles  the  verumontanum  in 
the  male  urethra.  It  is  lined  by  laminated  epithelium,  which  becomes  sphe- 
roidal at  the  bladder.  Its  external  orifice  is  surrounded  by  a  few  mucous 
follicles. 

The  urethra,  from  not  being  surrounded  by  dense  resisting  structures,  as  in 
the  male,  admits  of  considerable  dilatation,  which  enables  the  surgeon  to  remove 
with  considerable  facility  calculi,  or  other  foreign  bodies,  from  the  cavity  of 
the  bladder. 

The  Rectum. 

The  Rectum  is  more  capacious,  and  less  curved  in  the  female,  than  in  the  male. 

H\iQ  first  portion  extends  from  the  left  sacro-iliac  symphysis  to  the  middle  of 
the  sacrum.     Its  connections  are  similar  to  those  in  the  male. 

The  second  portion  extends  to  the  tip  of  the  coccyx.  It  is  covered  in  front  by 
the  peritoneum,  but  only  for  a  short  distance,  at  its  upper  part,  and  is  in  rela- 
tion with  the  posterior  wall  of  the  vagina. 

The  third  portion  curves  backwards,  from  the  vagina  to  the  anus,  leaving  a 
space  which  corresponds  on  the  surface  of  the  body  to  the  perineum.  Its  ex- 
tremity is  surrounded  by  the  Sphincter  muscles,  and  its  sides  are  supported  by 
the  Levatores  Ani. 

The  Yagina. 

The  Yagina  is  a  membranous  canal,  extending  from  the  vulva  to  the  uterus. 
It  is  situated  in  the  cavity  of  the  pelvis,  behind  the  bladder,  and  in  front  of 
the  rectum.  Its  direction  is  curved  forwards  and  downwards,  following  at  first 
the  line  of  the  axis  of  the  cavity  of  the  pelvis,  and  afterwards  that  of  the  out- 
let. It  is  cylindrical  in  shape,  flattened,  from  before  backwards,  and  its  walls 
are  ordinarily  in  contact  with  each  other.  Its  length  is  about  four  inches  along 
its  anterior  wall,  and  between  five  and  six  inches  along  its  posterior  wall.  It  is 
constricted  at  its  commencement,  and  becomes  dilated  near  its  uterine  extre- 
mity ;  it  surrounds  the  vaginal  portion  of  the  cervix  uteri,  a  short  distance 
from  the  os,  and  its  attachment  extends  higher  up  on  the  posterior  than  on  the 
anterior  wall  of  the  uterus. 

Relations.  Its  anterior  surface  is  concave,  and  in  relation  with  the  base  of  the 
bladder,  and  with  the  urethra.  Its  posterior  surface  is  convex,  and  connected  to 
the  anterior  wall  of  the  rectum,  for  the  lower  three-fourths  of  its  extent,  the 
upper  fourth  being  separated  from  that  tube  by  the  recto-uterine  fold  of  peri- 
toneum, which  forms  a  cul-de-sac  between  the  vagina  and  rectum.  Its  sides  give 
attachment  superiorly  to  the  broad  ligaments,  and  inferiorly  to  the  Levatores 
Ani  muscles  and  recto- vesical  fascia. 

Structure.  The  vagina  consists  of  an  external,  or  muscular  coat,  a  layer  of 
erectile  tissue,  and  an  internal  mucous  lining. 

The  muscular  coat  consists  of  longitudinal  fibres,  which  surround  the  vagina, 
and  are  continuous  with  the  superficial  muscular  fibres  of  the  uterus.  The 
strongest  fasciculi  are  those  attached  to  the  recto-vesical  fascia  on  each  side. 

The  erectile  tissue  is  inclosed  between  two  layers  of  fibrous  membrane  ;  it  is 
more  abundant  at  the  lower  than  at  the  upper  part  of  the  vagina. 

The  mucous  membrane  is  continuous,  above,  with  that  lining  the  uterus,  and 
below,  with  the  integument  covering  the  labia  majora.  Its  inner  surface  pre- 
sents, along  the  anterior  and  posterior  walls,  a  longitudinal  ridge,  or  raphe, 
called  the  columns  of  the  vagina^  and  numerous  transverse  ridges,  or  rugae,  ex- 
tending outwards  from  the  raphe  on  each  side.  These  ruga;  are  most  distinct 
near  the  orifice  of  the  vagina,  especially  in  females  before  parturitiou.     They 


UTERUS.  815 

indicate  its  adaptation  for  dilatation,  and  are  calculated  to  facilitate  its  enlari^e- 
ment  during  parturition.  The  mucous  membrane  is  covered  with  conical  and 
filiform  papillae,  and  provided  with  mucous  glands  and  follicles,  which  are 
especially  numerous  in  its  upper  part,  and  around  the  cervix  uteri. 

The  Uterus. 

The  Uterus  is  the  organ  of  gestation,  receiving  the  fecundated  ovum  in  its 
cavity,  retaining  and  supporting  it  during  the  development  of  the  foetus,  and 
becoming  the  principal  agent  in  its  expulsion  at  the  time  of  parturition. 

In  the  virgin  state  it  is  pear-shaped,  flattened  from  before  backwards,  and 
situated  in  the  cavity  of  the  pelvis,  between  the  bladder  and  rectum  ;  it  is  re- 
tained in  its  position  by  the  round  and  broad  ligaments  on  each  side,  and  pro- 
jects into  the  upper  end  of  the  vagina  below.  Its  upper  end,  or  base,  is -directed 
upwards  and  forwards;  its  lower  end,  or  apex,  downwards  and  backwards, 
in  the  line  of  the  axis  of  the  inlet  of  the  pelvis.  It  therefore  forms  an  angle 
with  the  vagina,  since  the  direction  of  the  vagina  corresponds  to  the  axis  of  the 
cavity  and  outlet  of  the  pelvis.  The  uterus  measures  about  three  inches  in 
length,  two  in  breadth  at  its  upper  part,  and  an  inch  in  thickness,  and  it  weighs 
from  an  ounce  to  an  ounce  and  a  half. 

^\iQ  fundus  is  the  upper  broad  extremity  of  the  organ ;  it  is  convex,  covered 
by  peritoneum,  and  placed  on  a  line  below  the  level  of  the  brim  of  the  pelvis. 

The  body  gradually  narrows  from  the  fundus  to  the  neck.  Its  anterior  surface 
is  flattened,  covered  by  peritoneum  in  the  upper  three-fourths  of  its  extent,  and 
separated  from  the  bladder  by  some  convolutions  of  the  small  intestine ;  the 
lower  fourth  is  connected  with  the  bladder.  Its  j^osterior  surface  is  convex, 
covered  by  peritoneum  throughout,  and  separated  from  the  rectum  by  some 
convolutions  of  the  intestine.  Its  lateral  margins  are  concave,  and  give  attach- 
ment to  the  Fallopian  tube  above,  the  round  ligament  below  and  in  front  of 
this,  and  the  ligament  of  the  ovary  behind  and  below  both  of  these  structures. 

The  cervix  is  the  lower  rounded  and  constricted  portion  of  the  uterus ;  around 
its  circumference  is  attached  the  upper  end  of  the  vagina,  which  extends  up- 
wards a  greater  distance  behind  than  in  front. 

At  the  vaginal  extremity  of  the  uterus  is  a  transverse  aperture,  the  os  uteris 
bounded  by  two  lips,  the  anterior  of  which  is  thick,  the  posterior  narrow  and 
long. 

Ligaments.  The  ligaments  of  the  uterus  are  six  in  number ;  two  anterior, 
two  posterior,  and  two  lateral.     They  are  formed  of  peritoneum. 

The  tivo  anterior  ligaments  {vesico -uterine)  are  two  semilunar  folds,  which  pass 
between  the  neck  of  the  uterus  and  the  posterior  surface  of  the  bladder. 

The  two  ])osterior  ligaments  [recto-uterine),  pass  between  the  sides  of  the  uterus 
and  rectum. 

The  two  lateral  or  broad  ligaments  pass  from  the  sides  of  the  uterus  to  the 
lateral  walls  of  the  pelvis,  forming  a  septum  across  the  pelvis,  which  divides 
that  cavity  into  two  portions.  In  the  anterior  part  are  contained  the  bladder, 
urethra,  and  vagina;  in  the  posterior  part,  the  rectum. 

The  cavity  of  the  uterus  is  small  in  comparison  with  the  size  of  the  organ ; 
that  portion  of  the  cavity  which  corresponds  to  the  body  is  triangular,  flattened 
from  before  backwards,  so  that  its  walls  are  closely  approximated,  and  having 
its  base  directed  upwards  towards  the  fundus.  At  each  superior  angle  is  a 
funnel-shaped  cavity,  which  constitutes  the  remains  of  the  division  of  the  body 
of  the  uterus  into  two  cornua ;  and  at  the  bottom  of  each  cavity  is  the  minute 
orifice  of  the  Fallopian  tube.  At  the  inferior  angle  of  the  uterine  cavity  is  a 
small  constricted  opening,  the  internal  orifice  [ostium  internum),  which  leads 
into  the  cavity  of  the  cervix.  The  cavity  in  the  cervix  is  somewhat  cylindrical, 
flattened  from  before  backwards,  broader  at  the  middle  than  at  either  extremity, 
and  communicates,  below,  with  the  vagina.     Each  wall  of  the  canal  presents  a 


816  FEMALE    ORGANS    OF    GENERATION. 

longitudinal  column,  from  whicli  proceed  a  number  of  small  oblique  columns, 
giving  the  appearance  of  branches  from  the  stem  of  a  tree,  and  hence  the  name 
arbor  vitse  uterinus  applied  to  it.  These  folds  usually  become  very  indistinct 
after  the  first  labor. 

Structure.  The  uterus  is  composed  of  three  coats :  an  external  serous  coat,  a 
middle  or  muscular  layer,  and  an  internal  mucous  coat. 

The  serous  coat  is  derived  from  the  peritoneum;  it  invests  the  fundus  and  the 
whole  of  the  posterior  surface  of  the  body  of  the  uterus ;  but  only  the  upper 
three-fourths  of  its  anterior  surface. 

The  muscular  coat  "forms  the  chief  bulk  of  the  substance  of  the  uterus.  In 
the  unimpregnated  state,  it  is  dense,  firm,  of  a  grayish  color,  and  cuts  almost 
like  cartilage.  It  is  thick  opposite  the  middle  of  the  body  and  fundus,  and  thin 
at  the  orifices  of  the  Fallopian  tubes.  It  consists  of  bundles  of  unstriped 
muscular  fibres,  disposed  in  layers,  intermixed  with  areolar  tissue,  bloodvessels, 
lymphatic  vessels  and  nerves.  In  the  impregnated  state,  the  muscular  tissue 
becomes  more  prominently  developed,  and  is  disposed  in  three  layers :  external, 
middle,  and  internal. 

The  external  layer  is  placed  beneath  the  peritoneum,  disposed  as  a  thin  plane 
on  the  anterior  and  posterior  surfaces.  It  consists  of  fibres,  which  pass  trans- 
versely across  the  fundus,  and,  converging  at  each  superior  angle  of  the  uterus, 
are  continued  on  the  Fallopian  tubes,  the  round  ligament,  and  ligament  of  the 
ovary  ;  some  passing  at  each  side  into  the  broad  ligament,  and  others  running 
backwards  from  the  cervix  into  the  recto- uterine  ligaments. 

The  middle  layer  of  fibres  presents  no  regularity  in  its  arrangement,  being 
disposed  longitudinally,  obliquely,  and  transversely. 

The  internal,  or  deep  layer,  consists  of  circular  fibres  arranged  in  the  form 
of  two  hollow  cones,  the  apices  of  which  surround  the  orifices  of  the  Fallopian 
tubes,  their  bases  intermingling  with  one  another  on  the  middle  of  the  body  of 
the  uterus.     At  the  cervix  these  fibres  are  disposed  transversely. 

The  mucous  membrane  is  thin,  smooth,  and  closely  adherent  to  the  subjacent 
tissue.  It  is  continuous,  through  the  fimbriated  extremity  of  the  Fallopian 
tubes,  with  the  peritoneum ;  and,  through  the  os  uteri,  with  the  mucous  mem- 
brane lining  the  vagina. 

In  the  body  of  the  uterus,  it  is  smooth,  soft,  of  a  reddish  color,  lined  by 
columnar-ciliated  epithelium,  and  presents,  when  viewed  with  a  lens,  the  orifices 
of  numerous  tubular  follicles  arranged  perpendicularly  to  the  surface.  They 
are  of  small  size  in  the  unimpregnated  uterus,  but  shortly  after  impregnation 
they  are  enlarged,  elongated,  presenting  a  contorted  or  waved  appearance  to- 
wards their  closed  extremities,  which  occasionally  dilate  into  two  or  three 
sacculated  extremities.  The  circular  orifices  of  these  glands  may  be  seen  on 
the  inner  surface  of  the  mucous  membrane,  many  of  which  during  the  early 
period  of  pregnancy  are  surrounded  by  a  whitish  ring  formed  of  epithelium 
which  lines  the  follicles. 

In  the  cervix,  the  mucous  membrane  between  the  rugse  and  around  the  os 
uteri  is  provided  with  numerous  mucous  follicles,  and  glands.  The  small,  trans- 
parent vesicular  elevations,  so  often  found  within  the  os  and  cervix  uteri  are 
due  to  closure  of  the  mouths  of  tliese  follicles,  and  their  distension  with  their 
proper  secretion.  They  were  called  the  ovula  of  Naboth.  The  mucous  mem- 
brane covering  the  lower  half  of  tlie  cervix  presents  numerous  papilla}. 

Vessels  and  Nerves.  The  arteries  of  the  uterus  are  the  uterine,  from  the  internal 
iliac ;  and  the  ovarian,  from  the  aorta.  They  are  remarkable  for  their  tortuous 
course  in  the  substance  of  the  organ,  and  for  their  frequent  anastomoses.  The 
veins  are  of  large  size,  and  correspond  with  the  arteries.  In  the  impregnated 
uterus  these  vessels  are  termed  the  uterine  sinuses^  consisting  of  the  lining  mem- 
brane of  the  veins  adhering  to  the  walls  of  canals  channelled  through  the  sub- 
stance of  the  uterus.  They  terminate  in  the  uterine  plexuses.  The  hjmj^hatics 
are  of  large  size  in  the  impregnated  uterus,  and  terminate  in  the  pelvic  and 


I 


I 


APPENDAGES    OF    THE    UTERUS. 


817 


lumbar  glands.      The  nerves  are  derived  from  the  inferior  hypogastric  and 
spermatic  plexuses,  and  from  the  third  and  fourth  sacral  nerves. 

The  form,  size,  and  situation  of  the  uterus,  vary  at  different  periods  of  life  and  under  different 
circumstances. 

In  the  foetus,  the  uterus  is  contained  in  the  abdominal  cavity,  projecting  beyond  the  brim  of 
the  pelvis.    The  cervix  is  considerably  larger  than  the  body. 

At  puberty,  the  uterus  is  pyriform  in  shape,  and  weighs  from  eight  to  ten  drachms.  It  has 
descended  into  the  pelvis,  the  fundus  being  just  below  the  level  of  the  brim  of  this  cavity.  The 
arbor  vitaj  is  distinct,  and  extends  to  the  upper  part  of  the  cavity  of  the  organ. 

During,  and  after  menstruation,  the  organ  is  enlarged,  and  more  vascular,  its  surfaces 
rounder ;  the  os  externum  is  rounded,  its  labia  swollen,  and  the  lining  membrane  of  the  body 
thickened,  softer,  and  of  a  darker  color. 

During  Pregnancy,  the  uterus  increases  so  as  to  weigh  from  one  pound  and  a  half  to  three 
pounds.  It  becomes  enormously  enlarged,  and  projects  into  the  hypogastric  and  lower  part  of 
the  umbilical  regions.  This  enlargement,  which  continues  up  to  the  sixth  month  of  gestation, 
is  partially  due  to  increased  development  of  pre-existing  and  new-formed  muscular  tissue.  The 
round  ligaments  are  enlarged,  and  the  broad  ligaments  become  encroached  upon  by  the  uterus 
making  its  way  between  their  lamina;.  The  mucous  membrane  becomes  more  vascular ;  its 
mucous  follicles  and  glands  enlarged ;  the  ruga;  and  folds  in  the  canal  of  the  cervix  become  ob- 
literated ;  the  blood  and  lymphatic  vessels  as  well  as  the  nerves,  according  to  the  researches  of 
Dr.  Lee,  become  greatly  enlarged. 

After  Parturition,  the  uterus  nearly  regains  its  usual  size,  weighing  from  two  to  three  ounces : 
but  its  cavity  is  larger  than  in  the  virgin  state  ;  the  external  orifice  is  more  marked,  and  assumes 
a  transverse  direction  ;  its  edges  present  a  fissured  surface  ;  its  vessels  are  tortuous  ;  and  its 
muscular  layers  are  more  defined. 

In  old  age,  the  uterus  becomes  atrophied,  and  paler  and  denser  in  texture ;  a  more  distinct 
constriction  separates  the  body  and  cervix.  The  ostium  internum,  and,  occasionally,  the  vagi- 
nal orifice,  often  become  obliterated,  and  its  labia  almost  entirely  disappear. 

Appendages  of  the  Uterus. 

The  Appendages  of  the  Uterus  are,  the  Fallopian  tubes,  the  ovaries  and  their 
ligaments,  and  the  round  ligaments.  These  structures,  together  with  their 
nutrient  vessels  and  nerves,  and  some  scattered  muscular  fibres,  are  inclosed 
between  the  two  folds  of  peritoneum,  which  constitute  the  broad  ligaments; 
they  are  placed  in  the  following  order ;  in  front  is  the  round  ligament ;  the 
Fallopian  tube  occupies  the  free  margin  of  the  broad  ligament ;  the  ovary  and 
its  ligament  are  behind  and  below  the  latter. 

The  Fallopian  Tubes,  or  oviducts,  convey  the  ova  from  the  ovaries  to  the 
cavity  of  the  uterus.     They  are  two  in  number,  one  on  each  side,  situated  in 

Fig.  443. — The  Uterus  and  its  Appendages.     Anterior  View. 


£mth  passed  through 


the  free  margin  of  the  broad  ligament,  extending  from  each  superior  angle  of 
the  uterus  to  the  sides  of  the  pelvis.  Each  tube  is  about  four  inches  in  length  ; 
its  canal  is  exceedingly  minute,  and  commences  at  the  superior  angle  of  the 
uterus  by  a  minute  orifice,  the  ostium  internum^  which  will  hardly  admit  a  fine 
52 


818 


FEMALE    ORGANS    OF    GENERATION. 


Fij?.  444. — Section  of  the  Ovary  of  a 
Virgin,  showing  the  Stroma  and 
Graafian  Vesicles. 


bristle;  it  continues  narrow  along  the  inner  half  the  tube,  and  then  gradually 
widens  into  a  trumpet-shaped  extremity,  which  becomes  contracted  at  its  termi- 
nation. This  orifice  is  called  the  ostium  abdominale,  and  communicates  with  the 
peritoneal  cavity.  Its  margins  are  surrounded  by  a  series  of  fringe-like  pro- 
cesses, termed  Jimbrise,  and  one  of  these  processes  is  connected  with  the  outer 
end  of  the  ovary.  To  this  part  of  the  tube  the  ndime  fimbriated  extremity  is  ap- 
plied ;  it  is  also  called  morsus  diaboU,  from  the  peculiar  manner  in  which  it 
embraces  the  surface  of  the  ovary  during  sexual  excitement. 

Structure.  The  Fallopian  tube  consists  of  three  coats,  serous,  muscular,  and 
mucous. 

The  external  or  serovs  coat  is  derived  from  the  peritoneum. 
The  middle  or  miiscular  coat  consists  of  an  external  longitudinal  and  an  internal 
or  circular  layer  of  muscular  fibres  continuous  with  those  of  the  uterus. 

The  internal  or  mucous  coat  is  continuous  with  the  mucous  lining  of  the  uterus, 
and  at  the  free  extremity  of  the  tube  with  the  peritoneum.  It  is  thrown  into 
longitudinal  folds  in  the  outer  part  of  the  tube,  which  indicate  its  adaptation 
for  dilatation,  and  is  covered  by  columnar  ciliated  epithelium.  This  form  of 
epithelium  is  also  found  on  the  inner  and  outer  surfaces  of  the  fimbrisB, 

The  Ovaries  {testes  muliebres,  Galen)  are  analogous  to  the  testes  in  the  male. 
They  are  oval-shaped  bodies,  of  an  elongated  form,  flattened  from  above  down- 
wards, situated  one  on  each  side  of  the  uterus,  in  the  posterior  part  of  the  broad 
ligament  behind  and  below  the  Fallopian  tubes.  Each  ovary  is  connected,  by 
its  anterior  margin,  to  the  broad  ligament ;  by  its  inner  extremity  to  the  uterus 
by  a  proper  ligament,  the  ligament  of  the  ovary;  and  by  its  outer  end  to  the 

fimbriated  extremity  of  the  Fallopian  tube 
by  a  short  ligamentous  cord.  The  ovaries 
are  of  a  whitish  color,  and  present  either  a 
smooth  or  puckered  uneven  surface.  They 
are  each  about  an  inch  and  a  half  in  length, 
three-quarters  of  an  inch  in  width,  and  about 
a  third  of  an  inch  thick;  and  weigh  from 
one  to  two  drachms.  The  surfaces  and  poste- 
rior convex  border  are  free,  the  anterior 
straight  border  being  attached  to  the  broad 
ligament. 

Structure.  The  ovary  is  invested  by  peri- 
toneum, excepting  along  its  anterior  attached 
margin ;  beneath  this,  is  the  proper  fibrous 
covering  of  the  organ,  the  tunica  alhugineay 
which  is  extremely  dense  and  firm  in  struc- 
ture, and  incloses  a  peculiar  soft  fibrous  tissue, 
or  stroma,  abundantly  supplied  with  blood- 
vessels (Fig.  444).  Imbedded  in  the  meshes 
of  this  tissue  are  numerous  small,  round, 
transparent  vesicles,  in  various  stages  of 
development ;  they  are  the  Graafian  vesicles, 
the  ovisacs  containing  the  ova.  In  women 
who  have  not  borne  children,  they  vary  in  number  from  ten  to  fifteen  or 
twenty ;  and  in  size  from  a  pin's  head  to  a  pea ;  but  Dr.  Martin  Barry  has  shown 
that  a  large  number  of  microscopic  ovisacs  exist  in  the  parenchyma  of  the 
organ,  few  of  which  produce  ova.  These  vesicles  have  thin,  transparent  walls, 
and  are  filled  with  a  clear,  colorless,  albuminous  fluid. 

The  Graafian  vesicles  arc,  during  their  early  development,  small,  and  deeply 
seated  in  the  substance  of  the  ovary ;  as  they  enlarge,  they  approach  the  sur- 
face; and,  when  mature,  form  small  projections  on  the  exterior  of  the  ovary 
beneath  the  peritoneum.  Each  vesicle  consists  of  an  external  fibro-vascular 
coat,  connected  with  the  surrounding  stroma  of  the  ovary  by  a  network  of 


Fig.  445. — Section  of  the  Graafian 
Vesicle.    After  Von  Baer. 


FtriifUUt' 


cte:.fftk4Cxfru^ 


I 


OVUM.  819 

bloodvessels ;  and  an  internal  coat,  named  ovi-capsule^  which  is  lined  by  a  layer 
of  nucleated  cells,  called  the  memhrana  gramdosa.  The  fluid  contained  in  the 
interior  of  the  vesicles  is  transparent  and  albuminous,  and  in  it  is  suspended 
the  ovum. 

The  formation,  development,  and  maturation  of  the  Graafian  vesicles  and 
ova  continue  uninterruptedly  from  infancy  to  the  end  of  the  fruitful  period  of 
woman's  life.  Before  puberty,  the  ovaries  are  small,  the  Graafian  vesicles  con- 
tained in  them  minute,  and  few  in  number;  and  few,  probably,  ever  attain  full 
development,  but  shrink  and  disappear,  their  ova  being  incapable  of  impregna- 
tion. At  puberty,  the  ovaries  enlarge,  are  more  vascular,  the  Graafian  vesicles 
are  developed  in  greater  abundance,  and  their  ova  capable  of  fecundation. 

Discharge  of  the  Ovum.  The  Graafian  vesicles,  after  gradually  approaching 
the  surface  of  the  ovary,  burst;  the  ovum  and  fluid  contents  of  the  vesicles  are 
liberated,  and  escape  on  the  exterior  of  the  ovary,  passing  from  thence  into  the 
Fallopian  tube,  the  fimbriated  processes  of  which  are  supposed  to  grasp  the 
ovary,  the  aperture  of  the  tube  being  applied  to  the  part  corresponding  to  the 
matured  and  bursting  vesicle.  In  the  human  subject  and  most  mammalia,  the 
maturation  and  discharge  of  the  ova  occur  at  regular  periods  only,  and  are 
indicated,  in  the  mammalia,  by  the  phenomena  of  heat  or  rut;  and  in  the  human 
female,  by  menstruation.  Sexual  desire  is  more  intense  in  females  at  this  pe- 
riod; and  if  the  union  of  the  sexes  takes  place,  the  ovum  may  be  fecundated. 

Corpus  Luteuw,.  Immediately  after  the  rupture  of  a  Graafian  vesicle,  and 
the  escape  of  its  ovum,  the  vesicle  is  filled  with  blood-tinged  fluid;  aiid  in  a 
short  time  the  circumference  of  the  vesicle  is  occupied  by  a  firm,  yellow  sub- 
stance, which  is  probably  formed  from  plasma  exuded  from  its  walls.  Dr.  Lee 
believes  that  this  yellow  matter  is  deposited  outside  both  the  membranes  of  the 
follicle;  Montgomery  regards  it  as  placed  between  the  layers;  while  Kolliker 
considers  it  as  a  thickening  of  the  inner  layer  of  the  outer  coat  of  the  follicle. 
The  exudation  is  at  first  of  a  dark  brown  or  brownish-red  color,  but  it  soon 
becomes  paler,  and  its  consistence  more  dense. 

For  every  follicle  in  the  ovary  from  which  an  ovum  is  discharged,  a  corpus 
luteura  will  be  found.  But  the  characters  it  exhibits,  and  the  changes  produced 
in  it,  will  be  determined  by  the  circumstance  of  the  ovum  being  impregnated 
or  not. 

Although  there  is  little  doubt  that  corpora  lutea  exist  in  the  ovaries  after  the 
escape  of  ova,  independent  of  coitus  or  impregnation,  it  appears  that  the  corpus 
luteum  of  pregnancy  (true  corpus  luteum)  possesses  characters  by  which  it  may 
be  distinguished  from  one  formed  in  a  follicle,  from  which  an  ovum  has  been 
discharged  without  subsequent  impregnation  (false  corpus  luteum). 

The  true  corpora  lutea  are  of  large  size,  often  as  large  as  a  mulberry;  of  a 
rounded  form,  and  project  from  the  surface  of  the  ovary,  the  summit  of  the 
projection  presenting  a  triangular  depression  or  cicatrix,  where  the  peritoneum 
appears  to  have  been  torn.  They  contain  a  small  cavity  in  their  centre  during 
the  early  period  of  their  formation,  which  becomes  contracted,  and  exhibits  a 
stellate  cicatrix  during  the  latter  stages  of  pregnancy.  Their  vascularity, 
lobulated  or  puckered  appearance,  firm  consistence,  and  yellow  color,  are  also 
characteristic  marks  of  true  corpora  lutea. 

False  corpora  lutea  are  of  small  size,  do  not  project  from  the  surface  of  the 
ovary,  are  angular  in  form,  seldom  present  any  cicatrix,  contain  no  cavity  in 
their  centre;  the  material  composing  them  is  not  lobulated,  its  consistence  is 
usually  soft,  often  resembling  coagulated  blood;  the  yellow  matter  exists  in  the 
form  of  a  very  thin  layer,  or  more  commonly  is  entirely  wanting.  False 
corpora  lutea  most  frequently  result  from  the  effusion  into  the  cavities  of  the 
Graafian  vesicles  of  serum  or  blood,  which  subsequently  undergoes  various 
changes,  and  is  ultimately  removed.  Dr.  Lee  states,  that  in  the  false  corpora 
lutea  the  yellow  substance  is  contained  within,  or  attached  to,  the  inner  surface 


820  FEMALE    ORGANS    OF    GENERATION. 

of  the  Graafian  vesicle,  and  does  not  surround  it,  as  is  the  case  in  the  true 
corpora  lutea. 

In  the  foetus,  the  ovaries  are  situated,  like  the  testes,  in  the  lumbar  region, 
near  the  kidneys.  They  may  be  distinguished  from  those  bodies  at  an  early 
period  by  their  elongated  and  flattened  form,  and  by  their  position,  which  is  at 
first  oblique,  and  then  nearly  transverse.  They  gradually  descend  into  the 
pelvis. 

The  Ligament  of  the  Ovary  is  a  rounded  cord,  which  extends  from  each  supe- 
rior angle  of  the  uterus  to  the  inner  extremity  of  the  ovary ;  it  consists  of 
fibrous  tissue,  and  a  few  muscular  fibres  derived  from  the  uterus. 

The  Round  Ligaments  are  two  rounded  cords,  between  four  and  five  inches 
in  length,  situated  between  the  layers  of  the  broad  ligament  in  front  of  and 
below  the  Fallopian  tube.  Commencing  on  each  side  at  the  superior  angle  of 
the  uterus,  this  ligament  passes  forwards  and  outwards  through  the  internal 
abdominal  ring,  along  the  inguinal  canal  to  the  labia  majora,  in  which  it  be- 
comes lost.  The  round  ligament  consists  of  areolar  tissue,  vessels,  and  nerves, 
besides  a  dense  bundle  of  fibrous  tissue,  and  muscular  fibres  prolonged  from 
the  uterus,  inclosed  in  a  duplicature  of  peritoneum,  which,  in  the  foetus,  is 
prolonged  in  the  form  of  a  tubular  process  for  a  short  distance  into  the  inguinal 
canal.  This  process  is  called  the  canal  of  Nuck.  It  is  generally  obliterated  in 
the  adult,  but  sometimes  remains  pervious  even  in  advanced  life.  It  is  analo- 
gous to  tiie  peritoneal  pouch  which  accompanies  the  descent  of  the  testis. 

Vessels  ami  Nerves.  The  arteries  of  the  ovaries  and  Fallopian  tubes  are  the 
ovarian  from  the  aorta.  They  anastomose  with  the  termination  of  the  uterine 
arteries,  and  enter  the  attached  border  of  the  ovary.  The  veins  follow  the 
course  of  the  arteries;  they  form  a  plexus  near  the  ovary,  the  pampiniform 
plexus.  The  nerves  are  derived  from  the  spermatic  plexus,  the  Fallopian  tube 
receiving  a  branch  from  one  of  the  uterine  nerves. 

Mammary  Glands. 

The  Mammae,  or  Breasts,  are  accessory  glands  of  the  generative  system, 
which  secrete  the  milk.  They  exist  in  the  male  as  well  as  in  the  female;  but 
in  the  former  only  in  a  rudimentary  state,  unless  their  growth  is  excited  by- 
peculiar  circumstances.  In  the  female,  they  are  two  large  hemispherical  emi- 
nences situated  towards  the  lateral  aspect  of  the  pectoral  region,  corresponding 
to  the  interval  between  the  third  and  sixth  or  seventh  ribs,  and  extending  from 
the  side  of  the  sternum  to  the  axilla.  Their  weight  and  dimensions  differ  at 
different  periods  of  life,  and  in  different  individuals.  Before  puberty  they  are 
of  small  size,  but  enlarge  as  the  generative  organs  become  more  completely 
developed.  They  increase  during  pregnancy,  and  especially  after  delivery,  and 
become  atrophied  in  old  age.  The  left  mamma  is  generally  a  little  larger  than 
the  right.  Their  base  is  nearly  circular,  flattened  or  slightly  concave,  and 
having  their  long  diameter  directed  upwards  and  outwards  towards  the  axilla;  W 
thoy  are  separated  from  the  Pectoral  muscles  by  a  thin  layer  of  superficial  W 
fascia.  The  outer  surface  of  the  mamma  is  convex,  and  presents,  just  below  the 
centre,  a  small  conical  prominence,  the  nipple  (mammilla).  The  surfiice  of  the  _. 
nipple  is  dark-colored,  and  surrounded  by  an  areola  having  a  colored  tint.  .I^fll 
the  virgin,  the  areola  is  of  a  delicate  rosy  hue;  about  the  second  month  of  im- 
pregnation, it  enlarges,  and  acquires  a  darker  tinge,  which  increases  as  preg- 
nancy advances,  becoming,  in  some  cases,  a  dark  brown  or  even  black  color. 
This  color  diminishes  as  soon  as  lactation  is  over,  but  is  never  entirely  lost 
through  life.  These  changes  in  the  color  of  the  areola  are  of  extreme  import- 
ancc  in  forming  a  conclusion  in  a  case  of  suspected  pregnancy. 

The  nipple  is  a  cylindrical  or  conical  eminence,  capable  of  undergoing  a  sort 
of  erection  from  mechanical  excitement.  It  is  of  a  pink  or  brownish  hue,  its 
surface  wrinkled  and  provided  with  papilla),  and  its  summit  perforated  by 


I 


MAMMARY    GLANDS.  821 

numerous  orifices,  tlie  apertures  of  the  lactiferous  ducts.  Near  the  base  of  the 
nipple,  and  upon  the  surface  of  the  areola,  are  numerous  sebaceous  glands, 
which  become  much  enlarged  during  lactation,  and  present  the  appearance  of 
small  tubercles  beneath  the  skin.  These  glands  secrete  a  peculiar  fatty  sub- 
stance, which  serves  as  a  protection  to  the  integument  of  the  nipple  in  the  act 
of  sucking.  The  nipple  consists  of  numerous  vessels,  which  form  a  kind  of 
erectile  tissue,  intermixed  with  plain  muscular  fibres. 

Stnicture.  The  mamma  consists  of  gland  tissue ;  of  fibrous  tissue,  connecting 
its  lobes ;  and  of  fatty  tissue  in  the  intervals  between  the  lobes.  The  mammary 
gland,  when  freed  from  cellular  tissue  and  fat,  is  of  a  pale  reddish  color,  firm 
in  texture,  circular  in  form,  flattened  from  before  backwards,  thicker  in  the 
centre  than  at  the  circumference,  and  presenting  several  inequalities  on  its  sur- 
face, especially  in  front.  It  consists  of  numerous  lobes,  and  these  are  com- 
posed of  lobules,  connected  together  by  areolar  tissue,  bloodvessels,  and  ducts. 
The  smallest  lobules  consist  of  a  cluster  of  rounded  vesicles,  which  open  into 
the  smallest  branches  of  the  lactiferous  ducts;  these  ducts  uniting,  form  larger 
ducts,  which  terminate  in  a  single  canal,  corresponding  with  one  of  the  chief 
subdivisions  of  the  gland.  The  number  of  excretory  ducts  varies  from  fifteen 
to  twenty ;  they  are  termed  the  tuhuli  lactiferi^  t.  galactophori.  They  converge 
towards  the  areola,  beneath  which  they  form  dilatations,  or  ampullae,  which 
ocrve  as  reservoirs  for  the  milk,  and,  at  the  base  of  the  nipple,  become  con- 
tracted, and  pursue  a  straight  course  to  its  summit,  perforating  it  by  separate 
orifices  considerably  narrower  than  the  ducts  themselves.  The  ducts  are  com- 
posed of  areolar  tissue,  with  longitudinal  and  transverse  elastic  fibres,  and 
longitudinal  muscular  fibres;  their  mucous  lining  is  continuous,  at  the  point  of 
the  nipple,  with  the  integument;  the  epithelium  is  of  the  tessellated  or  scaly 
variety. 

The  fibrous  tissue  invests  the  entire  surface  of  the  breast,  and  sends  down 
septa  between  its  lobes,  connecting  them  together. 

The  fatly  tissue  surrounds  the  surface  of  the  gland,  and  occupies  the  intervals 
between  its  lobes  and  lobules.  It  usually  exists  in  considerable  abundance,  and 
determines  the  form  and  size  of  the  gland.  There  is  no  fat  immediately  be- 
neath the  areola  and  nipple. 

Vessels  and  Nerves.  The  arteries  supplying  the  mammae  are  derived  from  the 
thoracic  branches  of  the  axillary,  the  intercostals,  and  internal  mammary.  The 
veiiis  describe  an  anastomotic  circle  round  the  base  of  the  nipple,  called  by 
Haller  the  circulus  venosus.  From  this,  large  branches  transmit  the  blood  to  the 
circumference  of  the  gland,  and  end  in  the  axillary  and  internal  mammary  veins. 
The  lymphatics  run  along  the  lower  border  of  the  Pectoralis  Major  to  the  axil- 
lary glands.  The  nerves  are  derived  from  the  anterior  and  lateral  cutaneous 
nerves  of  the  thorax. 


The  Surgical  Anatomy  of  Inguinal  Hernia. 

Dissection  (Fig.  446),  For  the  dissection  of  the  parts  concerned  in  inguinal  hernia,  a  male 
subject,  free  from  fat,  should  always  be  selected.  The  body  should  be  placed  in  the  supine  posi- 
tion, the  abdomen  and  pelvis  raised  by  means  of  blocks  placed  beneath  them,  and  the  lower  ex- 
tremities rotated  outwards,  so  as  to  make  the  parts  as  tense  as  possible.  If  the  abdominal  walls 
are  flaccid,  the  cavity  of  the  abdomen  should  be  inflated  by  an  aperture  through  the  umbilicus. 
An  incision  should  be  made  along  the  middle  hne,  from  the  umbilicus  to  the  pubes,  and  con- 
tinued along  the  front  of  the  scrotum  ;  and  a  second  incision,  from  the  anterior  superior  spine 
of  the  ilium  to  just  below  the  umbilicus.  These  incisions  should  divide  the  integument;  and  the 
triangular-shaped  flap  included  between  them  should  be.reflected  downwards  and  outwards,  when 
the  superficial  fascia  will  be  exposed. 

Inguinal  Hernia  is  that  form  of  protrusion  whicli  makes  its  way  through  the 
abdomen  in  the  inguinal  region. 

The  superficial  fascia  in  this  region  consists  of  two  layers,  between  which  are 
found  the  superficial  vessels  and  nerves,  and  the  inguinal  lymphatic  glands. 

The  superficial  layer  is  thick,  areolar  in  texture,  containing  adipose  tissue  in 
its  meshes,  the  quantity  of  which  varies  in  different  subjects.  Below,  it  passes 
over  Poupart's  ligament,  and  is  continuous  with  the  outer  layer  of  the  superficial 
fascia  of  the  thigh.  This  fascia  is  continued  as  a  tubular  prolongation  around 
the  outer  surface  of  the  cord  and  testis.  In  this  situation,  it  changes  its  charac- 
ter;  it  becomes  thin,  destitute  of  adipose  tissue,  and  of  a  pale  reddish  color,  and 
assists  in  forming  the  dartos.  From  the  scrotum,  it  may  be  traced  backwards 
to  be  continuous  with  the  superficial  fascia  of  the  perineum.  This  layer  should 
be  removed,  by  dividing  it  across  in  the  same  direction  as  the  external  incisions, 
and  reflecting  it  downwards  and  outwards,  when  the  following  vessels  and  nerves 
will  be  exposed  : —  ■I 

The  superficial  epigastric,  superficial  circumflex  iliac,  and  external  pudic  ves- 
sels; the  terminal  filaments  of  the  ilio-hypogastric  and  ilio-inguinal  nerves;  and 
the  upper  chain  of  inguinal  lymphatic  gland. 

The  superficial  epigastric  artery  crosses  Poupart's  ligament,  and  ascends  ob- 
liquely towards  the  umbilicus,  lying  midway  between  the  spine  of  the  ilium 
and  the  pubes.  It  supplies  the  integument,  and  anastomoses  with  the  deep  epi- 
gastric. This  vessel  is  a  branch  of  the  common  femoral  artery,  and  pierces  the 
fascia  lata,  below  Poupart's  ligament.  Its  accompanying  vein  empties  itself 
into  the  internal  saphenous,  after  having  pierced  the  cribriform  fascia. 

The  superficial  circumfiex  iliac  artery  passes  outwards  towards  the  crest  of  tho 
ilium. 

The  superficial  external  pudic  artery  passes  transversely  inwards  across  the 
spermatic  cord,  and  supplies  the  integument  of  the  hypogastric  region,  and  of 
the  penis  and  scrotum.  This  vessel  is  usually  divided  in  the  first  incision  made 
in  the  operation  for  inguinal  hernia,  and  occasionally  requires  the  application 
of  a  ligature. 

The  veins  accompanying  these  superficial  vessels  are  usually  much  larger 
than  the  arteries;  they  terminate  in  the  internal  saphenous  vein. 

Lymphatic  vessels  are  found,  taking  the  same  course  as  the  bloodvessels;  they 
return  the  lymph  from  the  superficial  structures  in  the  lower  part  of  the  abdo- 
men, the  scrotum,  penis,  and  external  surface  of  the  buttock,  and  terminate  in 
a  small  chain  of  lymphatic  glands,  three  or  four  in  number,  which  lie  on  a  level 
with  Poupart's  ligament. 

Nerves.  The  terminal  branch  of  the  ilio-inguinal  nerve  emerges  at  the  ex- 
ternal abdominal  ring  ;  and  the  hypogastric  branch  of  the  ilio-hypogastric  nerve 
822 


11 


I 


INGUINAL    HERNIA  — SUPERFICIAL    DISSECTION.      823 

perforates  the  aponeurosis  of  the  external  oblique,  above  and  to  the  outer  side 
of  the  external  ring. 

The  deep  layer  of  superficial  fascia  should  be  divided  across  in  the  same 
direction  as  the  external  incisions,  separated  from  the  aponeurosis  of  the  Ex- 
ternal Oblique,  to  which  it  is  connected  by  delicate  areolar  tissue,  and  reflected 
downwards  and  outwards.  It  is  thin,  aponeurotic  in  structure,  and  of  consider- 
able strength.  It  is  intimately  adherent,  in  the  middle  line,  to  the  linea  alba, 
and  below,  to  the  whole  length  of  Poupart's  ligament  and  the  upper  part  ofthe 
fascia  lata.  It  forms  a  thin  tubular  prolongation  round  the  outer  surface  of  the 
cord,  which  blends  with  the  superficial  layer,  and  is  continuous  with  thedartos 
of  the  scrotum.  From  the  back  of  the  scrotum,  the  conjoined  layers  may  be 
traced  into  the  perineum,  where  they  are  continuous  with  the  deep  layer  of  the 
superficial  fascia  in  that  region,  which  is  attached,  behind,  to  the  triangular 
ligament,  and  on  each  side,  to  the  ramus  of  the  pubes  and  ischium.  The  con- 
nections of  this  fascia  serve  to  explain  the  course  taken  by  the  urine  in  extra- 
vasation of  that  fluid  from  rupture  of  the  urethra  ;  passing  forwards  from  the 
perineum  into  the  scrotum,  it  ascends  on  to  the  abdomen,  but  is  prevented  ex- 
tending into  the  thighs  by  the  attachment  of  the  fascia  to  the  ramus  of  the 
pubes  and  ischium,  on  each  side,  and  to  Poupart's  ligament  in  front,  and  is  pre- 
vented from  passing  on  to  the  buttock  by  the  posterior  connections  of  the 
perineal  fascia. 

Fig.  446. — Inguinal  Hernia.    Superficial  Dissection. 


The  aponeurosis  of  the  External  Oblique  mtiscle  is  exposed  on  the  removalof 
this  fascia.     It  is  a  thin,  strong,  membranous  aponeurosis,  the  fibres  of  which 


824         SURGICAL    ANATOMY    OF    INGUINAL    HERNIA, 

are  directed  obliquely  downwards  and  inwards.  It  is  attached  to  the  anterior 
superior  spinous  process  of  the  ilium,  the  spine  of  the  pubes,  the  pectineal  line, 
front  of  the  pubes,  and  linea  alba.  That  portion  of  the  aponeurosis  which 
extends  from  the  anterior  superior  spine  of  the  ilium,  to  the  spine  of  the  pubes 
is  termed  Poupart's  ligament,  or  the  crural  arch ;  and  that  portion  which  is 
inserted  into  the  pectineal  line,  is  termed  Gimbernat's  ligament. 

Just  above  and  to  the  outer  edge  of  the  crest  of  the  pubes,  a  triangular 
interval  is  seen  in  the  aponeurosis  of  the  External  Oblique,  called  the  external 
ahdominal  ring,  which  transmits  the  spermatic  cord  in  the  male,  and  the  round 
ligament  in  the  female.  This  aperture  is  oblique  in  direction,  somewhat  trian- 
gular in  form,  and  corresponds  with  the  course  of  the  fibres  of  the  aponeurosis. 
It  usually  measures  from  base  to  apex  about  an  inch,  and  transversely  about 
half  an  inch.  It  is  bounded  below  by  the  crest  of  the  os  pubis ;  above,  by  a 
series  of  curved  fibres,  the  intercolumnar,  which  pass  across  the  upper  angle  of 
the  ring  so  as  to  increase  its  strength ;  and  on  either  side,  by  the  free  borders 
of  the  aponeurosis,  which  are  called  the  columns  or  pillars  of  the  ring. 

The  external  2nllar,  which,  at  the  same  time,  is  inferior  from  the  obliquity  of 
its  direction,  is  the  stronger ;  it  is  formed  by  that  portion  of  Poupart's  ligament 
which  is  inserted  into  the  spine  of  the  pubes;  it  is  curved  round  the  spermatic 
cord,  so  as  to  form  a  kind  of  groove,  upon  which  the  cord  rests. 

The  internal  ov  superior  pillar  is,  a  broad,  thin,  flat  band,  which  interlaces  with 
its  fellow  of  the  opposite  side,  in  front  of  the  symphysis  pubis,  that  of  the  right 
side  being  superficial. 

The  external  abdominal  ring  gives  passage  to  the  spermatic  cord  in  the  male, 
and  round  ligament  in  the  female ;  it  is  much  larger  in  men  than  women,  on 
account  of  the  large  size  of  the  spermatic  cord,  and  hence  the  greater  fre- 
quency of  inguinal  hernia  in  men. 

The  intercolumnar  fibres  are  a  series  of  curved  tendinous  fibres,  which  arch 
across  the  lower  part  of  the  aponeurosis  of  the  External  Oblique.  They  have 
received  their  name  from  stretching  across  between  the  two  pillars  of  the  ex- 
ternal ring;  they  increase  the  strength  of  the  membrane  which  bounds  the 
upper  part  of  this  aperture,  and  prevent  the  divergence  of  the  pillars  from  one 
another.  They  are  thickest  below,  where  they  are  connected  to  the  outer  third 
of  Poupart's  ligamentj  and  are  inserted  into  the  linea  alba;  describing  a  curve, 
with  the  convexity -downwards.  They  are  much  thicker  and  stronger  at  the 
outer  angle  of  the  external  ring  than  internally,  and  are  more  strongly  developed 
in  the  male  than  in  the  female.  These  fibres  are  continuous  with  a  thin  fascia, 
which  is  closely  connected  to  the  margins  of  the  external  ring,  and  has  received 
the  name  of  the  intercolumnar  or  external  spermatic  fascia ;  it  forms  a  tubular 
prolongation  around  the  outer  surface  of  the  cord  and  testis,  and  incloses  them 
in  a  distinct  sheath.  The  sac  of  an  inguinal  hernia,  in  passing  through  the 
external  abdominal  ring,  receives  an  investment  from  the  intercolumnar  fascia. 

The  finger  should  be  introduced  a  short  distance  into  the  external  ring,  and 
then,  if  the  limb  is  extended  and  rotated  outwards,  the  aponeurosis  of  the  Ex- 
ternal Oblique,  together  with  the  iliac  portion  of  the  fascia  lata,  will  be  felt  to 
become  tense,  and  the  -external  ring  much  contracted ;  if  the  limb  is,  on  the 
contrary,  flexed  upon  the  pelvis  and  rotated  inwards,  this  aponeurosis  will 
become  lax,  and  the  external  ring  sufficiently  enlarged  to  admit  the  finger  with 
comparative  ease;  hence  the  patient  should  always  be  put  in  the  latter  position 
when  the  taxis  is  applied  for  the  reduction  of  an  inguinal  hernia,  in  order  that 
the  abdominal  walls  may  be  as  much  relaxed  as  possible. 

The  aponeurosis  of  the  External  Oblique  should  be  removed  by  dividinp:  it  across  in  the  same 
direction  as  the  external  incisions,  and  reflecting  it  outwards ;  great  care  is  requisite  in  separat- 
ing it  from  the  aponeurosis  of  the  muscle  beneath.  The  lower  part  of  the  Internal  Oblique  and 
Creraaster  are  then  exposed,  together  with  the  inguinal  canal,  which  contains  the  spermatic 
cord  (Fig.  447).  The  mode  of  insertion  of  Poupart's  and  Gimbernat's  ligaments  into  the  pubea 
should  also  be  examined. 


I 


INTERNAL    OBLIQUE  — CREMASTER. 


825 


Poupart^s  ligament^  or  the  crural  arch,  extends  from  the  anterior  superior 
spine  of  the  ilium  to  the  spine  of  the  pubes.  It  is  also  attached  to  the  pectineal 
line  to  the  extent  of  about  an  inch,  forming  Gimbernat's  ligament.  Its  general 
direction  is  curved  towards  the  thigh,  where  it  is  continuous  with  the  fascia 
lata.  Its  outer  half  is  rounded,  oblique  in  its  direction,  and  continuous  with 
the  iliac  fascia.  Its  inner  half  gradually  widens  at  its  attachment  to  the  pubes, 
is  more  horizontal  in  direction,  and  lies  beneath  the  spermatic  cord. 

Oimhernais  ligament  is  that  portion  of  the  aponeurosis  of  the  Exter.nal  Ob- 
lique which  is  inserted  into  the  pectineal  line ;  it  is  thin,  membranous  in  struc- 
ture, triangular  in  shape,  the  base  directed  outwards,  and  passes  upwards  and 
backwards  beneath  the  spermatic  cord,  from  the  spine  of  the  os  pubis  to  the 
pectineal  line,  to  the  extent  of  about  half  an  inch. 

The  triangular  ligament  is  a  band  of  tendinous  fibres,  of  a  triangular  shape, 
which  is  continued  from  Poupart's  ligament  at  its  attachment  to  the  pectineal 
line  upwards  and  inwards,  behind  the  inner  pillar  of  the  external  ring  to  the 
linea  alba. 

The  Internal  Oblique  Muscle  has  been  described  (p.  361).  The  part  which  is 
now  exposed  is  partly  muscular  and  partly  tendinous  in  structure.  Those  fibres 
which  arise  from  the  outer  part  of  Poupart's  ligament  are  thin,  pale  in  color, 
curve  downwards,  and  terminate  in  an  aponeurosis,  which  passes  in  front  of  the 
Rectus  and  Pyramidalis  muscles,  to  be  inserted  into  the  crest  of  the  os  pubis 

Fig.  447. — Inguinal  Hernia,  showing  the  Internal  Oblique,  Cremaster,  and  Spermatic  Canal. 


and  pectineal  line,  to  the  extent  of  half  an  inch,  in  common  with  that  of  the 
Transversalis  muscle,  forming  by  their  junction  the  conjoined  tendon.  This 
tendon  is  placed  immediately  behind  Gimbernat's  ligament  and  the  external 
abdominal  ring,  and  serves  to  strengthen  what  would  otherwise  be  a  very  weak 
point  in  the  abdominal  wall.  When  a  direct  inguinal  hernia  passes  through  the 
external  ring,  the  conjoined  tendon  usually  forms  one  of  its  coverings. 

The  Cremaster  is  a  slender  muscular  fasciculus,  which  arises  from  the  middle 


826         SURGICAL    ANATOMY    OF    INGUINAL    HERNIA. 

of  Poupart's  ligament  at  the  inner  side  of  the  Internal  Oblique,  being  connected 
with  that  muscle,  and  also  occasionally  with  the  Transversalis.  It  passes  along 
the  outer  side  of  the  spermatic  cord,  descends  with  it  through  the  external  ring 
upon  the  front  and  sides  of  the  cord,  and  forms  a  series  of  loops,  which  differ 
in  thickness  and  length  in  different  subjects.  Those  at  the  upper  part  of  the 
cord  are  exceedingly  short,  but  they  become  in  succession  longer  and  longer, 
the  longest  reaching  down  as  low  as  the  testicle,  where  a  few  are  inserted  into 
the  tunica  vaginalis.  These  loops  are  united  together  by  areolar  tissue,  and 
form  a  thin  covering  over  the  cord,  the  fascia  cremasterica.  The  fibres  ascend 
along  the  inner  side  of  the  cord,  and  are  inserted  by  a  small  pointed  tendon, 
into  the  crest  of  the  os  pubis  and  front  of  tbe  sheath  of  the  Rectus  muscle. 

It  will  be  observed,  that  the  origin  and  insertion  of  the  Cremaster  is  precisely 
similar  to  that  of  the  lower  fibres  of  the  Internal  Oblique.  This  fact  affords  an 
easy  explanation  of  the  manner  in  which  the  testicle  and  cord  are  invested  by 
this  muscle.  At  an  early  period  of  foetal  life,  the  testis  is  placed  at  the  lower 
and  back  part  of  the  abdominal  cavity,  but,  during  its  descent  towards  the 
scrotum,  which  takes  place  before  birth,  it  passes  beneath  the  arched  border  of 
the  Internal  Oblique.  In  its  passage  beneath  this  muscle  some  fibres  are 
derived  from  its  lower  part,  which  accompany  the  testicle  and  cord  into  the 
scrotum. 

It  occasionally  happens  that  the  loops  of  the  Cremaster  surround  the  cord, 
some  lying  behind  as  well  as  in  front.  It  is  probable  that,  under  these  circum- 
stances, the  testis,  in  its  descent,  passed  through  instead  of  beneath  the  fibres  of 
the  Internal  Oblique. 

In  the  descent  of  an  oblique  inguinal  hernia,  which  takes  the  same  course  as 
the  spermatic  cord,  the  Cremaster  muscle  forms  one  of  its  coverings.  This 
muscle  becomes  largely  developed  in  cases  of  hydrocele  and  large  old  scrotal 
hernias.  No  such  muscle  exists  in  the  female,  but  an  analogous  structure  is 
developed  in  those  cases  where  an  oblique  inguinal  hernia  descends  beneath  the 
margin  of  the  Internal  Oblique. 

The  Internal  Oblique  should  be  detached  from  Poupart's  ligament,  separated  from  the  Trans- 
versalis to  the  same  extent  as  in  the  previous  incisions,  and  reflected  inwards  on  to  the  sheath  of 
the  Rectus  (Fig.  451).  The  circumflex  iliac  vessels,  which  lie  between  these  two  muscles,  form 
a  valuable  guide  to  their  separation.  hi 

The  Transversalis  muscle  has  been  previously  described  (p.  362).     Its  lower  fll 
part  is  partly  fleshy  and  partly  tendinous  in  structure;  this  portion  arises  from 
the  outer  third  of  Poupart's  ligament,  and,  arching  downwards  and  inwards  over  ^. 
the  cord,  terminates  in  an  aponeurosis,  which  is  inserted  into  the  linea  alba,  the  fli 
crest  of  the  pubes,  and  the  pectineal  line  to  the  extent  of  an  inch,  forming, 
together  with  the  Internal  Oblique,  the  conjoined  tendon.     Between  the  lower 
border  of  this  muscle  and  Poupart's  ligament,  a  space  is  left  in  which  is  seen  Ml 
the  fascia  transversalis.  ™i 

The  inguinal,  or  spermatic  canal,  contains  the  spermatic  cord  in  the  male,  and 
the  round  ligament  in  the  female.  It  is  an  oblique  canal,  about  an  inch  and  a 
half  in  length,  directed  downwards  and  inwards,  and  placed  parallel  with,  and 
a  little  above,  Poupart's  ligament.  It  communicates,  above,  ^yith  the  cavity  of 
the  abdomen,  by  means  of  the  internal  abdominal  ring,  which  is  the  point  where 
the  cord  enters  the  spermatic  canal ;  and  terminates,  below,  at  the  external  ring. 
It  is  bounded,  in  front,  by  the  integument  and  superficial  fascia,  by  the  aponeu- 
rosis  of  the  External  Oblique  throughout  its  whole  length,  and  by  the  Internal  H 
Oblique  for  its  outer  third;  behind,  by  the  conjoined  tendon  of  the  Internal 
Oblique  and  Transversalis,  the  triangular  ligament,  transversalis  fascia,  and  the 
subperitoneal  fat  and  peritoneum ;  above,  by  the  arched  fibres  of  the  Internal 
Oblique  and  Transversalis;  below,  by  the  union  of  the  fascia  transversalis  with 
Poupart's  ligament.  That  form  of  protrusion  in  which  the  intestine  follows  the 
course  of  the  spermatic  cord  along  the  spermatic  canal,  is  called  oblique  inguinal 
hernia. 


INTERNAL  ABDOMINAL  RING. 


82'r 


The  fascia  transversalis  is  a  thin  aponeurotic  membrane,  which  lies  between 
the  inner  surface  of  the  Transversalis  muscle  and  the  peritoneum.  It  forms 
part  of  the  general  layer  of  fascia  which  lines  the  interior  of  the  abdominal  and 
pelvic  cavities,  and  is  directly  continuous  with  the  iliac  and  pelvic  fasciae. 

In  the  inguinal  region,  the  transversalis  fascia  is  thick  and  dense  in  struc- 
ture, and  joined  by  fibres  from  the  aponeurosis  of  the  Transversalis ;  but  it 
becomes  thin  and  cellular  as  it  ascends  to  the  Diaphragm.  Below,  it  has  the 
following  attachments :  external  to  the  femoral  vessels,  it  is  connected  to  the 
posterior  margin  of  Poupart's  ligament,  and  is  there  continuous  with  the  iliac 
fascia.  Internal  to  the  vessels,  it  is  thin,  and  attached  to  the  pubes  and  pec- 
tineal line,  behind  the  conjoined  tendon,  with  which  it  is  united;  and,  corre- 
sponding to  the  point  where  the  femoral  vessels  pass  into  the  thigh,  this  fascia 
descends  in  front  of  them,  forming  the  anterior  wall  of  the  crural  sheath. 

Fig.  449, — Inguinal  Hernia,  showing  the  Transversnlis  Muscle,  the  Transversalis  Fascia, 
and  the  Internal  Abdominal  liinff. 


The  internal  abdominal  ring  is  situated  in  the  transversalis  fascia,  midway 
between  the  anterior  superior  spine  of  the  ilium  and  the  spine  of  the  pubes, 
and  about  half  an  inch  above  Poupart's  ligament.  It  is  of  an  oval  form,  the 
extremities  of  the  oval  directed  upwards  and  downwards,  varies  in  size  in 
different  subjects,  and  is  much  larger  in  the  male  than  in  the  female.  It  is 
bounded,  above,  by  the  arched  fibres  of  the  Transversalis  muscle,  and  inter- 
nally, by  the  epigastric  vessels.  It  transmits  the  spermatic  cord  in  the  male, 
and  the  round  ligament  in  the  female,  and  from  its  circumference  a  thin,  funnel- 
shaped  membrane,  the  infundihuliform  fascia,  is  continued  round  the  cord  and 
testis,  inclosing  them  in  a  distinct  pouch.  When  the  sac  of  an  oblique  inguinal 
hernia  passes  through  the  internal  ring,  the  infundibuliform  process  of  the 
transversalis  fascia  forms  one  of  its  coverings. 

Between  the  transversalis  fascia  and  the  peritoneum  is  a  quantity  of  loose 
areolar  tissue.  In  some  subjects  it  is  of  considerable  thickness,  and  loaded 
with  adipose  tissue.  Opposite  the  internal  ring,  it  is  continued  round  the  sur- 
face of  the  cord,  forming  a  loose  sheath  for  it. 


828         SURGICAL    ANATOMY    OF    INGUINAL    HERNIA. 

The  epigastric  artery  bears  a  very  important  relation  to  the  internal  abdomi- 
nal ring.  This  vessel  lies  between  the  transversalis  fascia  and  peritoneum,  and 
passes  obliquely  upwards  and  inwards,  from  its  origin  from  the  external  iliac, 
to  the  margin  of  the  sheath  of  the  Rectus  muscle.  In  this  course,  it  lies  along 
the  lower  and  inner  margin  of  the  internal  ring,  and  beneath  the  commencement 
of  the  spermatic  cord,  the  vas  deferens  curving  round  it  as  it  passes  from  the 
ring  into  the  pelvis. 

The  peritoneum,  corresponding  to  the  inner  surface  of  the  internal  ring,  pre- 
sents a  well-marked  depression,  the  depth  of  which  varies  in  different  subjects. 
A  thin  fibrous  band  is  continued  from  it  along  the  front  of  the  cord,  for  a  vari- 
able distance,  and  becomes  ultimately  lost.  This  is  the  remains  of  the  pouch 
of  peritoneum  which,  in  the  foetus,  accompanies  the  cord  and  testis  into  the 
scrotum,  the  obliteration  of  which  commences  soon  after  birth.  In  some  cases, 
the  fibrous  band  can  only  be  traced  a  short  distance ;  but  occasionally,  it  may 
be  followed,  as  a  fine  cord,  as  far  as  the  upper  end  of  the  tunica  vaginalis. 
Sometimes  the  tube  of  peritoneum  is  only  closed  at  intervals,  and  presents  a 
sacculated  appearance ;  or  a  single  pouch  may  extend  along  the  whole  length 
of  the  cord,  which  may  be  closed  above ;  or  the  pouch  may  be  directly  con- 
tinuous with  the  peritoneum  by  an  opening  at  its  upper  part. 

There  are  two  principal  varieties  of  inguinal  hernia :  external  or  oblique, 
and  internal  or  direct. 

External  or  ohlique  inguinal  hernia,  the  more  frequent  of  the  two,  takes  the 
same  course  as  the  spermatic  cord.  It  is  called  external,  from  the  neck  of  the 
sac  being  on  the  outer  or  iliac  side  of  the  epigastric  artery. 

Internal,  or  direct  inguinal  hernia,  does  not  follow  the  same  course  as  the 
cord,  but  protrudes  through  the  abdominal  wall  on  the  inner  or  pubic  side  of 
the  epigastric  artery. 

Oblique  Inguinal  Hernia. 

In  Oblique  Inguinal  Hernia,  the  intestine  escapes  from  the  abdominal  cavity 
at  the  internal  ring,  pushing  before  it  a  pouch  of  peritoneum,  which  forms  the 
hernial  sac.  As  it  enters  the  inguinal  canal,  it  receives  an  investment  from 
the  subserous  areolar  tissue,  and  is  inclosed  in  the  infundibuliform  process  of 
the  transversalis  fascia.  In  passing  along  the  inguinal  canal,  it  displaces  up- 
wards the  arched  fibres  of  the  Transversalis  and  Internal  Oblique  muscles,  and 
is  surrounded  by  the  fibres  of  the  Cremaster.  It  then  passes  along  the  front  of 
the  cord,  and  escapes  from  the  inguinal  canal  at  the  external  ring,  receiving  an 
investment  from  the  intercolumnar  fascia.  Lastly,  it  descends  into  the  scrotum, 
receiving  coverings  from  the  superficial  fascia  and  the  integument. 

The  coverings  of  this  form  of  hernia,  after  it  has  ]mssed  through  the  external 
ring,  are,  from  without  inwards,  the  integument,  superficial  fascia,  intercolum- 
nar fiiscia,  Cremaster  muscle,  infundibuliform  fascia,  subserous  cellular  tissue, 
and  peritoneum. 

This  form  of  hernia  lies  in  front  of  the  vessels  of  the  spermatic  cord,  and 
seldom  extends  below  the  testis,  on  account  of  the  intimate  adhesion  of  the 
coverings  of  the  cord  to  the  tunica  vaginalis. 

The  seat  of  strictiire  in  oblique  inguinal  hernia  is  either  at  the  external  ring, 
in  the  inguinal  canal,  caused  by  the  fibres  of  the  Internal  Oblique  or  Transver- 
salis or  at  the  internal  ring,  more  frequently  in  the  latter  situation.  If  it  is 
situated  at  the  external  ring,  the  division  of  a  few  fibres  at  one  point  of  its  cir- 
cumference, is  all  that  is  necessary  for  the  replacement  of  the  hernia.  If  in  the 
inguinal  canal,  or  at  the  internal  ring,  it  will  be  necessary  to  divide  the  aponeu- 
rosis of  the  External  Oblique  so  as  to  lay  open  the  inguinal  canal.  In  dividing 
the  stricture,  the  direction  of  the  incision  should  be  directly  upwards. 

When  the  intestine  passes  along  the  spermatic  canal,  and  escapes  from  the 
external  ring  into  the  scrotum,  it  is  called  complete  ohli(pie  inguinal,  or  scrotal 


DIRECT    INGUINAL    HERNIA.  829 

hernia.  If  the  intestine  does  not  escape  from  the  external  ring,  but  is  retained 
in  the  inguinal  canal,  it  is  called  incomplete  inguinal  hernia  or  bubonocele.  In 
each  of  these  cases,  the  coverings  which  invest  it  will  depend  upon  the  extent 
to  which  it  descends  in  the  inguinal  canal. 

There  are  two  other  varieties  of  oblique  inguinal  hernia :  the  congenital,  and 
infantile. 

Congenital  hernia  is  liable  to  occur  in  those  cases  where  the  pouch  of  perito- 
neum which  accompanies  the  cord  and  testis  in  its  descent  in  the  foetus  remains 
unclosed,  and  communicates  directly  with  the  peritoneum.  The  intestine 
descends  along  this  pouch  into  the  cavity  of  the  tunica  vaginalis,  and  lies 
in  contact  with  the  testis.  This  form  of  hernia  has  no  proper  sac,  being  con- 
tained within  the  tunica  vaginalis. 

In  infantile  hernia^  the  hernial  sac  descends  along  the  inguinal  canal  into 
the  scrotum,  behind  the  pouch  of  peritoneum  which  accompanies  the  cord  and 
testis  into  the  same  part.  The  abdominal  aperture  of  this  pouch  is  closed,  but 
the  portion  contained  in  the  inguinal  canal  remains  unobliterated.  The  hernial 
sac  is  consequently  invested,  more  or  less  completely,  by  the  posterior  layer 
of  the  tunica  vaginalis,  from  which  it  is  separated  by  a  little  loose  areolar 
tissue ;  so  that  in  operating  upon  this  variety  of  hernia,  three  layers  of  perito- 
neum would  require  division ;  the  first  and  second  being  the  layers  of  the 
tunica  vaginalis,  the  third  the  anterior  layer  of  the  hernial  sac. 

DiEECT  Inguinal  Hernia. 

In  Direct  Inguinal  Hernia,  the  protrusion  makes  its  way  through  some  part 
of  the  abdominal  wall  internal  to  the  epigastric  artery,  and  passes  directly 
through  the  abdominal  parietes  and  external  ring.  At  the  lower  part  of  the 
abdominal  wall  is  a  triangular  space  (Hesselbach's  triangle),  bounded,  externally, 
by  the  epigastric  artery ;  internally,  by  the  margin  of  the  Rectus  muscle ; 
below,  by  Poupart's  ligament.  The  conjoined  tendon  is  stretched  across  the 
inner  two-thirds  of  this  space,  the  remaining  portion  of  the  space  being  filled 
in  by  the  transversal  is  fascia. 

In  some  cases  the  hernial  protrusion  escapes  from  the  abdomen  on  the  outer 
side  of  the  conjoined  tendon,  pushing  before  it  the  peritoneum,  the  subserous 
cellular  tissue,  and  the  transversalis  fascia.  It  then  enters  the  inguinal  canal, 
passing  along  nearly  its  whole  length,  and  finally  emerges  from  the  external 
ring,  receiving  an  investment  from  the  intercolumnar  fascia.  The  coverings 
of  this  form  of  hernia  are  precisely  similar  to  those  investing  the  oblique  form. 

In  other  cases,  and  this  is  the  more  frequent  variety,  the  intestine  is  either 
forced  through  the  fibres  of  the  conjoined  tendon,  or  the  tendon  is  gradually 
distended  in  front  of  it,  so  as  to  form  a  complete  investment  for  it.  The  intes- 
tine then  enters  the  lower  end  of  the  inguinal  canal,  escapes  at  the  external 
ring  lying  on  the  inner  side  of  the  cord,  and  receives  additional  coverings  from 
the  superficial  fascia  and  the  integument.  This  form  of  hernia  has  the  same 
coverings  as  the  oblique  variety,  excepting  that  the  conjoined  tendon  is  sub- 
stituted for  the  Cremaster,  and  the  infundibuliform  fascia  is  replaced  by  a  part 
of  the  general  fascia  transversalis. 

The  seat  of  stricture  in  both  varieties  of  direct  hernia  is  most  frequently  at 
the  neck  of  the  sac,  or  at  the  external  ring.  In  that  form  of  hernia  which 
perforates  the  conjoined  tendon,  it  not  unfrequently  occurs  at  the  edges  of  the 
fissure  through  which  the  gut  passes.  In  dividing  the  stricture,  the  incision 
should  in  all  cases  be  directed  upwards. 

If  the  hernial  protrusion  passes  into  the  inguinal  canal,  but  does  not  escape 
from  the  external  abdominal  ring,  it  forms  what  is  called  incomplete  direct  hernia. 
This  form  of  hernia  is  usually  of  small  size,  and  in  corpulent  persons  very 
difficult  of  detection. 

Direct  inguinal  hernia  is  of  much  less  frequent  occurrence  than  the  oblique, 


830         SURGICAL    ANATOMY    OF    FEMORAL    HERXIA. 

their  comparative  frequency  being,  according  to  Cloquet,  as  one  to  five.  It 
occurs  far  more  frequently  in  men  than  women,  on  account  of  the  larger  size 
of  the  external  ring  in  the  former  sex.  It  differs  from  the  oblique  in  its 
smaller  size  and  globular  form,  dependent  most  probably  on  the  resistance 
offered  to  its  progress  by  the  transversalis  ftiscia  and  conjoined  tendon.  It 
differs  also  in  its  position,  being  placed  over  the  pubes,  and  not  in  the  course 
of  the  inguinal  canal.  The  epigastric  artery  runs  on  the  outer  or  iliac  side  of 
the  neck  of  the  sac,  and  the  spermatic  cord  along  its  external  and  posterior 
side,  not  directly  behind  it,  as  in  oblique  inguinal  hernia. 

SURGICAL  ANATOMY  OP  FEMORAL  HERNIA. 

The  dissection  of  the  parts  comprised  in  the  anatomy  of  femoral  hernia  should  be  performed, 
if  possible,  upon  a  female  subject  free  from  fat.  The  subject  should  lie  upon  its  back  ;  a  block 
is  first  placed  under  the  pelvis,  the  thigh  everted,  and  the  knee  slightly  bent,  and  retained  in 
this  position.  An  incision  should  then  be  made  from  the  anterior  superior  spinous  process  of 
the  ilium  along  Poupart's  ligament  to  the  symphysis  pubis  ;  a  second  incision  should  be  carried 
transversely  across  the  thigh  about  six  inches  beneath  the  preceding  ;  and  these  are  to  be  con- 
nected together  by  a  vertical  one  carried  along  the  inner  side  of  the  thigh.  These  several  in- 
cisions should  divide  merely  the  integument ;  this  is  to  be  reflected  outwards,  when  the  super- 
ficial fascia  will  be  exposed. 

The  superficial  fascia  at  the  upper  part  of  the  thigh,  consists  of  two  layers, 
between  which  are  found  the  cutaneous  vessels  and  nerves,  and  numerous 
lymphatic  glands. 

The  superficial  layer  is  a  thick  and  dense  cellulo-fibrous  membrane,  in  the 
meshes  of  which  is  found  a  considerable  amount  of  adipose  tissue,  varying  in 
quantity  in  different  subjects;  this  layer  may  be  traced  upwards  over  Poupart'.** 
lio-ament  to  be  continuous  with  the  superficial  fascia  of  the  abdomen;  whilst 
below,  and  on  the  inner  and  outer  sides  of  the  limb,  it  is  continuous  with  the 
superficial  fascia  covering  the  rest  of  the  thigh. 

This  layer  should  be  detached  by  dividing  it  across  in  the  same  direction  as  the  external  in- 
cisions; its  removal  will  be  facilitated  by  commencing  at  the  lower  and  inner  angle  of  the  space, 
detaching  it  at  first  from  the  front  of  the  internal  saphenous  vein,  and  dissecting  it  off  from  the 
anterior  surface  of  that  vessel  and  its  branches ;  it  should  then  be  reflected  outwards,  in  the 
same  manner  as  the  integument.  The  cutaneous  vessels  and  nerves,  and  superficial  inguinal 
glands  are  then  exposed,  lying  upon  the  deep  layer  of  the  superficial  fascia.  These  are  the  in- 
ternal saphenous  vein,  and  the  superficial  epigastric,  superficial  circumflexa  ilii,  and  superficial 
external  pudic  vessels,  as  well  as  numerous  lymphatics  ascending  with  the  saphenous  vein  to  the 
inguinal  glands. 

The  internal  saphenous  vein  is  a  vessel  of  considerable  size,  which  ascends 
obliquely  upwards  along  the  inner  side  of  the  thigh,  below  Poupart's  ligament. 
It  passes  through  the  saphenous  opening  in  the  fascia  lata  to  terminate  in  the 
femoral  vein.  This  vessel  is  accompanied  by  numerous  lymphatics,  which 
return  trie  lymph  from  the  dorsum  of  the  foot  and  inner  side  of  the  leg  and 
thigh ;  they  terminate  in  the  inguinal  glands,  which  surround  the  saphenous 
opening.  Diverging  from  the  same  point  are  the  superficial  epigastric  vessels, 
which  run  across  Poupart's  ligament,  obliquely  upwards  and  inwards,  to  the 
lower  part  of  the  abdomen;  the  superficial  circumflexa  ilii  vessels,  which  pass 
obliquely  outwards  along  Poupart's  ligament  to  the  crest  of  the  ilium ;  and  the 
superficial  external  pudic  vessels,  which  pass  inwards  to  the  perineum  and 
scrotum.  These  vessels  supply  the  subcutaneous  areolar  tissue  and  the  integu- 
ment, and  are  accompanied  by  numerous  lymphatic  vessels,  which  return  the 
lymph  from  the  same  parts  to  the  inguinal  glands. 

The  superficial  inrjuinal  glands  are  arranged  in  two  groups,  one  of  which  is 
disposed  above  and  parallel  with  Poupart's  ligament,  and  the  other  below  the 
ligament,  surrounding  the  termination  of  the  saphenous  vein,  and  following 
(occasionally)  the  course  of  that  vessel  a  short  distance  along  the  thigh.  The 
upper  chain  receives  the  lymphatic  vessels  from  the  penis,  scrotum,  lower  part 


I 

I 
I 

I 


FEMORAL    HERNIA  — SUPERFICIAL    DISSECTION. 


831 


ot  the  abdomen,  perineum,  and  buttock ;  the  lower  chain  receives  the  lymphatic 
vessels  from  the  lower  extremity. 

The  nerves  supplying  the  integument  of  this  region  are  derived  from  the  ilio- 
inguinal, the  genito-crural,  and  anterior  crural.  The  ilio-inguinal  nerve  may 
be  found  on  the  inner  side  of  the  internal  saphenous  vein,  the  terminal  branch 
of  the  genito-crural  nerve  outside  the  vein,  and  the  middle  and  external  cuta- 
neous nerves  more  external. 


Fig.  449,— Femoral  Hernia.    Superficial  Dissection. 


The  deep  layer  of  superficial  fascia  should  be  divided  in  the  same  direction 
as  the  external  incisions,  and  separated  from  the  fascia  lata ;  this  is  easily 
effected,  from  its  extreme  thinness.  It  is  a  thin  but  dense  membrane,  placed 
beneath  the  subcutaneous  vessels  and  nerves,  and  upon  the  surface  of  the  fascia 
lata.  It  is  intimately  adherent  above  to  the  lower  margin  of  Poupart's  liga- 
ment, and  about  one  inch  below  this  ligament  covers  the  saphenous  opening  in 
the  fascia  lata,  is  closely  united  to  its  circumference,  and  is  connected  to  the 
sheath  of  the  femoral  vessels  corresponding  to  its  under  surface.  The  portion 
of  fascia  covering  this  aperture  is  perforated  by  the  internal  saphenous  vein, 
and  by  numerous  blood  and  lymphatic  vessels ;  hence  it  has  been  termed  the 
cribriform  fascia,  the  openings  of  these  vessels  having  been  likened  to  the  holes 
in  a  sieve.  The  cribriform  fascia  adheres  closely  both  to  the  superficial  fiscia 
and  the  fascia  lata,  so  that  it  is  described  by  some  anatomists  as  a  part  of  the 
fascia  lata,  but  is  usually  considered  (as  in  this  work)  as  belonging  to  the  super- 
ficial fascia.  It  is  not  till  the  cribriform  fascia  has  been  cleared  away,  that  the 
saphenous  opening  is  seen,  so  that  this  opening  does  not,  in  ordinary  cases, 


832         SURGICAL    ANATOMY    OF    FEMORAL    HERNIA. 

exist  naturally,  but  is  the  result  of  dissection.  Mr.  Callender,  however,  speaks 
of  cases  in  which,  probably  as  the  result  of  pressure  from  enlarged  inguinal 
glands,  the  fascia  has  become  atrophied,  and  a  saphenous  opening  exists  inde- 
pendent of  dissection.^  A  femoral  hernia,  in  passing  through  the  saphenous 
opening,  receives  the  cribriform  fascia  as  one  of  its  coverings. 

The  deep  layer  of  superficial  fascia,  together  with  the  cribriform  fascia,  hav- 
ing been  removed,  the  fascia  lata  is  exposed. 


Fig.  450. — Femoral  Hernia,  showing  Fascia  Lata  and  Saphenous  Opening. 


The  Fascia  Lata,  already  described,  is  a  dense,  fibrous  aponeurosis,  which 
forms  a  uniform  investment  for  the  whole  of  this  region  of  the  limb.  At  the , 
upper  and  inner  part  of  the  thigh,  a  large  oval-shaped  aperture  is  observed 
in  it ;  it  transmits  the  internal  saphenous  vein  and  other  small  vessels,  and  is 
called  the  saphenous  opening.  In  order  the  more  correctly  to  consider  the  mode 
of  formation  of  this  aperture,  the  fascia  lata  in  this  part  of  the  thigh  is  described 
as  consisting  of  two  portions,  an  iliac  portion  and  a  pubic  portion.  ^      fll 

The  iliac  portion  of  the  fascia  lata  is  situated  on  the  outer  side  of  the  saphe-  "' 
nous  opening,  covering  the  outer  surface  of  the  Sartorius,  the  Rectus,  and  the 
Psoas  and  Iliacus  muscles.  It  is  attached  externally  to  the  crest  of  the  ilium 
and  its  anterior  superior  spine,  to  the  whole  length  of  Poupart's  ligament  as 
far  internallv  as  the  spine  of  the  pubes,  and  to  the  pectineal  line  in  conjunction 
with  Gimbernat's  ligament,  where  it  becomes  continuous  with  the  pubic  por- 
tion. From  the  spine  of  the  pubes,  it  is  reflected  downwards  and  outwards, 
forming  an  arched  margin,  the  outer  boundary  (superior  cornu)  of  the  saphe- 
nous opening.     This  is  sometimes  called  tha  falciform  j^rocess  of  the  fascia  lata 

'  Anatomy  of  Femoral  Rupture,  note  on  p.  18. 


FASCIA    LATA— SAPHENOUS    OPENING.  833 

(femoral  ligament  of  Hey) ;  it  overlies,  and  is  adherent  to,  the  sheath  of  the 
femoral  vessels  beneath ;  to  its  edge  is  attached  the  cribriform  fascia,  and  it  is 
continuous  below  with  the  pubic  portion  of  the  fascia  lata  by  a  well-defined 
curved  margin. 

The  pubic  portion  of  the  fascia  lata  is  situated  at  the  inner  side  of  the  saphe- 
nous opening:  at  the  lower  margin  of  this  aperture,  it  is  continuous  with  the 
iliac  portion :  traced  upwards,  it  covers  the  surface  of  the  Pectineus,  Adductor 
Longus,  and  Gracilis  muscles;  and  passing  behind  the  sheath  of  the  femoral 
vessels,  to  which  it  is  closely  united,  is  continuous  with  the  sheath  of  the  Psoas 
and  Iliacus  muscles,  and  is  finally  lost  in  the  fibrous  capsule  of  the  hip-joint. 
This  fascia  is  attached  above  to  the  pectineal  line,  and  internally  to  the  margin 
of  the  pubic  arch.  It  may  be  observed  from  this  description  that  the  iliac 
portion  of  the  fascia  lata  passes  in  front  of  the  femoral  vessels,  the  pubic  portion 
behind  them ;  an  apparent  aperture  consequently  exists  betweenthe  two,  through 
which  the  internal  saphenous  joins  the  femoral  vein. 

The  Saphenous  Opjening  is  an  oval-shaped  aperture,  measuring  about  an  inch 
and  a  half  in  length,  and  half  an  inch  in  width.  It  is  situated  at  the  upper  and 
inner  part  of  the  thigh,  below  Poupart's  ligament,  towards  the  inner  side,  and 
is  directed  obliquely  downwards  and  outwards. 

Its  outer  margin  is  of  a  semilunar  form,  thin,  strong,  sharply-defined,  and  lies 
on  a  plane  considerably  anterior  to  the  inner  margin.  If  this  edge  is  traced 
upwards,  it  will  be  seen  to  form  a  curved  elongated  process  or  cornu  (the 
superior  cornu),  or  falciform  process  of  Burns,  which  ascends  in  front  of  the 
femoral  vessels,  and  curving  inwards,  is  attached  to  Poupart's  ligament  and  to 
the  spine  of  the  pubes  and  pectineal  line,  where  it  is  continuous  with  the  pubic 
portion.^  If  traced  downwards,  it  is  found  continuous  with  another  curved 
margin,  the  concavity  of  which  is  directed  upwards  and  inwards;  this  is  the 
inferior  cornu  of  the  saphenous  opening,  and  is  blended  with  the  pubic  portion 
of  the  fascia  lata  covering  the  Pectineus  muscle. 

The  inyier  boundary  of  the  opening  is  on  a  plane  posterior  to  the  outer  mar- 
gin, and  behind  the  level  of  the  femoral  vessels;  it  is  much  less  prominent  and 
defined  than  the  outer,  from  being  stretched  over  the  subjacent  Pectineus  mus- 
cle. It  is  through  the  saphenous  opening  that  a  femoral  hernia  passes  after 
descending  along  the  crural  canal. 

If  the  finger  is  introduced  into  the  saphenous  opening  while  the  limb  is 
moved  in  different  directions,  the  aperture  will  be  found  to  be  greatly  con- 
stricted on  extending  the  limb,  or  rotating  it  outwards,  and  to  be  relaxed  on 
flexing  the  limb  and  inverting  it:  hence  the  necessity  of  placing  the  limb  in  the 
latter  position  in  employing  the  taxis  for  the  reduction  of  a  femoral  hernia. 

The  iliac  portion  of  the  fascia  lata,  together  with  its  falciform  process,  should  now  be  removed, 
by  detaching  it  from  the  lower  margin  of  Poupart's  ligament,  carefully  dissecting  it  from  the 
subjaceut  structures,  and  turning  it  aside  when  the  sheath  of  the  femoral  vessels  is  exposed 
descending  beneath  Poupart's  ligament  (Fig.  451). 

The  Crural  Arch,  or  Poupart^s  Ligament,  is  the  lower  border  of  the  aponeu- 
rosis of  the  External  Oblique  muscle,  which  stretches  across  from  the  anterior 

'  It  is  difficult  to  perceive  in  the  recognized  description  of  these  ligaments  (Hey's  and 
Burns's),  any  difference  between  the  two;  nor  is  it  clear  what  structure  Mr.  Hey  really  intended 
to  describe.  Mr,  Gay  (on  "Femoral  Rupture"  p.  16)  gives  very  cogent  reasons  for  thinking 
that  the  "  deep  crural  arch"  was  the  structure  which  Hey  had  in  view.  The  most  recent  writer 
on  Femoral  Hernia  speaks  thus  while  treating  of  these  parts  :  "  The  whole  upper  edge  of  the 
iliac  fascia  lata  is  commonly  called  the  'falciform  process,'  whilst  its  deeper  fibres  receive  the 
name  of  '  Burns's  ligament.'  Hey's  femoral  ligament  would  appear  to  consist  of  distinct  fibres 
connected  with  the  inner  fold  of  the  iliac  fascia,  which  extend  immediately  beneath  the  tendon 
of  the  external  oblique  to  the  subperitoneal  fascia."  (Callender,  ''On  the  Anatomy  of  the  Parts 
Concerned  in  Femoral  Rupture,'"  p.  19,  note.)  This  description  of  Hey's  ligament  accords 
closely  with  that  of  the  deep  crural  arch,  for  the  subperitoneal  fascia  is  Mr.  Callender's  name 
for  the  fascia  transversalis.  Mr.  Callender  goes  on  to  say,  "The  upper  border  of  this  (saphe- 
nous) opening  thus  receives,  by  an  unfortunate  complication,  the  names  of  'Falciform  process.' 
'  Femoral  ligament,'  '  Burns's  or  Hey's  ligament.'  'J'he  various  divisions  of  the  iliac  fascia  lata 
depend  in  great  measure  upon  the  skill  of  the  dissector,  and  are,  in  ray  opinion,  artificial." 
53 


834 


SURGICAL    ANATOMY    OF    FEMORAL    HERNIA. 


superior  spine  of  the  ilium,  to  the  spine  of  the  os  pubis  and  pectineal  line :  the 
portion  corresponding  to  the  latter  insertion  is  called  Gimbernat's  ligament. 
The  direction  of  Poupart's  ligament  is  curved  downwards  towards  the  thigh ; 
its  outer  half  being  oblique,  its  inner  half  nearly  horizontal.   Nearly  the  whole 

Fig.  451. — Femoral  Hernia.    Iliac  Portion  of  Fascia  Lata  removed,  and  Sheath  of  Femoral 
Vessels  and  Femoral  Canal  exposed. 


of  the  space  included  between  the  crural  arch  and  innominate  bone  is  filled  by 
the  parts  which  descend  from  the  abdomen  into  the  thigh.  The  outer  half  of 
the  space  is  occupied  by  the  Iliacus  and  Psoas  muscles,  together  with  the 
external  cutaneous  and  anterior  crural  nerves.  The  pubic  side  of  the  space  is 
occupied  by  the  femoral  vessels  included  in  their  sheath,  a  small  oval-shaped 
interval  existing  between  the  femoral  vein  and  the  inner  wall  of  the  sheath, 
which  is  occupied  merely  by  a  little  loose  areolar  tissue,  and  occasionally  by  a 
small  lymphatic  gland ;  this  is  the  ^crural  canal,  along  which  the  gut  descends 
in  femoral  hernia. 

Oimbernafs  Ligament'(Fig.  452)  is  that  part  of  the  aponeurosis  of  the  Ex- 
ternal Oblique  muscle  which  is  reflected  downwards  and  outwards,  to  be  inserted 
into  the  pectineal  line  of  the  os  pubis.  It  is  about  an  inch  in  length,  larger  in 
the  male  than  in  the  female,  almost  horizontal  in  direction  in  the  erect  posture, 
and  of  a  triangular  form,  the  base  directed  outwards.  Its  base,  or  outer  margin, 
is  concave,  thin  and  sharp,  lies  in  contact  with  the  crural  sheath,  and  is  blended 
with  the  pubic  portion  of  the  fascia  lata.  Its  apex  corresponds  to  the  spine  of 
the  pubcs.  Its  posterior  margin  is  attached  to  the  pectineal  line.  Its  anterior 
margin  is  continuous  with  Poupart's  ligament. 

Crural  Sheath.  If  Poupart's  ligament  is  divided,  the  femoral  or  crural  sheath 
may  be  demonstrated  as  a  continuation  downwards  of  the  fasciae  that  line  the 


I 

I 

II 


DEEP    CRURAL    ARCH.  835 

abdomen,  tlie  transversalis  fascia  passing  down  in  front  of  the  femoral  vessels, 
and  the  iliac  fascia  descending  behind  them ;  these  fasciae  are  directly  contin- 
uous on  the  iliac  side  of  the  femoral  artery,  but  a  small  space  exists  between 
the  femoral  vein  and  the  point  where  they  are  continuous  on  the  pubic  side  of 
that  vessel  which  constitutes  the  femoral  or  crural  canal.  The  femoral  sheath 
is  closely  adherent  to  the  contained  vessels  about  an  inch  below  the  saphenous 
opening,  becoming  blended  with  the  areolar  sheath  of  the  vessels,  but  opposite 
Poupart's  ligament  it  is  much  larger  than  is  required  to  contain  them  ;  hence 
the  funnel-shaped  form  which  it  presents.  The  outer  border  of  the  sheath  is 
perforated  by  the  genito-crural  nerve.  Its  inner  border  is  pierced  by  the  in- 
ternal saphenous  vein,  and  numerous  lymphatic  vessels.  In  front,  it  is  covered 
by  the  iliac  portion  of  the  fascia  lata  ;  and  behind  it  is  the  pubic  portion  of  the 
same  fascia. 

Deep  Crural  Arch.  Passing  across  the  front  of  the-  crural  sheath,  and  closely 
connected  with  it,  is  a  thickened  band  of  fibres,  called  the  deep  crural  arch.  It 
is  apparently  a  thickening  of  the  fascia  transversalis,  joining  externally  to  the 
centre  of  Poupart's  ligament,  and  arching  across  the  front  of  the  crural  sheath, 
to  be  inserted  by  a  broad  attachment  into  the  pectineal  line,  behind  the  conjoined 
tendon.  In  some  subjects,  this  structure  is  not  very  prominently  marked,  and 
not  unfrequently  it  is  altogether  wanting. 

If  the  anterior  wall  of  the  sheath  is  removed,  the  femoral  artery  and  vein  are 
seen  lying  side  by  side,  a  thin  septum  separating  the  two  vessels,  and  another 
septum  separates  the  vein  from  the  inner  wall  of  the  sheath.  The  septa  are 
stretched  between  the  anterior  and  posterior  walls  of  the  sheath,  so  that  each 
vessel  is  inclosed  in  a  separate  compartment.  The  interval  left  between  the 
vein  and  the  inner  wall  of  the  sheath  is  not  filled  up  by  any  structure,  except- 
ing a  little  loose  areolar  tissue,  a  few  lymphatic  vessels,  and  occasionally  a 
lymphatic  gland ;  this  is  the  femoral  or  crural  canal,  through  which  a  portion 
of  intestine  descends  in  femoral  hernia. 

The  criiral  caned  is  the  narrow  interval  between  the  femoral  vein  and  the  in- 
ner wall  of  the  crural  sheath.  It  exists  as  a  distinct  canal  only  when  the  sheath 
has  been  separated  from  the  vein  by  d'issection,  or  by  the  pressure  of  a  hernia 
or  tumor.  Its  length  is  from  a  q'uarter  to  half  an  inch,  and  it  extends  from 
Girabernat's  ligament  to  the  upper  part  of  the  saphenous  opening. 

Its  a^iterior  luall  is  very  narrow,  and  formed  by  the  fascia  transversalis,  Pou- 
part's ligament,  and  the  falciform  process  of  the  fascia  lata. 

Its  posterior  wall  is  formed  by  the  iliac  fascia  and  the  pubic  portion  of  the 
fascia  lata. 

Its  outer  wall  is  formed  by  the  fibrous  septum  covering  the  inner  side  of  the 
femoral  vein. 

Its  inner  wall  is  formed  by  the  junction  of  the  transversalis  and  iliac  fasciae, 
which  forms  the  inner  side  of  the  femoral  sheath,  and  covers  the  outer  edge  of 
Gimbernat's  ligament. 

This  £anal  has  two  orifices:  a  lower  one,  the  sajjJienous  opening,  closed  by  the 
cribriform  fascia;  an  upper  one,  the  femoral  oi  crural  ring,  closed  by  the  septum 
crurale. 

1^\\Q  femoral  or  crural  ring  (Fig.  452)  is  the  upper  opening  of  the  femoral 
canal,  and  leads  into  the  cavity  of  the  abdomen.^  It  is  bounded  in  front  by 
Poupart's  ligament  and  the  deep  crural  arch  ;  behind  by  the  pubes,  covered  by 
the  Pectineus  muscle,  and  the  pubic  portion  of  the  fascia  lata ;  internally,  by 
Gimbernat's  ligament,  the  conjoined  tendon,  tne  transversalis  fascia,  and  the 
deep  crural  arch  ;  externally,  by  the  femoral  vein,  covered  by  its  sheath.  The 
femoral  ring  is  of  an  oval  form,  its  long  diameter,  directed  transversely,  mea- 

'  This  ring,  like  the  crural  canal,  is  a  morbid  or  an  artificial  product.  "  Each  femoral  hernia 
makes  for  itself  (for  neither  outlet  exists  in  the  natural  anatomy  of  the  region)  a  crural  canal, 
and  a  crural  (femoral)  ring." — Callendeb,  op.  cit.,  p.  40. 


836 


SURGICAL    ANATOMY    OF    FEMORAL    HERNIA. 


sures  about  half  an  inch,  and  it  is  larger  in  the  female  than  in  the  male,  which 
is  one  of  the  reasons  of  the  greater  frequency  of  femoral  hernia  in  the  former 
sex. 

Fig.  452. — Hernia.    The  Relations  of  the  Femoral  and  Internal  Abdominal  Rings,  seen  from 

within  the  Abdomen.    Right  bide. 


Position  of  Parts  around  the  Ring.  The  spermatic  cord  in  the  male,  and  roun 
ligament  in  the  female,  lie  immediately  above  the  anterior  margin  of  the  femo- 
ral ring,  and  may  be  divided  in  an  operation  for  femoral  hernia  if  the  incision 
for  the  relief  of  the  stricture  is  not  of  limited  extent.  In  the  female,  this  is 
of  little  importance,  but  in  the  male  the  spermatic  artery  and  vas  deferens  may 
be  divided. 

The /emora?  vein  lies  on  the  outer  side  of  the  ring. 

The  epigastric  artery^  in  its  passage  inwards  from  the  external  iliac  to  the 
umbilicus,  passes  across  the  upper  and  outer  angle  of  the  crural  ring,  and  is 
consequently  in  danger  of  being* wounded  if  the  stricture  is  divided  in  a  direction 
upwards  and  outwards. 

The  communicating  branch  between  the  epigastric  and  obturator  lies  in  front 
of  the  ring-. 

The  circumference  of  the  ring  is  thus  seen  to  be  bounded  by  vessels  in  every 
part  excepting  internally  and  behind.  It  is  in  the  former  position  that  the 
stricture  is  divided  in  cases  of  strangulated  femoral  hernia.   . 

The  obturator  artery,  when  it  arises  by  a  common  trunk  with  the  epigastric, 
which  occurs  once  in  every  three  subjects  and  a  half,  bears  a  very  important 
relation  to  the  crural  ring.  In  some  cases  (Fig.  453),  it  descends  on  the  inner 
side  of  the  external  iliac  vein  to  the  obturator  foramen,  and  will  consequently 
lie  on  the  outer  side  of  the  crural  ring,  where  there  is  no  danger  of  its  being 
wounded  in  the  operation  for  dividing  the  stricture  in  femoral  hernia.  Occa- 
sionally, however,  the  obturator  artery  curves  along  the  free  margin  of  Gim- 
bernat's  ligament  in  its  passage  to  the  obturator  foramen;  it  would,  conse- 
quently, skirt  along  the  greater  part  of  the  circumference  of  the  crural  canal, 
and  could  hardly  avoid  being  wounded  in  the  operation  (Fig.  45-i). 

Septum.  Criirale.  The  femoral  ring  is  closed  by  a  layer  oj^  condensed  areolar 
tissue,  called,  by  J.  Cloquct,  the  septum  crurale.  This  serves  as  a  barrier  to  the 
protrusion  of  a  hernia  through  this  part.  Its  upper  surface  is  slightly  concave, 
and  supports  a  small  lymphatic  gland,  by  which  it  is  separated  from  the  subse- 
rous areolar  tissue  and  peritoneum.     Its  under  surface  is  turned  towards  the 


nd|| 


DESCENT    OF    HERNIA.  837 

femoral  canal.  The  septum  crurale  is  perforated  by  numerous  apertures  for 
the  passage  of  lymphatic  vessels,  connecting  the  deep  inguinal  glands  with  those 
surrounding  the  external  iliac  artery. 

Tariations  in  Origin  and  Course  of  Obturator  Artery. 
Fig.  453.  •  Fig.  454. 


The  size  of  the  femoral  canal,  the  degree  of  tension  of  its  orifices,  and,  con- 
sequently, the  degree  of  constriction  of  a  hernia,  varies  according  to  the  position 
of  the  limb.  If  the  leg  and  thigh  are  extended,  abducted,  or  everted,  the 
femoral  canal  and  its  orifices  are  rendered  tense,  from  the  traction  on  these 
parts  by  Poupart's  ligament  and  the  fascia  lata,  as  may  be  ascertained  by  pass- 
ing the  finger  along  the  canal.  If,  on  the  contrary,  the  thigh  is  flexed  upon  the 
pelvis,  and,  at  the  same  time,  adducted  and  rotated  inwards,  the  femoral  canal 
and  its  orifices  become  considerably  relaxed ;  for  this  reason,  the  limb  should 
always  be  placed  in  the  latter  position  when  the  application  of  the  taxis  is  made 
in  attempting  the  reduction  of  a  femoral  hernia. 

The  septum  crurale  is  separated  from  the  peritoneum  by  a  quantity  of  loose 
subserous  areolar  tissue.  In  some  subjects,  this  tissue  contains  a  considerable 
amount  of  adipose  substance,  which,  when  protruded  forwards  in  front  of  the 
sac  of  a  femoral  hernia,  may  be  mistaken  for  a  portion  of  omentum. 

Descent  of  the  Hernia.  From  the  preceding  description  it  follows,  that  the 
femoral  ring  must  be  a  weak  point  in  the  abdominal  wall ;  hence  it  is,  that  when 
violent  or  long-continued  pressure  is  made  upon  the  abdominal  viscera,  a  por- 
tion of  intestine  may  be  forced  into  it,  constituting  a  femoral  hernia ;  and  the 
changes  in  the  tissues  of  the  abdomen  which  are  produced  by  pregnancy,  to- 
gether with  the  larger  size  of  this  aperture  in  the  female,  serve  to  explain  the 
frequency  of  this  form  of  hernia  in  women. 

When  a  portion  of  intestine  is  forced  through  the  femoral  ring,  it  carries 
before  it  a  pouch  of  peritoneum,  which  forms  what  is  called  the  hernial  sac ;  ib 
receives  an  investment  from  the  subserous  areolar  tissue,  and  from  the  septum 
crurale,  and  descends  vertically  along  the  crural  canal  in  the  inner  compartment 
of  the  sheath  of  the  femoral  vessels  as  far  as  the  saphenous  opening:  at  this 
point,  it  changes  its  course,  being  prevented  from  extending  further  down  the 
sheath,  on  account  of  the  narrowing  of  the  sheath  and  its  close  contact  with  th© 
vessels,  and  also  from  the  close  attachment  of  the  superficial  fascia  and  crural 
sheath  to  the  lower  part  of  the  circumference  of  the  saphenous  opening ;  the 
tumor  is,  consequently,  directed  forwards,  pushing  before  it  the  cribriform  fascia, 
and  then  curves  upwards  on  to  the  falciform  process  of  the  fascia  lata  and  lower 
part  of  the  tendon  of  the  External  Oblique,  being  covered  by  the  superficial 
fascia  and  integument.  While  the  hernia  is  contained  in  the  femoral  canal,  it 
is  usually  of  small  size,  owing  to  the  resisting  nature  of  the  surrounding  parts; 
but  when  it  has  escaped  from  the  saphenous  opening  into  the  loose  areolar  tissue 
of  the  groin,  it  becomes  considerably  enlarged.  The  direction  taken  by  a  femoral 
hernia  in  its  descent  is  at  first  downwards,  then  forwards  and  upwards;  this 
should  be  borne  in  mind,  as  in  the  application  of  the  taxis  for  the  reduction  of 
a  femoral  hernia,  pressure  should  be  directed  in  the  reverse  order. 

Coverings  of  tlie  Hernia.    The  coverings  of  a  femoral  hernia  from  within  out- 


838         SURGICAL    ANATOMY    OF    FEMORAL    HERXIA. 

wards  are  peritoneum,  subserous  areolar  tissue,  the  septum  crurale,  crural  sheath, 
cribriform  fascia,  superficial  fascia,  and  integument.* 

Varieties  of  Femoral  Hernia.  If  the  intestine  descends  along  the  femoral  canal 
only  as  far  as  the  saphenous  opening,  and  does  not  escape  from  this  aperture, 
it  is  called  incomplete  femoral  hernia.  The  small  size  of  the  protrusion  in  this 
form  of  hernia,  on  account  of  the  firm  and  resisting  nature  of  the  canal  in 
which  it  is  contained,  renders  it  an  exceedingly  dangerous  variety  of  the  disease, 
from  the  extreme  difficulty  of  detecting  the  existence  of  the  swelling,  especially 
in  corpulent  subjects.  The  coverings  of  an  incomplete  femoral  hernia  would 
be,  from  without  inwards,  integument,  superficial  fascia,  falciform  process  of 
fascia  lata,  fascia  propria,  septum  crurale,  subserous  cellular  tissue,  and  perito- 
neum. When,  however,  the  hernial  tumor  protrudes  through  the  saphenous 
opening,  and  directs  itself  forwards  and  upwards,  it  forms  a  complete  femoral 
hei-nia.  Occasionally,  the  hernial  sac  descends  on  the  iliac  side  of  the  femoral 
vessels,  or  in  front  of  these  vessels,  or  even  sometimes  behind  them. 

The  seat  of  stricture  of  a  femoral  hernia  varies:  it  may  be  in  the  peritoneum 
at  the  neck  of  the  hernial  sac ;  in  the  greater  number  of  cases  it  would  appear 
to  be  at  the  point  of  junction  of  the  falciform  process  of  the  fascia  lata  with  the 
lunated  edge  of  Gimbernat's  ligament;  or  at  the  margin  of  the  saphenous  open- 
ing in  the  thigh.  The  stricture  should  in  every  case  be  divided  in  a  direction 
upwards  and  inwards;  and  the  extent  necessary  in  the  majority  of  cases  ij3 
about  two  or  three  lines.  By  these  means,  all  vessels  or  other  structures  of 
importance,  in  relation  with  the  neck  of  the  hernial  sac,  will  be  avoided. 

'  Sir  A.  Cooper  has  described  an  investment  for  femoral  hernia  under  the  name  of  "  Fascia 
propria,"  lying  immediately  external  to  the  peritoneal  sac,  but  frequently  separated  from  it  by 
more  or  less  adipose  tissue.  Surgically,  it  is  important  to  remember  the  existence  (at  any  rate 
the  occasional  existence)  of  this  layer,  on  account  of  the  ease  with  which  an  inexperienced  ope- 
rator may  mistake  the  fascia  for  the  peritoneal  sac,  and  the  contained  fat  for  omentum.  Anatomi- 
cally, this  fascia  appears  to  be  identical  with  what  iscalled  in  the  text  "  subserous  areolar  tissue." 
the  areolar  tissue  being  thickened  .and  caused  to  assume  a  membranous  appearance,  by  the 
pressure  of  the  hernia. 


Surgical  Anatomy  of  the  Perineum  and  Ischio- 

Rectal  Region. 

Dissection. — The  student  should  select  a  well-developed  muscular  subject,  free  from  fat,  and 
the  dissection  should  be  commenced  early,  in  order  that  the  parts  may  be  examined  in  as  recent 
a  state  as  possible.  A  staff  having  been  introduced  into  the  bladder,  and  the  subject  placed  in 
the  position  shown  in  Fig.  455,  the  scrotum  should  be  raised  upwards,  and  retained  in  that  posi- 
tion, and  the  rectum  moderately  distended  with  tow. 

The  space  which  is  now  exposed,  corresponds  to  the  inferior  aperture,  or 
outlet  of  the  pelvis.  Its  deep  boundaries  are,  in  front,  the  pubic  arch  and  sub- 
pubic ligament ;  behind,  the  tip  of  the  coccyx ;  and  on  each  side,  the  ramus  of 
the  pubes  and  ischium,  the  tuberosity  of  the  ischium,  and  great  sacro-sciatic 
ligament.  The  space  included  by  these  boundaries  is  somewhat  lozenge-shaped, 
and  is  limited  on  the  surface  of  the  body  by  the  scrotum,  in  front,  by  the  but- 
tocks behind,  and  on  each  side  by  the  inner  side  of  the  thighs.  It  measures, 
from  before  backwards,  about  four  inches,  and  about  three  in  the  broadest  part 
of  its  transverse  diameter,  between  the  ischial  tuberosities.  A  line  drawn  trans- 
versely between  the  anterior  part  of  the  tuberosity  of  the  ischium,  on  each  side, 
in  front  of  the  anus,  subdivides  this  space  into  two  portions.  The  anterior 
portion  contains  the  penis  and  urethra,  and  is  called  the  perineum.  The  poste- 
rior portion  contains  the  termination  of  the  rectum,  and  is  called  the  ischio-recial 
region. 

ISCHIO-EECTAL   REGION". 

The  Ischio-rectal  Region  corresponds  to  the  portion  of  the  outlet  of  the 
pelvis  situated  immediately  behind  the  perineum  :  it  contains  the  termination 
of  the  rectum.  A  deep  fossa,  filled  with  fat,  is  seen  on  either  side  of  the  intes- 
tine, between  it  and  the  tuberosity  of  the  ischium  :  this  is  called  the  ischio-rectal 
fossa. 

The  ischio-rectal  region  presents,  in  the  middle  line,  the  aperture  of  the  anus ; 
around  this  orifice,  the  integument  is  thrown  into  numerous  folds,  which  are 
obliterated  on  distension  of  the  intestine.  The  integument  is  of  a  dark  color, 
continuous  with  the  mucous  membrane  of  the  rectum,  and  provided  with  nume- 
rous follicles,  which  occasionally  inflame  and  suppurate,  and  may  be  mistaken 
for  fistula.  The  veins  around  the  margin  of  the  anus  are  occasionally  much 
dilated,  forming  a  number  of  hard,  pendent  masses,  of  a  dark  bluish  color, 
covered  partly  by  mucous  membrane,  and  partly  by  the  integument.  These 
tumors  constitute  the  disease  called  external  piles. 

Dissection. — Make  an  incision  through  the  integument,  along  the  median  line,  from  the  base 
of  the  scrotum  to  the  anterior  extremity  of  the  anus ;  carry  it  round  the  margins  of  this  aper- 
ture to  its  posterior  extremity,  and  continue  it  backwards  about  an  inch  behind  the  tip  of  the 
coccyx.  A.  transverse  incision  should  now  be  carried  across  the  base  of  the  scrotum,  joining 
the  anterior  extremity  of  the  preceding ;  a  second,  carried  in  the  same  direction,  should  be  made 
in  front  of  the  anus  ;  and  a  third  at  the  posterior  extremity  of  the  gut.  These  incisions  should 
be  sufficiently  extensive  to  enable  the  dissector  to  raise  the  integument  from  the  inner  side  of 
the  thighs.  The  flaps  of  skin  corresponding  to  the  Ischio-rectal  region  (Fig.  455,  2),  should 
now  be  removed.  In  dissecting  the  integument  from  this  region,  great  care  is  required,  other- 
wise the  External  Sphincter  will  be  removed,  as  it  is  intimately  adherent  to  the  skin. 

The  superficial  fascia  is  exposed  on  the  removal  of  the  skin  :  it  is  very  thick, 
areolar  in  texture,  and  contains  much  fat  in  its  meshes.     In  it  are  found  rami- 
fyino;  two  or  three  cutaneous  branches  of  the  small  sciatic  nerve;  these  turn 
^    °  »  839 


840 


SURGICAL    ANATOMY    OF    THE    PERIXEIJM. 


round  the  inferior  border  of  the  Glutaeus  Maximus,  and  are  distributed  to  the 
integument  in  this  region. 


Fig.  455. — Dissection  of  Perineum  and  Ischio-Eectal  Region. 


The  External  Sj^hinder  is  a  thin  flat  plane  of  muscular  fibres,  elliptical  in 
shape,  and  intimately  adherent  to  the  integument  surrounding  the  margin  of 
the  anus.  It  measures  about  three  or  four  inches  in  length,  from  its  anterior 
to  its  posterior  extremity,  being  about  an  inch  in  breadth,  opposite  the  anus. 
It  arises  from  the  tip  of  the  coccyx,  by  a  narrow  tendinous  band  ;  and  from  the 
superficial  fascia  in  front  of  that  bone ;  and  is  inserted  into  the  tendinous  centre 
of  the  perineum,  joining  with  the  Transversus  Perinei,  the  Levator  Ani,  and  the 
Accelerator  Urinse.  Like  other  Sphincter  muscles,  it  consists  of  two  planes  of 
muscular  fibre,  which  surround  the  margin  of  the  anus,  and  join  in  a  commis- 
sure before  and  behind. 

Relations.  By  its  superficial  surface,  with  the  integument ;  by  its  deep  surface 
it  is  in  contact  with  the  Internal  Sphincter  ;  and  is  separated  from  the  Levator 
Ani  by  loose  areolar  tissue. 

The  Sphincter  Ani  is  a  voluntary  muscle,  supplied  by  the  hsemorrhoidal 
branch  of  the  fourth  sacral  nerve.  This  muscle  is  divided  in  the  operation  for 
fistula  in  ano ;  and  also  in  some  cases  of  fissure  of  the  rectum,  especially  if 
attended  with  much  pain -or  spasm.  The  object  of  its  division  is  to  keep  the 
parts  at  rest  and  in  contact  during  the  healing  process. 

The  Internal  Sphincter  is  a  muscular  ring,  about  half  an  inch  in  breadth,  which 
surrounds  the  lower  extremity  of  the  rectum,  about  an  inch  from  the  margin 
of  the  anus.  This  muscle  is  about  two  lines  in  thickness,  and  is  formed  by  an 
aggregation  of  the  involuntary  circular  fibres  of  the  intestine.  It  is  paler  in 
color,  and  less  coarse  in  texture,  than  the  External  Sphincter. 

The  ischio-rectal  fossa  is  situated  between  the  end  of  the  rectum  and  the  tube- 
rosity of  the  ischium  on  each  side.  It  is  triangular  in  shape,  its  base,  directed 
to  the  surface  of  the  body,  is  formed  by  the  integument  of  the  ischio-rectal 
region ;  its  a;jex,  directed  upwards,  corresponds  to  the  point  of  division  of  the 
obturator  fascia,  and  the  thin  membrane  given  off  from  it,  which  covers  the 
outer  surface  of  the  Levator  Ani  (ischio-rectal  fascia).  Its  dimensions  are  about 
an  inch  in  breadth,  at  the  base,  and  about  two  inches  in  depth,  being  deeper 
behind  than  in  front.  It  is  bounded,  internally,  by  the  Sphincter  Ani,  Levator 
Ani,  and  Coccygeus  muscles ;  externalb/,  by  the  tuberosity  of  the  ischium,  and 
the  obturator  fascia,  which  covers  the  inner  surface  of  the  Obturator  Internus 
muscle;  in  front,  it  is  limited  by  the  line  of  junction  of  the  superficial  and  deep 
perineal  fasciae :  and  behind,  by  the  margin  of  the  Glutfeus  Maximus,  and  the 
great  sacro-sciatic  ligament.  This  space  is  filled  with  a  large  mass  of  adipose 
substance,  which  explains  the  frequency  with  which  abscesses  in  the  neighbor- 
hood of  the  rectum  burrow  to  a  considerable  depth. 


I 


PERINEUM.  841 

If  the  subject  has  been  injected,  on  placing  the  finger  on  the  outer  wall  of 
this  fossa,  the  internal  pudic  artery,  with  its  accompanying  veins  and  nerve, 
will  be  felt  about  an  inch  and  a  half  above  the  margin  of  the  ischiatic  tubero- 
sity, but  approaching  nearer  the  surface  as  they  pass  forwards  along  the  inner 
margin  of  the  pubic  arch.  These  structures  are  inclosed  in  a  sheath  formed  by 
the  obturator  fascia,  the  pubic  nerve  lying  below  the  artery.  Crossing  the 
space  transversely,  about  its  centre,  are  the  inferior  hsemorrhoidal  vessels  and 
nerves,  branches  of  the  pudic;  they  are  distributed  to  the  integument  of  the 
anus,  and  to  the  muscles  of  the  lower  end  of  the  rectum.  These  vessels  are 
occasionally  of  large  size,  and  may  give  rise  to  troublesome  hemorrhage,  when 
divided  in  the  operation  of  lithotomy,  or  of  fistula  in  ano.  At  the  back  part 
of  this  space  may  be  seen  a  branch  of  the  fourth  sacral  nerve;  and,  at  the  fore 
part  of  the  space,  a  cutaneous  branch  of  the  perineal  nerve. 

Perineum. 

The  Perineal  Space  is  of  a  triangular  form;  its  deep  boundaries  are  limited, 
laterally,  by  the  rami  of  the  pubes  and  ischia,  meeting  in  front  at  the  pubic 
arch;  behind,  by  an  imaginary  transverse  line,  extending  between  the  tuberosi- 
ties of  the  ischia.  The  lateral  boundaries  vary,  in  the  adult,  from  three  inches 
to  three  inches  and  a  half  in  length ;  and  the  base  from  two  to  three  inches  and 
a  half  in  breadth ;  the  average  extent  of  the  base  being  two  inches  and  three- 
quarters.  The  variations  in  the  diameter  of  this  space  are  of  extreme  interest 
in  connection  with  the  operation  of  lithotomy,  and  the  extraction  of  a  stone 
from  the  cavity  of  the  bladder.  In  those  cases  where  the  tuberosities  of  the 
ischia  are  near  together,  it  would  be  necessary  to  make  the  incisions  in  the 
lateral  operation  of  lithotomy  less  oblique  than  if  the  tuberosities  were  widely 
separated,  and  the  perineal  space,  consequently,  wider.  The  perineum  is  sub- 
divided by  the  median  raphe  into  two  equal  parts.  Of  these,  the  left  is  the  one 
in  which  the  operation  of  lithotomy  is  performed. 

In  the  middle  line,  the  perineum  is  convex,  and  corresponds  to  the  bulb  of 
the  urethra.  The  skin  covering  it  is  of  a  dark  color,  thin,  freely  movable  upon 
the  subjacent  parts,  and  covered  with  sharp  crisp  hairs  which  should  be  re- 
moved before  the  dissection  of  the  part  is  commenced.  In  front  of  the  anus,  a 
prominent  line  commences,  the  raphe,  continuous  in  front  with  the  raphe  of  the 
scrotum.  The  flaps  of  integument  corresponding  to  this  space  having  been  re- 
moved, in  the  manner  shown  in  Figs.  455,  6,  the  superficial  fascia  is  exposed. 

The  Supej]ficial  Fascia  consists  of  two  layers,  superficial  and  deep,  as  in  other 
regions  of  the  body. 

The  superficial  layer  is  thick,  loose,  areolar  in  texture,  and  contains  much 
adipose  tissue  in  its  meshes,  the  amount  of  which  varies  in  different  subjects. 
In  front,  it  is  continuous  with  the  dartos  of  the  scrotum ;  behind,  it  is  con- 
tinuous with  the  subcutaneous  areolar  tissue  surrounding  the  anus;  and,  on 
either  side,  with  the  same  fascia  on  the  inner  side  of  the  thighs.  This  layer 
should  be  carefully  removed,  after  it  has  been  examined,  when  the  deep  layer 
will  be  exposed. 

The  deep  layer  of  superficial  fascia  (superficial  perineal  fascia)  is  thin,  .aponeu- 
rotic in  structure,  and  of  considerable  strength,  serving  to  bind  down  the  mus- 
cles of  the  root  of  the  penis.  It  is  continuous,  in  front,  with  the  dartos  of  the 
scrotum;  on  either  side,  it  is  firmly  attached  to  the  margins  of  the  rami  of  the 
pubes  and  ischium,  external  to  the  crus  penis,  and  as  far  back  as  the  tuberosity 
of  the  ischium;  posteriorly,  it  curves  down  behind  the  Transversus  Perinrei 
muscles  to  join  the  lower  margin  of  the  deep  perineal  fascia.  This  fascia  not 
only  covers  the  muscles  in  this  region,  but  sends  down  a  vertical  septum  from 
its  under  surface,  which  separates  the  back  part  of  the  subjacent  space  into  two, 
being  incomplete  in  front. 

In  rupture  of  the  anterior  portion  of  the  urethra,  accompanied  by  extravasa- 
tion of  urine,  the  fluid  makes  its  way  forwards,  beneath  this  fascia,  into  the 


842 


SURGICAL    ANATOMY    OF    THE    PERINEUM. 


areolar  tissue  of  the  scrotum,  penis,  and  anterior  and  lateral  portions  of  the 
abdomen;  it  rarely  extends  into  the  areolar  tissue  on  the  inner  side  of  the 
thighs,  or  backwards  around  the  anus.  This  limitation  of  the  extravasated 
fluid  to  the  parts  abore  named  is  easy  of  explanation,  when  the  attachments 

Fig.  456. —The  Perineum.    The  Integument  and  Superficial  Layer  of  Superficial  Fascia  refiected. 


of  the  deep  layer  of  the  superficial  fascia  are  considered.  When  this  fascia  is 
removed,  the  muscles  connected  with  the  penis  and  urethra  will  be  exposed; 
these  are,  in  the  middle  line,  the  Accelerator  Urinaj;  on  each  side,  the  Erector 
Penis,  and  behind,  the  Transversus  Perinaei. 

The  Accelerator  Urines  is  placed  in  the  middle  line  of  the  perineum,  immedi- 
ately in  front  of  the  anus.  It  consists  of  two  symmetrical  halves,  united  along 
the  median  line  by  a  tendinous  raphe.  It  arises  from  the  central  tendon  of  the 
perineum,  and  from  the  median  raphe  in  front.  From  this  point,  its  fibres 
diverge  like  the  plumes  of  a  pen;  the  most  posterior  form  a  thin  layer,  which 
are  lost  on  the  anterior  surface  of  the  triangular  ligament;  the  middle  fibres 
encircle  the  bulb  and  adjacent  part  of  the  corpus  spongiosum,  and  join  with  the 
fibres  of  the  opposite  side,  on  the  upper  part  of  the  corpus  spongiosum,  in  a 
strong  aponeurosis;  the  anterior  fibres,  the  longest  and  most  distinct,  spread 
out  over  the  sides  of  the  corpus  cavernosum,  to  be  inserted  partly  into  that 
body,  anterior  to  the  Erector  Penis;  partly  terminating  in  a  tendinous  expan- 
sion, which  covers  the  dorsal  vessels  of  the  penis.  The  latter  fibres  are  best 
seen  by  dividing  the  muscle  longitudinally,  and  dissecting  it  outwards  from  the 
surface  of  the  urethra. 

Action.  This  muscle  may  serve  to  accelerate  the  flow  of  the  urine  or  semen 
along  the  canal  of  the  urethra.  The  middle  fibres  are  supposed,  by  Krause,  to 
assist  in  the  erection  of  the  corpus  spongiosum,  by  compressing  the  erectile 
tissue  of  the  bulb.  The  anterior  fibres,  according  to  Tyrrel,  also  contribute  to 
the  erection  of  the  penis,  as  they  are  inserted  into,  and  continuous  with,  the 
fascia  of  the  penis,  compressing  the  dorsal  vein  daring  the  contraction  of  the 
muscle. 


MUSCLES    OF    THE    PERINEUM. 


843 


The  Erector  Penis  covers  the  unattached  part  of  the  crus  penis.  It  is  an 
elongated  muscle,  broader  in  the  middle  than  at  either  extremity,  and  situated 
on  either  side  of  the  lateral  boundary  of  the  perineum.  It  arises  by  tendinous 
and  fleshy  fibres  from  the  inner  surface  of  the  tuberosity  of  the  ischium,  behind 

Fig.  457. — The  Superficial  Muscles  and  Vessels  of  the  Perineum. 


Grf  Satfro-Setaiie  Ligf- 


Sfape^i'eial  Pentual Arttry 
Superficial  Perineal  Nrrve 
Internal  Pudic  Nerve 
Internal  Padic  Artery 


the  crus  penis,  from  the  surface  of  the  crus,  and  from  the  adjacent  portion  of 
the  ramus  of  the  pubes.  From  these  points,  fleshy  fibres  succeed,  which  end 
in  an  aponeurosis  which  is  inserted  into  the  side  and  under  surface  of  the  crus 
penis.  This  muscle  compresses  the  crus  penis,  and  thus  serves  to  maintain  the 
organ  erect. 

The  Transversus  Perinsei  is  a  narrow  muscular  slip,  which  passes  more  or  less 
transversely  across  the  back  part  of  the  perineal  space.  It  arises  by  a  small 
tendon  from  the  inner  and  fore  side  of  the  tuberosity  of  the  ischium,  and,  pass- 
ing obliquely  forwards  and  inwards,  is  inserted  into  the  central  tendinous  point 
of  the  perineum,  joining  in  this  situation  with  the  muscle  of  the  opposite  side, 
the  Sphincter  Ani  behind,  and  the  Accelerator  Urinae  in  front. 

Between  the  muscles  just  examined,  a  triangular  space  exists,  bounded  in- 
ternally by  the  Accelerator  Urinse,  externally  by  the  Erector  Penis,  and  behind 
by  the  Transversus  Perinsei.  The  floor  of  this  space  is  formed  hj  the  triangular 
ligament  of  the  urethra  (deep  perineal  fascia),  and,  running  from  behind  for- 
wards in  it,  are  the  superficial  perineal  vessels  and  nerves,  the  transverse 
perineal  artery  coursing  along  the  posterior  boundary  of  the  space,  on  the 
Transversus  Perinsei  muscle. 

In  the  lateral  operation  of  lithotomy,  the  knife  is  carried  obliquely  across 
the  back  part  of  this  space,  downwards  and  outwards,  into  the  ischio-rectal  fossa, 
dividing  the  Transversus  Perinsei  muscle  and  artery,  the  posterior  fibres  of  the 
Accelerator  Urinss,  the  superficial  perineal  vessels  and  nerve,  and  more  poste- 
riorly the  external  hsemorrhoidal  vessels. 

The  superficial  and  transverse  perineal  arteries  have  been  already  described; 
also  the  superficial  perineal  and  inferior  pudendal  nerves. 


844 


SURGICAL    ANATOMY    OF    THE    PERINEUM. 


The  muscles  of  the  perineum  in  the  female  are,  the 


Sphincter  Vaginse. 
Erector  Clitoridis. 
Transversus  Perinei. 


Compressor  Urethrae. 
Sphincter  Ani. 
Levator  Ani. 


Coccygeus. 

The  Sphincter  Vaginse  surrounds  the  orifice  of  the  vagina,  and  is  analogous 
to  the  Accelerator  Urinae  in  the  male.  It  is  attached,  posteriorly,  to  the  central 
tendon  of  the  perineum,  where  it  blends  with  the  Sphincter  Ani.  Its  fibres  pass 
forwards  on  each  side  of  the  vagina,  to  be  inserted  into  the  corpora  cavernosa 
and  body  of  the  clitoris. 

The  Erector  Clitoridis  resembles  the  Erector  Penis  in  the  male,  but  is  smaller 
than  it. 

The  Transversibs  Perinsei  is  inserted  into  the  side  of  the  Sphincter  Vaginae,  and 
the  Levator. Ani  into  the  side  of  the  vagina.  The  other  muscles  are  precisely 
similar  to  those  in  the  male. 

The  Accelerator  Urinse  and  Erector  Penis  muscles  should  now  be  removed,  when  the  deep 
perineal  fascia  will  be  exposed,  stretching  across  the  front  part  of  the  outlet  of  the  pelvis.  The 
urethra  is  seen  perforating  its  centre,  just  behind  the  bulb  ;  and  on  either  side  is  the  crus  penis, 
connecting  the  corpus  cavernosa  with  the  ramus  of  the  ischium  and  pubcs. 

Fig.  458. — Deep  Perineal  Fascia.    On  the  left  side,  the  anterior  layer  has  been  removed. 


Anterior  layer  ef 
ftp  Pirintai  Fdteia  rvmevid 


COMPRCtSOR     URCTMRiB 

Jnirmn/  PuJic  Arty. 
Arty  ^  tht  BifLli 
ConrjHrt   Gl»nd 


The  Deep  Perineal  Fascia  (triangular  ligament),  is  a  dense  membranous 
lamina,  which  closes  the  front  part  of  the  outlet  of  the  pelvis.  It  is  triangular 
in  shape,  about  an  inch  and  a  half  in  depth,  attached,  above,  by  its  apex  to 
the  under  surface  of  the  symphysis  pubis  and  subpubic  ligament;  and,  on  each 
side,  to  the  rami  of  the  ischium  and  pubes,  beneath  the  crura  penis.  Its  inferior 
margin,  or  base,  is  directed  towards  the  rectum,  and  connected  to  the  central 
tendinous  point  of  the  perineum.  It  is  continuous  with  the  deep  layer  of  the 
superficial  fascia  behind  the  Transversus  Perinei  muscle,  and  with  a  thin  fascia 
which  covers  the  cutaneous  surface  of  the  Levator  AniYnuscle. 

The  deep  perineal  fascia  is  perforated  by  the  urethra,  about  an  inch  below  the 
symphysis  pubis.  The  aperture  is  circular  in  form,  and  -about  three  or  four 
lines  in  diameter.  Above  this  is  the  aperture  for  the  dorsal  vein  of  the  penis; 
and,  outside  the  latter,  the  pudic  nerve  and  artery  pierce  it. 


ARTERY  OF  THE  BULB— LETATOR  ANI.      845 

Tlie  deep  perineal  fascia  consists  of  two  layers,  anterior  and  posterior ;  these 
are  separated  above,  but  united  below. 

The  anterior  layer  is  continued  forwards,  around  the  anterior  part  of  the  mem- 
branous portion  of  the  urethra,  becoming  lost  upon  the  bulb. 

The  2Mstenor  layer  is  derived  from  the  pelvic  fascia;  it  is  continued  backwards 
around  the  posterior  part  of  the  membranous  portion  of  the  urethra,  and  the 
outer  surface  of  the  prostate  gland. 

If  the  anterior  layer  of  this  fascia  is  detached  on  either  side,  the  following 
parts  are  seen  between  it  and  the  posterior  layer  ;  the  subpubic  .ligament  .above, 
close  to  the  pubes ;  the  dorsal  vein  of  the  penis  ;  the  membranous  portion  of 
the  urethra,  and  the  muscles  of  the  urethra ;  Cowper's  glands  and  their  ducts ; 
the  pudic  vessels  and  nerve  ;  the  artery  and  nerve  of  the  bulb,  and  a  plexus 
of  veins. 

The  Compressor  Ureihrse  (Constrictor  Urethrse),  surrounds  the  whole  length  of 
the  membranous  portion  of  the  urethra,  and  is  contained  between  the  two  layers 
of  the  deep  perineal  fascia.  It  arises,  by  aponeurotic  fibres,  from  the  upper  part 
of  the  ramus  of  the  pubes  on  each  side,  to  the  extent  of  half  or  three-quarters 
of  an  inch ;  each  segment  of  the  muscle  passes  inwards,  and  divides  into  two 
fasciculi,  which  surround  the  urethra  from  the  prostate  gland  behind,  to  the 
bulbous  portion  of  the  urethra  in  front ;  and  unite,  at  the  upper  and  lower  sur- 
faces of  this  tube,  with  the  muscle  of  the  opposite  side,  by  means  -of  a  tendi- 
nous raphe. 

Circular  Muscular  Fibres  surround  the  membranous  portion  of  the  urethra, 
from  the  bulb  in  front  to  the  prostate  gland  behind ;  they  are  placed  imme- 
diately beneath  the  transverse  fibres  already  described,  and  are  continuous  with 
the  circular  fibres  of  the  bladder.     These  fibres  are  involuntary. 

Cowper's  Glands  are  situated  immediately  below  the  membranous  portion  of 
the  urethra,  close  behind  the  bulb,  and  below  the  artery  of  the  bulb  (p.  801). 

The  Pudic  Vessels  and  Nerves  are  placed  along  the  inner  margin  of  the  pubic 
arch. 

The  Artery  of  the  Bulb  passes  transversely  inwards,  from  the  internal  pudic 
on  the  posterior  margin  of  the  triangular  ligament,  between  the  two  layers  of 
fascia,  accompanied  by  a  branch  of  the  pudic  nerve. 

If  the  posterior  layer  of  the  deep  perineal  fascia  is  removed,  and  the  crus 
penis  of  one  side  detached  from  the  bone,  the  under  or  perineal  surface  of  the 
Levator  Ani  is  brought  fully  into  view.  This  muscle,  with  the  triangular  liga- 
ment in  front  and  the  Coccygeus  and  Pyriformis  behind,  closes  in  the  outlet  of 
the  pelvis. 

The  Levator  Ani  is  a  broad  thin  muscle,  situated  on  each  side  of  the  pelvis. 
It  is  attached  to  the  inner  surface  of  the  sides  of  the  true  pelvis,  and,  descend- 
ing, unites  with  its  fellow  of  the  opposite  side  to  form  the  floor  of  the  pelvic 
cavity.  It  supports  the  viscera  in  this  cavity,  and  surrounds  the  various  struc- 
tures which  pass  through  it.  It  arises,  in  front,  from  the  posterior  surface  of 
the  body  and  ramus  of  the  pubes,  on  the  outer  side  of  the  symphysis ;  poste- 
riorly, from  the  inner  surface  of  the  spine  of  the  ischium  ;  and  between  these 
two  points,  from  the  angle  of  division  between  the  obturator  and  recto-vesical 
layers  of  the  pelvic  fascia  at  their  under  part ;  the  fibres  pass  downwards  to  the 
middle  line  of  the  floor  of  the  pelvis,  and  are  inserted,  the  most  posterior  fibres 
into  the  sides  of  the  apex  of  the  coccyx ;  those  placed  more  anteriorly  unite 
with  the  muscle  of  the  opposite  side,  in  a  median  fibrous  raphe,  which  extends 
between  the  coccyx  and  the  margin  of  the  anus.  The  middle  fibxcs,  which 
form  the  larger  portion  of  the  muscle,  are  inserted  into  the  side  of  the  rectum, 
blending  with  the  fibres  of  the  Sphincter  muscles;  lastly,  the  anterior  fibres, 
the  longest,  descend  upon  the  side  of  the  prostate  gland  to  unite  beneath  it  with 
the  muscle  of  the  opposite  side,  blending  with  the  fibres  of  the  external  sphinc- 
ter and  Transversus  Perintei  muscles,  at  the  tendinous  centre  of  the  perineum. 

The  anterior  portion  is  occasionally  separated  from  the  rest  of  the  muscle  by 
cellular  tissue.     From  this  circumstance,  as  well  as  from  its  peculiar  relation 


846  SURGICAL    ANATOMY    OF    THE    PERINEUM. 

■with  the  prostate  gland,  descending  by  its  side  and  surrounding  it  as  in  a  sling, 
it  has  been  described  by  Santorini  and  others  as  a  distinct  muscle,  under  the 
name  of  the  Levator  Prostatse.  In  the  female,  the  anterior  fibres  of  the  Levator 
Ani  descend  upon  the  sides  oi  the  vagina. 

Relations.  By  its  upper  or  pelvic  surface  with  the  recto- vesical  fascia,  which 
separates  it  from  the  viscera  of  the  pelvis  and  from  the  peritoneum.  By  its 
outer  or  perineal  surface^  it  forms  the  inner  boundary  of  the  ischio-rectal  fossa, 
and  is  covered  by  ^  quantity  of  fat,  and  by  a  thin  layer  of  fascia  continued  from 
the  obturator  fascia,  lis  posterior  border  is  continuous  with  the  Coccygeus  mus- 
cle. Its  anterior  border  is  separated  from  the  muscle  of  the  opposite  side  by  a 
triangular  space,  through  which  the  ureth];a  and,  in  the  female,  the  vagina 
pass  from  the  pelvis. 

Actions.  This  muscle  supports  the  lower  end  of  the  rectum  and  vagina,  and 
also  the  bladder  during  the  efforts  of  expulsion. 

The  Coccygeus  is  situated  behind  and  parallel  with  the  preceding.  It  is  a 
triangular  plane  of  muscular  and  tendinous  fibres,  arising,  by  its  apex,  from 
the  spine  of  the  ischium  and  lesser  sacro-sciatic  ligament,  and  inserted,  by  its 
base,  into  the  margin  of  the  coccyx  and  into  the  side  of  the  lower  piece  of  the 
sacrum.  This  muscle  is  continuous  with  the  posterior  border  of  the  Levator 
Ani,  and  closes  in  the  back  part  of  the  outlet  of  the  pelvis. 

Relations.  By  its  inner  or  pelvic  surface^  with  the  rectum.  By  its  external 
surface^  with  the  lesser  sacro-sciatic  ligament.  By  its  posterior  border^  with  the 
Pyriformis. 

Action.  The  Coccygei  muscles  raise  .and  support  the  coccyx,  after  it  has  been 
pressed  backwards  during  defecation  or  parturition. 

Position  of  the  Viscera  at  the  Outlet  of  the  Pelvis.  Divide  the  central  tendinous  point  of  the 
perineum,  separate  the  rectum  from  its  connections  by  dividing  the  fibres  of  the  Levator  Ani, 
which  descend  upon  the  sides  of  the  prostate  gland,  and  draw  the  gut  backwards  towards  the 
coccyx,  when  the  under  surface  of  the  prostate  gland,  the  neck  and  base  of  the  bladder,  the 
vesiculae  seminales,  and  vasa  deferentia  will  be  exposed. 

The  Prostate  Gland  is  placed  immediately  in  front  of  the  neck  of  the  bladder, 
around  the  prostatic  portion  of  the  urethra,  its  base  being  turned  backwards, 
and  its  under  surface  towards  the  rectum.  It  is  retained  in  its  position  by  the 
Levator  Prostatas  and  by  the  pubo-prostatic  ligaments,  and  is  invested  by  a  dense 
fibrous  covering,  continued  from  the  posterior  layer  of  the  deep  perineal  fascia. 
The  longest  diameters  of  this  gland  are  in  the  antero-posterior  directiou,  and 
transversely  at  its  base;  and  hence  the  greatest  extent  of  incision  that  can  be 
made  in  it  without  dividing  its  substance  completely  across,  is  obliquely  out- 
wards and  backwards.  This  is  the  direction  in  which  the  incision  is  made 
through  it  in  the  operation  of  lithotomy,  the  extent  of  which  should  seldom 
exceed  an  inch  in  length.  The  relations  of  the  prostate  to  the  rectum  should 
be  noticed ;  by  means  of  the  finger  introduced  into  the  gut,  the  surgeon  detects 
enlargement  or  other  disease  of  this  organ ;  he  is  enabled  also,  by  the  same  means, 
to  direct  the  point  of  a  catheter  when  its  introduction  is  attended  wtth  much 
difficulty,  either  from  injury  or  disease  of  the  membranous  or  prostatic  portions 
of  the  urethra. 

Behind  the  prostate  is  the  posterior  surface  of  the  neck  and  base  of  the  blad- 
der ;  a  small  triangular  portion  of  this  organ  is  seen,  bounded,  in  front  by  the 
prostate  gland ;  behind,  by  the  recto- vesical  fold  of  the  peritoneum ;  on  either 
side,  by  the  vesiculos  seminales  and  vasa  deferentia ;  and  separated  from  direct 
contact  with  the  rectum  by  the  recto-vesical  fascia.  The  relation  of  this  por- 
tion of  the  bladder  to  the  rectum  is  of  extreme  interest  to  the  surgeon.  In 
cases  of  retention  of  urine,  this  portion  of  the  organ  is  found  projecting  into 
the  rectum,  between  three  and  four  inches  from  the  margin  of  the  anus,  and 
may  be  easily  perforated  during  life  without  injury  to  any  important  parts;  this 
portion  of  the  bladder  is,  consequently,  frequently  selected  for  the  performance 
of  the  operation  of  tapping  the  bladder.  If  the  finger  is  introduced  into  the 
bowel,  the  surgeon  may,  in  some  cases,  learn  the  position,  as  well  as  the  size 


PARTS    CONCERNED    IN    LITHOTOMY. 


847 


and  "weight,  of  a  calculus  in  the  bladder ;  and  in  the  operation  for  its  removal 
if,  as  is  not  unfrequently  the  case,  it  should  be  lodged  behind  an  enlarged  pros- 
tate, it  may  be  displaced  from  its  position  by  pressing  upwards  the  base  of  the 
bladder  from  the  rectum. 

Fig.  459.— A  View  of  the  Position  of  the  Viscera  at  the  Outlet  of  the  Pelvis. 


^^*^y  «f  Corpus  Cavemosnm 
Dorsal  Artery  of  Peni4> 


Arttry  of  Balbt 
JtUemal  Pudle  Artery- 


Cowper't  Gland- 


Parts  concerned  in  the  Operation  of  Lithotomy.  The  triangular  ligament  must 
be  replaced  and  the  rectum  drawn  forwards  so  as  to  occupy  its  normal  position. 
The  student  should  then  consider  the  position  of  the  various  parts  in  reference 
to  the  lateral  operation  of  lithotomy.  This  operation  is  })erformed  on  the  left 
side  of  the  perineum,  as  it  is  most  convenient  for  the  right  hand  of  the  operator. 
A  staff  having  been  introduced  into  the  bladder,  the  first  incision  is  commenced 
midway  between  the  anus  and  the  back  of  the  scrotum  (^.  e.,  in  an  ordinary 
adult  perineum,  about  an  inch  and  a  half  in  front  of  the  anus),  a  little  on 
the  left  side  of  the  raphe,  and  carried  obliquely  backwards  and  outwards  to 
midway  between  the  anus  and  tuberosity  of  the  ischium.  The  incision  divides 
the  integument  and  superficial  fascia,  the  external  hsemorrhoidal  vessels  and 
nerves,  and  the  superficial  and  transverse  perineal  vessels;  if  the  fore-finger  of 
the  left  hand  is  thrust  upwards  and  forwards  into  the  wound,  pressing  at  the 
same  time  the  rectum  inwards  and  backwards,  the  staff  may  be  felt  in  the  mem- 
branous portion  of  the  urethra.  The  finger  is  fixed  upon  the  staff,  and  the 
structures  covering  it  are  divided  with  the  point  of  the  knife,  which  must  be 
directed  along  the  groove  towards  the  bladder,  the  edge  of  the  knife  being 
carried  outwards  and  backwards,  dividing  in  its  course  the  membranous  portion 
of  the  urethra,  and  part  of  the  left  lobe  of  the  prostate  gland,  to  the  extent  of 
about  an  inch.  The  knife  is  then  withdrawn,  and  the  forefinger  o*f  the  left 
hand  passed  along  the  staff  into  the  bladder ;  the  staff  having  been  withdrawn, 
and  the  position  of  the  stone  ascertained,  the  forceps  are  introduced  over  the 
finger  into  the  bladder.  If  the  stone  is  very  large,  the  opposite  side  of  the 
prostate  may  be  notched  before  the  forceps  are  introduced ;  the  finger  is  now 
withdrawn,  and  the  blades  of  the  forceps  opened,  and  made  to  grasp  the  stone, 
which  must  be  extracted  by  slow  and  cautious  undulating  movements. 

Parts  divided  in  the  operation.     The  various  structures  divided  in  this  opera- 


848 


LITHOTOMY. 


tion  are  as  follows :  the  integument,  superficial  fascia,  external  liEemorrhoidal 
vessels  and  nerves,  the  posterior  fibres  of  the  Accelerator  Urinae,  the  Trans- 
versus  Perina3i  muscle  and  artery  (and,  probably,  the  superficial  perineal  vessels 
and  nerves),  the  deep  perineal  fascia,  the  anterior  fibres  of  the  Levator  Ani, 
part  of  the  Compressor  Urethrae,  the  membranous  and  prostatic  portions  of 
the  urethra,  and  part  of  the  prostate  gland. 

Fig.  460. — A  Transverse  Section  of  the  Pelvis,  showing  the  Pelvic  Fascia. 


ArUe7norCruralAeivc^^>i-^. 


Obttiwataf  Fatefa 


Internal  Pudic  Vittth  L  A>rr* ArA 


Parts  to  he  avoided  in  the  operation.  In  making  the  necessary  incisions  in  the 
perineum  for  the  extraction  of  a  calculus,  the  following  parts  should  be  avoided. 
The  primary  incisions  should  not  be  made  too  near  the  middle  line,  for  fear  of 
wounding  the  bulb  of  the  corpus  spongiosum  or  the  rectum ;  nor  too  far  ex- 
ternally, otherwise  the  pudic  artery  may  be  implicated  as  it  ascends  along  the 
inner  border  of  the  pubic  arch.  If  the  incisions  are  carried  too  far  forward, 
the  artery  of  the  bulb  may  be  divided ;  if  carried  too  far  backwards,  the  entire 
breadth  of  the  prostate  and  neck  of  the  bladder  may  be  cut  through,  which 
allows  the  urine  to  become  infiltrated  behind  the  pelvic  fascia  into  the  loose 
cellular  tissue  between  the  bladder  and  rectum,  instead  of  escaping  externally; 
diffuse  inflammation  is  consequently  set  up,  and  peritonitis  from  the  close 
proximity  of  the  recto- vesical  peritoneal  fold  is  the  consequence.  If,  on  the  con- 
trary, the  prostate  is  divided  in  front  of  the  base  of  the  gland,  the  urine  makes 
its  way  externally,  and  there  is  less  danger  of  infiltration  taking  place. 

During  the  operation,  it  is  of  great  importance  that  the  finger  should  be  passed 
into  the  bladder  before  the  staff  is  removed ;  if  this  is  neglected,  and  the  incision 
made  through  the  prostate  and  neck  of  the  bladder  be  too  small,  great  diffi- 
culty may  be  experienced  in  introducing  the  finger  afterwards ;  and  in  the 
child,  where  tlie  connections  of  the  bladder  to  the  surrounding  parts  are  very 
loose,  the  force  made  in  the  attempt  is  sufiicient  to  displace  the  bladder  up  into 
the  abdomen,  out  of  the  reach  of  the  operator.  Such  a  proceeding  has  not 
unfrequently  occurred,  producing  the  most  embarrassing  results,  and  total 
failure  of  the  operation. 

It  is  necessary  to  bear  in  mind  that  the  arteries  in  the  perineum  occasionally 
take  an  abnormal  course.  Thus  the  artery  of  the  bulb,  when  it  arises,  as  some- 
times happens,  from  the  pudic,  opposite  the  tuber  ischii,  is  liable  to  be  wounded 


LITHOTOMY— PELVIC    FASCIA. 


849 


in  the  operation  for  lithotom}-,  in  its  passage  forwards  to  the  bulb.     The  acces- 
sory pudic  may  be  divided  near  the  posterior  border  of  the  prostate  gland,  if 

Fig.  461.— Side  View  of  the  Pelvic  Viscera  of  the  Male  Subject,  showing  the  Pelvic  and 

Perineal  Fasciae. 


this  is  completely  cut  across:  and  the  prostatic  veins,  especially  in  people 
advanced  in  life,  are  of  large  size,  and  give  rise,  when  divided,  to  troublesome 
hemorrhage. 

Pelvic  Fascia. 

The  Pelvic  Fascia  (Fig.  462)  is  a  thin  membrane  which  lines  the  whole  of 
the  cavity  of  the  pelvis,  and  is  continuous  with  the  transversalis  and  iliac 
fasciae.  It  is  attached  to  the  brim  of  the  pelvis  for  a  short  distance  at  the  side 
of  the  cavity,  and  to  the  inner  surface  of  the  bone  round  the  attachment  of  the 
Obturator  Internus.  At  the  posterior  border  of  this  muscle,  it  is  continued 
backwards  as  a  very  thin  membrane  in  front  of  the  Pyriformis  muscle  and 
sacral  nerves,  behind  the  branches  of  the  internal  iliac  artery  and  vein  which 
perforate  it,  to  the  front  of  the  sacrum.  In  front,  it  follows  the  attachment  of 
the  Obturator  Internus  to  the  bone,  arches  beneath  the  obturator  vessels,  com- 
pleting the  orifice  of  the  obturator  canal,  and  at  the  front  of  the  pelvis  is 
attached  to  the  lower  part  of  the  symphysis  pubis  ;  being  continuous  below 
the  pubes  with  the  fascia  of  the  opposite  side  so  as  to  close  the  front  part  of 
the  outlet  of  the  pelvis,  blending  with  the  posterior  layer  of  the  triangular 
ligament.  At  the  level  of  a  line  extending  from  the  lower  part  of  the  sym- 
physis pubis  to  the  spine  of  the  ischium,  is  a  thickened  whitish  band ;  this 
marks  the  attachment  of  the  Levator  Ani  muscle  to  the  pelvic  fascia,  and  cor- 
responds to  its  point  of  division  into  two  layers,  the  obturator  and  recto-vesical. 

The  obturator  fascia  descends  and  covers  the  Obturator  Internus  muscle.     It 
is  a  direct  continuation  of  the  pelvic  fascia  below  the  white  line  above  men- 
tioned, and  is  attached  to  the  pubic  arch  and  to  the  margin  of  the  great  sacro- 
64 


850 


PELYIC    FASCIA. 


sciatic  ligament.  This  fascia  forms  a  canal  for  the  pudic  vessels  and  nerve  in 
their  passage  forwards  to  the  perineum,  and  is  continuous  with  a  thin  mem- 
brane which  covers  the  perineal  aspect  of  the  Levator  Ani  muscle,  called  the 
ischio-reclal  or  anal  fascia. 

Fig.  462.— Pelvic  Fascia. 


The  recto-vesical fascia  (visceral  layer  of  the  pelvic  fascia)  descends  into  the 
pelvis  upon  the  upper  surface  of  the  Levator  Ani  muscle,  and  invests  the  pros- 
tate, bladder,  and  rectum.  From  the  inner  surface  of  the  symphysis  pubis  a 
short  rounded  band  is  continued  to  the  upper  surface  of  the  prostate  and  neck 
of  the  bladder,  forming  the  pubo-prostatic  or  anterior  true  ligaments  of  the 
bladder.  At  the  side,  this  fascia  is  connected  to  the  side  of  the  prostate,  inclos- 
ing this  gland  and  the  vesical  prostatic  plexus,  and  is  continued  upwards  on  the 
surface  of  the  bladder,  forming  the  lateral  true  ligaments  of  the  organ.  Another 

Erolongatiou  invests  the  vesiculiB  seminalcs,  and  passes  across  between  the 
ladder  and  rectum,  being  continuous  with  the  same  fascia  of  the  opposite  side. 
Another  thin  prolongation  is  reflected  round  the  surface  of  the  lower  end  of 
the  rectum.  The  Levator  Ani  muscle  arises  from  the  point  of  division  of  the 
pelvic  fascia ;  the  visceral  layer  of  the  fascia  descending  upon  and  being  inti- 
mately adherent  to  the  upper  surface  of  the  muscle,  while  the  under  surfaee-  of 
the  muscle  is  covered  by  a  thin  layer  derived  from  the  obturator  fascia,  called 
the  ischio-rectal  or  anal  fascia.  In  the  female,  the  vagina  perforates  the  recto- 
vesical fascia,  and  receives  a  prolongation  from  it. 


IISTDEX.' 


Abdomen,  723 

apertures  found  in,  724 

boundaries  of,  723 

lymphatics  of,  567 

muscles  of,  359 

regions  of,  724 

viscera  of,  723 
Absorbent  glands.     See  Lym- 
phatic Glands. 
Absorbents.    ^See  Lymphatics. 
Acervulus  cerebri,  598 
Acetabulum,  232 
Acromion,  204 
Adipose  tissue,  40 
Air-cells,  786 

-sacs  of  lung,  786 

-tubes,  777 
Alse  of  nose,  678 

of  vomer,  169 
Alimentary  canal,  709 

subdivisions  of,  709 
See  also  Stomach,  Intes- 
tines, &c. 
Allanto'is,  91 
Alveoli,  formation  of,  716 

of  lower  jaw,  171 

of  stomach,  731 

of  upper  jaw,  162 
Amnion,  91 
Amphiarthrosis,  262 
Ampullae  of  semicircular   ca- 
nals, 704 

of  tubuli  lactiferi,  821 
Amygdalse,  718 

of  cerebellum,  601 
Anastomosis  of  arteries,  436 
Andersch,  ganglion  of,  626 
Aneurism  of  aorta,  &c.     See 

Aorta,  &c. 
Angle  of  jaw,  pubes,  &c.     See 

Jaw,  Pubes,  &c. 
Ankle-joint,  307 

relations  of  tendons  and  ves- 
sels, 308 
Annulus  ovalis,  759 
Antihelix,  695 

fossa  of,  695 
Antitragus,  695 
Antrum  of  Highmore,  161 
Anus,  839 

development  of,  107 

muscles  of,  840 
Aorta,  437 


Aorta — 

development  of,  104 
sinuses  of,  438 
abdominal,  497 
branches  of,  498 
surgical  anatomy  of,  497 
arch  of,  437 

ascending  part  of,  438 
branches  of,  441 
descending  part  of,  440 
peculiarities  of,  440 

of  branches  of,  441 
surgical  anatomy  of,  440 
transverse  portion  of,  439 
descending,  494 
thoracic,  494 
branches  of,  495 
surgical  anatomy  of,  494 
Aperture.     See  Openings,  Ori- 
fice, <Src. 
Aponeurosis,  315 
of  deltoid,  377 

of  external  oblique,  in  ingui- 
nal region,  823 
infraspinous,  378 
of  occipito-frontalis,  319 
pharyngeal,  721 
subscapular,  377 
Bupra-hyoid,  336 
supra-spinous,  378 
vertebral,  352 
Apophysis,  51 
Apparatus  ligamentosus  colli, 

273 
Appendages  of  eye,  691 
of  skin,  80 
of  uterus,  817 
Appendices  epiploicse,  728,  740 
Appendix,  ensilbrm,  192 
of  left  auricle,  761 
of  right  auricle,  758 
vermiformis,  737 
xiphoid,  192 
Aqua  labyrinthi,  706 
Aquaeductus  cochleae,  147,  706 
Fallopii,  147,  699 
Sylvii,  598 
vestibuli,  147,  703 
Aqueous    chamber,    epithelial 
lining  of,  689 
humor,  688 

secreting    membrane     of, 
689 


Arachnoid  membrane  of  brain, 
578 

of  cord,  573 
Arbor  vitae  of  cerebellum,  602 

uterinus,  816 
Arch  of  aorta.  See  Aorta,  arch 
of. 

crural,  833 

femoral,  833 

nasal,  536 

palmar,  deep,  488 
superficial,  491 

plantar,  533 

of  pubes,  232 

supraorbital,  140 

of  vertebra,  116 

zygomatic,  183 
Arches,  aortic  (foetal),  104 

pharyngeal,  98 
Area,  germinal,  91 
Areola  of  breast,  821 
Areolar  tissue,  38 
Arm,  arteries  of,  479 

bones  of,  207 

fascia  of,  380 

lymphatic  glands  of,  564 

lymphatics  of,  565 

muscles  of,  380 

nerves  of,  637 

veins  of,  544 
Arnold's  ganglion,  624 

nerve,  629 
Arteria  or  Arteriae.  See  Artery. 
Arteriae  receptaculi,  464 
Artery  or  Arteries — 

anastomoses  of,  436 

capillary,  436 

development  of,  103 

distribution  of,  436 

general  anatomy  of,  72 

mode  of  division  of,  436 
of  origin  ofbranchesof,436 

nerves  of,  74 

sheath  of,  73 

structure  of,  72 

subdivision  of,  436 

systemic,  436 

vessels  of,  73 

accessory  pudic,  513 
acromial  thoracic,  482 
alar  thoracic,  482 
alveolar,  458 


'■  Each  Artery,  Nerve,  Muscle,  Ligament,  Canal,  &c.,  is  placed  in  the  Index  under  the  head  of  Artery, 
Nerve,  Muscle,  Ac;  Carotid  artery,  tor  example,  being  found  under  Artery,  carotid;  Median  nerve,  under 
Nerve,  median,  &c. 

851 


852 


INDEX. 


Artery  or  Arteries — 

anastomotica  magna  of  bra- 
chial, 487 
of  femoral,  523 
angular,  452 
anterior  auricular,  &c.     See 

Artery,  auricular,  &c. 
aorta.    See  Aorta, 
articular,  of  knee,  626 
ascending  cervical,  475 

pharyngeal,  454 
auricular,  anterior,  455 

posterior,  454 
axillary,  479 
branches  of,  481 
peculiarities  of,  481 
surgical  anatomy  of,  481 
azygos  articular  of  knee,  526 
basilar,  474 
brachial,  483 
branches  of,  484 
peculiarities  of,  484 
surgical  anatomy  of,  484 
bronchial,  495,  786 
buccal,  458 

of  bulb  of  urethra,  513,  845 
calcanean,  internal,  533 
carotid,  443 
common,  443 

peculiarities  of,  446 
surgical  anatomy  of,  446 
external,  447 

surgical  anatomy  of,  448 
internal,  461 

surgical  anatomy  of,  464 
carpal  of  radial,  489 
of  ulnar,  493 
posterior  of  radial,  489 
of  ulnar,  493 
of  cavernous  body,  514,  803 
centralis  modioli,  705 

retina?,  467,  688 
cerebellar,  474 
cerebral,  464,  467,  474 
cervical,  ascending,  475 

superficial,  476 
cervicis  princeps,  453 

profunda^  477 
choroid,  anterior,  468 

posterior,  474 
ciliary,  467,  690 
anterior,  407,  690 
long,  467,  690 
short,  467,  690 
circle  of  Willis,  474 
circumflex  of  arm,  482 
anterior,  482 
posterior,  482 
iliac,  518 

superficial,  522,  822 
of  thigh,  523 
external,  523 
internal,  523 
cochlear,  708 
coccygeal,  515 
coeliac  axis,  498 
colica  dextra,  502 
media,  503 
sinistra,  504 
comes  ncrvi  ischiadici,  515 
phreuici,  476 


Artery  or  Arteries — 

communicating,  anterior,  of 
brain,  467 
posterior  of  brain,  468 
communicating     branch     of 
dorsalis  pedis,  530 
of  ulnar,  493 
coronaria  ventriculi,  498 
coronary,  of  heart,  441 
inferior,  451 
left,  442 

of  upper  lip,  449 
of  lower  lip,  448 
of  corpus  cavernosum,  514 
cremasteric,  517 
crico-thyroid,  449 
cystic,  500 

deep  branch  of  ulnar,  493 
cervical,  477 
palmar  arch,  491 
temporal,  454 
deferent,  505 
dental,  inferior,  457 

superior,  458 
descending  palatine,  458 
digital,  of  plantar,  534 

of  ulnar,  493 
dorsal,  of  lumbar,  505 
of  penis,  514 

See  also  Artery,  dor- 
salis. 
dorsalis  hallucis,  530 
indicis,  490 
linguae,  450 
pedis,  529 

branches  of,  530 
peculiarities  of,  530 
surgical  anatomy  of,  530 
penis,  514 
pollicis,  490 
scapulaj,  482 
epigastric,  517 

peculiarities  of,  517 
relation  of,  to   external 
ring,  835 
to  internal  ring,  828 
superior,  477 
superficial,  522,  822 
ethmoidal,  465 
facial,  451      ' 

peculiarities  of,  453 
surgical  anatomy  of,  453 
transverse,  455 
femoral,  518 

branches  of,  521 
peculiarities  of,  520 
surgical  anatomy  of,  520 
deep,  522 
frontal,  467 
gastric,  498,  501 
of  splenic,  500 
gastro-duodcnalis,  500 
epiploica  dextra,  500 
sinistra,  501 
gluteal,  515 
deep,  515 
inferior,  515 
superficial,  516 
helicine,  803 

hemorrhoidal,  external,  513 
inferior,  513 


Artery  or  Arteries — 

middle,  511 

superior,  503 

hepatic,  499,  746 

hyoid  branch  of  lingual,  449 

of  superior  thyroid,  449 
hypogastric,  in  foetus, 509,467 
ileo-colic,  501 
iliac,  507 
circumflex,  517 
common,  507 
left,  507 
right,  507 

peculiarities  of,  507 
surgical  anatomy  of,  508 
external,  516 

surgical  anatomy  of,  517 
internal,  509 
at  birth,  509 
peculiarities  of,  in  foetus, 

509 
surgical  anatomy  of,  510 
ilio-lumbar,  515 
inferior  cerebellar,  coronary, 
&c.  See  Artery,  cerebellar, 
coronary,  &c. 
infra-orbital,  458 
innominate,  442 

peculiarities  of,  443 
surgical  anatomy  of,  443 
intercostal,  477,  495 
anterior,  477,  495 
dorsal,  495 
superior,  477,  495 
internal  auditory,  calcanean, 
&c.    See  Artery,  auditory 
calcanean,  &c. 
interosseous  of  ulnar,  492 
dorsal  of  foot,  530 
of  hand,  489 
anterior,  490 
posterior,  490 
of  radial,  486 
labial  inferior,  452 
lachrymal,  464 
laryngeal,  475 
inferior,  449 
superior,  449 
lateral  sacral,  515 

spinal,  473 
lateralis  nasi,  452 
lingual,  449 

surgical  anatomy  of,  450 
long  ciliary,  467,  690 

thoracic,  482 
lumbar,  505 
malleolar,  529 
external,  529 
internal,  529 
mammary,  internal,  476 
masseteric,  458 
maxillary,  internal,  455 
median,  473,  492 
of  forearm,  492 
of  spinal  cord,  473 
mediastinal,  477 
posterior,  495 
meningeal,    from    ascending 
pharyngeal,  454 
anterior,  from  carotid.  464 
inferior,  from  occipital,  453 


INDEX. 


853 


Artery  or  Arteries — 

middle,  from  internal  max- 
illary, 456 

posterior,  from  vertebral, 
473 

small,  from  internal  maxil- 
lary, 457 
mesenteric,  inferior,  503 

superior,  501 
metacarpal,  489 
metatarsea,  530 
metatarsal,  530 
middle  cerebral,  468 

sacral,  506 
musculo-phrenic,  477 
mylo-hyoid,  457 
nasal,  458 

of  ophthalmic,  467 

of  septum,  452 
nutrient  of  femur,  517 

fibula,  532 

humerus,  486 

radius,  492 

tibia,  532 

ulna,  492 
obturator,  511 

external,  512 

internal,  512 

peculiarities  of,  512 

relations  of,  in  hernia,  836 
occipital,  453 
oesophageal,  475,  495 
ophthalmic,  464 
orbital,  456 
ovarian,  505 
palatine,  ascending,  451 

descending,  458 

inferior,  451 

of  pharyngeal,  458 

posterior,  458 
palmar  arch,  deep,  488 
superficial,  491 

interosseaa,  490 
palpebral,  466 
pancreatic,  501 
pancreatica;  magnae,  501 

parvae,  501 
pancreatico-duodenalis,  500 

inferior,  501 
perforating  arteries,  490 

from     mammary    artery, 
477 

from  plantar,  534 

from  pi'ofunda,  523 
inferior,  523 
middle,  523 
superior.  523 
pericardiac,  477,  495 
perineal,  superficial,  513 

transverse,  513 
peroneal,  532 

anterior,  532 
pharyngea  ascendens,  454 
phrenic,  505 
plantar  external,  533 

internal,  533 
popliteal,  524 

branches  of,  526 

peculiarities  of,  525 

surgical  anatomy  of,  525 


Artery  or  Arteries — 
posterior  auricular,   carpal, 

&c.  See  Artery,  auricular, 

carpal,  &c. 
princeps  cervicis,  453 

pollicis,490 
profunda  of  arm,  inferior,  486 
superior,  486 

cervicis,  477 

femoris,  522 
pterygoid,  457 
pterygo-palatine,  458 
pudic,  accessory,  512 

external,  522 
deep, 522 
inferior,  522 
superficial,  522 
superior,  522 

internal,  512 

peculiarities  of,  513 
in  female,  514 
pulmonary,  534,  786 
pyloric,  inferior,  499 

of  hepatic,  499 
radial,  487 

branches  of,  489 

peculiarities  of,  488 

surgical  anatomy  of,  489 
radialis  indicis,  490 
ranine,  450 
recurrent  interosseous,  493 

radial,  489 

tibial,  529 

ulnar,  anterior,  492 
posterior,  492 
renal,  504,  792 
sacra  media,  506 
sacral,  lateral,  515 

middle,  506 
scapular,  posterior,  476 
sciatic,  514 
short  ciliary,  467,  690 
sigmoid,  504 
spermatic,  504,  805 
spheno-palatine,  458 
spinal,  anterior,  473 

from  intercostal,  495 

in  loins,  514 

in  neck,  473 

in  thorax,  495 

lateral,  473 

from  lumbar,  505 

median,  474 

posterior,  473 

from  vertebral,  472 
splenic,  500,  754 
sterno-mastoid,  449 
stylo-mastoid,  454 
subclavian,  468 

branches  of,  472 

first  part  of  left,  469 

left,  469 

peculiarities  of,  470 

right,  468 

second  portion  of,  470 

surgical  anatomy  of.  470 

third  portion  of,  470 
sublingual,  450 
submaxillary,  452 
submental,  452 
subscapular,  482 


Artery  or  Arteries — 
superficialis  vote,  489 
superior   cerebellar,  corona- 
ry, &c.     See  Artery,  cere- 
bellar, coronary,  &c. 
supra-orbital,  465 
-renal,  504 
-scapular,  475 
sural,  526 
tarsal,  530 
tarsea,  530 
temporal,  454 
anterior,  454 
deep,  457 
middle,  455 
posterior,  455 
surgical  anatomy  of,  456 
thoracic,  acromial,  482 
alar,  482 
aorta,  494 
long,  482 
superior,  481 
thyroid,  inferior,  475 
middle,  445 
superior,  448 
surgical  anatomy  of,  449 
axis,  475 
tibial,  anterior,  527 
branches  of,  529 
peculiarities  of,  528 
surgical  anatomy  of,  528 
posterior,  530 
branches  of,  531 
peculiarities  of,  530 
surgical  anatomy  of,  530 
recurrent,  529 
tonsillar,  452,  475 
transverse  of  basilar,  474 

facial,  455 
transversalis  colli,  475 
tympanic,  from  internal  caro- 
tid, 464 
from    internal    maxillary, 
456 
ulnar,  490 

branches  of,  492 
peculiarities  of,  491 
relations  of,  in  forearm, 
490 
in  hand,  491 
in  wrist,  491 
surgical  anatomy,  of  492 
recurrent,  anterior,  492 
posterior,  492 
umbilical  in  foetus,  767 
how  obliterated,  767 
uterine,  511 
vaginal,  511 

vasa  aberrantia  of  arm,  485 
brevia,  501 
intestini  tenuis,  501 
vertebral,  473 
vesical,  inferior,  511 
middle,  511 
superior,  510 
vestibular,  708 
Vidian,  458 
Arthrodia,  263 
Articulations,  260 

acromio-clavicular,  288 
ankle,  307 


854 


INDEX. 


Articulations — 
atlo-axoid,  269 
calcaneo-astragaloid,  309 

-cuboid.  310 

-scaphoid,  310 
carpal,  294 
carpo-metacarpal,  296 
classification  of,  261 
coccygeal,  283 
costo-clavicular,  286 

-sternal,  278 

-transverse,  277 

-vertebral,  275 
elbow,  289 
femoro-tibial,  301 
of  foot,  307 
hand, 295 
hip,  299 
immovable,  262 
knee,  301 
larynx,  769 
lower  extremity,  299 
metacarpal,  297 
metacarpo-phalangeal,  .298 
metatarsal,  312 
metatarso-phalangeal,  .313 
mixed,  262 
movable,  262 
movements  of,  265 
occipito-atloid,  271 

-axoid,  272 
of  pelvis,  281 

with  spine,  280 
phalanges,  298,  313 
pubic,  283 
radio-carpal,  294 
-ulnar,  inferior,  291 
middle,  291 
superior,  290 
sacro-coccygeal,  283 

-iliac,  281 

-sciatic,  282 

-vertebral,  280 
scapulo-clavicular,  286 

-humeral,  288 
shoulder,  288 

of  spine  with  cranium,  271 
sterno-clavicular,  285 
of  sternum,  280 
tarsal,  309 
tarso-metatarsal,  312 
temporo-maxillary,  273 
tibio-fibular,  inferior,  305 
middle,  305 
superior,  304 
of  the  trunk,  265 
of  tympanic  bones,  701 
of  upper  extremity,  285 
of  vertebral  column,  265 
wrist,  294 
Astragalus,  253 
Atlas,  118 

development  of,  125 
Atrabiliary  capsules,  794 
Auricle  of  ear,  694 

cartilage  of,  695 

ligaments  of,  695 

structure  of,  695 
of  heart,  758,  761 

appendix  of,  761 

left,  761 


Auricle  of  heart — 

openings  in,  758 — 763 
right,  758 

septum  of,  759,  762 
sinus  of,  758,  7G1 
valves  in,  759,  763 
Axes  of  pelvis,  236 
Axilla,  478 
dissection  of,  372 
surgical  anatomy  of,  478 
Axis,  119 

development  of.  125 
cerebro-spinal,  572 
coeliac,  498 
thyroid,  475 
Axis-cylinder  of  nerve  tubes, 
59 

Back,  muscles  of,  347 

Ball  and  socket  joint.    See  En- 

arthrodia. 
Bartholine,  duct  of,  721 

gland  of,  812 
Bauhin,  valve  of,  737 
Beale's  researches  on  the  liver, 
746 
on  motomerves,  59 
Beaunis  and  Bouchard,  table  of 

development,  112 
Bicuspid -teeth,  712 
Bladder,  795 

arteries  of,  798 

base  of,  796 

body  of,  796 

cervix  of,  796 

female,  relations  of,  813 

fundus  of,  796 

interior  of,  797 

ligaments  of,  796 

lymphatics  of,  569,  798 

neck  of,  796 

nerves  of,  798 

shape,  position,  and  relations 
of,  795 

structure  of,  797 

summit  of,  796 

surgical  anatomy  of,  796 

trigone  of,  798 

uvula  of,  798 

veins  of,  798 
Blastodermic  membrane,  90 
Blood,  circulation  of,  in  adult, 
757 
in  foetus,  765 

corpuscles,  33 
Body  of  tooth,  711 

of  vertebra,  117 
Bone,  animal  constituent  of,  39 

apophyses  of,  53 

articular  lamella  of,  260 

canaliculi  of,  46 

cancellous  tissue  of,  45 

cells,  48 

chemical  analysis  of,  48 

compact  tissue  of,  45 

development  of,  49 

diploe  of,  115 

earthy  constituent  of,  48 

eminences  and  depressions  of, 
116 

epiphyses  of,  53 


Bone — 
growth  of,  51 
Haversian  canals  of,  46 

systems  of.  47 

spaces  of,  47 
inorganic  constituent  of,  48 
lacunas  of,  46 
lamellae  of,  46 
lymphatics  of,  46 
marrow  of,  45 
medullary  canal  of,  45 

membrane  of,  45 
microscopic  structure  of,  47 
nerves  of,  46 
number  of,  115 
organic  constituent  of,  48 
ossification  of,  49 
•ossific  centres,  number  of.  52 
periosteum  of,  45 
spongy  tissue  of,  45 
structure  of,  45 
vessels  of,  46 

astragalus,  253 

atlas,  118 

axis,  119 

calcaneum,  249 

carpal,  219 

clavicle,  199 

coccyx,  130 

cranial,  134 

cuboid,  251 

cuneiform  of  carpus,  221 

of  tarsus,  254 
ear,  700 
ethmoid,  154 
facial,  158 
femur,  237 
fibula,  247 
foot,  249 
frontal,  140 
hand, 219 
humerus,  207 
hyoid,  189 
ilium,  228 
incus,  701 
innominate,  227 
ischium,  230 
lachrymal,  163 
lesser  lachrymal,  164 
lingual,  189 
magnum,  223 
malar,  164 
malleus,  700 
maxillary,  inferior,  170 

superior,  1.39 
metacarpal,  224 
metatarsal,  256 
nasal,  158 
navicular,  219,  254 
occipital,  134 
orbicular,  701 
palate,  166 
parietal,  138 
patella,  242 
pelvic,  234 
phalanges  of  foot,  257 

of  hand. 226 
pisiform,  221 
pubic,  232 
radius,  217 


INDEX. 


855 


Bone — 

ribs,  194 

sacrum,  126 

scaphoid  of  carpus,  219 
of  tarsus,  254 

scapula,  202 

semilunar,  220 

sesamoid,  259 

sphenoid,  149 

sphenoidal  spongy,  153 

stapes,  701 

sternum,  190 

tarsal,  249 

temporal,  143 

tibia,  243 

trapezium,  221 

trapezoid,  223 

triquetral,  157 

turbinated,  inferior,  168 
middle,  155 
superior,  155 

tympanic,  697 

ulna,  212 

unciform,  224 

vertebra  dentata,  119 
prominens,  120 

vertebrae,  cervical,  117 
coccygeal,  130 
dorsal,  121 
lumbar,  123 
sacral,  126 

vomer,  169 

Wormian,  157 
Bowman  on  structure  of  kid- 
ney, 793 
Brachia  of  optic  lobes,  598 
Brain,  57,  579.     ^See  also  Cere- 
brum. 

arachnoid  of,  578 

base  of,  587 

development  of,  99 

dura  mater  of,  576 

interior  of,  590 

lateral  ventricles  of,  593 

lobes  of,  587 

membranes  of,  576 

subdivision  into  parts,  579 

upper  surface  of,  585 

■weight  of,  580 
Breasts,  820 
Bronchi,  778 

mode  of  subdivision  in  lung, 
785 

septum  of,  778 

structure   of,   in  lobules   of 
lung,  785 
Brunner's  glands,  735 
Bubonocele,  829 
Bulb,  artery  of,  513,  845 

of  corpus  cavernosum,  803 

of  corpus  spongiosum,  803 

olfactory,  606 
Bulbi  vestibuli,  812 
Bulbs  of  fornix,  595 
Burns,  ligament  of,  833 
Bursae  mucosije,  261 

of  ham,  524 

of  shoulder,  289 

synovial,  261 


C^cuM,  737 

Calamus  scriptorius,  582 
Calcaneum,  249 
Calyces  of  kidney,  792 
Callender  on  hernia,  833 
Canal  or  Canals — • 

accessory  palatine,  166 

alimentary,  709 

anterior  dental,  160 
palatine,  162 

for  Arnold's  nerve,  148 

auditory,  697 

carotid,  146 

central  of  modiolus,  705 

for  chorda  tympani,  145,  703 

of  cochlea,  705 

crural,  835 

dental,  anterior,  161 
inferior,  172 
posterior,  160 

ethmoidal,  anterior,  142 

femoral,  835 

Haversian,  of  bone,  46 

incisive,  181 

infraorbital,  159 

inguinal,  826 

for  Jacobson's  nerve,  147 

lachrymal,  160,  694 

malar,  165 

nasal,  158 

naso-palatine,  159 

of  Nuck,  810,  820 

palatine,  accessory,  165 
anterior,  162 
posterior,  167 

of  Petit,  690 

portal,  743 

pterygoid,  152 

pterygo-palatine,  151 

sacral,  129 

spermatic,  826 

of  spinal  cord,  64 

spiral,  of  cochlea,  705 
of  modiolus,  705 

semicircular,  704.    See  Semi- 
circular canals. 

for  tensor  tympani,  148,  699 

vertebral,  133 

Yidian,  153 

of  Wirsung,  750 
Canaliculi  of  bone,  46 

of  eyelids,  694 
Canalis  spiralis  modioli,  705 
Canthi  of  eyelids,  691 
Capillaries,  74 

pulmonary,  786 
Capsule  of  Glisson,  727 

of  lens,  689 

in  foetus,  101,  689 

of  Malpighian  bodies  of  kid- 
ney, 790 

supra-renal,  793 
Caput  cornu  posterius,  63 

gallinaginis,  798 
Carpus,  219 

articulations  of,  294 

development  of,  226 
Cartilage  or  Cartilages,  41 

articular,  42 

arytenoid,  770 

of  auricle,  695 


Cartilage  or  Cartilages — 

of  bronchi,  779 

cells  of,  42 

circumferential,  43 

connecting,  43 

costal,  42,  198 

cricoid,  770 

cuneiform,  771 

of  ear,  694 

ensiform,  192 

of  epiglottis,  771 

fibro-,43.  iSeeFibro-cartilage. 

hyaline,  42 

interarticular,  44 

intercellular  substance  of,  43 

interosseous,  44 

of  knee,  303 

of  larynx,  769 

of  nose,  678 

of  pinna,  605 

of  Santorini,  771 

palpebral,  601 

permanent,  43 

reticular,  44 

semilunar  of  knee,  303 

of  septum  of  nose,  678 

sesamoid.  259 

spongy,  44 

stratiform,  45 

structure  of,  43 

tarsal,  691 

temporary,  41,  43 

thyroid,  769 

of  trachea,  778 

of  Wrisberg,  771 

xiphoid,  192 

yellow,  44 
Cartilago  triticea,  771 
Caruncle,  lachrymal,  692 
Caruncula  lacrymalis,  692 

mammillaris,  606 
Carunculse  myrtiformes,  812 
Casserian  ganglion,  616 
Cauda  equina,  574,  655 
Cava,  vena.     See  Vena  cava. 
Cavernous  body,  554 

artery  of,  514,  803 
Cavities  of  reserve  of  teeth,  716 
Cavity,  cotyloid,  232 

digital  of  fifth  ventricle,  592 
of  lateral  ventricle,  592 

glenoid,  205 

of  pelvis,  234 

sigmoid,  214.  218 
Cells  of  bone,  47 

ethmoidal,  155 

hepatic,  745 

mastoid,  145,  699 
Cement  of  teeth,  714 

formation  of,  714 
Centrum  ovale  majus,  590 

minus,  590 
Cerebelli  incisura  anterior,  600 

posterior,  600 
Cerebellum,  580,  600 

corpus  dentatum  of,  602 

ganglion  of,  602 

hemispheres  of,  601 

laminae  of,  602 

lobes  of,  601 

lobulus  centralis,  601 


856 


INDEX. 


Cerebellum — 

median  lobe  of,  601 

peduucles  of,  C02 

structure  of,  602 

valley  of,  601 

ventricle  of,  603 

weight  of,  600 
Cerebrum,  579 

base  of,  587 

commissures  of,  597 

convolutions  of,  585 

crura  of,  589 

fibres  of,  599 

fissures  of,  587 

general  arrangement  of,  590 

gray  matter  of,  586 

hemispheres  of,  599 

interior  of,  590 

labia  of,  590 

lobes  of,  587 

peduncles  of,  589 

structure  of,  599 

sulci  of,  586 

under  surface  of,  587 

upper  surface  of,  585 

ventricles  of,  592,  599 
Cervix  cornu  posterius,  63 

uteri,  815 
Chambers  of  eye,  688 
Cheeks,  structure  of,  710 
Chest,  muscles  of  front  of,  372 

muscles  of  side  of,  376 
Chiasma  or  optic  commissure, 

508,  607 
Chorda  dorsalis,  91,  97 

tympani,  612,  708 
Chordae  tendineae  of  left  ven- 
tricle, 763 
of  right,  761 

vocales,  773,  774 

Willisii,  542 
Choroid  coat  of  eye,  683 

plexus  of  fourth    ventricle, 
603 
of  lateral  ventricle,  593 
of  third  ventricle,  597 
Chyle,  37 

Chyli  rcceptaculum,  560 
Cilia  or  eyelashes,  692 
Circle  of  Willis,  475 
Circulation  of  blood  in  adults, 
757 

in  foetus,  765 
Circumduction,  265 
Cistern  of  Pecquet,  560 
Clarke,  Lockhart,  researches  on 
brain  and  spinal  cord,  61, 
62 

on  cranial  nerves,  631 
Clavicle,  199 

articulations  of,  201 

attachments  of   muscles  to, 
201 

development  of,  201 

fracture  of.     See  Fracture. 

peculiarities  of,  201 
Clitoris,  812 

frtuuum  of,  812 

lymphatics  of,  568 

muscles  of.  Hi 2,  844 

prepuce  of.  812 


Cloacal  cavity,  110 
Coccyx,  130 
articulations  of,  131 
attachment    of  muscles  to, 

131 
cornua  of,  131 
development  of,  131 
Cochlea,  704 
arteries  of,  708 
central  axis  of,  705 
cupola  of,  705 
denticulate  lamina  of,  706 
hamular  process  of,  706 
infundibulum  of,  705 
lamina  spiralis  of,  705 
membranous  zone  of,  706 
modiolus  of,  705 
nerves  of,  708 
osseous  zone  of,  706 
scala  tympani  of,  706 

vestibuli  of,  706 
spiral  canal  of,  705 
veins  of,  708 
Colles's  fracture,  401 
Colon,  738 
ascending,  738 
descending,  738 
sigmoid  flexure  of,  738 
transverse,  738 
Columella  cochlcie,  705 
Column,  posterior  vesicular  of 

spinal  cord,  63 
Columnaj  carneae  of  left  ventri- 
cle, 763 
of  right  ventricle,  761 
papillares,  761,  763 
Columns    of   abdominal    ring, 
824 
of  medulla  oblongata,  582 
of  spinal  cord,  575 
of  vagina,  814 
Commissura  brevis  of  cerebel- 
lum, 601 
simplex  of  cerebellum,  601 
Commissure  of  flocculus,  601 

optic,  588,  607 
Commissures  of  brain,  anterior, 
597 
middle,  597 
posterior,  576 
soft,  597 
of  spinal  cord,  gray,  570 
■white,  576 
Conarium.  598 
Concha,  695 
Condyles  of   femur,  «S:c.      Sec 

Femur,  &c. 
Coni  vasculosi,  807 
Conjunctiva,  692 

palpebral  folds  of,  693 
Conus  arteriosus,  760 
Convolution  of  corpus    callo- 
sum,  586 
of  longitudinal  fissure,  586 
supra-orbital,  580 
Convolutions  of  cerebrum,  cor- 
tical substance  of,  584 
structure  of,  61,  585 
white  matter  of,  584 
Cord,  spermatic.  See  Spermatic 
cord. 


Cord- 
spinal.     See  Spinal  Cord. 

umbilical,  96 
Cords,  vocal,  773,  774 
Corium,  674 
Cornea,  682 

arteries  and  nerves  of,  683 

elastic  laminae  of,  682 

proper  substance  of,  682 

structure  of,  682 
Cornicula  laryngis,  771 
Cornu  Ammonis,  594 
Cornua  of  coccyx,  130 

of  hyoid  bone,  189 

of  sacrum,  128 

of  thyroid  cartilage,  769 
Corona  glandis,  801 

radiata,  599 
Corpora  albicantia,  589 

Arantii,  761,  763 

cavernosa  clitoridis,  812 
penis,  802 
crura  of,  802 

geniculata,  599 

lutea,  819 
false,  819 

olivaria,  582 

pyramidalia,  582 

quadrigemina,  598 

restiformia,  582 

striata,  590,  593 
veins  of,  541 
Corpus  callosum,  586.  590 
convolution  of,  586 
genu  of,  591 
peduncles  of,  587, 591 
ventricle  of,  590 

cavernosum.      See    Corpora 
cavernosa. 

dentatum  of  cerebellum,  002 
of  olivary  body,  582 

fimbriatum,  593 — 595 

Highmorianum,  807  

luteum,819  ~ 

spongiosum,  802 

See  also  Corpora. 
Corpuscles,  blood,  33 

Malpighian,  of  kidney,  792 
of  spleen,  753 

Pacinian,  68 

tactile,  68,  80 
Cotunnius,  nerve  of,  621 
Coverings  of  hernia.     See  Her- 
nia. 

of  testis.     See  Testis. 
Cowpcr's  glands,  801,  845 
Cranial  nerves.    *Si?e  Nerves. 
Cranium.     See  Skull. 
Crest,  frontal,  140 

of  ilium.  229 

nasal,  158 

occipital,  134 
internal.  136 

of  pubes,  232 

of  tibia,  245 

turbinated,  of  palate,  168 
of  su])erior  maxillary,  162 
Crista  galli,  154 

ilii.  229 

pubis,  2.32 
Crown  of  tooth,  711 


INDEX. 


85T 


Crura  cerebelli,  602 

cerebri,  588,  589 

of  clitoris,  812 

of  corpora  cavernosa,  802 

of  diaphragm,  369 

of  fornix,  595 
Crus  penis,  802 
Crusta  peUosa  of  teeth,  713 
Crypts  of  Lieberklihn,  735 
Crystalline  lens.  See  Lens,  crys- 
talline. 
Cuboid  bone,  251 
Cuneiform  bone  of  foot,  254 
of  hand,  221 

external,  255 

internal,  254 

middle  255 
Cupola  of  cochlea,  705 
Curling  on  testes,  810 
Curvatures  of  spine,  132 
Cutaneous  nerves.  See  Nerves, 

cutaneous. 
Cuticle,  79 
Cutis  vera,  78 

Dartos,  804 
Deciduous  teeth,  713 
Dens  sapientiae,  712 
Dentine,  713 

chemical  composition  of,  713 

formation  of,  713 
Derma  or  true  skin,  78 
Development  of  atlas,  axis,  &c. 
See   Atlas,  axis,  &c.,   de- 
velopment of. 
Diaphragm,  369 

aortic  opening  of,  370 

lymphatics  of,  571 
Diaphysis,  51 
Diarthrosis,  262 

rotatorius,  263 
Digestion,  organs  of,  709 
Diploe,  115 

veins  of,  540 
Discus  proligerus,  819 
Dissection  of  muscles,  regions, 
hernia,  &c.     See  Muscles, 
Regions,  Hernia,  &c. 
Duct  or  Ducts — 

aberrant,  of  testis,  808 

of  Bartholine,  721 

biliary,  746 

common  choledoch,  748 

of  Cowper's  gland,  801 

cystic,  748 

ejaculatory,  809 

galactophorous,  821 

hepatic,  746,  747 

of  kidney,  793 

lactiferous,  821 

of  liver,  746 

lymphatic,  right,  561 

nasal,  694 

of  pancreas,  750 

parotid,  720 

seminal,  809 

Steno's,  720 

thoracic,  560 

Wharton's,  720 
Ductless  glands.    See  Spleen, 
Thyroid,  &c. 


Ductus  arteriosus,  765 

how  obliterated  in   foetus, 
768 
communis  choledochus,  748 
pancreaticus  minor,  750 
Riviniani,  721 
venosus,  767 

how  obliterated,  768 
Duodenum,  732 

vessels  and  nerves  of,  734 
Dura  mater  of  brain,  576 
arteries  of,  577 
nerves  of,  577 
processes  of,  577 
veins  of,  577 
of  cord,  572 

Ear,  694 

auditory  canal,  697 

auricle  of,  694 

cochlea,  705 

development  of,  102 

external,  694 

helix  of,  695 

internal,  703 

labyrinth,  703 
membranous,  706 

middle,  698 

muscles  of,  319,  696,  702 

ossicula  of,  701 

pinna,  694 

semicircular  canals,  704 

tympanum,   698.      See   also 
Tympanum. 

vestibule,  703 
Ecker  on  supra-renal  capsules, 

794 
Ejaculatory  ducts,  809 
Elbow,  bend  of,  484 

joint,  289 

vessels  and  nerves  of,  291 
Embryo,  human,  89 

growth  of,  96 
Eminence  of  aquseductus  Fal- 
lopii,  699 

canine,  159 

frontal,  140 

ilio-pectineal,  234 

jugular,  134 

nasal,  143 

parietal,  138 
Eminentia  articularis,  143 

coUateralis,  593,  594 
Enamel  of  teeth,  714 

formation  of,  714 

membrane,  714 

rods,  714 
p]narthrosis,  263 
Endocardium,  763 
Endolymph,  707 
Epidermis,  80 

development  and  growth  of, 
81 
Epididymis,  806 
Epiglottis,  771 
Epiphyses,  51 

separation  of,  53 
Erectile   tissue,   structure   of, 
803 

of  penis,  803 

of  vulva,  812 


Ethmoid  bone,  154 
articulations  of,  156 
cribriform  plate  of,  154 
development  of,  156 
lateral  masses  of,  154, 155 
perpendicular  plate  of,  155 
OS  planum  of,  155 
unciform  process  of,  155 
Eye,  680 
appendages  of,  691 
arteries  of,  690 
chambers  of,  688 
ciliary  ligament,  686 

muscle,  686 

processes,  684 
humors  of,  688 

aqueous,  688 

crystalline  lens,  689 

vitreous,  689 
membrana  pupillaris,  686 
membranes  of,  681 

choroid,  683 
t       conjunctiva,  692 

cornea,  682 

hyaloid,  689 

iris,  685 

Jacob's,  687 

retina,  686 

sclerotic,  681 
pupil  of,  685 
tunics  of,  681 
uvea  of,  688 
vessels  of  globe  of,  690 
Eyeball,  680 
muscles  of,  321 
nerves  of,  691 
tunics  of,  681 
vessels  of,  690 
Eyebrows,  691 
Eyelashes,  691 
Eyelids,  691 

cartilages  of,  691 
Meibomian  glands  of,  692 
muscles  of,  320,  691 
tarsal  ligament  of,  692 
Eye-teeth,  712 

Face,  184 

arteries  of,  451 

bones  of,  134,  158 

lymphatics  of,  561 

muscles  of,  316 

nerves  of,  610 

veins  of,  536 
Fallopian  tubes,  817 

fimbriated  extremity  of,  818 

lymphatics  of,  569 

nerves  of,  818 

vessels  of,  818 
Falx  cerebelli,  578 

cerebri,  578 
Fangs  of  teeth,  711 
Fascia  or  Fascia;,  315 

anal,  850 

aponeurotic,  315 

of  arm,  380 

cervical,  deep,  332 
superficial,  331 

costo-coracoid,  374 

af  cranial  region,  317 

cremasteric,  804,  826 


858 


INDEX. 


'  Fascia  or  FasciiB — 
cribriform,  831 
deep,  315 
dcntata,  595 
dorsal,  of  foot,  428 
fibro-areolar,  315 
of  foot,  309 
of  forearm,  383 
of  hand,  393 
iliac,  403 

infundibuliform,  827 
of  inguinal  region,  823 
intercolumnar,  361,  804,  824 
intercostal,  366 
intermuscular,  of  arm,  380 
of  foot,  426 
of  thigh,  405 
ischio-rectal,  850 
lata,  405,  832 

falciform  process  of,  832 
iliac  portion  of,  406 
pubic  portion  of,  406 
of  leg,  418 
lumbar,  363 
lumborum,  363 
of  neck,  331 
obturator,  849 
palmar,  394 
pelvic,  849 
perineal,  deep,  844 

superficial,  841 
plantar,  427 
propria,  of  spermatic   cord, 

804 
recto-vesical,  850 
spermatic,  .361,  824 
superficial,  315 

of  cranial  region,  317 
of  inguinal  region,  822 
of  ischio-rectal  region,  841 
perineal,  841,  844 
of  thigh,  403 
of  thoracic  region,  372 
of  upper  extremity,  372 
temporal,  328 
of  thigh,  deep,  405 

superficial,  405 
of  thorax,  372 
transversalis,  827 
Fasciculi  graciles,  681 

teretes,  582 
Fasciculus  unciformis.  588 
Fauces,  isthmus  of,  718 
Fecundation  of  ovum,  90 
Female  organs  of  geaoration, 
811 
bulbi  vestibuli,  812 
caruncula;  myrtiformes,  812 
clitoris,  812 
development  of.  111 
fossa  navicularis,  812 
fourchette,  812 
frainulum  pudondi.  812 
glands  of  Bartholine,  812 
hymen.  812 
labia  majora,  811 

minora,  812 
mons  veneris,  811 
nymphae,  812 
prajputium  clitoridis,  812 
uterus,  815 


Female  Organs  of  Generation — 

vagina,  814 

vestibule.  812 
Femoral  hernia.     See  Hernia, 

femoral. 
Femur,  237 

articulations  of,  242 

attachment   of   muscles   to, 
242 

development  of,  242 

fracture  of,  432 

structure  of,  241 
Fenestra  ovalis,  698,  704 

rotunda,  698,  705 
Ferrein,  pyramids  of,  792 

tubes  of,  791 
Fibrae  arciformes.  581 

transversae,  603 
Fibre  cells,  muscular,  55 
Fibrin  of  muscle,  315 
Fibro-cartilage,  43 

acromio-clavicular,  286 

circumferential,  44 

connecting,  44 

interarticular.    See  Tnterarti- 
cular  fibro-cartilage. 

intercoccygean,  283 

interosseous,  261 

intervertebral,  267 

of  knee,  303 

of  lower  jaw,  274 

pubic,  284 

radio-ulnar,  292 

sacro-coccygeal,  283 

semilunar,  303 

stcrno-clavicular,  286 

stratiform,  44 

triangular,  292 
Fibrous  tissue,  white  and  yel- 
low, 38 
Fibula,  247 

articulations  of,  249 

attachmentof  muscles  to,  249 

development  of.  249 

fracture  of,  with  dislocation 
of  the  tibia,  435 
Filum  terminale  of  cord,  574 
Fimbriae  of  Fallopian  tube,  818 
Fissura  palpebrarum.  691 
Fissure,  auricular,  148 

of  cerebellum,  600 

of  cranial  bones,  congenital, 
157 

of  ductus  venosus,  743 

of  eyelids,  691 

for  gall-bladder,  743 

Glaserian,  144,  698 

of  liver,  743 

longitudinal,  of  cerebrum,  587 
of  liver,  743 

of  lung,  784 

maxillary,  161 

of  mc«lulla  oblongata,  583 

palpebral,  691 

portal,  743 

pterygo-maxillary,  184 
spheno-maxillary,  184 
sphenoidal,  151 
of  spinal  cord,  lateral,  575 

median,  575 
of  Sylvius,  588 


Fissure — 

transverse,  of  cerebrum,  595 
of  liver,  743 

nmbilical,  of  liver,  743 

for  vena  cava,  743 
Flocculus,  601 
FcEtus,  circulation  in.  766 

Eustachian  valve  in,  765 

foramen  ovale  in,  765 

liver  of,  distribution  of  ves- 
sels in,  767 

ovaries  in,  109 

peculiarities  of  vascular  sys. 
tem  in,  7G5 

relics  in  heart  of.  759 
Folds,    ary teno  -  epiglottidea  a, 
771 

genital,  109 

recto-uterine,  816 

recto-vesical,  796 

vesico-uterine,  816 
Follicle  of  hair,  82 
Follicles,  dental,  716 

gastric,  731 

sebaceous,  83 
Fontanelles,  137,  156 
Foot,  arteries  of,  529,  533 

bones  of.  249 

development  of,  258 

fascia  of,  428 

ligaments  of,  309 

muscles  of,  428 

nerves  of,  660 

veins  of,  552 
Foramen.     See  also  Foramina. 

caBcum  of  frontal  bone,  141. 
177 
of  medulla  oblongata,  580 
of  tongue,  675 

carotid,  147 

condyloid.  137 

dental,  inferior,  172 

ethmoidal,  178 

incisive.  181 

infra-orbital,  160 

intervertebral,  133 

jugular,  179 

lacerum  antcrius,  179 
medium,  179 
posterius,  179 

magnum,  134 

mastoid,  145 

mental,  170 

of  Monro,  593,596 

obturator,  232 

optic,  150,  178 

ovale  of  heart,  765 
of  sphenoid.  151.  179 

palatine,  anterior.  162, 181 
posterior.  167,  181 

parietal,  139 

pterygoid,  153 

pterygo-palaline.  151 

rotundum,  151.  178 

sacro-sciatic,  2.'U.  282 

of  Sommering,  686 

spheno-palatine,  168,  189 

spinosum,  151,  178 

sternal,  192 

stylo-mastoid,  148 

supra-orbital,  141 


INDEX. 


859 


Foramen — 

thyroid,  232 

vertebral,  118 

Vesalii,  151 

of  Winslow,  727 
Foramina  of  diaphragm,  370 

external  orbitar,  152 

malar,  165 

olfactory,  154 

eacral,  128 

Thebesii,  558,  759 
See  also  Foramen. 
Forearm,  arteries  of,  486 

bones  of,  212 

fascia  of,  383 

lymphatics  of,  565 

muscles  of,  383 

nerves  of,  640 

veins,"  of,  545 
Foreskin,  801 
Fornix,  593,  595 

body  of,  595 

bulbs  of,  589 

crura  of,  595 
Fossa  of  antihelix,  695 

canine,  159 

cerebral,  176 

condyloid,  135 

cystidis  felleaj,  743 

digastric,  145 

digital,  238 

glenoid,  144 

of  helix,  695 

iliac,  229 

infra- spinous,  204 

incisive,  159 

innominata,  695 

ischio-rectal,  840 

jugular,  182 

lachrymal,  142 

myrtiform,  159 

navicular  of  urethra,  798 
of  vulva,  812 

occipital,  135 

ovalis,  759 

palatine,  anterior,  162,  179 

pituitary,  150 

pterygoid  of  sphenoid,  1 53 
of  lower  jaw,  172 

scaphoid,  153 

scaphoidea,  695 

spheno-maxillary,  184 

of  skull,  anterior,  176 
middle,  178  ' 
posterior,  179 

sublingual,  171 

submaxillary,  172 

subscapular,  202 

supra-spinous,  203 

temporal,  183 

trochanteric,  238 

zygomatic,  184 
Fossije,  cranial,  176 

nasal,  187,  679 
Fourchette,  812 
Fovea  centralis  retinae,  686 

hemispherica,  703 

semi-elliptica,  704 
Fracture  of  acromion  process, 
399 

clavicle,  399 


Fracture — 

acromial  end  of,  399 
centre  of,  399 
sternal  end  of,  399 
Colles's,  401 
ooracoid  process,  399 
corouoid  process  of  ulna,  400 
femur  above  condyles,  433 
below  trochanters,  433 
neck  of,  433 
fibula,  with  dislocation  of  ti- 
bia, 435 
humerus,  399 

anatomical  neck,  399 
shaft  of,  400 
surgical  neck,  399 
olecranon  process,  400 
patella,  434 
Pott's,  435 
radius,  401 

lower  end  of,  401 
neck  of,  401 
shaft  of,  401 
and  ulna,  401 
tibia,  434 
ulna,  401 
Frsena  of  ileo-coecal  valve,  738 
Fraenulum  cerebri,  599 
pudendi,  812 
of  Yieussens's  valve,  599 
Fraenum  clitoridis,  812 
labii  inferioris,  709 

superioris,  709 
linguae,  675 
prseputii,  801 
Frontal  bone,  140 

articulations  of,  143 
attachment  of  muscles  to, 

143 
development  of,  143 
structure  of,  143 
Fundus  of  bladder,  796 

of  uterus,  815 
Furrow,    auriculo- ventricular, 
757 
genital.  111 
interventricular,  758 

Gall-bladder,  747 

development  of,  107 

duct  of,  747 

fissure  for,  743 

structure  of,  747 

valve  of,  747 
Ganglion  or  Ganglia — 

Arnold's,  624 

of  Andersch,  626 

cardiac,  668 

carotid,  665 

Casserian,  616 

cephalic,  617,  663 

of  cerebellum,  602 

cervical,  inferior,  666 
middle,  666 
superior,  665 

ciliary,  617 

on  circumflex  nerve,  614 

diaphragmatic,  669 

on  facial  nerve,  611 

of  fifth  nerve,  617 

glosso-pharyngeal,  62G 


Ganglion  or  Ganglia — 

impar,  663,  671 

intercarotid,  666 

on  interosseous  nerve,  poste- 
rior, 646 

jugular,  626 

lenticular,  617 

lingual,  666 

lumbar,  671 

lymphatic.    See  Lymphatic 
glands. 

Meckel's,  620 

mesenteric,  670 

ophthalmic,  617 

otic,  624 

petrous,  626 

pharyngeal,  666 

pneumogastric,  628 

of  portio  dura,  611 

renal,  670 

of  Ribes,  663 

of  root  of  vagus,  628 

sacral,  671 

semilunar  of  abdomen,  669 
of  fifth  nerve,  616 
of  sympathetic,  669 

solar,  669 

spheno-palatine,  620 

of  spinal  nerves,  633 

submaxillary,  625 

supra-renal,  670 

of  sympathetic  nerve,  663 

temporal,  666 

thoracic,  668 

thyroid,  666 

of  trunk  of  vagus,  628 

of  Wrisberg,  668 
Ganglion  corpuscles,  64 
Generative  organs,  female.  See 
Female  organs  of  genera- 
tion. 

male.    See  Penis,  Scrotum, 
&c. 
Genu  of  corpus  callosum,  591 
Germinal  area,  89 

spot  of  ovum,  89 

vesicle  of  ovum,  89 
Gimbernat's  ligament,  359, 825, 

834 
Ginglymos,  263 
Gladiolus,  192 
Gland  or  Glands — 

absorbent,  78 

accessory  of  parotid,  720 

aggregate,  736 

agminate,  736 

arytenoid,  777 

of  Barlholinc,  812 

of  biliary  ducts,  749 

Brunner's,  735 

buccal,  710 

ceruminous,  698 

coccygeal,  506 

conglobate,  559 

Cowper's,  801,  845 

duodenal,  735 

ductless.     See  Spleen,  Thy- 
mus, &c. 

epiglottic,  776 

gastric,  732 
genital,  108 


860 


INDEX. 


Gland  or  Glands — 

of  Havers,  261 

inguinal,  830 

kidney,  790 

labial,  709 

lachrymal,  693 

of  larynx,  776 

lingual,  666 

of  Littr6,  799 

liver,  741 

lumbar,  506 

Luschka's,  506 

lymphatic.     See  Lymphatic 
glands. 

mammary,  820 

Meibomian,  692 

molar,  710 

mucilaginous  of  Havers,  261 

odoriferae,  801 

oesophageal,  723 

of  Pacchioni,  577 

palatal,  718 

pancreas,  749 

parotid,  719 

peptic,  732 

Peyer's,  736 

pharyngeal,  722 

pineal,  598 

pituitary,  589 

prostate,  800 

salivary,  719 

sebaceous,  83 

solitary,  735,  740 

sublingual,  720 

submaxillary,  720 

sudoriferous,  84 

supra-renal,  792 

sweat,  84 

thymus,  788 

thyroid,  787 

of  tongue,  676 

tracheal,  779 

of  Tyson,  801 

uterine,  816 

of  vagina,  815 

of  vulva,  811 
Glandulse  odoriferaj,  801 

Pacchioni,  577 

solitariae,  735,  740 

Tysonii,  801 
Glans  clitoridis,  812 

penis,  801 
Gliding  movement,  263 
Glisson's  capsule,  744 
Globus  major  of   epididymis, 
806 

minor  of  epididymis,  806 
Glottis,  773 

rima  of,  773 
Gomphosis,  262 
Graafian  vesicles,  818 

mcmbrana  granulosa  of,  819 

ovicapsule  of,  819 

structure  of,  819 
Gray   matter    of    cerebellum, 
602 

of  cerebrum,  586 

of  fourth  vt'utriclc,  603 

of  medulla  oblongata,  583 

of  sj)inal  cord,  62 

of  third  ventricle,  597 


Groin,  822 

cribriform  fascia  of,  831 

cutaneous  vessels  and  nerves 
of,  822 

region  of,  822 

superficial  fascia  of,  822 

surgical  anatomy  of,  822 
Groove,    auriculo -ventricular, 
757 

bicipital,  207 

cavernous,  150 

dental,  715 

infra^orbital,  160 

lachrymal,  IGl 

mylo-hyoid,  171 

nasal,  158 

occipital,  145 

optic,  150 

subclavian,  200 
Grooves  in  radius,  218 

ventricular,  757 
Growth  of  bone,  51 

of  body,  89 
Gubernaculum  testis,  810 
Gums,  710 
Gyri  operti,  588 
Gyrus  fornicatus,  586,  590 

Hairs,  82 

follicles  of,  82 

root  of,  83 

shaft  of,  83 

sheath  of,  83 

structure  of,  82 
Ham,  region  of,  524 
Hamstring    tendons,    surgical 

anatomy  of,  418 
Hand,  arteries  of,  486 

bones  of,  219 

development  df,  226 

fascia  of,  393 

ligaments  of,  291 

muscles  of,  393 

nerves  of,  from  median,  643 
from  radial,  646 
from  ulnar,  644 

veins  of,  546 
Harmonia,  262 
Havers,  glands  of,  261 
Haversian  canals,  46 
Head,  lymphatics  of,  561 
muscles  of,  317 
veins  of,  536 
Heart,  757 

annular  fibres    of   auricles, 
764 

arteries  of,  437,  441,  765 

auricles  of,  758,  761 

circular  fibres  of,  764 

development  of.  103 

endocardium,  763 

fibres  of  auricles,  764 
of  ventricles,  764 

fibrous  rings  of,  764 

foetal  relics  in,  759 

infundibulum  of,  760 

left  auricle,  761 
ventricle,  762 

looped  fibres  of  auricles,  764 

lymphatics  of,  571,  765 

muscular  structure  of,  764 


Heart — 

nerves  of,  630,  667,  765 
openings  into,  758,  760 
peculiarities  of,  in  foetus,  765 
position  of,  767 
right  auricle,  758 

ventricle,  762 
septum  ventriculorum,  762 
size  and  weight,  757 
spiral  fibres  of,  764 
structure  of,  763 
subdivision  into  cavities,  757 
valves  of,  759—763 
veins  of,  765 
vortex  of,  764 
Helicotreraa  of  cochlea,  706 
Helix,  695 
fossa  of,  695 
muscles  of,  695 
process  of,  695 
Hernia,  congenital,  829 
direct  inguinal,  829 
course  of,  829 
coverings  of,  829 
diagnosis  of,  830 
incomplete,  829 
femoral,  complete,  837 
cutaneous      vessels      and 

nerves  of,  830 
coverings  of,  837 
descent  of,  837 
dissection  of,  830 
incomplete,  838 
seat  of  stricture  in,  838 
superficial  fascia  of,  830 
surgical  anatomy  of,  830 
varieties  of,  838 
infantile,  829 
inguinal,  822 

dissection  of,  828 
external,  828 
internal,  828 
surgical  anatomy  of,  822 
oblicjue  inguinal,  828 
course  of,  828 
coverings  of,  828 
scrotal,  828 
Hesselbach's  triangle,  829 
Hey's  ligament,  833 
Hiatus  Fallopii,  146 
Highmore,  antrum  of,  161 
Hilton's  muscle,  774 
Hilum  of  kidney,  790 

of  spleen,  750 
Hip-joint,  299 

muscles  of,  410 
Hippocampus  major,  594 

minor,  593 
Huguier,  canal  of,  145 
Humerus.  207 

articulations  of,  211 
attachment   of    muscles   to, 

211 
development  of,  211 
nutrient  artery  of,  486 
tuberosities  of,  207 
Humors  of  ej-o,  681 
Hyaloid  membrane  of  eye,  682 
Hymen,  812 
llyoid  bone,  189 
'attachment ol'muscles  to,  190 


^1 


INDEX. 


861 


Hyoid  bone^ 

development  of,  190 

Ileum,  734 
Ilium,  228 
Impressio  colica,  744 

renalis,  744 
Incisor  teeth,  711 
Incisura  cerebelli,  GOO 
intertragica,  695 
Santorini,  697 
Incus,  701 
ligament  of,  "701 
suspensory,  701 
Inferior  maxillary  bone.     See 

Jaw,  lower. 
Infundibula  of  kidney,  792 
Infundibulum  of  brain,  589 
of  cochlea,  705 
of  ethmoid,  156 
of  heart,  760 
Ingrassias,  processes  of,  152 
Innominate  bone,  227 
articulations  of,  234 
attachment  of  muscles  to, 

234 
development  of,  234 
Interarticular     fibro-cartilage, 
43 
of  jaw,  274 
of  knee,  303 
of  pubes,  284 
of  radio-ulnar  joint,  292 
of    sacro-coccygeal  joint, 

283 
of  scapulo-clavicular  joint, 

286 
of  sterno-clavicular  joint, 
286 
Intercellular  substance  of  car- 
tilage, 42 
Intercostal  spaces,  194 
Intestine,  large,  736 
cellular  coat  of,  740 
ileo-cajcal  valve,  737 
mucous  membrane  of,  740. 
muscular  coat  of,  739 
serous  coat  of,  739 
small,  732 

cellular  coat  of,  732 
divisions  of,  732 
glands  of,  735 
mucous  coat  of,  734 
muscular  coat  of,  734 
serous  coat  of,  734 
simple  follicles  of,  735 
valvuL-B  conniventes,  734 
villi  of,  734 
Intumescentia  ganglifonnis,611 
Iris,  685 
Ischium,  230 
Island  of  Ileil,  588 
Isthmus  of  fauces,  718 

of  thyroid  gland,  788 
Iter  ad  infundibulum,  598 

a  tertio  ad  quartumventri- 
culum,  597 
Ivory  of  tooth,  713 

Jacob's  membrane,  687 
Jacobson's  nerve,  626,  703 


Jacobson's  nerve — 

canal  for,  147 
Jaw,  lower,  170 

articulations  of,  174 
attachment  of  muscles  to, 

174 
changes  produced  by  age 

in,  174 
development  of,  174 
ligaments  of,  273 
rami  of,  172 
symphysis  of,  170 
upper,     ^"ee  Superior  maxil- 
lary bone. 
Jejunum,  734 
Joint.     See  Articulations. 

Kerkring,  valves  of,  734 
Kidneys,  790 

artery  of,  792 

calyces  of,  792 

cortical  substance  of,  790 

development  of,  108 

ducts  of,  792 

hilum  of,  790 

infundibula  of,  792 

lymphatics  of,  569,  793 

Malpighian  bodies  of,  792 

mammillae  of,  791 

medullary  substance  of,  791 

nerves  of,  793 

papillae  of,  791 

pelvis  of,  792 

pyramids  of  Ferrein,  792 
of  Malpighi,  791 

sinus  of,  790 

tubes  of  Ferrein,  791 

tubuli  uriniferi,  791 

veins  of,  792 

weight  and  dimensions  of,  790 
Knee-joint,  301 
Kuhne  on  motor  nerves,  70 

Labia  cerebri,  590 
pudendi  majora,  811 
minora,  812 
lymphatics  of,  569 
Labyrinth,  703 
arteries  of,  708 
fibro-serous  membrane  of,  706 
membranous,  706 
nerves  of,  708 
veins  of,  708 
Lachrymal  apparatus,  693 
bones,  163 

articulations  of,  164 
attachment  of  muscles  to, 

164 
development  of,  164 
Lacteals,  570,  735 
Lacuna  magna,  799 
Lacunae  of  bone,  46 
Lacus  lacrymalis,  691 
Lamella,  articular,  260 
of  bone,  46 
horizontal,  of  ethmoid,  154 
perpendicular,    of   ethmoid, 
155 
Lamina  cinerea,  587 

cribrosaof  sclerotic,  681 
deniiculate  of  cochlea,  706 


Lamina — 
fusca  of  sclerotic,  681 
membranacea,  705 
spiralis  of  cochlea,  705 
Lamina  of  cornea,  elastic,  682 

of  vertebrae,  117 
Lancisi,  nerve  of,  591 
Laryngo-tracheotomy,  779 
Laryngotomy,  779 
Larynx,  769 
arteries  of,  777 
cartilages  of,  769 
cavity  of,  773 
glands  of,  776 
glottis,  773 
interior  of,  772 
ligaments  of,  771 
lymphatics  of,  777 
mucous  membrane  of,  776 
muscles  of,  774 

actions  of,  776 
nerves  of,  777 
rima  glottidis,  773 
superior  aperture  of,  772 
veins  of,  777 
ventricle  of,  772 
vocal  cords  of,  false,  774 
inferior,  773 
superior,  773 
true,  773 
Lee,  researches  on  sympathetic 

nerve,  672 
Leg,  arteries  of,  527 
bones  of,  242 
fascia  of,  418 

deep,  423 
ligaments  of,  305 
lymphatics  of,  565 
muscles  of,  418 
nerves  of,  651 
veins  of,  551 
Lens,  crystalline,  689 
capsule  of,  689 
changes  produced  in  by  age, 

690 
development  of,  101 
structure  of,  690 
suspensory  ligament  of,  690 
Lieberklihn,  crypts  of,  735 
Ligament  or  Ligaments,  struc- 
ture of,  260 
accessory,  288 

acromio-clavicular,  superior, 
286 
inferior,  286 
alar  of  knee,  304 
of  ankle,  anterior,  307 

lateral,  307 
annular  of  ankle,  426 
anterior,  427 
external,  427 
internal,  427 
of  radius  and  ulna,  291 
of  stapes,  702 
of  wrist,  anterior,  393 
posterior,  393 
anterior  of  knee,  301 
arcuate,  369 
aryteno-epiglottic,  771 
astragalo-scaphoid,  311 
atlo-axoid,  anterior,  269 


862 


INDEX. 


Ligament  or  Ligaments — 

posterior,  2(59 

of  bladder,  false,  796 

true,  796 
broad  of  liver,  741 

of  uterus,  820 
calcaneo-astragaloid,    exter- 
nal, 309 

interosseous,  309 

posterior,  309 
calcaneo-cuboid,  internal,  310 

long,  310 

short,  310 

superior,  310 
calcaneo-scaphoid,    inferior, 
310 

superior,  310 
capsular.        See    Individual 

Joints, 
carpo-metacarpal,  295 
of  carpus,  294 
central,  of  spinal  cord,  574 
check,  273 
ciliary  of  eye,  686 
common  vertebral,  anterior, 
266 

posterior,  266 
conoid,  286 
coraco-acromial.  287 

-clavicular,  286 

-humeral,  288 
coracoid,  288 
coronary  of  knee,  304 

of  liver,  742 
costo-clavicular,  285 

-sternal,  anterior,  278 
posterior,  278 

-transverse,  277 

-vertebral,  275 

-xiphoid,  278 
cotyloid,  300 
crico-arytenoid,  772 

-thyroid,  772 
crucial  of  keee,  303 
cruciform,  271 
deltoid,  307 

dorsal.  <SeeIndividualJoints. 
of  elbow,  289 

anterior,  289 

external  lateral,  290 

internal  lateral,  290 

posterior,  289 
falciform  of  liver,  742 
femoral,  833 
gastro-phrenic,  730 
Gimbernat's,  359,  825,  834 
glenoid,  288,  298 
glosso-epiglottidean,  771 
iley's,  833 
of  hip,  299 

hyo-epiglottic,  771,  772 
ilio-fcmoral,  300 

-lumbar,  281 
of  incus,  701 
intorarticular  of  ribs,  276 
iutercluviculur,  285 
inie roost al,  279 
interosseous.    See  Individual 

Joints, 
interspinous,  268 
interlransversej  268 


Ligament  or  Ligaments. — 
intervertebral,  267 
of  jaw,  273 
of  knee,  301 
of  larynx,  771 
lateral.         ^ee     Individual 

Joints, 
longitudinal  of  liver,  742 
lumbo-iliac,  281 

-sacral,  281 
of  malleus,  701 
metacarpal,  297 
metacarpo-phalangeal,  298 
metatarsal,  312 
metatarso-phalangeal,  313 
mucosum,  304 
nuchse,  348 
oblique,  291 
obturator,  284 

occipito-atloid,  anterior,  271 
lateral,  272 
posterior,  272 

-axoid,  272 
odontoid,  273 
orbicular,  291 
of  ossicula,  701 
of  ovary.  820 
palmar,  295 
palpebral,  692 
of  patella,  301 
of  pelvis,  281 
of  phalanges  of  hand,  298 

of  foot,  313 
of  pinna,  695 
plantar,  312 

long,  312 
posterior  of  knee,  301 
posticum  Winslowii,  301 
Poupart's,  359,  825,  833 
pterygo-maxillary,  327 
pubic,  anterior,  283 

posterior,  283 

superior,  283 
pubo-prostatic,  796,  800 
radio-carpal,  294 
radio-nlnar.  anterior,  291 

middle,  291 

posterior,  291 
recto-uterine,  815 
rhomboid,  285 
round,  of  hip,  299 

of  liver,  742 

of  radius  and  ulna,  291 

of  uterus,  815 
sacro-coccygeal,  anterior,283 

posterior,  283 
sacro-iliac,  anterior,  282 

oblique,  282 

posterior,  282 
sacro-sciatic,  anterior,  great- 
er, 282 
lesser,  282 

posterior,  282 
sacro-vertebral,  283 
of  scapula,  287 
Bcapulo-clavicular,  286 
of  shoulder,  288 
of  stapes.  702 
stellate,  275 

sterno-clavicular,      anterior, 
285 


Ligament  or  Ligaments — 

posterior,  285 
of  sternum.  280 
stylo-maxillary,  274 
subflavous,  268 
subpubic,  284 
Bupra-spinous,  268 
suspensory,  of  incus,  702 

of  lens,  690 

of  liver,  741 

of  malleus,  701 

of  mamma,  372 

of  penis,  801 

of  spleen,  750 
sutural,  260 
tarsal,  309 

of  eyelids,  692 
tarso-metatarsal,  312 
thyro-arytenoid.  inferior,  774 
superior,  773 

-epiglottic,  771,  772 

-hyoid,  772 
tibio-fibular,  306 

-tarsal,  307 
transverse  of  atlas,  269 

of  hip,  300 

of  knee,  304 

of  scapula,  288 

of  tibio-fibular,  306 
trapezoid,  286 
triangular,  360,  825 
of  tympanic  bones,  700 
of  urethra,  825 
of  uterus,  815 
of  vertebne,  265 
vesico-uterine,  815 
of  Winslow,  301 
of  wrist,  294 

anterior,  294 

lateral,  external,  294 
internal,  294 

posterior,  294 
of  Zinn,  322 
Ligamenta  alaria,  304 
subflava,  268 
suspensoria  of  mamma,  372 
See  also  Ligament. 
Ligamentum   arcuatum  exter- 
num, 369 

internum,  369 
denticulatum,  574 
latum  pulmonis,  781 
mucosum,  304 
nuchas,  348 
patellifi,  301 

posticum  "SVinslowii,  301 
teres.    See  Ligament,  round. 
See  also  Ligament. 
Ligation  of  arteries.     See  Ope- 
ration. 
Limbus  luteus,  686 

Linea  alba,  365  

aspera,  239 
ileo-pectinca,  234 
quadrati,  239 
splendcns,  574 
Linea)  somilunares,  365 

transversa)  of  abdomen,  365 

of  fourth  ventricle,  607 
Lingual  bone,  189 
Linjjuetta  laminosa,  599 


INDEX. 


863 


Lips,  709 

arteries  of,  452 
Liquor  amnii,  91 

chyli,  37 

Cotunnii,  706 

Morgagnii,  689 

sanguinis,  33,  37 

Scarpae,  707 

.  seminis,  809 
Lithotomy,  parts  avoided  in, 848 

parts  concerned  in,  847 
divided  in,  848 
Littr6,  glands  of,  799 
Liver,  741 

arteries  of,  499,  746 

changes  of  position  in,  741 

development  of,  107 

distribution  of  vessels  to,  in 
fffitus,  768 

ducts  of,  746 

fibrous  coat  of,  745 

fissures  of,  743 

ligaments  of,  742 

lobes  of,  744 

lobules  of,  745 

lymphatics  of,  569,  744 

nerves  of,  744 

situation,  size,   and  weight, 
741 

structure  of,  744 

surfaces  and  borders  of,  741 

vessels  of,  744 
Lobes  of  cerebellum,  601 
digastric,  602 
inferior,  posterior,  602 
pneumogastric,  602 
slender,  602 
subpeduncular,  602 

of  cerebrum.    See  Cerebrum. 

of  liver.     See  Liver. 

of  lung,  784 

optic,  598 

of  prostate,  800 

of  testis,  807 

of  thymus,  788 

of  thyroid,  787 
Lobule  of  ear,  695 
Lobules  of  liver,  745 

of  lung,  786 
Lobulettes  of  lung,  786 
Lobuli  testis,  807 
Lobulus  caudatus,  744 

centralis  of  cerebellum,  601 

quadratus,  744 

Spigelii,  744 
Locus  caeruleus,  603 

niger,  590 

perforatus  anterior,  589 
posterior,  589 
Lower  extremity,  arteries   of, 
516 

bones  of,  227 

fascia  of,  403 

ligaments  of,  299 

lymphatics  of,  565 

muscles  of,  403 

nerves  of,  671 

veins  of,  551 
Lower,  tubercle  of,  759 
Lungs,  782 

air-cells  of,  786 


Lungs — 

air-sacs  of,  786 

capillaries  of,  786 

development  of,  107 

in  foetus,  787 

lobes  and  fissures  of,  784 

lobules  of,  786 

lobulettes  of,  786 

lymphatics  of,  571,  787 

nerves  of,  787 

parenchyma  of,  786 

pulmonary  artery,  786 
veins,  787 

root  of,  784 

structure  of,  785 

subdivision  of  bronchi  in,  786 

weight,  color,  etc.,  785 
Lunulas  of  nails,  82 
Luschka's  gland,  506 
Lymph,  37 
Lymph  sinus,  78 
Lymphatic  duct,  right,  561 
Lymphatic  glands,  78 

auricular  posterior,  561 

axillary,  564 

brachial,  565 

bronchial,  571 

buccal,  561 

cervical,  deep,  563 
superficial,  563 

of  elbow,  565 

gluteal,  566 

of  head,  superficial,  561 

iliac,  external,  567 
internal,  567 

inguinal,  deep,  566 
superficial,  565 

intercostal,  570 

internal  mammary,  570 

ischiatic,  566 

of  large  intestine,  570 

of  lower  extremity,  565 

lumbar,  567. 

mammary,  570 

mediastinal,  570 

mesenteric,  570 

of  neck,  563 

occipital,  561 

parotid,  561 

of  pelvis,  567 
deep,  567 

popliteal,  566 

radial,  565 

sacral,  567 

of  small  intestine,  570 

of  spleen,  570 

of  stomach,  569 

submaxillary,  561 

of  thorax,  570 

tibial,  anterior,  565 

ulnar,  565 

of  upper  extremity,  564 

zygomatic,  561 
Lymphatics,  77 

abdomen,  567 

arm,  565 

bladder,  569 

bone,  46 

broad  ligaments,  569 

cardiac,  571 

cerebral,  562 


Lymphatics — 
cervical,  563 
chest,  570 
clitoris,  568 
cranium,  562 
diaphragm,  571 
face,  deep,  562 

superficial,  562 
Fallopian  tubes,  569 
gluteal  region,  567 
groin,  822 
head,  561 
heart,  571 
intercostal,  571 
internal  mammary,  571 
intestines,  570 
kidneys,  569,  793 
labia,  568 
lacteals,  570 
large  intestine,  570 
leg,  566 
liver,  569,  744 
lower  extremity,  565 
lung,  571 
meningeal,  562 
mesenteric,  570 
mouth,  562 
neck,  563 
nose,  562 
nympha},  568 
oesophagus,  571 
ovaries,  569 
pancreas,  569 
pelvis,  567 
penis,  568 
perineum,  567 
pharynx,  563 
prostate,  569 
radial,  565 
rectum,  569 
scrotum,  567 
small  intestine,  570 
spleen,  570 
stomach,  570 
testicle,  569 
thoracic  duct,  560 
thorax,  570 
thymic,  571 
thyroid,  571 
upper  extremity,  564 
uterus,  569 
vagina,  569 
Lyra  of  fornix,  596 

Macula  cribrosa,  703 

germinativa,  89 
Magnum  (os)  of  carpus,  223 
Malar  bone,  164 

articulations  of,  165 
attachment  of  muscles  to, 

165 
development  of,  165 
Male  organs  of  generation,  800 
Malleolus,  external,  247 

internal,  246 
Malleus,  700 

suspensory  ligament  of,  701 
Malpighi,  pyramids  of,  791 
Malpighian   bodies  of  kidney, 
792 
corpuscles  of  spleen,  753 


«64 


INDEX. 


Mamma,  820 

areola  of,  820 

development  of,  103 

lobules  of,  820 

mamilla  of,  820 

nerves  of,  821 

nipple,  820 

structure  of,  821 

vessels  of,  821 
Mammary  gland,  fi'ee  Mamma. 
Mammilla  of  breast,  820 

of  kidney,  791 
Manubrium  of  malleus,  701 

of  sternum,  192 
Marrow  of  bone,  45 

spinal,  .574 
Mastoid    cells,    openings    of, 
699 

portion  of  temporal  bone,  145 
Matrix  of  nail,  103 
Maxillary  bone,  inferior,   170. 
See  Jaw,  lower, 
superior,  159.     See  Supe- 
rior maxillary  bone. 
Meatus  audiloriusexternus,146 
internus,  147 

of  nose,  inferior.  189,  679 
middle,  189,  679 
superior,  189.  679 

urinarius,  female,  799 
male,  812 
Meckel's  ganglion,  620 
Mediastinum,  anterior,  782 

middle,  782 

posterior,  781,  782 

testis,  807 
Medulla  oblongata,  580 

anterior  pyramids  of,  582 

back  of,  583 

corpora  pyramldalia  of,  581 

fasciculi  graciles  of,  581 

fissures  of,  582 

ffray  matter  of,  583 
ateral  tract  of,  581,  582 
olivary  body,  581,  582 
pyramids  of,  anterior,  581 

posterior,  581 
restiform  bodies,  581 
septum  of,  582 
structure  of,  583 
Medulla   spinalis,    574.      See 

Spinal  cord. 
Medullary  canal  of  bone,  46 
membrane  of  bone,  47 
substance  of  brain,  59 
of  kidney,  791 
of  supra-renal  capsules, 794 
velum,  posterior,  of  cerebel- 
lum, 601 
Meibomian  glands,  692 
Membrana  fusca,  684 

f granulosa,  087 
imitans,  688 
nictitans,  693 
papillaris,  686 
sacciformis,  292 
tympani,  700 
secundaria,  699 
Membrane  of  aqueous  chamber, 
689 
arachnoid,  cerebral,  578 


Membrane — 

spinal,  573 

choroid,  683 

costo-coracoid,  374 

crico-thyroid,  772 

fenestrated,  72 

hyaloid,  689 

hyoglossal,  676 

Jacob's,  687 

limiting,  688  / 

mucous,  87 

obturator,  415 

pituitary,  679 

pupillary,  686 

Schneiderian,  679 

thyro-hyoid,  771 

vitelline,  89 
Membranes  of  spinal  cord,  572 

of  brain,  576 
Membranous  labyrinth,  706 

portion  of  urethra,  797 

semicircular  canals,  707 

zone,  706 
Meninges,  cerebral,  572 

spinal,  576 
Menisci,  44 
Mesentery,  728 
M6soc6phale,  584 
Mesocsecum,  728 
Mesocolon,  ascending,  728 

descending,  728 

sigmoid,  728 

transverse,  728 
Mesorchium,  810 
Mesorectum,  728 
Metacarpus,  224 

development  of,  226 

peculiar  bones  of,  225 
Metatarsus,  256 

development  of,  258 
Milk  teeth,  713 
Mitral  valve,  763 
Modiolus  of  cochlea,  705 
Molar  teeth,  712' 
Monro,  foramen  of,  593,  596 
Mons  Veneris,  811 
Monticulus  cerebelli,  601 
Morgagni,  liquor  of,  689 
Morsus  diaboli,  818 
Mouth.  709 

mucous  membrane  of,  709 
Mucous  membrane,  87 
Multicuspidate  teeth,  712 
Muscles,  General  Anatomy  of, 
53 

of  animal  life,  53 

aponeuroses   of.     See  Apo- 
neuroses. 

arrangement  of  fibres  of,  54 

bipenniform,  314 

bloodvessels  of,  56 

development  of,  103 

fasciculi  of,  54 

fibrils  of,  54 

form  of,  314 

insertion  of,  314 

involuntary,  55 

lymphatics  of,  56 

mode    of     connection    with 
bone,  &c.,  315 

nerves  of,  56 


Muscle — 
nomenclature  of,  314 
of  organic  life,  53 
origin  of,  314 
penniform,  314 
primitive  fasciculi  of,  54 

fibrils  of,  54 
radiated,  314 
sarcous  elements  of,  54 
sheath  of,  54 
size  of,  314 
striped,  53 
structure  of,  54 
tendons  of,  315 
unstriped,  55 
voluntary,  55 
Muscle  or  Muscles,  Descriptive 
Anatomy  of,  314 
of  abdomen,  359 
abductor  indicis,  396 

minimi  digiti  of  foot,  429 
of  hand,  396 

pollicis  of  foot,  428 
of  hand,  394      . 
accelerator  urinoe,  842 
accessorius  ad  sacro-lumba- 
lem,  354 

orbicularis  oris,  326 

pedis,  430 
adductor  brevis,  411 

longus,  411 

magnus,  411 

pollicis  of  hand,  396 
of  foot,  431 
anconeus,  390 
anomalus,  324 
antitragicus,  696 
arytajno  -  epiglottideus    infe- 
rior, 774,  776 

superior,  776 
arytasnoideus,  775 
attollens  aurem,  319 
attrahens  aurem,  319 
of  auricular  region,  319 
azygos  uvula3,  343 
basio-glossus,  339 
biceps  of  arm,  381 

of  leg,  417 
biventer  cervicis,  355 
brachialis  anticus,  382 
buccinator,  327 
cerato-glossus,  339 
cervicalis  asccndens,  354 
chondro-glossus.  339 
ciliary  of  eye,  686 
circumflexus  palati,  342 
coccygeus,  846 
cochlearis,  706 
complcxus,  355 
compressor  nasi,  324 

narium  minor,  324 

sacculi  laryngis,  774,  776 

urethrte,  845 
constrictor  isthmi  faucium, 
3:{9,  -MW 

phiirvniris  inferior,  340 
nioiiius,  340 
superior,  341 

urethra;,  845 
coraco-brachialis,  380 
corrugator  supercilii,  320 


INDEX. 


865 


Muscle  or  Muscles — 
cranial  region,  317 
cremaster,  825 
crico-arytsenoideus  lateralis, 
775 
posticus,  774 
crico-thyroid,  774 
era  reus,  408 
dartos,  804 
deltoid,  377 

depressor  alae  nasi,  324 
anguli  oris,  326 
epiglottidis,  776 
labii  inferioris,  326 
diaphragm,  368 
digastric,  336 
dilator  naris  anterior,  324 

posterior,  324 
of  epicranial  region,  317 
erector  clitoridis,  844 
penis,  843 
spinoe,  354 
of  external  ear,  319 
extensor    brevis    digitorum, 
428 
carpi  radialis  brevior,  389 
longior,  388 
ulnaris,  390 
coccygis,  357 
communis  digitorum,  390 
indicis,  392 
longus  digitorum,  420 
minimi  digiti,  390 
ossis     metacarpi    poUicis, 

391 
primi    internodii  pollicis, 

391 
proprius  pollicis,  419 
secundi  internodii  pollicis, 
391 
of  eyelids,  320 
of  face,  318 

femoral  region,  anterior,  405 
internal,  410 
posterior,  417 
fibular  region,  419 
flexor  accessorius,  430 
brevis  minimi  digiti  of  foot, 
430 
of  hand,  396 
brevis  digitorum,  429 
pollicis  of  foot,  431 
of  hand, 395 
carpi  radialis,  384 

ulnaris,  385 
digitorum  profundus,  386 

sublimis,  385 
longus  digitorum,  424 
pollicis  of  foot,  423 
of  hand,  387 
ossis    metacarpi    pollicis, 
394 
of  foot,  426 
gastrocnemius,  421 
gemellus  inferior,  416 

superior,  415 
genio-hvo-glossus,  338 

-hyoid,  337 
gluteus  maximus,  412 
medius,  414 
minimus,  414 
55 


Muscle  or  Muscles — 
of  gluteal  region,  412 
gracilis,  410 
of  hand,  394 
of  head  and  face,  317 
helicis  major,  696 

minor,  697 
Hilton's,  776 

humeral     region,     anterior, 
380 

posterior,  382 
hyo-glossus,  339 
of  hyoid  bone   and   larynx, 

334,  336 
iliac  region,  403 
iliacus,  404 
ilio-costalis,  354 
infra-costal,  367 
infra-spinatus,  379 
intercostal,  366 
external,  366 
internal,  367 
of     intermaxillary     region, 

326 
interossei,  dorsal,  396 
palmar,  397 
plantar,  432 
inter-spinales,  357 
inter-trans versales,  357 
kerato-glossus,  339 
of  larynx,  774 
latissimus  dorsi,  348 
laxator  tympani  major,  702 

minor,  702 
of  leg,  418 

levator  anguli  oris,  325 
scapulae,  350 
ani,  845 

glandulfe  thyroideEe,  788 
labii  inferioris,  325 
superioris,  325 
alaeque  nasi,  324 
proprius,  325 
proprius  alas  nasi,  324 
menti,  325 
palati,  342 
palpebrte,  321 

superioris,  321,  691 
prostatas,  802 
levatores  costarum,  367 
lingualis,  339 
lougissimus  dorsi,  354 
longus  colli,  345 
of  lower  extremity,  402 
lumbricales  of  foot,  430 

of  hand,  397 
masseter,  327 
of  mouth,  326 
multifidus  spinas,  356 
mylo-hyoid.  337 
naso-labialis,  326 
of  neck,  331 
of  nose,  324 

obliquus  abdominis  externus, 
359,  823 

internus,  361,  825 
asccndcns,  361,  825 
auris,  696 
capitis  inferior,  359 

superior,  358 
descendcns,  359,  823 


Muscle  or  Muscles — 
oculi  inferior,  323 
superior,  322 
obturator  externus,  416 

internus,  415 
occipito-frontalis,  318 
omo-hyoid,  335 
opponcns  minimi  digiti,  397 

pollicis,  395 
orbicularis  oris,  326 
palpebrarum,  320 
of  orbital  region,  321 
of  palatal  region,  342 
palato-glossus,  339,  343 

-pharyngeus,  343 
palmaris  brevis,  396 

longus,  385 
of  palpebral  region,  320 
pectineus,  411 
pectoralis  major,  372 

minor,  374 
of  penis,  843 
of  perineum,  female.  844 

male,  842 
peroneus  brevis,  425 
longus,  425 
tertius,  420 
of  pharynx,  340 
of  pinna,  695 
plantaris,  422 
platysma  myoides,  331 
popliteus,  423 
pronator  quadratus,  387 

radii  teres,  384 
psoas  magnus,  403 

parvus,  404 
pterj-goid,  external,  330 

internal,  329 
pyramidalis  abdominis,  365 

nasi,  324 
pyriformis,  414 
quadratus  femoris,  416 
lumborum,  365 
menti,  326 
quadriceps  extensor  cruris, 

408 
radial  region,  394 
rectus  abdominis,  364 
capitis  anticus  major,  340 
minor,  344 
posticus  major,  357 
minor,  357 
femoris,  408 
lateralis,  344 
oculi  externus,  322 
inferior,  322 
internus,  322 
superior,  321 
retrahens  aurem,  319 
rhomboideus,  324 
major,  350 
minor,  350 
risorius  of  Santorini,  327 
rotatores  spina),  356 
sacro-lumbalis,  354 
sartorius,  407 
scalenus  anticus,  346 
medius,  346 
posticus,  346 
scapular     region,     anterior, 
377 


866 


INDEX. 


Muscle  or  Muscles — 
posterior,  378 
semi-membranosus,  417 
serni-spinalis  colli,  356 

dorsi,  356 
semi-tendinosus,  417 
serratus  magnus,  376 
posticus  inferior,  351 
superior,  351 
soleus,  422 

sphincter  ani,  external,  840 
internal,  840 
vagina),  844 
spinalis  cervicis,  355 

dorsi,  355 
splenius,  352 
capitis,  352 
colli,  352 
stapedius,  702 
Bterno-cleido-mastoid,  332 
-hyoid,  334 
-thyroid,  335 
stylo-glossus,  339 
-hyoid,  337 
-pharyngeus,  341 
Bubanconeus,  383 
subclavius,  375 
subcrureus,  409 
subscapularis,  377 
supinator  brevis,  391 

longus,  388 
supra-spinales,  357 
supra-spinatus,  378 
temporal,  328 
tensor  palati,  342 
tarsi,  321 
tympani,  702 
vaginae  fcmoris,  407 
teres  major,  380 
'         minor,  379 
of  thigh,  405 

of  thoracic  region,  anterior, 
372 
lateral,  376 
of  thorax,  366 
of  thumb,  394 
thyro-aryta;noideus,  775 
-epiglottideus,  775 
-hyoid,  339 
tibialis  anticus,  419 

posticus,  424 
tibio-fibular  region,  anterior, 
419 
posterior,  421 
of  tongue,  338 
trachclo-mastoid,  355 
tragicus,  696 

transversalis  abdominis,  362, 
826 
colli,  355 
transvcrsus  auricula},  696 
pedis,  431 
perinci,  843 
in  female,  844 
trapezius,  347 
trianjriilaris  stcrni,  367 
triceps  extensor  cruris,  408 
cubiti,  382 
fern  oralis,  400 
of  tympanum,  702 
of  upper  extremity,  371 


Muscle  or  Muscles — 
of  ureters,  793 
of  urethra,  842 
vastus  externus,  408 

internus,  408 
vertebral    region,    anterior, 
344 
lateral,  346 
zygomaticus  major,  325 
minor,  325 
Musculi  papillares  of  left  ven- 
tricle, 763 
of  right  ventricle,  761 
pectinati,  in  left  auricle,  762 
in  right  auricle,  759 
Musculus.    ^See  Muscle. 

Nails,  82 

chemical  composition  of,  83 
general  anatomy  of,  82 
lunula  of,  83 
matrix  of.  83  • 
root  of,  83 
structure  of,  83 
Nares,  anterior,  187 
posterior,  721 
septum  of,  188,  678 
Nasal  bones,  158 

articulations  of,  158 
development  of,  158 
fossae,  187,  679 
arteries  of,  680 
mucous  membrane  of,  679 
nerves  of,  680 
veins  of,  680 
Nates  of  brain,  598 
Navicular  bone,  219,  254 
Neck,  muscles  of,  331 
triangle  of,  anterior,  459 

posterior,  461 
veins  of,  538 
Nerve  or  Nerves,  65,  605 
General  Anatomy  of — 65 
afferent,  66 
centrifugal,  66 
centripetal,  66 
cerebro-spinal,  65 
composition  of,  65 
junction  of  funiculi  of, 

65 
neurilemma  of,  65 
origin  of,  65 
plexus  of,  66 
sheath  of,  65 
structure  of,  65 
subdivision  of,  65 
termination  of,  66 
cells,  58 
corpuscles,  58 
cfierent,  66 
fibres,  59 
motor,  69 
sensory,  67 
of  special  sense,  605 
spinal,  roots  of,  632 
sympathetic,  66,  663 
Descriptive  Anatomy  of — 
abducens,  609 
accessory  obturator,  653 
acromial,  635 
auditory,  607,  708 


Nerve  or  Nerves — 

auricular,    of    auricularis 
magnus,  635 
of  auriculo-temporal,  623 
posterior,   from     facial, 

613 
of  second  cervical,  637 
of  small  occipital,  635 
of  vagus,  629 
auricularis  magnus,  635 
buccal,  613,  622 
of  facial.  613 
cardiac,  667 
inferior,  667 
middle,  667 
of  pneumogastric,  630 
superior,  667 
cardiacus  magnus,  667 

minor,  667 
carotid,  627 

cavernous,  of  penis,  673 
cervical,  anterior,  633 
posterior,  636 
superficial  branches  of,  634 
cervico-facial,  613 
chorda  tympani,  612,  703 
ciliary,  long,  617 

short,  618 
circumflex,  640 
clavicular,  635 
coccygeal,  656 
cochlear,  708 
communicans  noni,  636 

peronei,  660 
of  Ootunnius,  621 
cranial,  605 
crural,  651 

anterior,  653 
cutaneous,  of  accessory  ob- 
turator, 653 
of  arm,  external,  640 
internal,  640 
lesser  internal  640 
of  buttock  and  thigh.  659 
of  cervical  plexus,  635 
circumflex,  640 
coccygeal,  656 
crural,  anterior,  654 
dorsal  nerves,  647 
dorsalis  penis,  657 
hajmorrhoidal.  inferior,  657 
ilio-hypogastric,  650 

-inguinal.  651 
of  inguinal  region,  831 
intercostal,  648 
of  ischio-rcctal  region,  840 
lateral  of  dorsal,  649 
of  intercostal,  048 
lumbar,  649 
median,  643 

musculo -cutaneous,     640, 
662 
-spiral.  616 
obturator.  653 
palmar.  644 
of  patella,  6")  I 
perineal,  657 
peroneal,  661 
plantar,  660 
popliteal,  external,  661 
internal,  660 


INDEX. 


86t 


Nerve  or  Nerves- 
radial,  646 
sacral,  655 
sciatic,  lesser,  659 

small,  659 
of  thigh,  external,  651 
internal,  654 
middle,  654 
of  thorax,  anterior,  G47   • 

lateral,  647 
tibial,  anterior,  662 

posterior,  660 
ulnar,  644 
dental,  anterior,  619 
inferior,  623 
posterior,  618 
descendens  noni,  615 
digastric,  from  faciiil.  613 
dxigital  of  foot,  dorsal,  6G1 
plantar,  660 
of  hand,  dorsal,  644 

palmar,  median,  643 
radial,  646 
ulnar,  644 
dorsal,  647 

anterior  branches  of,  647 
posterior    branches    of, 

647 
roots  of,  647 
of  penis,  657 
dorsi-Iumbar,  648 

-spinal,  647 
of  dura  mater,  577 
eighth  pair,  625 
of  eyeball,  691 
facial,  610 
fifth,  615 
fourth,  608 
frontal,  616 
ganglionic  brancli  of  nasal, 

617 
gastric  branches   of  vagus, 

630 
genital,  651 
genito-crural,  651 
glosso-pharyngeal,  625 
gluteal,  inferior,  659 

superior,  657 
gustatory,  623 
of  heart,  630,  667,  765 
hemorrhoidal,  inferior,  657 
hepatic,  670,  744 
hypogastric.  651 
hypoglossal,  614 
iliac,  651 
ilio-hypogastric,  650 

-inguinal,  651 
incisor,  624 

infra-maxillary,  of  facial,  613 
-orbital  of  facial,  613,  617 
-trochlear,  617 
intercostal,  647 
lower,  648 
upper,  647 
intercosto-humeral,  648 
interosseous,  anterior,  643 

posterior,  646 
ischiatic,  great,  659 

small,  657 
Jacobson's,  626,  703 
labial,  620 


Nerve  or  Nerves — 
of  labyrinth,  7()8 
lachrymal,  616 
of  Lancisi,  591 
laryngeal,  external,  629 
inferior,  630 
internal.  629 
recurrent,  630 
superior.  629 
lingual,  623,  627 

of  glosso-pharyngeal,  627 
lumbar,  649 

branches  of,  649 
roots  of,  649 
lumbo-sacral.  649 
malar  branch  of  facial,  613 

of  orbital  nerve,  618 
masseteric,  622 
mastoid,  635 
maxillary,  inferior,  622 

superior,  617 
median,  643 
mental,  624 
motor  oculi,  common,  608 

external,  609 
musculo-cutaneous  of  abdo 
men,  650 
of  arm,  640 
from  peroneal.  662 
nuisculo-spiral.  645 
mylo-hyoid,  624 
nasal,  from  Meckel's  gangli- 
on, 620 
of  ophthalmic,  617 
from   superior    maxillary, 

620 
from  Vidian,  621 
naso-palatine,  621 
ninth,  614 
obturator,  651 

accessory,  653 
occipital  of  facial,  613 
great.  637 
small,  635 

of  third  cervical,  637 
occipitalis  major,  637 

minor,  635 
oesophageal,  630 
olfactory,  587,  605 
ophthalmic,  616 
optic,  606,  607 
orbital,  618 
relations  of,  610 
in  cavernous  sinus,  610 
in  orbit,  610 
in    sphenoidal    fissure, 
610 
palatine,  621 

anterior  or  large,  621 
external,  621 
middle,  621 
posterior  or  small,  621 
palmar  cutaneous  of  median, 
643 
ulnar,  644 
palpebral,  620 
par  vagum,  628 
pathetic,  608 
perforans  Casserii,  640 
perineal,  657 
superficial,  657 


Nerve  or  Nerves — 
peroneal,  661 
petrosal,  small,  611 

superficial     external,     or 
large,  611,  621 
pharyngeal,  of  external   la- 
ryngeal, 629 
of  glosso-pharyngeal,  627 
of  Meckel's  ganglion.  621 
of  pneumogastric,  629 
of  sympathetic,  666 
phrenic,  636 
plantar,  cutaneous,  660 
external,  661 
internal,  660 
pneumogastric,  628 
popliteal,  external,  661 

internal,  659 
portio  dura,  610 
inter   durara    et    moUem, 

610 
mollis,  607 
pterygoid,  622 
pterygo-palatine,  622 
pudendal,  inferior,  657 
pudic,  657 

pulmonary,  from  vagus,  630 
radial,  646 
recurrent  laryngeal,  630 

to  tentorium,  609 
renal  splanchnic,  670 
respiratory,  external,  639 

internal,  636 
sacral,  655 

roots  of,  655 
saphenous,  external,  orshort, 
660 
internal,  or  long,  654 
sciatic,  great,  659 

small,  657 
seventh,  607,  610 
sixth,  609 
spermatic,  670 
spheno-palatinc,  618 
spinal,  63.  See  Spinal  nerves. 

accessory,  627 
splanchnic,  great,  669 
lesser,  669 

renal,  or  smallest,  669 
splenic,  670 
sternal,  635 

stylo-hyoid  of  facial,  613 
subclavian,  639 
suboccipital,  633,  639 
subscapular,  640 
Buperficialis  colli,  634 
supra-clavicular,  635 
-maxillary  of  facial,  613 
-orbital,  616 
-scapular,  639 
-trochlear,  616 
sympathetic,  663 

cephalic  portion  of,  665 
cervical  portion  of.  GGo 
lumbar  i)ortion  of,  671 
pelvic  portion  of,  G71 
thoracic  portion  of,  668 
tarsal,  6G2 

temporal,  of  auriculo-tempo- 
ral.  G23 
deep,  622 


868 


INDEX. 


Nerve  or  Nerves — 
of  facial,  613 
of  orbital  nerve.  618 
temporo-facial,  613 

-malar  or  orbital,  618 
third  or  motor  oculi,  608 
thoracic,  anterior,  639 
cardiac,  630 
long,  639 
posterior,  639 
thyro-hyoid,  615 
tibial,  anterior,  611 

posterior,  660 
of  tongue,  677 
tonsillar,  627 
trifacial,  615 
trigeminus,  615 
trochlear,  608 
tympanic  of  facial,  612 
of  glosso-pharyngeal,  626, 
703 
ulnar,  644 
uterine,  672 
vaginal,  673 
vagus,  628 
branches  of,  629 
ganglions  of,  628 
vestibular,  708 
Vidian,  621 
of  Wrisberg,  641 
Nervous    substance,  chemical 
analysis  of,  60 
microscopic  appearance  of, 
58 
Nervous  System,  General  An- 
atomy of,  57 
of  animal  life,  57 
cerebro-spinal  axis,  572 
cortical  substance,  57 
fibrous  nervous  matter,  59 
ganglia,  64 
gray  or  cineritious  substance, 

57 
of  organic  life,  57 
sympathetic,  66 
composition  of,  66 
gelatinous  fibres  of,  59 
tubular  fibres  of,  59 
vesicular  matter,  57 
white  or  medullary  substance 
of,  59 
Neurilemma,  65 

of  cord,  573 
Neuroglia,  60 
Nidus  hirundinis,  601 
Nipple,  820 

Nodule  of  cerebellum,  601 
Noduli  Arantii,  761 
Nose,  677 
arteries  of,  679 
bones  of,  158 
cartilages  of,  678 

of  septum  of,  678 
development  of,  102 
fossiB  of,  187,  679 
meatuses  of,  189,  679 
mucous  membrane  of,  677 
muscles  of,  324,  678 
nerves  of,  679 
veins  of.  5!U),  679 
Notch,  cotyloid,  232 


Notch— 

ethmoidal,  142 

intercondyloid,  240 

nasal,  141 

pterygoid,  152 

sacro-sciatic,  greater,  230 
lesser,  230 

sigmoid,  174 

spheno-palatine,  168 

supra-orbital,  141 
-scapular,  205 
Nuck,  canal  of,  810,  820 
NymphjE,  812 

lymphatics  of,  568 

Occipital  bone,  134 
articulations  of,  138 
attachment  of  muscles  to, 

138 
crests  of,  134 
development  of,  137 
structure  of,  137 
Occiput,  arteries  of,  453 
CEsophagus,  722 
lymphatics  of,  571 
structure  of,  723 
surgical  anatomy  of,  722 
Oesterlen,  on  supra-renal  cap- 
sules, 794 
Olecranon,  212 

Olfactory  bulb.    See  Bulb,  ol- 
factory, 
nerve.   See  Nerve,  olfactory. 
Olivary  bodies  of  medulla  ob- 
longata, 581,  582 
Omenta,  727 

Omentum,  gastro-colic,  727 
gastro-hepatic,  725,  727 

-splenic,  728 
great,  727 
lesser,  725,  727 
sac  of,  725 
Opening,  aortic,  in  diaphragm, 
369 
in  left  ventricle,  763 
caval  in  diaphragm,  370 
of  coronary  sinus,  759 
of  inferior  cava,  759 
left  auriculo-ventricular,  761 
oesophageal    in    diaphragm, 

369 
of  pulmonary  artery,  760 

veins,  762 
right     auriculo  -  ventricular, 

759 
saphenous,  406,  832 
of  superior  cava,  759 
Operation  for  club-foot,  426 
of  laryngotomy,  779 
of  laryngo-trachcotomy,  779 
ligation  of  arteries.    See  In- 
dividual Arteries, 
of  lithotomy,  847 
of  ocsophagotomy,  723 
of  stapnylorraphy,  344 
for  strabismus,  323 
tracheotomy,  780 
for  wryneck.  334 
Opercula  of  dental  grooves,  716 
Optic  commissure,  586.  607 
lobes,  596 


Ora  serrata,  688 
Orbicular  bone,  701 
Orbits,  185 

arteries  of,  464 

muscles  of,  321 

relation  of  nerves  in,  608 
Orifice,     auriculo-ventricular, 
759,  760 

oesophageal,     of     stomach, 
729 

pyloric,  of  stomach,  729 

of  uterus,  815 

of  vagina,  811 
See    also    Opening,  Aperture, 

and  Ostium. 
Os  calcis,  249 

hyoides,  189 

innominatum,  227 

magnum  of  carpus,  223 

orbiculare,  701 

planum,  154 
See  also  Bone. 

uteri,  815 
Ossa  triquetra,  157 
Ossicles  of  ear,  697 
Ossicula  of  tympanum,  697 
Ossification  of  bone,  49 
intracartilaginous,  49 
intramembranous,  49 
of  spine,  progress  in,  130 
Osteo-dentine,  715 
Osteology.  45 

Ostium  abdominale   of  Fallo- 
pian tube,  818 

uteri  internum,  815 

uterinum,  815,  817 
Otoliths,  707 
Outlet  of  pelvis,  236 
Ovary,  818 

corpus  luteum  of,  819 

development  of,  109 

Graafian  vesicles  of,  818 

ligament  of,  820 

lymphatics  of,  569 

nerves  of,  820 

ovisacs  of,  819 

shape,    position,  and  dimen- 
sions of,  819 

situation  of,  in  foetus,  109 

stroma  of,  819 

tunica  albuginea  of,  818 

vessels  of,  820 
Ovicapsule  of  Graafian  vesicle, 

819 
Oviducts,  817 
Ovisacs  of  ovary,  819 
Ovulaof  Naboth,  816 
Ovum,  89 

discharge  of,  819 

discus  proligerus.  819 

fecundation  of,  90 

germinal  spot,  89 
vesicle,  HO 

vitelline  membrane  of,  89 

yelk  of,  89 

zona  pcUucida,  89 

Pacchionian  depressions,  139 
Pacinian  corpuscles.  68 
Palate,  arches  of,  718 
development  of,  99 


INDEX. 


869 


Palate — 

hard,  718 
muscles  of,  342 
soft,  718 
bone,  166 

articulations  of,  168 
attacliraent  of  muscles  to, 

168 
development  of,  168 
Palmar  arch.     See  Arch. 
Palpebraj,  691 
Pampiniform  plexus  of  veins, 

655,  805 
Pancreas,  749 
development  of,  107 
duct  of,  750 
structure  of,  750 
vessels  snd  nerves  of,  750 
Papilla  lacrymalis,  691,  694 
Papilla;,  conjunctival,  693 
of  kidney,  781 
of  skin,  80 
of  tongue,  675 
circuravallatae,  675 
conicaj,  675 
filiformes,  675 
fungiformes,  675 
maximae,  675 
mediae,  675 
minimse,  675 
structure  of,  676 
of  tooth,  715 
Par  vagum,  628 
Parietal  bones,  138 

articulations  of,  140 
attachment  of  muscles  to, 

140 
development  of,  140 
Parotid  gland,  719 

accessory  portion  of,  720 
duct  of,  720 
lymphatics  of,  561 
nerves  of,  720 
vessels  of,  720 
Patella,  242 

articulations  of,  243 
attachment  of  muscles  of,  243 
development  of,  243 
fracture  of,  434 
Pecquet,  cistern  of,  560 

reservoir  of,  560 
Pedicles  of  vertebra,  118 
Peduncles  of  cerebellum,  602 
of  cerebrum,  589 
of  corpus  callosum,  587 
of  pineal  gland,  598 
Pelvic  fascia.  *S'eeFascia,pelvic. 

bones.     See  Pelvis. 
Pelvis,  234,  794 
arteries  of,  513 
articulation  of,  281 

with  spine,  280 
axes  of,  236 
boundaries  of,  234 
brim  of,  234 
cavity  of,  234,  794 
diameters  of,  234 
false,  234 
inlet  of,  234 
ligaments  of,  281 
lymphatics  of,  567 


Pelvis — 

male    and    female,    differ- 
ences of,  236 
outlet  of,  236 
position  of,  236 

of  viscera  at  outlet  of,846 
true,  234 
of  kidney,  792 
Penis,  801 
arteries  of,  803 
body  of,  801 
corpora  cavernosa,  802 
corpus  spongiosum,  802 
development  of.  111 
dorsal  artery  of,  514 
nerve  of,  657 
vein,  554 
glans,  801 

lymphatics  of,  568,  803 
muscles  of,  842 
nerves  of,  657,  804 
prepuce  of,  801 
root  of,  801 

suspensory  ligament  of,  802 
Perforated  space,  anterior,  588 

posterior,  589 
Pericardium,  755 
relations  of,  755 
structure  ojf,  7S6 
fibrous  layer  of,  756 
serous  layer  of,  757 
vessels  of,  756 
Perichondrium,  42 
Perilymph,  706 
Perimysium,  53 
Perineum,  841 
abnormal  course  of  arteries 

in,  848 
deep  boundaries  of,  841 
fascia,  deep,  844 
superficial,  841 
lymphatics  of,  567 
muscles  of,  842 
surgical  anatomy  of,  839 
Periosteum,  45 
of  teeth,  711 
Peritoneum,  725 
folds  of,  727 
lesser  cavity  of,  727 
ligaments,  727 
mesenteries,  727 
omenta  of,  727 
reflections  of,  727 
Pes  accessorius,  594 

hippocampi,  594 
Petit,  canal  of,  690 
Petrous    portion  of  temporal 

bone,  145 
Peyer's  glands,  736 
Phalanges  of  foot,  257 

articulations  of,  257,  309 
development  of,  259 
of  hand,  226 

articulations  of,  226,  313 
development  of,  226 
Pharynx,  721 
aponeurosis  of,  721 
arteries  of,  454 
development  of,  107 
mucous  membrane  of,  722 
muscles  of,  340 


Phlebolites,  553 
Pia  mater  of  brain,  579 
of  cord,  573 

structure  of,  583 
testis,  807 
Pigment,  41 

cells  of  iris,  686 
Pigmentary  layer  of  choroid, 

684 
Pillars  of  external  abdominal 
ring,  824 
of  diaphragm,  369 
of  fauces,  718 
of  fornix,  595 
Pineal  gland,  598 

peduncles  of,  598 
Pinna  of  ear,  694 
cartilage  of,  695 
ligaments  of,  695 
muscles  of,  695 
nerves  of,  696 
structure  of,  695 
vessels  of,  696 
Pisiform  bone,  221 
Pituitary  body,  589 
Plate,  cribriform  of  ethmoid, 
154 
external  pterygoid,  152 
perpendicular,  of  ethmoid, 
154 
Pleura,  780 

cavity  of,  780 
parietal  layer  of,  781 
reflections  of,  781 
vessels  and  nerves  of,  782 
visceral  layer  of,  780 
costalis,  780 
pulmonalis,  780 
Plexus,  biliary,  745 
interlobular,  745 
lobular,  745 
Plexus  of  Nerves,  66 
aortic,  670 
brachial,  637 
cardiac,  anterior,  668 
deep,  or  great,  ^67 
superficial,  668 
carotid,  665 
cavernous,  665 
cerebral,  666 
cervical,  034 
cceliac,  670 
colic,  left,  071 
middle,  671 
right,  671 
coronary,  anterior,  668 

posterior,  668 
cystic,  670 
diaphragmatic,  669 
epigastric,  669 
facial,  666 
gastric,  670 
gastro-duodenal,  670 
-epiploic,  670 
left,  070 
hemorrhoidal     inferior, 
671 
superior,  671 
hepatic,  070 
hypogastric,  669 
inferior,  671 


870 


INDEX. 


Plexus  of  Nerves — 
ilco-colic,  670 
infra-orbital,  620 
lumbar,  649 
meningeal,  666 
mesenteric,  inferior,  670 

superior,  670 
oesophageal,  628,  630 
ophthalmic,  666 
ovarian,  670 
pancreatic,  670 
pancreatico-duodenal, 

670 
patellar,  654 
pharyngeal,  629,  666 
phrenic,  669 
prostatic,  673 
pulmonary,  anterior,  628 

posterior,  628,  668 
pyloric,  670 
renal,  670 
sacral,  656 
sigmoid,  671 
Bolar,  669 
spermatic,  670 
splenic,  670 
supra-renal,  669 
tonsillar,  627 
tympanic,  627,  703 
vaginal,  673 
vertebral,  667 
vesical,  673 
of  Veins,  335 
choroid.    See  Choroid, 
haemorrhoidal,  555 
ovarian,  555,  820 
pampiniform,  555,  805, 

820 
pharyngeal,  539 
pterygoid,  538 
spermatic,  555,  805 
uterine,  554 
vaginal,  554 
vesico-prostatic,  553 
Plica  semilunaris,  693 
Pomum  Adami,  769 
Pons  hepatis,  743 
Tarini,  589 
Varolii,  580,  584 
Popliteal  space.     <S'ee  Space, 

popliteal. 
Pores  of  skin,  80 
Portio  dura  of  seventh  nerve, 
610 
inter  duram  et  moUem,  610 
mollis,  607 
Porus  opticus  of  sclerotic,  682 
Pott's  fracture,  435 
Pouches,  laryngeal,  774 
Poupart's  ligament,  359,  825, 

833 
Pra;putium  clitoridis,  812 
Prepuce,  801 

Process    or   Processes,    acro- 
mion, 204 
alveolar,  1G2 
angular,  external,  141 

internal,  141 
auditory.  144 
basilar,  1.37 
ciliary,  684 


Process  or  Processes — 
clinoid,  anterior,  152 

middle,  150 

posterior,  150 
cochleariform,  700 
condyloid  of  lower  jaw,  172 
coracoid,  205 
coronoid,  of  lower  jaw,  172 

of  ulna,  212 
ethmoidal,  of  inferior  turbi- 
nated, 169 
falciform,  833 
frontal,  of  malar,  65 
hamular,  of  cochlea,  706 

of  lachrymal,  1G4 

of  sphenoid,  152 
of  helix,  695 
of  Ingrassias,  152 
jugular,  134 

lachrymal,  of  inferior  turbi- 
nated bone,  1G9 
malar  of  superior  maxillary, 

161 
mastoid,  145 

maxillary,  of  inferior  turbi- 
nated, 169 

of  malar  bone,  165 
mental,  170 
nasal,  162 

odontoid  of  axis,  119 
olecranon,  212 
olivary,  150 

of  malar,  165 

of  palate,  167 
palate,  162 

palatine,  of  superior  maxil- 
lary, 160 
pterygoid,  of  palate  bone,  1G7 

of  sphenoid,  152 
sphenoidal,  of  palate,  168 
spinous,  of  ilium,  229 

of  sphenoid,  151 

of  tibia,  244 

of  vertebra;,  117 
styloid,  of  radius,  218 

of  temporal,  148 

of  ulna,  216 
transverse,  of  vertebra},  117 
unciform,  224 

of  ethmoid,  155 
vaginal  of  sphenoid,  151 

of  temporal,  148 
vermiform  of  cerebellum,  601 
zygomatic,  165 
Processus  ad  meduUam,  603 
ad  pontem,  603 
ad  testes,  599 
brevis,  of  malleus,  701 
caudatus,  695 
clavatus,  581 
cochleariformis,  700 
e  cerebello  ad  testes,  599, 602 
gracilis,  of  malleus,  701 
Promontory  of  sacrum,  127 

of  tympanum,  699 
Prostate  gland,  800 
lobes  of,  800 

levator  muscle  of,  800,  846 
position  of,  800,  846 
secretion  from,  801 
size  and  shape  of,  800 


Prostate  Gland — 

structure  of,  800 

surgical  anatomy  of,  801 

vessels  and  nerves  of,  846 
Protovertebroe,  101 
Protuberance,  occipital,  exter- 
nal, 1.34 

internal,  136 
Pubes,  232 

articulations  of,  234,  283 

attachmentofmusclesto,  234 

development  of,  233 

structure  of,  233 

symphysis  of,  232,  283 
Pudendum,  811 
Puncta  lachrymalia,  691 

vasculosa,  590 
Pulp  cavity  of  tooth,  716 

development  of,  716 
Pupil  of  eye,  685 

dilator  muscle  of,  685 

membrane  of,  686 

sphincter  muscle  of,  685 
Pylorus,  729 
Pyramid  of  cerebellum,  601 

of  thyroid  gland,  788 

of  tympanum,  G99 
Pyramids,  anterior,  601 
decussation  of,  601 

of  Ferrein,  792 

of  Malpighi,  791 

posterior,  601 

of  spine,  131 

QuADRiOEMiNAL  bodies,  598 

Radius,  217 

articulations  of,  219 
development  of,  219 
muscles  attached  to,  219 
Eamus  of  ischium.  231 
of  lower  jaw,  172 
of  pubes,  232 
Raphe  of  corpus  callosum,  591 
of  palate,  718 
of  perineum,  841 
of  tongue,  674 
Receptaculum  chyli,  560 
Rectum,  739 
folds  of,  740 
lymphatics  of,  570 
relations  of,  in  female,  814 
male,  739 
Region  of  abdomen,  359,  724 
acromial,  muscles  of,  377 
auricular,  muscles  of,  319 
of  back,  muscles  of,  347 
brachial,  anterior,  muscles  of, 
386  ' 

posterior,  390 
cervical,  superficial,  muscles 

of,  331 
diaphragmatic,  368 
dorsal,  of  foot,  muscles   of, 

428 
epicranial,  muscles  of,  317 
epigastric,  725 
femoral,  anterior,  muscles  of, 
405 
internal,  410 
posterior,  417 


INDEX. 


8T1 


Region — 
fibular,  425 
foot,  dorsum  of,  428 

sole  of,  428 
gluteal,  muscles  of,  412 
groin,  822 

of  hand,  muscles  of,  394 
humeral,  anterior,  380 

posterior,  382 
hypochondriac,  725 
hypogastric,  725 
iliac,  muscles  of,  403 
infra-hyoid,  muscles  of,  334 
inguinal,  725,  822 
intermaxillary,    muscles    of, 

326 
ischio-rectal,  surgical  anato- 
my of,  839 
laryngo  -  tracheal,     surgical 

anatomy  of,  779 
lingual,  muscles  of,  338 
lumbar,  725 

maxillary,   inferior,  muscles 
of,  325 
superior,  muscles  of,  325 
nasal,  muscles  of,  324 
orbital,  muscles  of,  321 
palatal,  muscles  of,  342 
palmar,  muscles  of,  397 
palpebral,  muscles  of,  320 
pectoral,  muscles  of,  372 
of  perineum,  841 
pharyngeal,  muscles  of,  340 
plantar,  muscles  of,  428 
popliteal,  524 
pterygo  -  maxillary,  muscles 

of,  329 
pubic,  725 

radial,  muscles  of,  388,  394 
scapular,   anterior,   muscles 
of,  377 
posterior,  378. 
Scarpa's  triangle,  518 
of  skull,  anterior,  184 

lateral,  183 
supra-hyoid,  muscles  of,  336 
temporo  -  maxillary,  muscles 

of,  327 
thoracic,  muscles  of,  366 
anterior,  372 
lateral,  376 
tibio-flbular,  anterior,  419 

posterior,  421 
ulnar,  muscles  of,  396 
umbilical,  725 

vertebral,  anterior,  muscles 
of,  344 
lateral,  346 
Reil,  island  of,  588 
Reservoir  of  Pecquet,  560 

of  thymus,  787 
Respiration,  organs  of,  769 

development  of,  107 
Restiform  bodies  of   medulla 

oblongata,  581,  582 
Rete  mucosum  of  slkin,  80 

testis,  807 
Retina,  686 
arteria  centralis  of,  467,  688 
external  layer  of,  687 
fovea  centralis  of,  686 


Retina — 

granular  or  middle  layer  of, 
687 

internal  or  nervous  layer  of, 
687 

Jacob's  membrane  of,  687 

limbus  luteus  of,  686 

membrana  limitans  of,  688 

nummular  layer  of,  687 

radiating  fibres  of,  688 

structure  of,  687 

yellow  spot  of,  685 
Retinacula  of  ileo-caecal  valve, 

788 
Ribs,  194 

attachment  of  muscles  to,  198 

common  characters  of,  197 

development  of,  198 

false,  194 

floating,  194 

ligaments  of,  275 

peculiar,  196 

true,  194 

vertebral,  194 

vertebro-costal,  194 
-sternal,  194 
Ridge,  internal  occipital,  136 

mylo-hyoidean,  I'll 

pterygoid,  151 

superciliary,  140 

temporal,  143 
Rima  glottidis,  773 
Ring,  abdominal,  external,  360, 
824 
internal,  827 

crural  or  femoral,  835 

fibrous,  of  heart,  764 
Rolando,  tubercle  of,  583 
Rosenmiiller,  organ  of,  109 
Rostrum  of   corpus  callosum, 
591 

of  sphenoid  bone,  151 
Rotation,  263 
Ruga)  of  stomach,  731 

of  vagina,  814 

Sac,  dental,  715 

lachrymal,  694 

of  omentum,  725 
Sacculus  laryngis,  774 

of  vestibule,  707 
Sacrum,  126 

articulations  of,  130 

attachment  of  muscles  to,  130 

cornua  of,  128 

development  of,  130 

peculiarities  of,  129 

structure  of,  129 
Salivary  glands,  719 

structure  of,  721 
Santorini,  cartilages  of,  771 
Sarcolemma,  315 
Sarcous   elements   of  muscle, 

315 
Scalaj  of  cochlea,  705,  706 
Scaphoid  bone  of  foot,  2.54 

of  hand, 219 
Scapula,  202 

articulations  of,  207 

attachment  of  muscles  to,  207 

development  of,  206 


Scapula — 
ligaments  of,  286 
muscles  of,  377 
structure  of,  206 
Scarfskin,  80 
Scarpa's  triangle,  518 
Schindylesis,  262 
Schneiderian  membrane,  679 
Schwann,  white  substance  of, 

69 
Sclerotic,  681 
Scrotal  hernia,  828 
Scrotum,  804 
dartos  of,  804 
lymphatics  of,  805 
nerves  of,  805 
septum  of,  805 
vessels  of,  805 
Sella  turcica,  150, 178 
Semen,  809 
liquor  seminis  of,  809 
seminal  granules  of,  809 
spermatozoa  of,  809 
Semicircular  canals,  704 
Semilunar  bone,  220 
Seminal   vesicles.     See   Vesi- 

culiE  seminales. 
Seminiferous  tubes,  807 
Senac,  on  structure  of  heart's 

valves,  760 
Senses,  organs  of,  674 
Septum  auricularum,  759,  764 
between  bronchi,  778 
crurale,  836 
lucidum,  592,  595 
of  medulla  oblongata,  582 
of  nose,  188 

cartilage  of,  678 
pectiniforme,  802 
of  pons  Varolii,  584 
scroti,  804 
subarachnoid,  573 
of  tongue,  675 
ventriculorum,  760 
Serous  membranes,  86 
Sesamoid  bones,  259 
Sheath  of  arteries,  436 
crural  or  femoral,  834 
of  muscles,  316 
of  nerves,  65 
Shoulder-joint,  288 
bones  of,  199 
muscles  of,  377 
vessels  and  nerves  of,  289 
Sigmoid  flexure.     See  Colon. 
Simon,  on  supra-renal  capsules, 

794 
Sinus  or  Sinuses — 
of  aorta,  438,  761 
cavernous,  543 
circular,  543 
circularis  iridis,  686 
confluence  of,  542 
coronary,  558,  759 
of  dura  mater,  536,  542 
ethmoidal,  156 
frontal,  140 
of  jugular  vein,  539 
of  kidney,  792 
lateral,  543 
of  left  auricle,  761 


872 


INDEX. 


Sinus  or  Sinuses — 

longitudinal,  inferior,  542 
superior,  542 

maxillary,  161 

occipital,  543 

petrosal,  inferior,  544 
superior,  544 

placental,  95 

pocularis,  798 

prostatic,  798 

pulmonary,  759 

of  right  auricle,  758 

straight,  543 

sphenoidal,  150 

terminal,  144 

transverse,  544 

uro-genital,  93,  111 

uterinus,  816 

of  Valsalva,  aortic,  438,  761 
pulmonary,  759 

venous,  536 
Skeleton,  33 
Skin,  anatomy  of,  78 

appendages  of,  81 

areolae  of,  80 

corium  of,  80 

cuticle  of,  80 

derma  of,  78 

development  of,  81, 102 

epidermis  of,  80 

furrows  of,  80 

hairs,  82 

lymphatics  of,  81 

muscular  fibres  of,  80 

nails,  81 

nerves  of,  81 

papillary  layer  of,  80 

rete  mucosum  of,  80 

sebaceous  glands  of,  83 

sudoriferous  or  sweat  glands, 
84 

tactile  corpuscles  of,  68,  80 

true,  78 

vessels  of,  81 
Skull,  133, 176 

anterior  region  of,  184 

base  of,  176 

bones  of,  133 

cerebral  or  internal  surface, 
176 

external  surface  of,  176 

fissures  of,  157 

fossa  of,  anterior,  176 
middle,  178 
posterior,  179 

lateral  region  of,  183 

sutures  of,  174 

tables  of,  115 

vertex  of,  176 
Socia  parotidis,  720 
Soemmering,  foramen  of,  686 
Soft  palate,  718 

aponeurosis  of,  718 

arches  or  pillars  of,  718 

muscles  of^  342 
Sole  of  foot,  muscles  of,  428 
Space,  anterior  perforated,  588 

axillary,  478 

Haversian,  47 

intercostal,  194 

popliteal,  524 


Space — 

posterior  perforated,  589 
Spermatic  cord,  805 
arteries  of,  805 
lymphatics  of,  805 
nerves  of,  805 
relation  of  to  femoral  ring, 
836 
in  inguinal    canal,  805, 
827 
veins  of,  805 
Spermatozoa,  809 
Sphenoid  bone,  149 
articulations  of,  153 
attachment  of  muscles  to,154 
development  of,  153 
Sphenoidal  spongy  bones,  153 
Spinal  column,  116,  131.     See 

also  Vertebra. 
Spinal  cord,  62 
arachnoid  of,  573 
arrangement    of    gray    and 

white  matter  in,  62 
central  canal  of,  64 

ligament  of,  574 
columns  of,  575 
development  of,  100 
dura  mater  of,  572 
filum  terminale  of,  574 
fissure  of,  575 
foetal  peculiarity  of,  574 
gray  commissure  of,  576 
ligamentum  denticulatura  of, 

574 
membranes  of,  572 
neurilemma  of,  573 
pia  mater  of,  573 
structure  of,  02 
white  matter  of,  62 
Spinal  nerves,  63,  632 

arrangement  into  groups, 

632 
branches  of,  633 
ganglia  of,  633 
roots  of,  anterior,  632 
posterior,  632 
Spine,  116.    See  Vertebra  and 
Process,  spinous, 
ethmoidal,  149 
of  ischium,  231 
nasal,  142 
anterior,  163 
posterior,  166 
pharyngeal,  135 
of  pubes,  232 
of  scapula,  204 
Spleen,  750 
artery  of,  754 
capillaries  of,  754 
fibrous  elastic  coat  of,  752 
fissure  of,  751 
hilum  of,  751 
lymphatics  of,  570,  754 
Malpighian  corpuscles  of,753 
nerves  of,  754 
proper  substance  of,  752 
serous  coat  of.  751 
structure  of.  751 
suspensory  ligament  of,  751 
trabeculiu  of.  752 
veins  of,  754 


Squamous  portion  of  temporal 

bone,  143 
Stapes,  701 

annular  ligament  of,  701 
Steno's  duct,  720 
Sternum,  190 
articulations  of,  194 
attachment  of  muscles  to, 194 
development  of,  193 
ligaments  of,  278,  280 
Stomach,  728 
alteration  in  position  of,  730 
alveoli  of,  732 
cardia  of,  729 
cellular  coat  of,  731 
curvatures  of,  729 
development  of,  107 
fundus  of,  729 
follicles  of,  731 
ligaments  of,  730 
lymphatics  of,  570,  732 
mucous  glands  of,  732 
mucous  membrane  of,  731 
muscular  coat  of,  730 
orifices  of,  729 
peptic  glands  of,  731 
pyloric  end  of,  728 
pylorus,  730 
serous  coat  of,  730 
splenic  end  of,  729 
structure  of,  730 
surfaces  of,  730 
vessels  and  nerves  of,  732 
Striae  laterales,  591 

longitudinales,  591 
Stroma  of  ovary,  819 
Subarachnoid  fluid,  579 
septum,  574 
space  of  brain,  578 
of  cord,  573 
Sublingual  gland,  720 

duct  of,  721 
Submaxillary  gland,  720 

duct  of,  720 
Subpeduncular  lobe  of  cerebel- 
lum, 601 
Sulci  of  cerebrum,  586 
Supercilia,  691 
Superior  maxillary  bone,  159 
articulations  of,  163 
attachment  of  muscles  to, 

163 
development  of,  163 
Supra-renal  capsules,  793 
development  of,  108 
nerves  of,  794 
vessels  of,  794 
Surffical  anatomy — 
of  abdominal  aorta.  497 
anterior  tibial,  527 
arch  of  aorta,  440 
axilla,  478 
axillary  artery,  481 
base  of  bladder,  847 
bend  of  elbow,  485 
brachial  artery,  485 
common  carotid  artery,44J 

iliac  artery,  508 
dorsalis  pedis,  530 
external  carotid,  448 
iliac,  517 


INDEX. 


873 


Surgical  Anatomy — 

of  facial  artery,  453 
femoral  artery,  520 

hernia,  830 
hamstring  tendons,  418 
innominate  artery,  443 
inguinal  hernia,  822 
internal  carotid,  464 

iliac,  510 
ischio-rectal  region,  839 
laryngo-tracheal      region, 

779 
lingual  artery,  450 
muscles  of  eye,  323 
of  lower  extremity,  432 
of  soft  palate,  344 
of  upper  extremity,  398 
cEsophagus,  722 
perineum,  841 
popliteal  artery,  525 
posterior  tibial,  531 
prostate  gland,  846 
radial  artery,  489 
Scarpa's  triangle,  518 
sterno-mastoid  muscle,  334 
subclavian  artery,  471 
superior  thyroid,  449 
talipes,  426 
temporal  artery,  456 
thoracic  aorta,  494 
triangles  of  neck,  459 
ulnar  artery,  492 
Sustentaculum  tali,  251 
Sutura,  262 

dentata,  262 

harmonia,  262 

limbosa,  262 

notha,  262 

serrata,  262 

squamosa,  262 

vera,  262 
Suture,  basilar,  175 

coronal,  175 

cranial,  174 

ethmo-sphenoidal,  177 

ethmoido-frontal,  177 

frontal,  174 

fronto-malar,  187 
-maxillary,  187 
-parietal,  175 
-sphenoidal,  177 

intermaxillary,  185 

internasal,  185 

interparietal,  174 

lambdoid,  175 

malo-maxillary,  187 

masto-occipital,  175 
-parietal,  175 

naso-maxillary,  185 

occipito-parietal,  175 

petro-occipital,  175 
-sphenoidal,  178 

sagittal,  174 

spheno-parietal,  175,  178 

squamo-parietal,  175 
-sphenoidal,  175 

squamous,  178 

temporal,  178 

transverse,  175 
Swallow's  nest  of  cerebellum, 
601 


Sweat-glands,  84 
Symphysis  of  jaw,  170 

pubis,  232,  283 
Synarthrosis,  262 
Synovia,  261 
Synovial  membrane,  87,  260 

articular,  261 

bursal,  261 

vaginal,  261.     See  also  indi- 
vidual Joints. 
System,  Haversian,  47 

Tables  of  skull,  115 
Taenia  hippocampi,  593 
semicircularis,  593 
violacea,  603 
Tarsus,  249 

articulations  of,  309 
development  of,  258 
Teeth,  711 
bicuspid,  711 
canine,  712 
cement  of,  714 
cortical  substance  of,  714 
crown  of,  711 
crusta  petrosa  of,  714 
cuspidate,  712 
deciduous,  713 
dentine  of,  714 
development  of,  715 
enamel  of,  714 
eruption  of,  717 
eye,  712 
fang  of,  711 
growth  of,  716 
incisors,  711 

intertubular  tissue  of,  714 
ivory  of,  713 
milk,  713 
molar,  712 
multicuspidate,  712 
permanent,  711 
pulp  cavity  of,  715 
roots  of,  711 
structure  of,  713 
temporary,  713,  717 
tubuli  of,  714 
wisdom,  712 
Temporal  bone,  143 

articulations  of,  148 
attachment  of  muscles  to, 

148 
development  of,  148 
mastoid  portion  of,  145 
petrous  portion  of,  145 
squamous  portion  of,  143 
structure  of,  148 
Tendo  Achillis,  422 
oculi,  320 
palpebrarum,  320 
Tendon,  315 

central,  of  diaphragm,  369 
conjoined,  of  internal  oblique 
and    transversalis,  362, 
825 
cordiform,  of  diaphragm,  369 
Tentorium  cerebelli,  578 
Testicle.     See  Testes. 
Testes,  804 

aberrant  duct  of,  808 
coni  vasculosi  of,  807 


Testes— 

coverings  of,  803,  805 
tunica  albuginea,  806 
Vaginalis,  806 
vasculosa.  807 

development  of,  109 

gubernaculura,  810 

lobules  of,  807 

lymphatics  of,  569 

mode  of  descent  of,  810 

pia  mater  of,  807 

rete  of,  807 

size  and  weight  of,  806 

structure  of,  807 

tubuli  seminiferi  of,  807 

vas  deferens  of,  808 

vasa  elTerentia  of,  807 
recta,  807 

vasculum  aberrans  of,  808 
Thalami  optici,  590,  593,  596 
Theca  vertebralis,  573 
Thigh,  bone  of,  237 

fascia  of,  405 
lata  of,  405 

muscles  of,  405,  417 
Thorax,  190,  755 

base  of,  755 

bones  of,  190 

boundaries  of,  755 

cutaneous  nerves  of,  648 

fasciae  of,  372 

lymphatics  of,  570 

muscles  of,  366 

openings  of,  755 

parts  passing  through  upper 
openings  of,  755 

viscera  contained  in,  755 
Thumb,  muscles  of,  394 
Thymus  gland,  788 

chemical  composition  of,  789 

lobes  of,  788 
Thyro-hyoid  membrane,  771 
Thyroid  gland,  787 

chemical  composition,  788 
isthmus  of,  788 
lymphatics  of,  563 
vessels  and  nerves  of,  788 
Tibia,  243 

articulations  of,  247 

attachment  of   muscles   to, 
247 

development  of,  247 

structure  of,  247 
Tongue,  674 

arteries  of,  677 

development  of,  107 

epithelium  of,  676 

fibrous  septum  of,  676 

follicles  of,  676 

mucous  glands  of,  676 
membrane  of,  675 

muscular  fibres  of,  676 

muscles  of,  338 

nerves  of,  677 

papilliB  of.     See  Papillae. 
Tonsils,  718 

nerves    and    vessels    of, 
719 

of  cerebellum,  601 
'I'ooth.     See  Teeth. 
Torcular  Herophili,  136,  542 


8T4 


IXDEX. 


Trabeculre  of  corpus  caverno- 
sura,  803 
of  foetal  skull,  98 
of  spleen,  753 
of  testis,  807 
Trachea,  777 
cartilages  of,  778 
glands  of,  779 
relations  of,  778 
structure  of,  778 
surgical  anatomy  of,  779 
vessels  and  nerves  of,  779 
Tracheotomy,  780 
Tract,  optic,  606 
Tractus    intermedio    lateralis, 
576 
opticus,  606 
Tragus,  695 
Trapezium  bone,  221 
Trapezoid  bone,  223 
Triangle  of  Hesselbach,  829 
inferior  carotid,  459 
of  neck,  anterior,  459 
posterior,  461 
surgical  anatomy  of,  459 
occipital,  461 
Scarpa's,  518 
subclavian,  461 
submaxillary,  460 
superior  carotid,  462 
Trigone  of  bladder,  798 
Trigonum  vesica?,  798 
Trochanters,  greater  and  lesser, 

238 
Trochlea  of  humerus,  210 
Tube,  auditory,  697 
Eustachian,  700,  722 
Fallopian.      See    Fallopian 
tube. 
Tuber  cinereum,  589 

ischii,  231 
Tubercle,  conoid,  199 
deltoid,  199 
of  femur,  239 
genial,  171 
lachrymal,  162 
laminated,  of  cerebellum,  601 
of  Lower,  759 
for  odontoid  ligaments,  134 
of  scaphoid,  219 
of  tibia,  244 
of  ulna,  214 
of  zygoma.  144 
Tubcrcula  c|Uiidrigemina,  598 
Tuberculo  ciiierco,  583 
Tuberculum  Lowcri,  759 
Tuberosities  of  humerus,  great- 
er and  lesser,  207 
of  tibia,  244 
Tuberosity  of  ischium,  231 
ma.xillary,  160 
of  palate  bone,  167 
of  radius,  217 
Tubes,  bronchial,  778 

structure  of,  in  lung,  785 
Tuhuli.  dental,  713 
of  Ferrcin.  791 
galactophori,  821 
lactifori.  821 
recti.  H07 
scminiferi,  807 


Tubnli— 

uriniferi,  701 
Tubulus  centralis  modioli,  705 
Tuft,  vascular,  in  Malpighian 

bodies  of  kidney,  792 
Tunica  albuginea,  806 
of  ovary,  818 

Ruyschiana,  684    . 

vaginalis,  806,  810 
propria,  806 
reflexa,  806 

vasculosa  testis,  807 
Turbinated  bone,  inferior,  168 

middle,  156 

superior,  155 
Tutamina  oculi,  691 
Tympanic  bone,  697 
Tympanum,  698 

arteries  of,  702 

cavity  of,  698 

membrane  of,  700 

mucous  membrane  of,  702 

muscles  of,  702 

nerves  of,  703 

openings  of,  698 

ossicula  of,  700 

veins  of,  702 

Ulna,  212 

articulations  of,  216 
development  of,  216 
muscles  attached  to,  217 
Umbilicus,  96 
Unciform  bone,  224 
Upper  extremity,  arteries   of, 
468 
articulations  of,  284 
bones  of,  199 
fascia  of,  372 
ligaments  of,  284 
lymphatics  of,  564 
muscles  of,  371 
nerves  of,  637 
surgical  anatomy  of,  398 
veins  of,  544 
Urachus,  796 
Ureters,  793 
muscles  of,  793 
nerves  of,  793 
vessels  of,  793 
Urethra,  female,  813 
male,  798 

bulbous  portion  of,  799 
caput  gallinaginis  of,  798 
development  of,  108 
membranous    portion    of, 

799 
prostatic  portion  of,  798 

sinus  of,  798 
rupture  of,  course  taken  by 

urine  iu,  848 
sinus  pocularis  of,  798 
spongy  portion  of,  799 
structure  of,  799 
veru  montaiium  of,  708 
vesicula  prostatica  of,  798 
Urinary  organs,  791 
Uterus,  815 

appendages  of,  817 
arl)or  vitaj  of.  816 
cavity  of,  815 


Uterus —  ,  • 

cervix  of,  815 

development  of,  109 

in  foetus.  817 

fundus  of,  815 

ganglia  of,  GT2 

ligaments  of,  815.  820 

lymphatics  of,  .")(J0,  821 

nerves  of,  672,  816 

during  menstruation,  817 

in  old  age,  817 

after  parturition,  817 

during  pregnancy,  817 

at  puberty,  817 

shape,  position,  &c.,  of,  815 

structure  of,  816 

vessels  of,  816 
Uterus  masculinus,  799 
Utricle  of  vestibule,  706 
Uvea,  685 
Uvula,  718 

of  cerebellum,  601 

vesicae,  797 

Vagina,  814 
columns  of,  814 
lymphatics  of,  569 
orifice  of,  812 
Vagus.     See  Par  Vagum. 
Valley  of  cerebellum,  601 
Valsalva,  sinuses  of,  438,  761, 

763 
Valve  or' Valves — 
of  Bauhin,  737 
of  cystic  duct,  748 
of  gall-bladder.  748 
of  heart,  coronary,  759 
Eustachian,  759 
mitral,  763 
of  right  auricle,  759 
semilunar,  aortic,  763 

pulmonic,  763 
tricuspid,  760 
ileo-caical,  737 
of  lymphatics,  77 
of  Kerkring,  734 
of  veins,  76 
of  Vieussens,  599 
Valvula  Bauhini,  737 
Valvuloe  conniventes,  734 
Vas  aberrans,  807 

deferens.  808 
Vasa  aberrantia  of  brachial  ar- 
tery, 485 
afferentia  of  lymphatic  glands, 

560 
brevia  arteries,  501 

veins,  556 
efferentia  of  testis,  807 

of  lymphatic  glands,  560 
intestini  tenuis,  501 
recta,  807 

vasorum  of  arteries,  73 
of  veins,  76 
Vascular  system,  changes  in,  at 
birth,  7G8 
peculiarities  of.  in  foetus,  765 
Vasculum  aberrans,  808 
Vein  or  Veins — 

General  Anatomy  of,  75 
anastomoses  of,  535 


INDEX. 


875 


Vein  or  Veins — 
coats  of,  75 
development  of,  105 
muscular  tissue  of,  TG 
plexus  of,  335.   See  Plexus 

of  veins, 
sinuses  of.     See  Sinus, 
structure  of,  75 
valves  of,  7G 
vessels  and  nerves  of,  76 
Vein  or  Veins — 

Descriptive    Anatomy    of, 
535 
of  aliB  nasi,  536 
angular,  536 
articular,  of  knee,  553 

of  jaw,  537 
auricular,  anterior,  538 

posterior,  538 
axillary,  546 
azygos,  549 
basilic,  545 
basi- vertebral,  551 
of  bone,  46 
brachial,  546 
bracluo-cephalic,  545 
bronchial,  549,  787 
buccal,  536 
cardiac,  557 
anterior,  558 
great,  557 
posterior,  558 
cardinal,  106 
cava,  inferior,  554 

superior,  548 
cephalic,  545 
cerebellar,  541 
cerebral,  541 
cervical  ascending,  540 
deep,  540 
transverse,  539 
choroid  of  brain,  541 
circumflex  iliac,  552 

superficial,  552 
condyloid,  posterior,  540 
coronary,  558 
of  corpora  cavernosa,  803 
of  corpus  spongiosum,  803 

striatum,  541,  593 
cystic,  557 
deep,  535 

dental,  inferior,  538 
digital  of  hand,  546 
of  diploe,  540 
dorsal,  of  penis,  554 
dorsalis  nasi,  536 

pedis,  552 
dorsi-spinal,  550 
epigastric,  553 

superficial,  552 
of  eveball,  691 
facial,  536 
femoral,  553 
frontal,  536 
of  Galen,  541,  596 
gastric,  556 

gastro-epiploic,  left,  556 
gluteal,  553 
ha;morrhoidal,  553 
of  head,  536 
hepatic,  555,  744 


Vein  or  Veins — 
iliac,  common,  554 
external,  553 
internal,  553 
ilio-lumbar,  554 
innominate,  547 
intercostal,  superior,  548 
interlobular,  747 
interosseous,     of    forearm, 

546 
intralobular,  747 
jugular,  anterior,  539 
external,  538 

posterior,  539 
internal,  539 
of  kidney,  792 
labial,  inferior,  536 

superior,  536 
laryngeal,  539 
lateral  sacral,  554 
lingual,  539 
of  liver,  555,  744 
longitudinal,  inferior,  542 

superior,  542 
of  lower  extremity,  551 
lumbar,  555 
mammary,  internal,  547 
masseteric,  538 
mastoid,  538 
maxillary,  internal,  538 
median,  545 
basilic,  .545 
cephalic,  545 
cutaneous,  546 
medulli-spinal,  551 
meningeal,  538 
meningo-rachidian,  550 
mesenteric,  inferior,  556 

superior,  556 
nasal,  536 
of  neck,  538 
oblique,  558 
obturator,  553 
occipital,  538 
ossophageal,  549 
ophthalmic,  543 
ovarian,  555 
palatine,  inferior,  537 
palmar,  deep.  546 
palpebral,  inferior,  536 

superior,  536 
pancreatic,  556 
pancreatico-duodenal,  556 
parotid,  537 
peroneal,  552 
pharyngeal,  539 
phrenic,  555 
plantar,  external,  552 

internal,  552 
popliteal,  553 
portal,  535,  556,  744 
profunda  femoris,  552 
from  pterygoid  plexus,  538 
pudic,  external,  553 

internal,  553 
pulmonary,  553,  558,  787 
radial,  545 
ranine,  537 
renal,  555,  792 
sacral,  lateral,  554 
middle,  554 


Vein  or  Veins — 
saphenous,  external  or  short, 
552 
internal  or  long,  552,  830 
sciatic,  553 
spermatic,  555 
spheno-palatine,  539 
spinal,  549 

longitudinal,  550 
splenic,  556 
stylo-mastoid,  538 
subclavian,  547 
sublobular,  747 
submaxillary,  537 
submental,  536 
superficial,  535 
supra-orbital,  536 
supra-renal,  555 
supra-scapular,  539 
sural,  552 
systemic,  535 
temporal,  537 
middle,  537 
temporo-maxillary,  538 
thyroid,  inferior,  548 
middle,  539 
superior,  539 
tibial,  anterior.  552 

posterior,  552 
transverse  cervical,  537 

facial,  536 
ulnar,  anterior,  545 
deep,  545 
posterior,  545 
umbilical,  767 

of  upper  extremity  and  tho- 
rax, 544 
vaginal,  of  liver,  746 
vasa  brevia,  556 
ventricular,  541 
of  vertebra;,  540,  551 
Vidian,  539 

See  also  Vena  and  Venae. 
Velum  interpositum,  593,  596 
medullary,  601 
pendulum  palati,  718 
Vena  cava,  foetal,  105 
inferior,  554 
superior,  548 
corporis  striati,  541,  593 
innominata,  547 
porta;,  535,  556,  744 
salvatella,  545 
See  also  Vein. 
Venje  basis  vertebrarum,  551 
comites,  535 
corporis  striati.  593 
Galeni,  541,  596 
minimoe  cordis,  759 
Thebesii,  558,  765 
vorticosre.  684 
See  also  Vein. 
Venter  of  ilium,  229 

of  scapula,  202 
Ventricle  of  brain,  third,  597 
fourth,  603 
fifth,  595 
lateral,  592 
of  coi'pus  callosum,  590 
of  heart,  left,  762 
right,  760 


s:6 


INDEX. 


Ventricle — 

of  larynx,  773 
Vertebra  dentata,  119 

prorainens,  120 
Vertebrae,  116 

articulations  of,  265 

attachment  of  muscles  to,  126 

cervical,  117 

coccygeal,  127 

development  of,  97,  124 

dorsal,  121 

general  characters  of,  116 

ligaments  of,  265 

lumbar,  123 

ossification  of,  124 

sacral,  126 

structure  of,  124 
Vertebral  column.     See  Ver- 
tebrae. 
Vertex  of  skull,  176 
Veru  montanum,  798 
Vesicles,  auditory,  102 

cerebral,  99 

germinal,  89 

Graafian,  818 

ocular,  101 

umbilical,  93 


Vesicttla  prostatica,  800 
Vesiculfe  seminales,  form  and 

size  of,  809 
Vestibule  of  ear,  703 

aqueduct  of,  147,  703 
.  of  vulva,  812 
Vibrissse  of  nose,  677 
Vieussens,  valve  of,  599 
Villi,  735 
Vincula  accessoria   tendinum, 

386 
Vitelline  duct,  93 

membrane,  89 
Vitellus,  89 
Vitreous  body,  689 
humor  of  eye,  689 
table  of  skull,  115 
Vocal  cords,  false,  773 
inferior,  774 
superior,  773 
true,  774 
Voice,  organs  of,  769 
Vomer,  169 
aljB  of,  169 
articulations  of,  170 
development  of,  170 
Vortex  of  heart,  764 


Vulva,  811 
development  of.  111 

Waters,  on  the  lung,  786 
Wharton's  duct,  720 
White  substance  of  brain,  59 

of  Schwann,  59 
Willis,  circle  of,  475 
Winslow,  foramen  of,  727 
Wirsung,  canal  of,  750 
Wisdom  tooth,  712 
AVolffian  body,  108 
Womb.     See  Uterus. 
Wormian  bones,  157 
Wrisberg,  cartilages  of,  771 

ganglion  of,  6G8 

nerve  of,  641 
Wrist-joint,  294 

Y-SHAPED  centre   of  acetabu- 
lum, 232 
Yelk  of  ovum,  89 
Yellow  spot  of  retina,  686 

ZoxA  pcUucida,  89 
Zygoma,  165 


THE    END. 


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